WO2019157293A1

WO2019157293A1 - Apratoxin analogs

Info

Publication number: WO2019157293A1
Application number: PCT/US2019/017230
Authority: WO
Inventors: Craig Forsyth; Matthew JACKEL; Li Xiao
Original assignee: Ohio State Innovation Foundation
Priority date: 2018-02-08
Filing date: 2019-02-08
Publication date: 2019-08-15

Abstract

Disclosed herein are apratoxin analogs.

Description

APRATOXIN ANALOGS

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 62/627,984, filed February 8, 2018, the contents of which are hereby incorporated in its entirety.

FIELD OF THE INVENTION

The invention is directed to apratoxin analogs having improved biological properties.

BACKGROUND

Marine microorganisms, for instance algaes, phytoplanktons, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, and mangroves produce a wide variety of secondary metabolites that have long served as a source for compounds for biological exploration. Although many of these marine natural products are themselves unsuitable as pharmaceutical agents, due to the toxicity or unfavorable pharmacokinetic profiles, they have served as inspiration for several clinically relevant compounds. For instance, the anti-cancer agent eribulin mesylate was derived from the natural product halichondrin B.

Apratoxin F is a potent cytotoxic natural product that was isolated from the marine cyanobacterium Lyngbya bouillonii near Palmyra Atoll in the Central Pacific by Valeriote, Gerwick, and coworkers in 2010. It is a cyclodepsipeptide cytotoxin of the apratoxin family.

Structurally similar to apratoxin A~E, apratoxin F is composed of a polyketide and a polypeptide domain, apratoxin F features highly methylated amino acids (TV-methyl isoleucine, A-methyl alanine, and O-methyl tyrosine) and a dihydroxylated fatty acid moiety, 3,7-dihydroxy-2,5,8,8- tetramethylnonanoic acid. Additionally, apratoxin F contains an A - ethyl alanine ester and a cysteine-derived thiazoline moiety that link the polyketide and polypeptide domains:

Apratoxin F Apratoxin F illustrated high cytotoxicity to H-460 cancer cells with ICso values of 2 nM. Recently, other apratoxin congeners have been discovered to specifically target the pancreas; animals treated with apratoxin A exhibited severe pancreatic atrophy as a result of exposure. However, molecules in the apratoxin family have been demonstrated to have a narrow therapeutic window in vivo, and are poorly tolerated in mice. The complete mode of action of these natural products is currently under investigation, although mechanistic studies have suggested their participation in the secretory pathway along with the process of chaperone- mediated autophagy. It is also hypothesized that the biological activity of the apratoxins cannot be correlated with inhibition of microtubule polymerization/depolymerization, interactions with the microfilament network or interference with topoisomerase I, which are known to induce cy toxicity.

The apratoxins have also been implicated in the inhibition of STAT3 activity and T-cell activation, suggesting possible immunosuppressive activity. The isolation of apratoxin F and its bioactivity study demonstrated a new mechanism for developing a biosynthetic pathway to differentiate the suite of expressed secondary metabolites, including the adjustment of an NRPS adenylation domain specificity pocket. Molecules of the apratoxin family have a wide range in their cytotoxic profile, although the data is incomplete due to the limiting amounts of compounds. Biological activities are affected significantly by slight structural changes in the primary structure of the apratoxins, which can lead to large conformational alterations.

There remains a need for improved apratoxin analogs with improved physiological properties. For instance, there remains a need for apratoxin analogs with reduced toxicity, improved pharmacokinetic profiles, and enhanced activity against specified targets. The remains a need for apratoxin analogs to further elucidate the mechanisms by which this class of compounds exert their physiological effect.

SUMMARY

Disclosed herein are novel apratoxin analogs. The details of one or more embodiments are set forth in the descriptions below. Other features, objects, and advantages will be apparent from the description and from the claims.

DETAILED DESCRIPTION

Before the present methods and systems are disclosed and described, it is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

As used in the specification and the appended claims, the singular forms“a,”“an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from“about” one particular value, and/or to“about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

“Optional” or“optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as“comprising” and“comprises,” means“including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means“an example of’ and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes.

Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods.

Unless stated to the contrary, a formula with chemical bonds shown only as solid lines and not as wedges or dashed lines contemplates each possible isomer, e.g ., each enantiomer,

diastereomer, and meso compound, and a mixture of isomers, such as a racemic or scalemic mixture.

The term“alkyl” as used herein is a branched or unbranched hydrocarbon group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and the like. The alkyl group can also be substituted or unsubstituted. Unless stated otherwise, the term“alkyl” contemplates both substituted and unsubstituted alkyl groups. The alkyl group can be substituted with one or more groups including, but not limited to, alkoxy, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, or thiol. An alkyl group which contains no double or triple carbon-carbon bonds is designated a saturated alkyl group, whereas an alkyl group having one or more such bonds is designated an unsaturated alkyl group.

Unsaturated alkyl groups having a double bond can be designated alkenyl groups, and unsaturated alkyl groups having a triple bond can be designated alkynyl groups. Unless specified to the contrary, the term alkyl embraces both saturated and unsaturated groups.

The term“cycloalkyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. The term“heterocycloalkyl” is a cycloalkyl group as defined above where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, selenium or phosphorus. The cycloalkyl group and heterocycloalkyl group can be substituted or unsubstituted. Unless stated otherwise, the terms“cycloalkyl” and“heterocycloalkyl” contemplate both substituted and unsubstituted cyloalkyl and heterocycloalkyl groups. The cycloalkyl group and heterocycloalkyl group can be substituted with one or more groups including, but not limited to, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, or thiol. A cycloalkyl group which contains no double or triple carbon-carbon bonds is designated a saturated cycloalkyl group, whereas an cycloalkyl group having one or more such bonds (yet is still not aromatic) is designated an unsaturated cycloalkyl group. Unless specified to the contrary, the term cycloalkyl embraces both saturated and unsaturated, non-aromatic, ring systems.

The term“aryl” as used herein is an aromatic ring composed of carbon atoms. Examples of aryl groups include, but are not limited to, phenyl and naphthyl, etc. The term“heteroaryl” is an aryl group as defined above where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, selenium or phosphorus. The aryl group and heteroaryl group can be substituted or unsubstituted. Unless stated otherwise, the terms“aryl” and“heteroaryl” contemplate both substituted and unsubstituted aryl and heteroaryl groups. The aryl group and heteroaryl group can be substituted with one or more groups including, but not limited to, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, or thiol. Exemplary heteroaryl and heterocyclyl rings include: benzimidazolyl, benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl, benzoxazolinyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazolinyl, carbazolyl, 4aH carbazolyl, carbolinyl, chromanyl, chromenyL cirmolinyl, decahydroquinolinyl, 2H,6H~ l,5,2-dithiazinyl, dihydrofuro[2,3 bjtetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, lH-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, 3H-indolyl, isatinoyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl, methylenedioxyphenyl, morpholinyl, naphthyridinyl, octahydroisoquinolinyl, oxadiazolyl, 1,2,3- oxadiazolyl, l,2,4-oxadiazolyl, l,2,5-oxadiazolyl, l,3,4-oxadiazolyl, oxazolidinyl, oxazolyl, oxindolyl, pyrimidinyl, phenanthridinyl, phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxathinyl, phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, piperonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothi azole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, 2H-pyrrolyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl, quinuclidinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, tetrazolyl, 6H-l,2,5-thiadiazinyl, l,2,3-thiadiazolyl, l,2,4-thiadiazolyl, l,2,5-thiadiazolyl, 1,3,4- thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, and xanthenyl.

The terms“alkoxy,”“cycloalkoxy,”“heterocycloalkoxy,”“cycloalkoxy,”“aryloxy,” and “heteroaryloxy” have the aforementioned meanings for alkyl, cycloalkyl, heterocycloalkyl, aryl and heteroaryl, further providing said group is connected via an oxygen atom.

As used herein, the term“substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described below. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, the heteroatoms, such as nitrogen, can have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valencies of the heteroatoms. This disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Also, the terms“substitution” or“substituted with” include the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g ., a compound that does not

spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. Unless specifically stated, a substituent that is said to be“substituted” is meant that the substituent can be substituted with one or more of the following: alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, or thiol. In a specific example, groups that are said to be substituted are substituted with a protic group, which is a group that can be protonated or deprotonated, depending on the pH.

Unless specified otherwise, the term“patient” refers to any mammalian animal, including but not limited to, humans.

Pharmaceutically acceptable salts are salts that retain the desired biological activity of the parent compound and do not impart undesirable toxicological effects. Examples of such salts are acid addition salts formed with inorganic acids, for example, hydrochloric, hydrobromic, sulfuric, phosphoric, and nitric acids and the like; salts formed with organic acids such as acetic, oxalic, tartaric, succinic, maleic, fumaric, gluconic, citric, malic, methanesulfonic, p- toluenesulfonic, napthalenesulfonic, and polygalacturonic acids, and the like; salts formed from elemental anions such as chloride, bromide, and iodide; salts formed from metal hydroxides, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, and magnesium hydroxide; salts formed from metal carbonates, for example, sodium carbonate, potassium carbonate, calcium carbonate, and magnesium carbonate; salts formed from metal bicarbonates, for example, sodium bicarbonate and potassium bicarbonate; salts formed from metal sulfates, for example, sodium sulfate and potassium sulfate; and salts formed from metal nitrates, for example, sodium nitrate and potassium nitrate. Pharmaceutically acceptable and non- pharmaceutically acceptable salts may be prepared using procedures well known in the art, for example, by reacting a sufficiently basic compound such as an amine with a suitable acid comprising a physiologically acceptable anion. Alkali metal (for example, sodium, potassium, or lithium) or alkaline earth metal (for example, calcium) salts of carboxylic acids can also be made.

In some embodiments the apratoxin analog can be a compound of Formula (1):

Formula (1),

or a pharmaceutically acceptable salt thereof, wherein

R^m is selected from hydrogen, Ci-salkyl, C₂-xalkenyl, C₂-xalkynyl, aryl, heteroaryl, C3-8cycloalkyl, Ci-8heteroaryl; -(CH2CH₂0)n-Q, wherein n is an integer selected from 0-300, and Q is a protein conjugating moiety;

X¹ is selected from O, S, and N-R^x, wherein R^x is selected from hydrogen, Ci-salkyl, C₂-xalkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

X² is selected from O and S;

X³ is a group of the formula -(CR^10aR^10b)m-, wherein m is selected from 0-6;

R¹ is selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, heteroaryl, C3-8cycloalkyl, and Ci-sheteroaryl;

R^2a is selected from R^2ar, OR^2ar, N(R^2ar)2, SiR^2ar ₃, SR^2ar, S0₂R^2ar, S0₂N(R^2ar)2, C(0)R^2ar;

C(0)OR^2ar, OCOR^2ar; C(0)N(R^2ar)2, 0C(0)N(R^2ar)2, N(R^2ar)C(0)N(R^2ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^2ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^2b is selected from R^2br, OR^2br, N(R^2br)2, SiR^2br3, SR^2br, S0₂R^2br, S0₂N(R^2br)2, C(0)R^2br;

C(0)OR^2br, OC(0)R^2br; C(0)N(R^2bt)2, 0C(0)N(R^2br)2, N(R^2br)C(0)N(R^2br)2, F, Cl, Br, I, cyano, and nitro, wherein R^2br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^2a and R^2b together form a carbonyl, an imine of formula (=NR^abr), or olefin of formula

(=CR^2arR^2br);

R³ is selected from hydrogen, Ci-salkyl, C2-salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3- 8cycloalkyl, or Ci-sheterocyclyl; R^4a is selected from R^4ar, OR^4ar, N(R^4ar)2, SiR^4ar ₃, SR^4ar, S0₂R^4ar, S0₂N(R^4ar)2, C(0)R^4ar;

C(0)0R^4ar, OCOR^4ar; C(0)N(R^4ar)₂, 0C(0)N(R^4ar)₂, N(R^4ar)C(0)N(R^4ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^4ar is in each case independently selected from hydrogen, C i-xalkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^4b is selected from R^4br, OR^4br, N(R^4br)₂, SiR₃, SR^4br, S0₂R^4br, S0₂N(R^4br)₂, C(0)R^4br;

C(0)0R^4br, OCOR^4br, C(0)N(R^4br)₂, 0C(0)N(R^4br)₂, N(R^4br)C(0)N(R^4br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^4br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl; or

R^4a and R^4b together form a carbonyl, an imine of formula (=NR^4ba), or olefin of formula (=CR^4arR^4br);

R^5ais selected from R^5ar, OR^5ar, N(R^5ar)₂, SiR^5ar ₃, SR^5ar, S0₂R^5ar, S0₂N(R^5ar)₂, C(0)R^5ar;

C(0)0R^5ar, OCOR^5ar; C(0)N(R^5ar)₂, 0C(0)N(R^5ar)₂, N(R^5ar)C(0)N(R^5ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^5ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl;

R^5b is selected from R^5br, OR^5br, N(R^5br)₂, SiR^5br ₃, SR^5br, S0₂R^5br, S0₂N(R^5br)₂, C(0)R^5br;

C(0)0R^5br, OCOR^5br; C(0)N(R^5br)₂, 0C(0)N(R^5br)₂, N(R^5br)C(0)N(R^5br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^5br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl; or

R^5a and R^5b together form a carbonyl, an imine of formula (=NR^br), or olefin of formula (=C R^5ar

R^5br);

R^6a is selected from R^6ar, OR^6ar, N(R^6ar)₂, SiR^6ar ₃, SR^6ar, S0₂R^6ar, S0₂N(R^6ar)₂, C(0)R^6ar;

C(0)0R^6ar, OCOR^6ar; C(0)N(R^6ar)₂, 0C(0)N(R^6ar)₂, N(R^6ar)C(0)N(R^6ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^6ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl;

R^6b is selected from R^6br, OR^6br, N(R^6br)₂, SiR^6br ₃, SR^6br, S0₂R^6br, S0₂N(R^6br)₂, C(0)R^6br;

C(0)0R^6br, OCOR^6br; C(0)N(R^6br)₂, 0C(0)N(R^6br)₂, N(R^6br)C(0)N(R^6br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^6br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl; or

R^6a and R^6b together form a carbonyl, an imine of formula (=NR^6ar), or olefin of formula (=CR^6arR^6br);

R^7a is selected from R^7ar, OR^7ar, N(R^7ar)₂, SiR^7ar ₃, SR^7ar, S0₂R^7ar, S0₂N(R^7ar)₂, C(0)R^7ar;

C(0)0R^7ar, OCOR^7ar; C(0)N(R^7ar)₂, 0C(0)N(R^7ar)₂, N(R^7ar)C(0)N(R^7ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^7ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- 8alkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C₃-8cycloalkyl, or Ci-sheterocyclyl; R^7b is selected from R^7br, OR^7br, N(R^7br)2, SiR^7br ₃, SR^7br, S0₂ R^7br, S0₂N(R^7br)2, C(O) R^7br;

C(0)0 R^7br, OCO R^7br, C(0)N(R^7br)2, 0C(0)N(R^7br)2, N(R^7br)C(0)N(R^7br)2, F, Cl, Br, I, cyano, and nitro, wherein R^7br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^7a and R^7b together form a carbonyl, an imine of formula (=NR^7ar), or olefin of formula (=CR^7arR^7br);

R^8a is selected from R^8ar, OR^8ar, N(R^8ar)2, SiR^8ar3, SR^8ar, S0₂R^8ar, S0₂N(R^8ar)2, C(0)R^8ar;

C(0)0R^8ar, OCOR^8ar, C(0)N(R^8ar)2, 0C(0)N(R^8ar)2, N(R^8ar)C(0)N(R^8ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^8ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^8b is selected from R^8br, OR^8br, N(R^8br)2, SiR^8br ₃, SR^8br, S0₂R^8br, S0₂N(R^8br)2, C(0)R^8br;

C(0)0R^8br, OCOR^8br, C(0)N(R^8br)2, 0C(0)N(R^8br)2, N(R^8br)C(0)N(R^8br)2, F, Cl, Br, I, cyano, and nitro, wherein R^8br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^8a and R^8b together form a carbonyl, an imine of formula (=NR^8ar), or olefin of formula (=CR^8arR^8br);

R^9a is selected from R^9ar, OR^9ar, N(R^9ar)2, SiR^9ar ₃, SR^9ar, S0₂R^9ar, S0₂N(R^9ar)2, C(0)R^9ar;

C(0)0R^9ar, OCOR^9ar, C(0)N(R^9ar>2, 0C(0)N(R^9ar)2, N(R^9ar)C(0)N(R^9ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^9ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^9b is selected from R^9br, OR^9br, N(R^9br)2, SiR^9br ₃, SR^9br, S0₂R^9br, S0₂N(R^9br)2, C(0)R^9br;

C(0)0R^9br, OCOR^9br, C(0)N(R^9br)2, 0C(0)N(R^9br)2, N(R^9br)C(0)N(R^9br)2, F, Cl, Br, I, cyano, and nitro, wherein R^9br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^9a and R^9b together form a carbonyl, an imine of formula (=NR^9ar), or olefin of formula (=CR^9arR^9br);

R^10a, when present, is in each case independently selected from R^10a, OR^10a, N(R^10a)2, SiR^10a3, SR^10a, SO₂R^10a, SO₂N(R^10a)₂, C(O)R^10a; C(O)OR^10a, OCOR^10a, C(O)N(R^10a)₂, OC(O)N(R^10a)₂, N(R^10a)C(O)N(R^10a)2, F, Cl, Br, I, cyano, and nitro, wherein R^10a is in each case independently selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^10b, when present, is in each case independently selected from R^10br, OR^10br, N(R^10br)2, SiR^10br3, SR^10br, SO₂R^10br, SO₂N(R^10br)2, C(O)R^10br; C(O)OR^10br, OCOR^10br, C(O)N(R^10b

OC(O)N(R^10br)2, N(R^10br)C(O)N(R^10br)2, F, Cl, Br, I, cyano, and nitro, wherein

case independently selected from hydrogen, Ci-salkyl, C2-salkenyl, C2-salkynyl, aryl, Ci- sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^10a and R^10b together form a carbonyl, an imine of formula (=NR^10ar), or olefin of formula (=CR^10arR^10br);

R^lla is selected from R^llar, OR^llar, N(R^llar)2, SiR^llar3, SR^llar, S0₂R^llar, S0₂N(R^llar)2, C(0)R^llar; C(0)0R^llar, OCOR^llar, C(0)N(R^llar)2, 0C(0)N(R^llar)2, N(R^llar)C(0)N(R^llar)2, F, Cl, Br, I, cyano, and nitro, wherein R^llar is in each case independently selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^llb is selected from

C(0)0R^llbr, OCOR^l

cyano, and nitro, wherein R^llbr is in each case independently selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^lla and R^llb together form a carbonyl, an imine of formula (=NR^llar), or olefin of formula (=CR^llarR^llbr);

wherein any two or more of R¹, R^2a, R^2b, R³, R^4a, R^4b, R^x, R^5a, R^5b, R^6a, R^6b, R^7a, R^7b, R^8a, R^8b, R^9a, R^9b, R^10a, R^10b, R^lla and R^llb may together form a ring; or

wherein one of R^6a and R^6b, along with one of R^7a and R⁷¹¹, together form an (E) or ( Z) olefin, wherein one of R^8a and R^8b, along with one of R^9a and R^9b, together form an (E) or (Z) olefin, wherein one of R^9a and R^9b, along with one of R^10a and R^10b, together form an (E) or (Z) olefin.

In certain embodiments, when R^m is either hydrogen or Ci-salkyl, it is preferred that either R^7a is not methyl, R^6a is not hydroxyl, or R^5b is not methyl.

In some embodiments, Q can be a protein conjugating moiety such as biotin. Such groups can be installed using conventional bioconjugation techniques, including azide/alkyne coupling (“Click” chemistry).

In certain cases, m can preferably be 0, 1, or 2. When m is a non-zero number, R^10a and R^10b can in each case be hydrogen. In certain embodiments, reduced apratoxin analogs are provided, for instance when R^8a, R^8b, R^9a, and R^9b are each hydrogen. However, in other cases, R^8a and R^9b can together form an olefin, for instance, an (E) olefin. When R^9a is not hydrogen, it can be preferred that R^9a is Ci-salkyl, for instance methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2- butyl, isobutyl, or tert-butyl. In certain embodiments, R^9a can be C i-xalkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy.

In some embodiments, des-alkyl and des-hydroxyl apratoxin analogs may be provided, for instance when R^6a, R^6b, R^7a, and R^8b are each hydrogen. However, unsaturated analogs may also be provided, for instance, when R^6b and R^7a together form an olefin, for instance (E) olefin. When R^7b is not hydrogen, is can be preferred that R ^b is Ci-salkyl, for instance, methyl, ethyl, 1- propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^7b can be Ci- salkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. Likewise, when R^7a is not hydrogen, is can be preferred that R^7a is Ci-salkyl, for instance, methyl, ethyl, 1 -propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^7a can be C i-xalkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In other embodiments, R^7a and R ^b can together form a ring, for instance a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. The ring systems can be heterocyclyl, for instance when one or more of the carbon atoms is replaced with an oxygen, sulfur, or nitrogen ring, e.g., an oxirane, thiirane, aziridine, oxetane, azetidine, thietane, furan, thiofuran, pyrrolidine, pyran, thiopyran, or piperidine. All of these ring systems can be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In yet further embodiments, R^7a and R^7b can each be C i-xalkyl, for instance, methyl, ethyl, 1 -propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl, either or both of which may be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In certain preferred embodiments, R^7a and R^7b can each be methyl.

In certain cases, R^6b is OH or O-Ci-salkyl, for instance O-methyl, O-ethyl, O-n-propyl, O- i-propyl, butoxy, e.g., n-butoxy, isobutoxyl, tert-butoxy. Such O-Ci-xalkyl can be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. For such cases when R^6b is OH or O-Ci-xalkyl, R^6a can be hydrogen or Ci-salkyl, such as defined above.

In certain cases, R^6a is OH or O-Ci-salkyl, for instance O-methyl, O-ethyl, O-n-propyl, O- i-propyl, butoxy, e.g., n-butoxy, isobutoxyl, tert-butoxy. Such O-Ci-salkyl can be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. For such cases when R^6a is OH or O-Ci-salkyl, R^6b can be hydrogen or Ci-salkyl, such as defined above.

In some embodiments, one or both of R^7a and R ^b may form a ring with one or both of R^6a and R^6b. In some instances, the ring may be a cycloalkyl or heterocyclyl having the formula:

wherein R^6a, R^6b, R^7a, and R^7b are as defined above, and Z^7a, Z^7b, Z⁷, Z^6a, and Z^6b are each independently selected from null (provided that at least one Z^7a, Z^7b, Z⁷, Z^6a, and Z^6b is present,

O, S, NR^z7 , or Ci-salkylene, which may contain elements of unsaturation, or be optionally substituted as one or more times with any of R^z7, OR^z7, N(R^z7)2, SiR^z73, SR^z7, S0₂R^z7,

S0₂N(R^Z7)2, C(0)R^z7; C(0)0R^z7, OCOR^z7, C(0)N(R^z7)₂, 0C(0)N(R^z7)₂, N(R^Z7)C(0)N(R^z7)₂, F, Cl, Br, I, cyano, and nitro, wherein R^z7 is in each case independently selected from hydrogen, Ci- salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

wherein R^z7 is selected from C(0)R^7c; C(0)0R^7c, OCOR^7c, C(0)N(R^7c)₂, wherein R^7c is in each case independently selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci- 8heteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl.

In certain preferred embodiments, Z^6a or Z^6b can be oxygen, Z⁷ can be null, and Z^7a or Z^7b can be Ci-salkylene. In other preferred embodiments, Z^7a or Z^7b can be oxygen, Z⁷ can be null, and Z^6a or Z^6b can be Ci-salkylene.

In other embodiments, the ring can be aromatic. Exemplary aromatic systems include:

wherein R^7z and R^7z are as defined above.

In some embodiments, R^5b can be hydrogen and R^5a is C i-salkyl, for instance, methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^5a can be C i-salkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy.

In other embodiments, R^5a can be hydrogen and R^5b is C i-salkyl, for instance, methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^5b can be Ci-salkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In other embodiments, R^5a and R^5b can together form a ring, for instance a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. The ring systems can be heterocyclyl, for instance when one or more of the carbon atoms is replaced with an oxygen, sulfur, or nitrogen ring, for instance an oxirane, thiirane, aziridine, oxetane, azetidine, thietane, furan, thiofuran, pyrrolidine, pyran, thiopyran, or piperidine. All of these ring systems can be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci- 3haloalkoxy. In yet further embodiments, R^5a and R^5b can each be Ci-salkyl, for instance, methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, isobutyl, or tert-butyl, either or both of which may be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy.

In some embodiments, one or both of R^6a and R^6b may form a ring with one or both of R^5a and R^5b. In some instances, the ring may be a cycloalkyl or heterocyclyl having the formula:

wherein R^5a, R^5b, R^6a, and R^6b are as defined above, and Z^5a, Z^5b, Z⁷, Z^6a, and Z^6b are each independently selected from null (provided that at least one Z^6a, Z^6b, Z⁷, Z^5a, and Z^5b is present,

wherein R^z7 is selected from C(0)R^7c; C(0)0R^7c, OCOR^7c, C(0)N(R^7c)₂, wherein R^7c is in each case independently selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci- sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl.

In certain preferred embodiments, Z^5a or Z^5b can be oxygen, Z⁷ can be null, and Z^6a or Z^6b can be Ci-salkylene. In other preferred embodiments, Z^6a or Z^6b can be oxygen, Z⁷ can be null, and Z^7a or 77 can be Ci-salkylene.

wherein R^7z is as defined above. In some embodiments, R^llb can be hydrogen and R^lla is Ci-salkyl, for instance, methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^lla can be C i-xalkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy.

In other embodiments, R^lla can be hydrogen and R^llb is C i-xalkyl, for instance, methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R^llb can be Ci-xalkyl substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy.

In other embodiments, R^lla and R^llb can together form a ring, for instance a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. The ring systems can be heterocyclyl, for instance when one or more of the carbon atoms is replaced with an oxygen, sulfur, or nitrogen ring. The ring systems can be heterocyclyl, for instance when one or more of the carbon atoms is replaced with an oxygen, sulfur, or nitrogen ring, e.g., an oxirane, thiirane, aziridine, oxetane, azetidine, thietane, furan, thiofuran, pyrrolidine, pyran, thiopyran, or piperidine. All of these ring systems can be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In yet further embodiments, R^lla and R^llb can each be C i-xalkyl, for instance, methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl, either or both of which may be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In certain cases, R^lla can be C1-5 alkyl, substituted one or more times with a leaving group, for instance with OR^z, -0S0₂R^z, COOR^z, N3, an alkynyl; COR^zl; F, Cl, Br, I, or cyano, wherein R^z is Ci- 8alkyl or aryl, substituted with one or more electron withdrawing groups, and R^zl is selected from

F, Cl, Br, H, Ci-salkyl, and aryl.

In some embodiments, one or both of R^lla and R^llb may form a ring with one or both of R^5a and R^5b. In some instances, the ring may be a cycloalkyl or heterocyclyl having the formula:

wherein R^5a, R^5b, R^lla, and R^llb are as defined above, and Z^lla, Z^llb, Z⁷, Z^5a, and Z^5b are each independently selected from null (provided that at least one Z^lla, Z^llb, Z⁷, Z^5a, and Z^5b is present, O, S, NR^z7 , or Ci-salkylene, which may contain elements of unsaturation, or be optionally substituted as one or more times with any of R^z7, OR^z7, N(R^z7)2, SiR^z73, SR^z7, S0₂R^z7,

S0₂N(R^Z7)2, C(0)R^z7; C(0)0R^z7, OCOR^z7, C(0)N(R^z7)₂, 0C(0)N(R^z7)₂, N(R^Z7)C(0)N(R^z7)₂, F, Cl, Br, I, cyano, and nitro, wherein R^z7 is in each case independently selected from hydrogen, Ci- salkyl, C2-salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

wherein R^z7 is selected from C(0)R^7c; C(0)0R^7c, OCOR^7c, C(0)N(R^7c)2, wherein R^7c is in each case independently selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci- sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl.

In certain preferred embodiments, Z^5a or Z^5b can be oxygen, Z⁷ can be null, and Z^lla or Z^llb can be Ci-salkylene. In other preferred embodiments, Z^lla or Z^llb can be oxygen, Z⁷ can be null, and Z^5a or Z^5b can be Ci-salkylene.

wherein R^7z is as defined above.

In certain cases, R^4a and R^4b can each be hydrogen, or either of R^4a or R^4b can form a ring with R³. For instance, R³ and R^4b can together form a ring, and R^4a can be hydrogen or Ci-salkyl, for instance, methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, isobutyl, or tert-butyl, either or both of which may be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In such embodiments R³ and R^4b can together form a four-membered ring, a five-membered ring, a six-membered ring, a seven-membered ring, or a higher order ring system. Generally in such cases, R^4a will be hydrogen. In other cases, R³ and R^4a can together form a ring, and R^4b can be hydrogen or Ci- salkyl, for instance, methyl, ethyl, 1 -propyl, 2-propyl, 1 -butyl, 2-butyl, isobutyl, or tert-butyl, either or both of which may be substituted one or more times with various groups, for instance with hydroxyl, Ci-3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In such embodiments R³ and R^4a can together form a four-membered ring, a five-membered ring, a six-membered ring, a seven-membered ring, or a higher order ring system. Generally, in such cases, R^4b will be hydrogen.

When R³ does not form a ring, it can be hydrogen or Ci-salkyl, for instance methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl. In certain embodiments, R³ can be Ci-salkyl substituted one or more times with various groups, for instance with hydroxyl, Ci- 3alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In some embodiments, it is preferred that R³ is methyl.

The apratoxin analog may be in the macrolactone form, e.g., when X¹ is O, or it may be the macrolactam analog, e.g., when X¹ is NR^X. In such cases, it is preferred that X¹ is NH or

NCi-salkyl, for instance methyl, ethyl, l-propyl, 2-propyl, l-butyl, 2-butyl, isobutyl, or tert-butyl, optionally substituted one or more times with various groups, for instance with hydroxyl, Ci- ₃alkoxy, aryl, heterocyclyl, halogen, or Ci-3haloalkoxy. In other cases, however, NR^X. can form a ring with any one or more of R^4a, R^4b, R^lla, or R^llb, for instance, a five membered ring or a six membered ring.

In some embodiments, R^2a can be C i-xalkyl and R^2b is hydrogen. In preferred embodiments, R^2a can be C2-4 alkyl, e.g., n-propyl, i-propyl, n-but-2-yl, for instance in the (S) configuration.

In certain embodiments, the apratoxin analog can be a bridged ring analog, for instance having the formula:

wherein R^2a, R^2b, R³, R^4a, R^4b, X¹, R^lla, R^llb, R^5a, R^5b, R^7a, R^7b, X², R^8a, R^8b, R^9a, R^9b and X³ are as defined above,

p is an integer from 0-10; X^4a is selected from chemical bond, -C(=0)0-, -C(=0)NH-, and - C(=0)-; and X^4b is selected from chemical bond, -0C(=0)-, -NC(=0)-, and -C(=0)-.

In certain cases, the apratoxin analog can be a compound of Formula (2):

[Formula (2)],

or a pharmaceutically acceptable salt thereof, wherein

A is selected from Ci-salkyl or aryl;

X¹ is selected from O, S, and N-R^x, wherein R^x is selected from hydrogen, Ci-salkyl, C₂-xalkenyl, C₂-xalkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

X² is selected from O and S;

R^2b is selected from R^2br

C(0)OR^2br, OC(0)R^2br;

cyano, and nitro, wherein R^2br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R³ is selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3- 8cycloalkyl, or Ci-sheterocyclyl;

R^4b is selected from R^4br, OR^4br, N(R^4br)2, S1R3, SR^4br, S0₂R^4br, S0₂N(R^4br)2, C(0)R^4br;

C(0)0R^4br, OCOR^4br, C(0)N(R^4br>2, 0C(0)N(R^4br)2, N(R^4br)C(0)N(R^4br)2, F, Cl, Br, I, cyano, and nitro, wherein R^4br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^7a is selected from ^r;

C(0)0R^7ar, OCOR⁷

cyano, and nitro, wherein R^7ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^7b is selected from R^7br, OR^7br, N(R^7br)2, SiR^7br ₃, SR^7br, SO2 R^7br, S0₂N(R^7br)2, C(O) R^7br;

C(0)0 R^7br, OCO R^7br, C(0)N(R^7br>2, 0C(0)N(R^7br)2, N(R^7bt)C(0)N(R^7br)2, F, Cl, Br, I, cyano, and nitro, wherein R^Tbl is in each case independently selected from hydrogen, C i-xalkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^7a and R^7b together form a carbonyl, an imine of formula (=NR^7ar), or olefin of formula

(=CR^7arR^7br);

R^8a is selected from R^8ar, OR^8ar, N(R^8ar)2, SiR^8ar ₃, SR^8ar, S0₂R^8ar, S0₂N(R^8ar)2, C(0)R^8ar;

C(0)0R^8ar, OCOR^8ar, C(0)N(R^8ar>2, 0C(0)N(R^8ar)2, N(R^8ar)C(0)N(R^8ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^8ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

C(0)0R^8br, OCOR^8br, C(0)N(R^8br>2, 0C(0)N(R^8br)2, N(R^8br)C(0)N(R^8br)2, F, Cl, Br, I, cyano, and nitro, wherein R^8br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^lla is selected from R^llar, OR^llar, N(R^llar)2, SiR^llar ₃, SR^llar, S0₂R^llar, S0₂N(R^llar)2, C(0)R^llar; C(0)0R^llar, OCOR^llar, C(0)N(R^llar)2, 0C(0)N(R^llar)2, N(R^llar)C(0)N(R^llar)2, F, Cl, Br, I, cyano, and nitro, wherein R^llar is in each case independently selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

wherein any two or more of R^2b, R³, R^4b, R^x, R^7a, R^7b, and R^lla may together form a ring.

In certain embodiments, the analog may have the formula:

wherein X⁵ is -(CFh)p-, wherein p is selected from 0-10, and other variable groups are as defined above. In some cases, R^7a and R⁷¹⁵ together form a ring, e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl ring, while in other cases R^7a and R^7b are independently selected from hydrogen, S1R3 (e.g., Si(CH3)3>, or Ci-6alkyl, wherein said Ci-6alkyl group may be substituted one or more times with groups independently selected from aryl, heteroaryl, heterocycle, cycloalkyl, or halogen. In some cases R^7b is Si(CH₃)3. In certain embodiments, it is preferred that R^7a is not methyl.

The apratoxin analogs can include additional rings, for instance R³ and R^4b together form a five-membered or six-membered ring, while in other instances, R³ and R^4b are independently selected from hydrogen or Ci-6alkyl such as R³ and R^4b are each methyl.

Other suitable rings include when R^2b and R³ together form a five-membered or six- membered ring. In other cases, R^2b is a Ci-6alkyl group such as methyl, ethyl, prop-2-yl, prop-l- yl, n-but-l-yl, (S)-but-2-yl, and tert-butyl. Apratoxin analogs include those wherein R^lla is selected from Ci-6alkyl, halogen, OR, SO2R, C(0)R; C(0)0R, F, Cl, Br, I, and cyano. When R^lla is a Ci-6alkyl group, it may be substituted one or more times with a group independently selected from halogen, OR, SO2R, C(0)R; C(0)0R, F, Cl, Br, I, and cyano.

EXAMPLES

The following examples are for the purpose of illustration of the invention only and are not intended to limit the scope of the present invention in any manner whatsoever. The skilled person will be able to prepare other analogs as described herein by modification of the processes discloses below.

General Methods: Unless specially stated, all moisture and oxygen-sensitive reactions were performed under an argon atmosphere using oven-dried glassware and anhydrous solvents. Solvents and solutions sensitive to oxygen and/or moisture were transferred using standard cannula and syringe techniques. All commercial available reagents were purchased as reagent grade without further purification, unless otherwise noted. All organic solvents were used dry: diethyl ether (Et20), tetrahydrofuran (THF), dimethylformamide (DMF), dichloromethane (CH2CI2), and toluene were purified by a Pure Solv MD-6 Solvent Purification System; dimethyl sulfoxide (DMSO) was stored over activated 4Ά molecular sieves; diisopropylethylamine (DIPEA), triethylamine (EtfN), diisopropylamine, acetonitrile and methanol were distilled from CaFb. Thin-layer chromatography was performed on Silicycle Glass Backed TLC Plates TLG- R10014BK-323 Silia Plate™ 250 pm, with F254 indicator, Optimized for KMn0₄, Vanillin and Anisaldehyde revelation. The column chromatography purifications were performed using Silicycle SiliaF/as i® P60 silica gel (40-63 pm). The Prep-TLC separations were performed using TLG-R10011B-341 Silia Plate™ 1000 pm, with F254 indicator. Nuclear Magnetic

Resonance (NMR) spectra were obtained for proton ('H) and carbon (¹³C) nuclei using Bruker DPX-400, DPX-600 and DRX-700 NMR spectrometers; residual solvent peak signals for CDCb were set at 7.26 and 77.16 ppm in the ¾ and ¹³C spectra, and residual solvent peak signals for is-DMSO were set at 2.50 and 39.52 ppm in the ¾ and ¹³C spectra, respectively. Optical rotations were measured by a Perkin-Elmer Model 241 Polarimeter at 589 nm with a sodium lamp and concentraions are reported in g/lOO mL. High-resolutions mass spectrometric data were obtained using a Bruker MicroTOF (ESI) Mass Spectrometer.

(S)-4-hydroxy-5,5-dimethylhexan-2-one (2.9)

OH O D-proline (172.7 mg, 1.5 mmol) was stirred in the mixture of DMSO (400 mL) and acetone (100 mL) for 15 min. Pivaldyhyde 2.6 (430.6 mg, 5 mmol) was

added in the solution and the mixture was stirred at 23 °C for 3 days. The

2.9

mixture was quenched with saturated aqueous NLLCl, and extracted with EtOAc. The organic layer was combine and dried over MgS0₄, filtered and concentrated. Flash column chromatography (5: 1 hexanes/EtOAc, v/v) was performed on silica gel and provided alcohol 2.9 (490.1 mg, 68%) as a white solid.

R/0.57 (3: 1 hexanes/EtOAc, v/v);

¾ NMR (400 MHz, CDCb) 5 3.72 (dd, J= 10.2, 2.0 Hz, 1H), 2.63 (dd, J= 17.3, 2.0 Hz, 1H), 2.48 (dd, J= 17.3, 10.2 Hz, 1H), 2.20 (s, 3H), 0.91 (s, 9H); ¹³C NMR (100 MHz, CDCb) 210.6, 75.0, 45.2, 34.3, 31.0, 25.8;

HRMS (ESI) m/z for C8Hl6Na02 [M+Na]⁺ calcd 167.1048, found 167.1051.

(4X,6X)-4-ferf-Butyl-6-methyl-2-dioxo-l,3,2-dioxathiane (3.7)

O O (i^^-S^-dimethylhexan^^-diol 2.10 (1.17g, 8 mmol) and pyridine (2.1 mL,

O' "O 25.6 mmol) were dissolved in Et₂0 (80 mL) and the reaction mixture was

cooled to 0 °C. SOCL (0.88 mL, 12.1 mmol) was added dropwise to above

3.725 mixture and stirred for 30 min at 0 °C. The reaction was diluted with water (100 mL) and warmed to 23 °C. The aqueous layer was extracted with Et₂0 (3 x 50 mL) and the combined organic phase were dried over anhydrous MgS0_4, filtered, and concentrated. The resulting diastereomeric cyclic sulfites were dissolved in a mixture solvents of FLO (40 mL), CFLCN (20 mL), and tolune (20 mL). RuCb*H₂0 (83 mg, 0.4 mmol) and NaI0₄ (2.6 g, 12 mmol) were added successively to above mixture. The reaction was stirred at 23 °C for 1 h, the mixture was diluted with Et₂0 (150 mL), and the organic phase was washed with saturated aqueous NaHC03 (50 mL) and brine (50 mL). The organic phase was dried over MgS0₄ filtered, and concentrated. Flash column chromatography (5: 1 hexanes/EtOAc, v/v) was performed on silica gel and provided cyclic sulfate 3.7 (1.50 g, 91% for 2 steps) as a white solid.

R/0.27 (5: 1 hexanes/EtOAc, v/v); [a]²¾ = -3.1 (c 1.23, CHCb);

¾ NMR (400 MHz, CDCb) d 4.97-4.92 (m, 1H), 4.54 (dd, J= 5.2 Hz, 1H), 1.88-1.84 (m, 2H), 1.48 (d, J= 6 Hz, 3H), 1.01 (s, 9H); ¹³C NMR (100 MHz, CDCb) 91.8, 81.0, 34.3, 31.7, 25.3,

20.8; IR (neat) 2966, 1391, 1186, 1045, 893 cm ¹;

HRMS (ESI) m/z for C8Hl6Na04S [M+Na]⁺ calcd 231.0662, found 231.0667.

(3A,5A)-2,2,5-Trimethyloct-7-en-3-ol (3.8)

Cul (9.51 g, 50.0 mmol) was dissolved in THF (50 mL) and a solution of cyclic sulfate 3.7 (8.67 g, 41.7 mmol) in THF (50 mL) was added to above mixture at 23 °C. The reaction was cooled to -30 °C, followed by

allylmagnesium bromide (150 mL, 150 mmol, 1 M solution in Et₂0) added dropwise. After stirring for at -30 °C for 6 h, the reaction was warmed to 23 °C and dissolved in Et₂0 (400 mL). The mixture was cooled to 0 °C, at which a 20% H₂S0₄ (150 mL) was added slowly. After stirring at 23 °C for 12 h, the aqueous layer was extracted with Et₂0 (3 x 200 mL). The combined organic phases were washed by brine (150 mL), dried over Na₂S0₄, filtered, and concentrated. Purification via flash column chromatography on silica gel (10: 1 hexanes/EtOAc, v/v) produced alcohol 3.8 (5.95 g, 84 %) as a clear, colorless oil.

R/0.43 (7: 1 hexanes/EtOAc, v/v); [a]²⁵o = -44.5 (c 1.42, CHCb);

¾ NMR (400 MHz, CDCb) d 5.83-5.73 (m, 1H), 5.06-5.02 (m, 2H), 3.34 (dd, 7= 10.4, 1.6 Hz, 1H), 2.27-2.20 (m, 1H), 1.94-1.86 (m, 1H), 1.85-1.76 (m, 1H), 1.45 (ddd, J= 14.4, 9.6, 2 Hz, 1H), 1.36 (br s, 1H), 1.22 (ddd, j= 14, 10, 4 Hz, 1H), 0.98 (dd, j= 6.4 Hz, 3H), 0.91 (s, 9H); ¹³C NMR (100 MHz, CDCb) d 137.1, 116.0, 77.6, 39.8, 38.5, 35, 29.9, 25.6, 20.9; IR (neat) 3995, 2955, 1640, 1366, 1069 cm ¹;

HRMS (ESI) m/z for Cl lH22NaO [M+Na]⁺ calcd 193.1563, found 193.1557

(AV,5,V)-2,2,5-tnmethyloct-7-en-3-yl-/V-(tert-butoxycarbonyl)-/V-methyl-L-alaninate (3.9)

CH₂Cl₂ (20 mL) was transferred to the reaction and warmed to 23 °C. After stirring at 23 °C for 12 h, the mixture was filtered through a pad of Celite^® and the filtrate was washed with saturated aqueous NaHCCh (200 mL). The resulting aqueous layer was extracted with CH2CI2 (3 x 150 mL) and the combined organic layers were washed with brine(l00 mL), dried over Na2S0₄, filtered, and concentrated. Purification via flash column chromatography on silica gel (9: 1 hexanes/EtOAc, v/v) provide ester 3.9 (1.7607 g, 93%) as a clear, colorless oil.

R/0.21 (7: 1 hexanes/EtOAc, v/v); [a]²¾ = -22.5 (c 1.00, CHCb);

¾ NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 5.77-5.69 (m, 1H); 5.03-4.96 (m,

2H), 4.95-4.86 (m, 0.5H), 4.90-4.8l(m, 1H), 4.75-4.66 (m, 0.5H), 2.89-2.82 (d, 1.5H, 7=14.1 Hz), 2.82-2.76 (d, 1.5H, 7=8.1 Hz), 2.26-2.16 (m, 1H), 1.92-1.82 (m, 1H), 1.48-1.28 (m, 3H), 1.48-1.28 (m, 3 H), 1.46 (s, 4H), 1.44 (s, 5H), 0.89 (s, 9H), 0.87 (d, 6.4 Hz, 3 H); ¹³C NMR (150

MHz, CDCb, mixture of carbamate rotamers) d 172.6, 172.5, 156.3, 155.7, 137.0 136.7, 116.7,

116.5, 80.4, 80.1, 79.9, 54.5, 53.8, 39.9, 36.8, 35.2, 35.1, 35.1, 30.6, 30.5, 30.2, 30.0, 29.7, 29.6,

28.7, 26.3, 26.2, 21.0, 16.0, 15.4, 15.3;

HRMS (ESI) m/z for C2oH37NNaC>4 [M+Na]⁺ calcd 378.2615, found 378.2600

(7V,5/?)-2,2,5-tnmethyl-7-oxoheptan-3-yl-/V-(tert-butoxycarbonyl)-/V-methyl-L-alaninate

(3.4)

(1.965 g, 7.5 mmol) was added to the solution and the reaction was stirred at -78 °C for 30 min. The reaction was warmed to 23 °C and stirred for an additional 1 h, and then concentrated under reduced pressure. Purification via flash column chromatography on silica gel (6: 1 to 3 : 1 hexanes/EtOAc, v/v) yielded aldehyde 3.4 (994.6 mg, 93%) as a colorless oil.

R/0.20 (6: 1 hexanes/EtOAc, v/v); [a]²¾ = -11.2 (c 0.50, CHCb);

¾ NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 9.70 (s, 0.6H), 9.66 (d, J = 2.5 Hz, 0.4H), 4.89-4.81 (m, 0.6H), 4.81-4.76 (m, 1H), 4.76-4.69 (m, 0.4H), 2.88-2.78 (m, 3H), 2.65 (dd, 7= 15.9, 3,3 Hz, 1H), 2.20-2.04 (m, 1H), 2.04-1.88 (m, 1H), 1.68-1.58 (m, 0.5H), 1.57- 1.48 (m, 1.5 H), 1.45 (s, 9H), 1.44-1.39 (d, 7= 7.5 Hz, 3H), 0.96 (d, 7= 6.5 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (150 MHz, CDCb, mixture of carbamate rotamers) d 202.7, 202.4, 201.9, 172.7, 172.4, 172.3, 155.9, 155.8, 155.2, 80.2, 79.9, 78.9, 77.2, 77.0, 76.8, 60.3, 54.2, 54.1, 53.6, 49.3, 49.2, 36.7, 34.6, 34.6, 30.5, 30.3, 29.7, 28.5, 28.3, 28.2, 25.9, 25.8, 25.7, 25.1, 24.9, 21.2, 20.9, 15.7, 15.5, 15.0, 14.9, 14.1; HRMS (ESI) m/z for CiiftsNNaOs [M+Na]⁺ calcd 380.2407, found 380.2403.

(2R,4S,5S, ZV,9,V)-9-((/V-(tert-butoxycarbonyl)-/V-methyl-L-alanyl)oxy)-5-hydroxy-4, 7,10,10- tetramethyl-3-oxoundecan-2-yl benzoate (3.10)

3.10a Et₂0 (8 mL) dropwise. The resulting mixture was warmed to 0 °C and stirred for 2 h, and then re-cooled to -78 °C. A solution of aldehyde 3.4 (0.8145 g, 2.28 mmol) in Et₂0 (4.00 mL) was added via cannula and the reaction mixture was stirred at - 78 °C for 2 h. The reaction was held at -20 °C (Freezer) for 14 h before warming to 0 °C. The reaction was slowly quenched with MeOH (3 mL), followed by the addition of pH 7 buffer (16 mL) and H₂0₂ (12 mL, 30% aqueous solution). After stirring at 23 °C for 8 h, the mixture was diluted with Et₂0 (20 mL). The aqueous phase was extracted with Et₂0 (3 x 10 mL). The combined organic layers were dried over Na₂S0₄, filtered, and concentrated. Purification via flash column chromatography on silica gel (6: 1 to 3 : 1 hexanes/EtOAc, v/v) provided b-hydroxy ketone 3.10a (1.0625 mg, 85%) as a colorless oil;

R/0.41 (3 : 1 hexanes/EtOAc, v/v); [a]²¾ = -32.4 (c 1.08, CHCb);

¹H NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 8.08 (m, 2H), 7.58-7.55 (m, 1H), 7.47-7.42 (m, 2H), 5.43 (q, J= 7.0 Hz, 1H), 4.79 (t, J= 8.9 Hz, 1H), 4.79 (m, 0.5H), 4.71 (m, 0.5H), 3.80 (m, 1H), 2.88 (m, 1H), 2.55 (d, J= 6.6 Hz, 0.2H), 2.49 (d, J= 6.6 Hz, 0.4H), 2.24 (d, J= 6.6 Hz, 0.4H), 1.65-1.58 (m, 1H), 1.58-1.54 (m, 1H), 1.56 (d, J= 7.0 Hz, 3H), 1.53-1.46 (m, 1H),1.45 (s, 6H), 1.43 (s, 3H), 1.42-1.37 (d, J= 7.5 Hz, 3H), 1.35-1.27 (m, 1H), 1.15-1.10 (m, 1H), 0.96 (d, J= 6.8 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (150 MHz, CDCb, mixture of carbamate rotamers) d 210.8, 173.1, 165.8, 156.1, 133.2, 129.9, 128.4, 80.2, 80.0, 79.7, 79.2, 79.0, 75.2, 75.0, 70.9, 54.4, 53.7, 49.5, 49.4, 40.0, 39.7, 37.7, 34.5, 30.6, 30.4, 29.8, 28.4, 26.0, 25.9, 25.5, 25.4, 20.8, 15.6, 15.0, 13.7, 13.6;

HRMS (ESI) m/z for Csr^NNaOs [M+Na]⁺ calcd 586.3350, found 586.3341. (2S,3S,5S, ZV)-7-((/V-(tert-butoxycarbonyl)-/V-methyl-L-alanyl)oxy)-3-hydroxy-2, 5,8,8- tetramethylnonanoic acid (3.2)

aqueous phase was extracted with CH2CI2 (3 x 10 mL). The combined organic layers were dried over Na2S0₄, filtered and concentrated under reduced pressure. The resulting crude //-hydroxy ketone in /-BuOH (6.0 mL) and H2O (1.2 mL) was added NalCL (235.4 mg, 1.10 mmol) and stirred at 23 °C for 3 h. Saturated aqueous sat’d NLLCl (4 mL) was added to the reaction mixture and the aqueous phase was extracted with EtOAc (3 x 15 mL). The combined organic layers were dried over Na₂S0₄, filtered, and concentrated.

Purification via flash column chromatography on silica gel (97:3 CLLCk/MeOH, v/v) gave b- hydroxy acid 3.2 (134.6 mg, 71%) as a white foam.

R/0.29 (92:8 CLLCk/MeOH, v/v); [a]²⁵o = -25.6 (c 0.39, CHCh);

¾ NMR (600 MHz, CDCh, mixture of carbamate rotamers) d 4.84 (dd, J= 11.0, 3.8 Hz, 1H); 4.65 (q, j= 7.9 Hz, 1H), 3.74 (ddd, j= 8.4, 6.8, 2.0 Hz, 1H), 2.85 (s, 3H), 2.53-2.41 (m, 1H), 1.75-1.65 (m, 1H), 1.65-1.51 (m, 2H), 1.45 (d, J= 7.8 Hz, 3H), 1.46 (s, 9H), 1.23 (d, J= 7.2 Hz, 3 H), 1.23-1.14 (m, 1H), 0.95 (d, J= 6.8 Hz, 3H), 0.89 (s, 9H); ¹³C NMR (175 MHz, CDCh, mixture of carbamate rotamers) d 176.9, 176.8, 173.0, 172.9, 156.5, 156.1, 80.6, 80.4, 80.0, 78.8, 77.8, 70.9, 54.7, 53.9, 45.8, 44.1, 40.0, 37.6, 37.4, 47.2, 37.0, 34.6, 30.6, 28.4, 28.3, 28.2, 26.0, 26.0, 25.3, 25.2, 20.9, 20.6, 15.0, 14.9, 13.8, 13.7;

HRMS (ESI) m/z for C₂₂H _iNNaC>7 [M+Na]⁺ calcd 454.2775, found 454.2765. (S, ii)-4-((tert-butoxycarbonyl)amino)-2-methyl-5-(tritylthio)pent-2-enoic acid (3.3)

To a solution of /V-Boc-(ri'-Trt)-D-Cys-OH (2.00 g, 4.32 mmol) in CH2CI2 (22 mL) was added N, L-di i sopropyl ethyl ami ne (1.88 mL, 10.8 mmol), EDCLHCl (1.08 g, 5.62 mmol) and HOBt (760 mg,

5.62 mmol). The reaction mixture was stirred at 23 °C for 3 h, then

quenched with 1M HC1. The aqueous layer was extracted with EtOAc (3 x 20 mL). The combined organic layer was washed with saturated aqueous NaHC03, dried over MgS0₄ and concentrated. Purification via flash column chromatography on silica gel (3 : 1 hexanes/EtOAc, v/v) provided (A)-A-methyl-A-m ethoxy -2 -tert-butoxycarbonylamino-3- (triphenylmethylthio)-propionamide (2.10 g, 96%) as a white amorphous solid. To a solution of the above Weinreb amide (2.10 g, 4.10 mmol) in toluene (40 mL) was added dropwise DIBAL (9.10 mL, 1.0 M in toluene, 9.11 mmol) at -78 °C. After being stirred at the same temperature for 15 min, the reaction mixture was quenched with MeOH and aqueous potassium sodium tartrate at 0 °C, stirred at room temperature for 1 h and the aqueous layer was extracted with diethyl ether. The combined organic layer was washed with brine, dried over Na2S0₄ and concentrated in vacuo. The residue was used for the next reaction without further purification. To a solution of crude aldehyde in toluene (24 mL) was added Ph3P=C(CH3)C02Et (2.70 g, 7.54 mmol) at 0 °C under argon. After being at room temperature for 3.0 h, the reaction mixture was concentrated in vacuo. The residue was purified by column chromatography on silica gel (8% ethyl acetate in hexane) to give 15 (1.96 g, 3.69 mmol, 90% in 2 steps) as a white amorphous solid. To a 0 °C solution of tert-butyl (ri^,,£)-4-(3-methoxy-2-methyl-3-oxoprop-l-en- l-yl)-2,2-dimethyloxazolidine-3-carboxylate (2.02 g, 6.74 mmol) in a mixture solution of I- BuOH (34 mL), THF (17 mL), and H2O (17 mL) was added LiOHTLO (0.56 g, 13.48 mmol). After stirring at 23 °C for 4 h, the reaction mixture was quenched with 1M HC1 and the mixture was acidified to pH = 3. The aqueous layer was extracted with EtOAc (5 x 30 mL) and the combined organic layers were washed with brine, dried over Na2S0₄, filtered, and concentrated. Purification via flash column chromatography on silica gel (3 : 1 to 2: 1 hexanes/EtOAc, v/v) yielded acid 3.3 (1.72 g, 90%) as a white amorphous solid.

R/0.32 (2: 1 hexanes/EtOAc, v/v); [a]²¾ = -15.9 (c 0.99, CHCh);

¾ NMR (700 MHz, CDCh, mixture of carbamate rotamers) d 7.41-7.38 (m, 6H), 7.29 (dd, J =

7.5, 7.5 Hz, 6H), 7.21 (dddd, j= 7.5, 7.5, 1.3, 1.3 Hz, 3H), 6.52 (dd, J=9.0, 1.0 Hz, 1H), 4.65- 4.55 (m, 1H), 4.45-4.31 (m, 1H), 2.43 (dd, J= 12.5, 7.1 Hz, 1H), 2.40-2.33 (m, 1H), 1.76 (s, 3H), 1.41 (s, 9H); ¹³C NMR (175 MHz, CDCh, mixture of carbamate rotamers) d 172.5, 155.0,

144.5, 142.6, 129.7, 128.2, 127.0, 80.0, 67.3, 48.4, 36.3, 28.5, 12.6;

HRMS (ESI) m/z for CioftiNNaChs [M+Na]⁺ calcd 526.2023, found 526.2030. allyl A-(A^L((»V)-2-((tert-butoxycarbonyl)amino)-3-(4-methoxyphenyl)propanoyl) -/V-methyl- L-alanyl)-/V-methyl-L-isoleucinate (3.2)

concentrated under a stream of nitrogen, followed by adding additional toluene (40 mL). After concentrating the reaction mixture under a stream of nitrogen, the crude product was placed under high vacuum for 2 h.

z-PnNEt (2.4 mL, 13.6 mmol) and PyAOP (2.38 g, 4.58 mmol) were added to a 23 °C solution of A-Boc-O-methyl-L-tyrosine (1.36 g, 5.58 mmol) in CH2CI2 (50 mL). After stirring for 5 min at 23 °C, a solution of above crude product in CH2CI2 (10 mL) was added dropwise. After 12 h, the reaction mixture was concentrated under reduced pressure after stirring at 23 °C for 12 h. Purification via flash column chromatography on silica gel (3 : 1 hexanes/EtOAc, v/v) yielded diamide 2.1 (2.59 g, 83% for 2 steps) as a white amorphous solid.

R/0.51 (2: 1 hexanes/EOAc, v/v); [a]²¾ = -96.6 (c 1.16, CHCh);

¾ NMR (500 MHz, CDCh, mixture of carbamate rotamers) d 7.09 (d, J= 8.5 Hz, 2H), 6.76 (d, J= 8.5 Hz, 2H), 5.89-5.81 (m, 1H), 5.37 (q, J= 6.5 Hz, 1H), 5.26 (dd, 7 = 18.5 Hz, 1H), 5.19 (dd, j= 10, 1 Hz, 1H), 4.89 (d, 7= 10 Hz, 1H), 4.79 (ddd, J= 7.5, 7.5, 7.5 Hz, 1H), 4.56-4.55 (m, 2H), 3.73 (s, 3H), 2.96 (dd, 7= 13, 7 Hz, 1H), 2.91 (s, 3H), 2.76 (dd, J= 13.5, 6 Hz, 1H), 2.66 (s, 3H), 2.00-1.88 (m, 1H), 1.36 (s, 9H), 1.23 (d, J= 7 Hz, 3H), 0.97-0.90 (m, 2H), 0.90 (d, J= 6.5 Hz, 3H), 0.81 (t, J= 7.5 Hz, 3H); ¹³C NMR (125 MHz, CDCh, mixture of carbamate rotamers) d 171.7, 171.7, 170.6, 158.5, 155.1, 131.7, 130.4, 128.4, 118.6, 113.9, 79.8, 65.3, 60.5, 55.2, 51.8, 49.7, 38.2, 33.3, 30.9, 30.4, 28.3, 24.9, 15.7, 14.3, 10.3; IR (neat) 3304, 2970, 1738, 1643, 1248 cm ¹;

HRMS (ESI) m/z for Ci^sNsNaO? [M+Na]⁺ calcd 570.3150, found 570.3129. allyl /V-(/V-((A)-2-((A,ii)-4-((tert-butoxycarbonyf)amino)-2-methyl-5-(tritylthio)-pent-2- enamido)-3-(4-methoxyphenyl)propanoyl)-/V-methyl-L-alanyl)-/V-methyl-L-isoleucinate

(3.1)

3.2 nitrogen, the crude product was placed under high vacuum for 2 h.

To a solution of acid 3.3 (0.453 g, 0.90 mmol) in CH2CI2 (10 mL) at 23 °C was added z-PnNEt

(0.47 mL, 2.70 mmol), followed by PyAOP (0.468 g, 0.90 mmol). After stirring for 5 min, a solution of crude deprotected diamide 7 in CH2CI2 (5 mL) was added and the mixture was stirred at 23 °C for 6 h before concentrated under reduced pressure. Purification via flash column chromatography on silica gel (3 : 1 to 1 : 1 hexanes/EtOAc, v/v) gave triamide 9 (0.382 g, 74% for 2 steps) as a white amorphous solid.

R/0.26 (1 : 1 hexanes/EOAc, v/v); [a]²¾ = -66.2 (c 0.96, CHCb);

¾ NMR (700 MHz, CDCb, mixture of rotamers) d 7.39 (d, J= 7.6, 6H), 7.28 (dd, J= 7.5, 7.5 Hz, 6H), 7.21 (dd, j= 7.3, 7.3, 3H), 7.06 (d, j= 8.5 Hz, 2H), 6.76 (d, j= 8.5 Hz, 2H), 6.36 (d, J = 8.1 Hz, 1H), 5.99-5.93 (m, 1H), 5.91-5.84 (m, 1H), 5.40 (q, 7= 6.9 Hz, 1H), 5.30 (dd 7 =

17.2, 1.2 Hz, 1H), 5.23 (dd, 7= 10.5, 0.9 Hz, 1H), 5.21-5.17 (m, 1H), 4.94 (d, 7= 10.3 Hz, 1H), 4.62-4.54 (m, 2H), 4.55-4.46 (m, 1H), 4.37-4.27 (m, 1H), 3.73 (s, 3H), 3.04 (d, J= 10.3 Hz,

1H), 2.96 (s, 3H), 2.87-2.81 (m, 1H), 2.76 (s, 3H), 2.43-2.35 (m, 1H), 2.34-2.28 (m, 1H), 2.01- 1.95 (m, 1H), 1.87-1.82 (m, 1H), 1.73 (s, 3H), 1.40 (s, 9H), 1.28-1.24 (m, 4H), 0.97-0.90 (m, 1H), 0.94 (d, J= 6.5 Hz, 3H), 0.86 (t, J= 7.5 Hz, 3H); ¹³C NMR (175 MHz, CDCb, mixture of rotamers) d 171.9, 171.4, 170.6, 167.8, 158.6, 154.8, 144.5, 135.8, 132.4, 131.8, 130.4, 129.6, 126.8, 118.7, 115.9, 79.7, 65.4, 60.5, 55.2, 50.6, 49.7, 37.8, 36.7, 33.4, 31.1, 28.5, 25.1, 15.9, 14.5, 13.2, 10.7;

HRMS (ESI) m/z for C₅₄H68N₄NaS09 [M+Na]⁺ calcd 955.4650, found 955.4692. allyl N-(N-((S)-2-((6S,9S,HS,HS,14S,l ZV,L -9-(tert-butyl)-13-hydroxy-2,2,5,6, 11,14,19- heptamethyl-4,7,15-trioxo-17-((tritylthio)methyl)-3,8-dioxa-5,16-diazaicos-18-en-20- amido)-3-(4-methoxyphenyl)propanoyl)-/V-methyl-L-alanyl)-/V-methyl-L-isoleucinate (3.18)

mmol), followed by HATU (0.361 g, 0.95 mmol). After stirring for 1 min at 23 °C, a solution of crude deprotected product in CH2CI2 (5 mL) was added. The reaction mixture was stirred at 23 °C for 12 h, and then concentrated under reduced pressure. Purification via flash column chromatography on silica gel (96:4 CH2Cb/MeOH, v/v) gave amide 3.18 (0.840 g, 71 % for 2 steps) as a white amorphous solid. R/0.21 (25: 1 OECb/MeOH, v/v); [a]²⁵o = -68.0 (c 0.99, CHCb);

¾ NMK (700 MHz, CDCb, mixture of carbamate rotamers) d 7.38 (d, J= 7.3 Hz, 6H), 7.29-

7.24 (m, 6H), 7.20 (dd, J= 7.1, 6.9 Hz, 3H), 7.06 (d, J= 8.5 Hz, 2H), 6.67 (d, J= 8.5 Hz, 2H), 6.42 (d, J= 8.0 Hz, 0.25H), 6.35 (d, J= 8.0 Hz, 0.5H), 6.21 (d, J= 8.0 Hz, 0.25H), 6.04 (d, J = 8.8 Hz, 0.5H), 6.00 (d, J= 8.0 Hz, 0.5H), 5.91-5.84 (m, 1H), 5.42-5.35 (m, 1H), 5.30 (dd, J =

17.2, 1.4 Hz, 1H), 5.23 (dd, 7= 10.5, 1.4 Hz, 1H), 5.20-5.14 (m, 1H), 4.93 (dd, J= 10.3, 3.4 Hz, 1H), 4.88-4.79 (m, 1H), 4.78-4.68 (m, 1H), 4.67-4.53 (m, 1H), 4.62-4.58 (m, 2H), 3.74 (s, 3H), 3.68-3.62 (m, 0.5H), 3.61-3.56 (m, 0.5H), 3.07-2.98 (m, 1H), 2.92 (s, 3H), 2.87-2.81 (m, 1H), 2.82 (s, 3H), 2.77-2.72 (m, 1H), 2.71-2.69 (m, 3H), 2.56-2.48 (m, 0.5H), 2.48-2.41 (m, 0.5H), 2.41-2.33 (m, 0.5H), 2.33-2.26 (m, 0.5H), 2.20-2.07 (m, 1H), 1.98-1.92 (m, 1H), 1.74 (d, J =

1.4 Hz, 1H), 1.74-1.64 (m, 2H), 1.67 (s, 3H), 1.44 (s, 9H), 1.41-1.33 (d, J= 7.4 Hz, 3H), 1.28-

1.24 (m, 3H), 1.17-1.13 (m, 3H), 1.15-0.95 (m, 2H), 0.94 (d, J= 6.5 Hz, 3H), 0.90 (m, 3H), 0.87 (s, 9H), 0,85-0.83 (m, 3H); ¹³C NMR (175 MHz, CDCb, mixture of carbamate rotamers) d 171.9, 171.4, 170.8, 167.8, 167.7, 158.8, 156.4, 144.8, 144.7, 144.6, 135.0, 134.8, 132.5, 131.9, 130.6, 129.8, 129.7, 128.1, 128.1, 127.0, 126.9, 120.0, 118.8, 114.0, 80.4, 80.2, 79.1, 78.6, 71.6,

71.1, 71.0, 65.5, 60.5, 55.3, 54.1, 53.9, 50.7, 50.7, 49.8, 47.7, 47.6, 47.2, 46.9, 46.8, 46.1, 40.9,

40.3, 37.9, 37.3, 37.1, 36.3, 34.9, 34.7, 34.5, 33.4, 31.0, 30.6, 30.0, 28.6, 28.5, 26.2, 26.0, 25.2,

21.1, 21.0, 19.5, 16.3, 15.9, 15.6, 15.4, 15.2, 15.1, 15.0, 14.5, 13.2, 11.8, 10.7;

HRMS (ESI) m/z for CviHwNsNaSOii [M+Na]⁺ calcd 1268.6903, found 1268.6980. allyl N-(N-((S)-2-((6S,9S,HS,13S,14S,17S,E)-9-(tert-butyl)-2,2,5,6,ll,14,19-hepta-methyl- 4,7,15-trioxo- 13-(((2,2,2-trichloroethoxy)car bonyl)oxy)- 17-((tr itylthio)-methyl)-3,8-dioxa- 5,16-diazaicos-18-en-20-amido)-3-(4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N- methyl-L-isoleucinate (3.19)

chromatography on silica gel (96:4 CFbCb/MeOH, v/v) gave 3.19 (126.3 mg, 89 %) as a white amorphous solid.

R/0.38 (2: 1 ObCb/MeOH, v/v); [a]²⁵o = -41.3 (c 0.08, CHCb)

'H NMR (700 MHz, CDCb, mixture of carbamate rotamers) 'H NMR (700 MHz, CDCb, mixture of carbamate rotamers) d 7.38 (d, J= 7.3 Hz, 6H), 7.28 (t, J= 7.3 Hz, 6H), 7.21 (dd, J =

7.1, 6.9 Hz, 3H), 7.06 (d, J= 8.5 Hz, 2H), 6.67 (d, J= 8.5 Hz, 2H), 6.35 (d, J= 8.0 Hz, 1H), 6.04 (d, J= 8.8 Hz, 0.5H), 6.00 (d, J= 8.0 Hz, 0.5H), 5.97-5.89 (m, 1H), 5.53-5.47 (m, 1H), 5.39 (q, j= 7.2 Hz, 1H), 5.30 (dd, j= 17.2, 1.4 Hz, 1H), 5.23 (dd, j= 10.5, 1.4 Hz, 1H), 5.16 (dd, j =

7.2, 7.0 Hz, 1H), 5.08-4.97 (m, 1H), 4.94 (d, J= 10.3 Hz, 1H), 4.86-4.79 (m, 1H), 4.78-4.68 (m, 2H), 4.67-4.53 (m, 2H), 4.62-4.58 (m, 2H), 3.74 (s, 3H), 3.07-2.98 (dd, J= 14.7, 7.2 Hz, 1H), 2.94 (s, 3H), 2.87-2.81 (m, 1H), 2.82 (s, 3H), 2.77-2.72 (m, 1H), 2.71-2.69 (m, 3H), 1.98-1.92 (m, 2H), 1.72 (s, 3H), 1.67 (s, 3H), 1.44 (s, 9H), 1.41-1.33 (d, j= 7.4 Hz, 3H), 1.29-1.25 (m, 2H), 1.28-1.24 (m, 3H), 1.12-1.07 (m, 3H), 1.15-0.95 (m, 2H), 0.94 (d, J= 6.5 Hz, 3H), 0.90 (m, 3H), 0.87 (s, 9H), 0,85-0.83 (m, 3H); ¹³C NMR (175 MHz, CDCb, mixture of carbamate rotamers) d 172.2, 171.8, 171.8, 171.6, 171.4, 170.7, 169.6, 167.6, 167.5, 158.6, 155.9, 155.4, 153.8, 144.6, 144.4, 131.7, 130.4, 130,3, 129.6, 128.0, 127.9, 126.9, 118.7, 113.9, 78.6, 78.4, 65.4, 60.5, 55.2, 53.7, 50.6, 49.6, 47.0, 45.1, 45.0, 37.7, 37.5, 36.0, 33.3, 30.9, 30.6, 28.4, 25.9, 25.9, 25.8, 25.0, 20.2, 20.0, 15.8, 15.2, 14.4, 13.1, 13.0, 10.6;

HRMS (ESI) m/z for CsiHssNsNaO [M+H]⁺ calcd 970.6111, found 970.6101 apratoxm t (i.i)

o owe y y . mg, . pmo an e reac on mixture was stirred at 23 °C for 48 h. The reaction mixture was concentrated under reduced pressure. Purification via preparative thin layer chromatography (99: 1 EtOAc/MeOH, v/v) yielded apratoxin F (30.8 mg, 60 % for 2 steps) as a white amorphous solid.

R/0.19 (25: 1 ObCb/MeOH, v/v); [a]²⁵o = -138.5 (c 0.12, CHCb); ¾ NMR (700 MHz, CDCh, mixture of rotamers) d 7.16 (d, J= 8.6 Hz, 2H), 6.80 (d, J= 8.6 Hz, 2H), 6.36 (dd, J= 9.9, 1.1 Hz, 1H), 6.04 (d, 7= 9.3 Hz, 1H), 5.48 (d, 7= 11.5 Hz, 1H), 5.25 (ddd, 7=9.2, 9.2, 4.2 Hz, 1H), 5.05 (ddd, 7=9.6, 9.6, 4.9 Hz, 1H), 4.89 (dd, 7= 12.7, 2.3 Hz,

1H), 4.52 (m, 1H), 4.47 (q, 7= 7.6 Hz, 1H), 3.78 (s, 3H), 3.56 (m, 1H), 3.46 (dd, 7= 10.8, 8.7 Hz, 1H), 3.29-3.27 (m, 1H), 3.28 (s, 3H), 3.15 (dd, 7= 11.6, 4.3 Hz, 1H), 3.10 (d, 7= 11.6, 1H), 2.87 (dd, 7= 12.6, 4.8Hz, 1H), 2.79 (s, 3H), 2.68 (s, 3H), 2.64 (dd, 7= 10.1, 6.9 Hz, 1H), 2.30- 2.23 (m, 1H), 2.18-2.10 (m, 1H), 1.97 (d, 7= 1.6 Hz, 3H), 1.79 (ddd, 7= 13.6, 13.6, 3.0Hz, 1H), 1.47 (m, 1H), 1.44 (d, 7= 7.6 Hz, 3H), 1.29-1.25 (m, 2H), 1.22 (d, 7= 6.7 Hz, 3H), 1.11 (m,

1H), 1.06 (d, 7= 6.9 Hz, 3H), 1.00 (d, 7= 6.9 Hz, 3H), 0.92 (d, 7= 6.9 Hz, 3H), 0.90 (m, 3H), 0.88 (s, 9H); ¹³C NMR (175 MHz, CDCh, mixture of rotamers) d 177.6, 173.7, 173.2, 170.6,

170.2, 169.6, 158.8, 136.3, 130.7, 130.6, 128.3, 114.1, 114.0, 77.5, 72.5, 71.8, 60.5, 55.4, 54.9, 54.5, 50.6, 48.9, 38.4, 37.8, 37.7, 37.3, 36.8, 35.0, 31.8, 31.2, 30.5, 26.2, 24.7, 24.4, 19.9, 16.8, 14.9, 14.2, 14.0, 8.9;

HRMS (ESI) m/z for C45H70N5O9 [M+H]⁺ calcd 812.5168, found 812.5168.

(1S,2E,6S,9SH2R,15SH8S,20S,22S,23S,24Z)-12-((S)- sec-butyl)-18-(tert-butyl)-22-hydroxy- 6-(4-methoxybenzyl)-3,8,9,ll,14,15,20,23-octamethyl-17-oxa-25-thia-5,8,1144,27- pentaazabicyclo[22.2.1]heptacosa-2,24(27)-diene-4,7,10,13,16-pentaone (l.ib)

1.41 (d, 7= 7.6 Hz, 3H), 1.32-1.25 (m, 2H), 1.22 (d, 7= 6.7 Hz, 3H), 1.11 (m, 1H), 1.06 (d, 7= 6.9 Hz, 3H), 1.00 (d, 7= 6.9 Hz, 3H), 0.92 (d, 7= 6.9 Hz, 3H), 0.90 (m, 3H), 0.88 (s, 9H); ¹³C NMR (175 MHz, CDCh, mixture of rotamers) d 177.6, 173.7, 170.9, 170.6, 170.2, 169.6, 169.4, 158.6, 141.3, 136.1, 130.6, 130.4, 128.2, 119.8, 113.9,

72.4, 71.8, 55.3, 50.7, 48.8, 38.2, 37.7, 37.6, 37.2, 35.0, 31.6, 30.1, 26.1, 24.4, 24.2, 20.0, 16.7,

15.5, 14.1, 14.0, 13.7, 13.3, 10.1, 8.9; (A,E)-3-(3-(tert-butoxycarbonyl)-2,2-dimethyloxazolidin-4-yl)-2-methylacrylic acid (4.3)

To a 0 °C solution of tert-butyl (S, //)-4-(3 -m ethoxy-2-m ethyl -3 - oxoprop- 1 -en- 1 -yl)-2,2-dimethyloxazolidine-3 -carboxylate (2.02 g, 6.74 mmol) in a mixture of /-BuOH (34 mL), H2O (17 mL), and THF (17 mL), LiOHTLO (0.56 g, 13.48 mmol) was added. After warming

to 23 °C and stirring for 4 h, the reaction mixture was quenched with 1M HC1 to pH = 3. The aqueous layer was extracted with EtOAc (5 x 30 mL) and the combined organic layers were washed with brine, dried over Na₂S0₄, filtered, and concentrated.

Purification via flash column chromatography on silica gel (25: 1 CHCb/MeOH, v/v) yielded acid 4.3 (1.72 g, 90%) as a colorless viscous oil.

R/0.32 (25: 1 CH₂Cl₂/MeOH, v/v); [a]²⁵o = +9.6 (c 1.0, CHCb);

¾ NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 6.77 (d, J= 8 Hz, 1H), 4.73-4.60 (m, 1H), 4.11 (dd, J= 8.5, 6.5 Hz, 1H), 3.70 (dd, j= 9, 3.5 Hz, 1H), 1.87 (s, 3H), 1.62 (s, 3H), 1.54 (s, 3H), 1.39 (s, 9H); ¹³C NMR (150 MHz, CDCb, mixture of carbamate rotamers) d 172.9, 151.7, 143.3, 127.4, 94.6, 80.3, 67.5, 55.4, 28.4, 26.2, 24.2, 12.2;

HRMS (ESI) m/z for C HwNNaOs [M+Na]⁺ calcd 308.1468, found 308.1469. tert-butyl (A)-4-((5S,8S,llS,E)-ll-((S)-sec-butyl)-5-(4-methoxybenzyl)-2,7,8,10-tetramethyl-

3,6,9,12-tetraoxo-13-oxa-4,7,10-triazahexadeca-l,15-dien-l-yl)-2,2-dimethyloxazolidine-3- carboxylate (4.6)

o a so u on o ac . . g, . mmo n

CH₂Cb (3 mL) at 23 °C, z-PnNEt (0.38 mL, 2.19 mmol) was added, followed by PyAOP (0.38 g, 0.72 mmol). After stirring for 5 min, a solution of crude deprotected diamide 2.1 in CH₂Cb (2 mL) was added and the mixture was stirred at 23 °C for 8 h. The reaction mixture was concentrated under reduced pressure. Purification via flash column chromatography on silica gel (3 : 1 to 1 : 1 hexanes/EtOAc, v/v) gave triamide 4.6 (0.382 g, 74% for 2 steps) as a white amorphous solid. R/0.26 (1 : 1 hexanes/EOAc, v/v); [a]²¾ = -69.5 (c 0.94, CHCb);

¾ NMR (500 MHz, CDCb, mixture of rotamers) d 7.07 (d, J= 7.0 Hz, 2H), 6.76 (d, J= 7.0 Hz, 2H), 6.44-6.42 (m, 0.6H), 6.10-6.08 (m, 0.4H), 5.91-5.84 (m, 1H), 5.41 (m, 1H), 5.29 (dd J = 17.5, 1.5 Hz, 1H), 5.22 (dd, J= 10.5, 1 Hz, 1H), 5.23-5.18 (m, 1H), 4.95^1.93 (m, 1H), 4.62- 4.54 (m, 2H), 4.07 (dd, J= 9, 6.5 Hz, 1H), 3.74 (s, 3H), 3.67-3.65 (m, 1H), 3.10-2.97 (m, 4H), 2.89-2.76 (m, 4H), 2.01-1.95 (m, 1H), 1.90-1.78 (m, 3H), 1.61 (m, 3H), 1.51 (s, 9H), 1.36 (m, 5H), 1.28 (m, 4H), 0.97-0.90 (m, 1H), 0.94 (d, J= 6.5 Hz, 3H), 0.86 (t, J= 7.5 Hz, 3H); ¹³C NMR (125 MHz, CDCb, mixture of rotamers) d 171.9, 171.6, 170.6, 169.6, 168.1, 158.6, 151.7,

135.1, 131.7, 130.4, 119.8, 118.7, 114.1, 114.0, 94.4, 93.8, 80.4, 80.0, 67.8, 66.0, 65.4, 60.5,

55.1, 50.4, 49.7, 33.3, 31.0, 30.4, 29.9, 28.4, 26.4, 24.0, 16.1, 15.8, 15.7, 14.9, 12.8, 11.6, 10.6; IR (neat) 2976, 1738, 1694, 1645, 1514 cm ¹;

HRMS (ESI) m/z for CsuHsdNUNaOg [M+Na]⁺ calcd 737.4096, found 737.4096. allyl N-(N-((,V)-2-((6,V,9,V,//,V,/J,V, / V, / ZV,£^')-9-(tert-butyl)-13-hydroxy-17-(hydroxy- methyl)-2,2,5,6,ll,14,19-heptamethyl-4,7,15-trioxo-3,8-dioxa-5,16-diazaicos -18-en-20- amido)-3-(4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl-L-isoleucinate (4.7)

CH2CI2 (2 mL) was added. The resulting yellow solution was stirred for 12 h at 23 °C, and concentrated under reduced pressure. Purification via flash column chromatography on silica gel (96:4 CH2Cb/MeOH, v/v) gave amide 4.7 (0.480 g, 71 % for 2 steps) as a white foam.

R/0.26 (24: 1 chloroform/MeOH, v/v); [a]²¾ = -47.9 (c 1.01, CHCb);

¹H NMR (700 MHz, r/6-DMSO, mixture of carbamate rotamers) d 8.04 (d, J = 7.5 Hz, 1H), 7.77

(m, 1H), 7.18 (d, J= 8.5 Hz, 2H), 6.82 (d, J= 8.5 Hz, 2H), 6.10 (d, J= 8.5 Hz, 1H), 5.92-5.83

(m, 1H), 5.28 (ddd, j= 17.2, 1.7, 1.7 Hz, 1H), 5.26 (d, j= 6.9 Hz, 1H), 5.22 (dq, j= 10.3, 1.5

Hz, 1H), 4.88 (q, J= 7.2 Hz, 1H), 4.76-4.70 (m, 2H), 4.72 (dd, J= 5.9 Hz, 1H), 4.69-4.63 (m, 1H), 4.61-4.52 (m, 1H), 4.61-4.56 (dddd, j= 14.4, 5.3, 1.5, 1.5 Hz, 2H), 4.27 (m, 1H), 3.71 (s, 3H), 3.57-3.51 (m, 1H), 3.37-3.33 (m, 1H), 2.90 (dd, J= 14.9, 4.9 Hz, 1H), 2.87 (s, 3H), 2.85 (dd, j= 12.8, 4.9 Hz, 1H), 2.72 (s, 3H), 2.59 (s, 3H), 2.25-2.20 (dq, j= 7.6, 6.6 Hz, 1H), 1.97- 1.88 (m, 1H), 1.77 (s, 3H), 1.65-1.58 (m, 1H), 1.52-1.44 (m, 1H), 1.42-1.29 (m, 1H), 1.40 (s, 9H), 1.36 (d, J= 5.8 Hz, 3H), 1.34 (d, J= 7.1 Hz, 3H), 1.21-1.16 (m, 1H), 1.10 (d, J= 6.8 Hz, 3H), 1.05-0.96 (m, 2H), 0.94 (d, J= 6.6 Hz, 3H), 0.90-0.80 (m, 2H), 0.86 (d, J= 6.6 Hz, 3H), 0.85 (s, 9H), 0.86 (d, J= 7.3 Hz, 3H); ¹³C NMR (175 MHz, ά-DMSO, mixture of carbamate rotamers) d 174.2, 171.5, 171.4, 170.9, 170.6, 170.4, 169.9, 169.2, 168.3, 168.2, 157.9, 157.7, 155.1, 154.5, 134.0, 132.4, 132.3, 130.2, 129.2, 119.2, 118.0, 113.6, 113.5, 69.5, 65.4, 64.7, 63.3, 60.0, 54.9, 53.4, 51.2, 49.4, 48.9, 46.3, 37.6, 36.1, 34.5, 34.4, 32.4, 30.5, 30.0, 28.0, 27.9, 25.8, 25.6, 25.5, 24.3, 20.1, 15.8, 15.6, 15.5, 14.8, 14.6, 14.1, 13.9, 13.8, 13.2, 11.3, 10.0;

HRMS (ESI) m/z for CsiHssNsNaOis [M+Na]⁺ calcd 1010.6036, found 1010.6015. allyl N-(N-((S)-2-((E)-3-((S)-2-((2S,3S,5S,7S)-7-((N-(tert-butoxycarbonyl)-N-methyl-L- alanyl)oxy)-3-hydroxy-5,8,8-trimethylnonan-2-yl)-4,5-dihydrooxazol-4-yl)-2- methylacrylamido)-3-(4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl -L- isoleucinate (4.9)

mg, 81 %) as a white amorphous solid.

R/0.18 (95:5 CLLCh/MeOH, v/v); [a]²⁵o = -41.3 (c 0.08, CHCh) ;

¾ NMK (600 MHz, i¾-DMSO, mixture of carbamate rotamers) d 8.19 (d, J = 7.8 Hz, 1H), 7.18 (d, J= 8.5 Hz, 2H), 6.82 (d, J= 8.5 Hz, 2H), 6.05 (d, J= 8.5 Hz, 1H), 5.93-5.84 (m, 1H), 5.27 (ddd, j= 17.2, 1.7, 1.7 Hz, 1H), 5.24 (d, j= 6.9 Hz, 1H), 5.21 (dq, j= 10.3, l .5Hz, 1H), 4.86 (q, J= 7.2 Hz, 1H), 4.81 (q, J= 9.1 Hz, 1H), 4.75 (dd, J= 10.5, 2. Hz, 2H), 4.68-4.64 (m, 0.4H), 4.62-4.58 (m, 0.6H), 4.61-4.53 (m, 2H), 4.47-4.35 (m, 1H), 4.40 (dd, J= 9.2, 9.2 Hz, 1H), 3.85 (dd, J= 8.3, 8.3 Hz, 1H), 3.76-3.69 (m, 1H), 3,71 (s, 3H), 2.90 (dd, J= 14.9, 4.9 Hz, 1H), 2.87 (s, 3H), 2.85 (dd, J= 12.8, 4.9 Hz, 1H), 2.72 (m, 3H), 2.59 (s, 3H), 1.97-1.88 (m, 1H), 1.77 (s, 3H), 1.67-1.60 (m, 1H), 1.54-1.46 (m, 1H), 1.42-1.29 (m, 1H), 1.40 (s, 5H), 1.36 (s, 4H), 1.36 (d, J= 5.8 Hz, 3H), 1.33 (d, 7= 7.1 Hz, 3H), 1.21-1.16 (m, 1H), 1.09 (d, 7= 6.8 Hz, 3H), 1.04 (d, J= 7.2 Hz, 3H), 1.05-0.96 (m, 2H), 0.90-0.80 (m, 2H), 0.86 (d, J= 6.6 Hz, 3H), 0.85 (s, 9H), 0.76 (d, J= 7.3 Hz, 3H); ¹³C NMR (175 MHz, 7₆-DMSO, CDCb, mixture of carbamate rotamers) d 172.0, 171.9, 171.4, 171.4, 170.9, 170.4, 169.9, 169.7, 168.6, 168.5, 158.4, 158.2, 155.6, 155.0, 136.1, 135.9, 132.8, 132.7, 132.4, 132.3, 130.7, 130.4, 129.8, 119.7, 118.5, 114.0,

113.9, 71.9, 69.2, 69.0, 65.9, 65.2, 63.8, 63.6, 60.5, 55.4, 55.4, 54.5, 54.2, 54.1, 53.9, 51.8, 51.7,

49.9, 49.2, 38.8, 38.7, 37.6, 36.5, 36.0, 35.0, 35.0, 34.1, 32.9, 31.0, 30.9, 30.5, 30.4, 30.0, 30.0,

29.5, 28.5, 28.3, 26.6, 26.5, 26.1, 26.0, 24.9, 24.8, 20.6, 20.5, 16.3, 16.0, 15.6, 15.3, 150.1, 15.0,

14.6, 13.7, 13.2, 13.1, 13.0, 11.7, 10.5;

HRMS (ESI) m/z for C52H84N5O12 [M+H]⁺ calcd 970.6111, found 970.6101

Oxazoline apratoxin F (4.1)

then high vacuum for 1 h.

To a solution of above crude trimethyl silyl ether in THF (0.2 mL) at 0 °C, tetrabutylammonium fluoride (38 pL, 38 pmol, 1 M solution in THF) was added. After stirring at 0 °C for 30 min, the reaction was quenched with saturated aqueous NaHCCb (0.2 mL) at 0 °C the mixture was warmed to 23 °C. The aqueous layer was extracted with CHCb (10 x 1 mL) and the combined organic layers were dried over Na2S0₄, filtered, and concentrated under reduced pressure.

To a solution of amine (7.7 mg, 8.7 pmol) in THF (0.15 mL) at 23 °C, morpholine (9.1 pL, 104 pmol) was added, followed by Pd(PPh₃)4 (1.5 mg, 1.3 pmol). After stirring for 30 min the reaction mixture was concentrated under reduced pressure. The resulting crude solid was azeotropically dried with toluene (2 x 1 mL) and then place under high vacuum for 2 h. The crude amino acid was dissolved in CH2CI2 (8.7 mL, 0.001 M) and cooled to 0 °C. z-PnNEt (9.1 pL, 52 pmol) was added dropwise, followed by PyAOP (6.6 mg, 12.6 pmol) and the reaction mixture was warmed to 23 °C. After stirring at 23 °C for 48 h, the reaction mixture was concentrated under reduced pressure. Purification via preparative thin layer chromatography (99: 1 CHCb/MeOH, v/v) yielded cyclic depsipeptide oxa-apratoxin F (3.4 mg, 33 % for 4 steps) as a white amorphous solid: R/0.19 (95:5 CFhCh/MeOIT, v/v); [a]²¾ = -137.5 (c 0.12, CHCh); ¾ NMR (600 MHz, CDCb, mixture of rotamers) d 7.16 (d, J= 8.6 Hz, 2H), 6.80 (d, J= 8.6 Hz, 2H), 6.19 (dd, 7= 9.2, 1.2 Hz, 1H), 6.02 (d, 7= 9.3 Hz, 1H), 5.52 (d, 7= 11.6 Hz, 1H), 5.05 (ddd, 7=10.2, 10.2, 4.8 Hz, 1H), 4.89 (dd, 7= 12.7, 2.2 Hz, 1H), 4.79 (ddd, 7=9.2, 9.2, 5.9 Hz, 1H), 4.48 (d, 7= 10.8 Hz, 1H), 4.47 (q, 7= 10.8 Hz, 1H), 4.35 (d, 7= 8.7, 8.7 Hz, 1H), 4.16 (dd, 7= 8.7, 5.9 Hz, 1H), 3.77 (s, 3H), 3.65 (dddd, 7= 10.8, 10.8, 10.8, 2.8 Hz, 1H), 3.32-3.25 (m, 1H), 3.27 (s, 3H), 3.11 (dd, 7= 12.6, 11.2 Hz, 1H), 2.86 (dd, 7= 12.6, 4.8Hz, 1H), 2.79 (s, 3H), 2.71 (s, 3H), 2.42 (dd, 7= 10.2, 6.9 Hz, 1H), 2.39-2.31 (m, 1H), 2.20-2.08 (m, 1H), 1.92 (s, 3H), 1.78 (ddd, 7= 13.0, 13.0, 2.5 Hz, 1H), 1.48-1.43 (m, 2H), 1.44 (d, 7= 7.8 Hz, 3H), 1.29-1.25 (m, 1H), 1.23 (d, 7= 6.7 Hz, 3H), 1.11 (m, 1H), 1.06 (d, 7= 6.9 Hz, 3H), 0.98 (d, 7= 6.6 Hz,

3H), 0.94 (t, 7= 7.8 Hz, 3H), 0.94 (d, 7= 7.8 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (175 MHz, CDCb, mixture of rotamers) d 173.7, 173.0, 172.4, 172.0, 171.5, 171.5, 171.4, 170.4, 170.4, 170.3,

169.9, 169.5, 168.2, 158.6, 139.0, 138.3, 131.5, 130.8, 130.6, 130.5, 129.7, 128.7, 128.5, 128.2,

128.0, 114.0, 113.9, 72.4, 71.8, 70.7, 70.5, 62.7, 62.6, 60.7, 55.8, 55.3, 55.3, 54.6, 54.4, 53.3, 53.0, 50.8, 50.5, 46.3, 46.3, 43.5, 42.7, 39.3, 38.7, 38.4, 37.7, 37.3, 37.1, 36.7, 35.0, 34.9, 33.5,

31.9, 31.6, 31.1, 30.9, 30.4, 30.2, 30.0, 29.8, 29.7, 28.8, 27.0, 26.5, 26.4, 26.1, 25.2, 24.9, 24.4,

24.3, 22.7, 20.2, 19.8, 18.6, 17.4, 15.4, 14.9, 14.8, 14.4, 14.3, 14.1, 14.0, 13.2, 12.3, 9.5, 8.7;

HRMS (ESI) m/z for C45H70N5O9 [M+H]⁺ calcd 812.5168, found 812.5168.

Methyl-(5S,7S,E)-7-((N-(tert-butoxycarbonyl)-N-methyl-L-alanyl)oxy)-2,5,8,8-tetra- methylnon-2-enoate (5.4)

was concentrated under reduced pressure. Purification via flash column chromatography on silica gel (9: 1 to 4: 1 hexanes/EtOAc, v/v) yielded a,b- unsaturated ester 5.4 (81 mg, 90 %) as a colorless, viscous oil.

R/0.48 (6: 1 hexanes/EOAc, v/v); [a]²¾ = -39.1 (c 1.00, CHCh); ¾ NMR (600 MHz, CDCh, mixture of carbamate rotamers) d 6.73 (t, ./ = 6.6 Hz, 1H), 4.92- 4.86 (m, 0.6H), 4.83 (t, J= 4.5 Hz, 1H), 4.76-4.69 (m, 0.4H), 3.73 (s, 1.2H), 3.72 (s, 1.8H), 2.88-2.78 (m, 3H), 2.38-2.30 (m, 1H), 2.07-1.97 (m, 1H), 1.84 (s, 3H), 1.64-1.51 (m, 1H), 1.51-1.38 (m, 4 H), 1.46 (s, 5H), 1.44 (s, 4H), 0.91 (d, J= 5.9 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (150 MHz, CDCh, mixture of carbamate rotamers) d 202.7, 202.4, 201.9, 172.7, 172.4, 172.3, 155.9, 155.8, 155.2, 80.2, 79.9, 78.9, 77.2, 77.0, 76.8, 60.3, 54.2, 54.1, 53.6, 49.3, 49.2, 36.7,

34.6, 34.6, 30.5, 30.3, 29.7, 28.5, 28.3, 28.2, 25.9, 25.8, 25.7, 25.1, 24.9, 21.2, 20.9, 15.7, 15.5, 15.0, 14.9, 14.1;

HRMS (ESI) m/z for C23H_4iNNa0₆ [M+Na]⁺ calcd 450.2826, found 450.2827.

(5S,7S,E)-7-((N-(tert-butoxycarbonyl)-N-methyl-L-alanyl)oxy)-2,5,8,8-tetra-methylnon-2- enoic acid (5.3)

, u w qu w p 3 and the aqueous layer was extracted with EtOAc (5 x 5 mL). The combined organic layers were dried ofNa₂SC>4, filtered, and concentrated under reduced pressure. Purification via flash column chromatography on silica gel (3 : 1 to 1 : 1 hexanes/EtOAc, v/v) produced acid 5.3 (95.4 mg, 81 %) as a white foam.

R/0.17 (2: 1 hexanes/EOAc, v/v); [a]²¾ = -43.6 (c 1.00, CHCh);

¾ NMR (600 MHz, CDCh, mixture of carbamate rotamers) d 6.92-6.85 (m, 1H), 4.94-4.84 (m, 0.5H), 4.86-4.80(m, 1H), 4.77-4.66 (m, 0.5H), 2.82 (d, J= 9.7 Hz, 3H), 2.41-1.31 (m, 1H), 2.14-1.98 (m, 1H), 1.84 (s, 3H), 1.67-1.53 (m, 1.6H), 1.53-1.39 (m, 3H), 1.53-1.32 (m, 3H), 1.45 (s, 9H), 0.90 (d, J= 5.5 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (150 MHz, CDCh) d 173.1, 172.5, 172.4, 172.2, 156.0, 155.4, 143.0, 142.7, 142.6, 130.4, 128.3, 128.1, 80.2, 80.0, 79.4, 79.2, 54.2,

53.5, 36.8,35.6, 34.7, 34.6, 34.1, 30.3, 30.2, 29.9, 29.7, 29.5, 29.3, 28.4, 26.0, 25.9, 20.8, 20.8,

20.5, 15.7, 15.1, 14.9, 12.2;

HRMS (ESI) m/z for CiiftgNNaOe [M+Na]⁺ calcd 436.2670, found 436.2665 allyl N-(N-((S)-2-((6S,9S,HS,13E,17S,18E)-9-(tert-butyl)-17-(hydroxymethyl)- 2,2,5,6,11 4,19-heptamethyl-4,7,15-trioxo-3,8-dioxa-5,16-diazaicosa-13,18-dien-20-amido)- 3-(4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl-L-isoleucinate (5.5)

resulting yellow solution was stirred at 23 °C for 12 h, at which the reaction mixture was concentrated under reduced pressure. Purification via flash column chromatography on silica gel (96:4 CLLCh/MeOH, v/v) gave amide 5.5 (0.571 g, 88 % for 2 steps) as a white foam.

R/0.26 (24: 1 chloroform/MeOH, v/v); [a]²¾ = -46 (c 1.00, CHCh);

¾ NMR (700 MHz, CDCh, mixture of carbamate rotamers) d 7.08 (d, J= 8.5 Hz, 2H), 6.78 (d, J= 8.5 Hz, 2H), 6.61 (d, J= 8.0 Hz, 0.6H), 51 (d, J= 8.4 Hz, 1H), 6.43-6.38 (m, 0.3H), 6.38- 6.23 (m, 0.9H), 6.26 (d, J= 8.7 Hz, 1H), 6.20 (d, J= 8.9 Hz, 0.2H), 5.92-5.72 (m, 1H), 5.50 (dd, J= 6.7, 6.9 Hz, 0.2H), 5.50 (dd, J= 6.7, 6.9 Hz, 0.8H), 5.29 (dd, J= 17.1, 1.3 Hz, 1H), 5.23 (d, J = 10.5 Hz, 1H), 5.23-5.14 (m, 0.8H), 5.10-5.05 (m, 0.2H), 4.93 (d, 7= 10.5 Hz, 1H), 4.887 (d, J = 10.8 Hz, 1H), 4.85-4.76 (m, 1.6H), 4.76-4.66 (m, 0.4H), 4.60 (dd, J= 5.6, 5.8 Hz, 2H), 3.76 (s, 3H), 3.74-3.63 (m, 2H), 3.12-3.09 (m, 1H), 3.04 (dd, J = 13.7, 7.5 Hz, 1H), 2.94 (s, 3H), 2.84 (s, 3H), 2.83-2.79 (m, 2H), 2.72 (s, 3H), 2.30-2.23 (m, 0.5H), 2.23-2.18 (m, 0.5H), 2.05-1.99 (m, 1H), 1.98-1.94 (m, 0.4H), 1.94 (s, 3H), 1.90-1.86 (m, 0.6H), 1.84 (m, 3H), 1.74 (m, 3H), 1.56-1.47 (m, 2H), 1.45 (s, 9H), 1.42 (d, J = 6.5 Hz, 3H), l .30-l .23(m, 1H), 1.26 (d, J= 6.8 Hz, 3H), 1.00-0.97 (m, 1H), 0.96-0.89 (m, 3H), 0.94 (d, J= 6.6 Hz, 3H), 0.86 (s, 9H); ¹³C NMR (175 MHz, CDCh, mixture of carbamate rotamers) d 173.1, 171.8, 171.4, 171.3, 170.7, 170.1,

169.6, 167.8, 167.6, 158.6, 135.3, 135.2, 134.9, 133.7, 132.6, 131.7, 131.5, 131.3., 131.2, 130.5,

130.4, 130.3, 128.3, 127.9, 127.7, 119.9, 118.7, 114.2, 113.9, 80.1, 79.9, 79.7, 79.6, 66.0, 65.5,

65.4, 65.0, 64.6, 63.6, 55.3, 55.2, 55.1, 54.1, 54.0, 53.8, 50.7, 50.6, 50.5, 50.2, 49.9, 49.7, 49.1, 37.8, 37.5, 37.2, 35.1, 34.9, 34.7, 34.4, 33.3, 31.0, 30.9, 30.4, 30.3, 29.9, 29.7, 29.5, 28.4, 25.9,

25.8, 25.0, 22.2, 22.0, 21.8, 16.1, 15.8, 15.7, 15.0, 14.9, 14.4, 13.3, 12.9, 11.6, 10.6, 10.5;

HRMS (ESI) m/z for CsiHsiNsNaO [M+Na]⁺ calcd 992.5930 found 992.5914. allyl N-(N-((S)-2-((E)-3-((S)-2-((5S,7S,E)-7-((N-(tert-butoxycarbonyl)-N-methyl-L- alanyl)oxy)-5,8,8-trimethylnon-2-en-2-yl)-4,5-dihydrooxazol-4-yl)-2-methylacryl-amido)-3- (4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl-L-isoleucinate (5.6)

solid.

R/0.23 (25: 1 CLLCh/MeOH, v/v); [a]²⁵o = -40.0 (c 0.91, CHCh) ;

¾ NMR (700 MHz, CDCh, mixture of carbamate rotamers) 57.08 (d, J= 8.5 Hz, 2H), 6.78 (d, J

= 8.5 Hz, 2H), 6.68-6.62 (m, 0.2H), 6.50-6.45 (m, 0.7H), 6.45-6.40 (m, 0.6H), 6.35 (m, 0.2H), 6.17 (d, J= 8.1 Hz, 0.3H), 6.13 (dd, J= 8.7, 1.2 Hz, 0.5H), 6.06 (dd, J= 8.7, 1.2 Hz, 0.2H), 5.92-5.84 (m, 1H), 5.92-5.84 (m, 0.3H), 5.52 (q, J= 6.7 Hz, 0.2H), 6.17 (qd, J= 6.7, 1.5 Hz, 0.8H), 5.30 (ddd, j= 17.4, 1.4, 1.4 Hz, 1H), 5.22 (ddd, j= 10.6, 1.4, 1.7 Hz, 1H), 5.22-5.18 (m, 1H), 5.12-5.07 (m, 0.3H), 4.97-4.92 (m, 0.5H), 4.94 (d, J= 10.3 Hz, 1H), 4.87-4.81 (m, 1H),

4.76-4.68 (m, 0.5H), 4.63-4.54 (m, 2H), 4.51-4.41 (m, 1H), 4.17 (d, J= 10.3 Hz, 0.2H), 3.96- 3.87 (m, 1H), 3,76 (s, 3H), 3.08-3.02 (m, 1H), 2.98 (s, 3H), 2.87-2.78 (m, 4H), 2.75 (m, 3H), 2.42-2.31 (m, 1H), 1.96 (s, 1.5H), 1.93 (s, 2H), 1.89 (d, J= 5.5 Hz, 2.5H), 1.82 (d, J= 5.5 Hz, 0.5H), 1.49-1.38 (m, 6H), 1.46 (s, 4H), 1.44 (s, 5H), 1.30-1.22 (m, 6H), 1.02-0.96 (m, 2H), 0.93-0.89 (m, 2H), 0.94 (d, J= 6.6 Hz, 3H), 0.88 (s, 9H), 0.86 (d, J= 7.3 Hz, 3H); ¹³C NMR

(175 MHz, CDCh, mixture of carbamate rotamers) d 172.4, 172.3, 172.2, 171.8, 171.8, 171.8, 171.5, 171.4, 171.3, 170.7, 170.5, 169.6, 168.2, 168.1, 166.8, 166.5, 158.9, 158.6, 158.5, 155.9, 155.3, 138.2, 137.2, 136.8, 135.4, 135.1, 133.1, 131.7, 131.7, 131.3, 130.5, 130.4, 130.3, 128.2, 127.9, 125.1, 124.9, 119.9, 118.8, 118.7, 114.2, 114.0, 113.9, 80.1, 279.9, 79.7, 79.6, 79.5, 79.3, 71.9, 71.8, 66.0, 65.5, 65.4, 64.6, 64.0, 63.4, 60.9, 60.5, 55.3, 55.2, 54.1, 53.5, 53.3, 53.0, 50.5,

49.6, 49.1, 39.9, 37.7, 37.3, 36.8, 36.8, 35.2, 35.2, 34.7, 34.5, 33.8, 33.5, 33.3, 31.9, 31.0, 30.9,

30.6, 30.3, 30.2, 20.1, 29.9, 29.8, 29.7, 29.7, 29.6, 29.5, 29.4, 29.1, 28.4, 25.9, 25.9, 25.2, 25.0,

24.8, 22.7, 22.0, 21.0, 20.9, 20.8, 16.1, 15.8, 15.7, 15.4, 15.1, 15.0, 14.4, 14.1, 13.6, 13.5, 13.4,

11.6, 10.6, 10.5;

HRMS (ESI) m/z for CsiHssNsNaO [M+Na]⁺ calcd 952.6005, found 952.6015

Dehydro-Oxazoline apratoxin F (5.1)

To the resulting amine in THF (0.15 mL) at 23 °C was added morpholine (9 pL, 100 pmol), followed by Pd(PPh₃)4 (1.7 mg, 1.5 pmol). After stirring for 30 min at 23 °C, the reaction mixture was concentrated under reduced pressure. The resulting crude solid was azeotropically dried with toluene (2 x 1 mL) and then place under high vacuum for 2 h. The crude amino acid was dissolved in CH2CI2 (10 mL, 0.001 M) and cooled to 0 °C. z-PnNEt (9.1 pL, 52 pmol) and PyAOP (5.2 mg, 10 pmol) were sequentially added and the reaction mixture was stirred at 23 °C for 48 h, at which the reaction mixture was concentrated under reduced pressure. Purification via preparative thin layer chromatography (99: 1 CHCb/MeOH, v/v) yielded cyclic depsipeptide oxa-apratoxin F (3.5 mg, 43 % for 3 steps) as a white

amorphous solid

R/0.21 (25: 1 CFLCh/MeOH, v/v); [a]²⁵o = -140.1 (c 0.01, CHCb);

¾ NMR (600 MHz, CDCb, mixture of rotamers) d 7.18 (dd, J= 8.6, 3.6 Hz, 2H), 6.83 (d, J =

8.6 Hz, 2H), 6.65-6.60 (m, 0.4H), 6.52 (t, J= 6.5 Hz, 0.3H), 6.50-6.45 (m, 0.3H), 6.31 (d, J = 10.0, 1.0 Hz, 0.6H), 6.18 (d, J= 9.6, 0.2H), 6.05 (d, J= 9.3 Hz, 0.2H), 6.00-5.95 (m, 0.2H), 5.47-5.38 (m, 0.4H), 5.37-5.30 (m, 0.6H), 5.20 (d, J= 11.4 Hz, 0.5H), 5.14-5.02 (m, 1H), 4.99- 4.87 (m, 1H), 4.81-4.71 (m, 1H), 4.38 (dd, 7=8.8, 8.8 Hz, 0.3H), 4.38-4.21 (m, 0.7H), 4.05 (dd, J= 8.4, 6.0 Hz, 0.3H), 3.80 (s, 3H), 3.33-3.27 (m, 0.5H), 3.24 (dd, J= 12.3, 10.6 Hz, 0.5H), 3.07 (s, 3H), 2.94 (dd, J= 12.5, 4.6 Hz, 1H), 2.89 (d, J= 4.6, 2H), 2.81 (s, 1H), 2.76 (s, 0.5H), 2.63 (s, 1.5H), 2.48-2.41 (m, 0.5H), 2.40-2.34 (m, 0.5H), 2.20-2.11 (m, 0.5H), 2.11-2.06 (m, 0.5H), 1.96 (s, 1H), 1.93 (d, J= 6.0 Hz, 2H), 1.88 (s, 1.5H), 1.86 (s, 1.0H), 1.84-1.78 (m, 0.5H), 1.76- 1.70 (m, 0.5H), 1.96-1.59 (m, 2H), 1.44 (d, J= 7.8 Hz, 3H), 1.42 (d, J= 7.8 Hz, 1.5H), 1.38 (d, J = 7.8 Hz, 1.5H), 1.35-1.25 (m, 2H), 1.05 (d, J= 6.9 Hz, 1.5H), 1.04-1.01 (m, 2H), 1.00 (d, J = 6.9 Hz, 2H), 0.94 (d, J= 10.8 Hz, 3H), 0.88 (s, 9H), 0.85 (t, J= 7.3 Hz, 3H), 0.82 (d, J= 6.6 Hz, 1H), 0.80-0.76 (m, 1H), 0.74 (d, J= 6.6 Hz, 1H); ¹³C NMR (175 MHz, CDCb, mixture of rotamers) d 172.3, 171.9, 171.7, 171.1, 170.9, 170.3, 170.1, 170.0, 169.5, 169.4, 168.1, 167.7,

167.4, 166.8, 158.6, 158.6, 138.5, 138.2, 136.8, 136.7, 132.1, 130.7, 130.5, 130.4, 129.2, 128.5,

128.4, 124.8, 124.1, 114.0, 113.8, 81.8, 78.1, 78.0, 72.8, 72.1, 71.7, 70.6, 63.4, 62.9, 62.8, 60.2,

56.0, 55.9, 55.8, 55.3, 55.3, 55.2, 55.1, 54.3, 53.4, 52.0, 51.7, 51.0, 50.4, 39.2, 38.5, 37.3, 37.3,

37.1, 36.8, 36.6, 36.5, 35.9, 35.6, 35.0, 35.0, 34.8, 34.1, 33.9, 33.7, 33.4, 33.3, 32.3, 31.9, 31.0,

30.7, 30.4, 30.4, 30.2, 30.0, 30.0, 29.7, 29.6, 29.6, 29.4, 29.4, 29.1, 29.0, 28.9, 28.8, 27.2, 26.7,

26.1, 26.0, 26.0, 25.6, 25.5, 25.1, 23.8, 23.2, 22.7, 21.0, 21.0, 19.1, 15.8, 15.8, 15.6, 15.0, 14.8,

14.7, 14.6, 14.5, 14.2, 13.7, 13.5, 13.3, 13.3, 13.2, 12.6, 11.8, 10.5, 10.1, 9.9;

HRMS (ESI) m/z for C44H68N5O8 [M+H]⁺ calcd 794.5062, found 794.5048. methyl (3S,5S, 7,V)-7-((N-(tert-butoxycarbonyl)-N-methyl-L-alanyl)oxy)-3-hydroxy- 2,2,5,8,8-pentamethylnonanoate (5.7)

, t

5.7 25 which methyl trimethyl silyl dimethylketene acetal (109.0 pL,

1.18 mmol) and aldehyde 3.4 (383.0 mg, 1.074 mmol) were added sequentially at -78 °C. The reaction mixtures were stirred at -78 °C for 3 h, and then quenched by pH=7 buffer (25 mL).

The aqueous layer was extracted with Et20 (30 mL ^c 3), and the combined organic layers were combined, washed with brine (15 mL) and dried with anhydrous MgSCri. Purification via column chromatography silica gel (6: 1 to 3 : 1 hexanes/EtOAc, v/v) was applied to give product as a colorless oil (477.9 mg, 80 %).

R/0.42 (3 : 1 hexanes/EtOAc, v/v); [a]²¾ = -45.8 (c 1.08, CHCh);

¾ NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 4.86-4.82 (m, 0.5H), 4.79 (dd, J = 11.52, 1.60 Hz, 1H), 4.76-4.69 (m, 0.5H), 3.70 (s, 3H), 3.67-3.62 (m, 1H), 2.80 (m, 3H), 2.39-2.33 (m, 0.5H), 2.11 (d, 7 = 8.01 Hz, 0.5H), 1.59-1.55 (m, 2H), 1.47-1.42 (m, 9H), 1.42- 1.38 (m, 3H), 1.20-1.13 (m, 6H), 0.92 (d, J= 6.7 Hz, 3H), 0.88 (s, 9H); ¹³C NMR (150 MHz, CDCb, mixture of carbamate rotamers) d 178.2, 177.7, 173.3, 173.2, 173.1, 156.1, 155.8, 155.4,

155.3, 80.5, 80.3, 80.1, 80.0, 79.9, 79.5, 79.2, 19.0, 28.9, 73.9, 73.8, 54.4, 54.1, 53.7, 53.5, 51.8, 51.7, 47.5, 47.4, 37.6, 37.5, 37.4, 37.3, 37.2, 34.9, 34.5, 34.4, 30.7, 30.3, 29,9, 29.8, 29.7, 28.4,

28.3, 27.9, 26.0, 25.9, 25.7, 25.5, 21.5, 21.3, 21.2, 21.1, 21.0, 20.9, 20.8, 20.7, 15.7, 15.5, 15.0, 14.9;

HRMS (ESI) m/z for C24H₄₅NNa07 [M+Na]⁺ calcd 482.3088, found 482.3081.

(3S,5S, 7,V)-7-((N-(tert-butoxycarbonyl)-N-methyl-L-alanyl)oxy)-3-hydroxy-2,2,5,8,8- pentamethylnonanoic acid (5.8)

3

acidified to pH = 3. The aqueous layer was extracted with EtOAc (5 x 30 mL) and the combined organic layers were washed with brine, dried over Na2S0₄, filtered, and concentrated.

Purification via flash column chromatography on silica gel (25: 1 CH2Cb/MeOH, v/v) gave b- hydroxy acid 5.8 (313.4 mg, 72%) as a white foam.

R/0.41 (10: 1 OLCb/MeOH, v/v); [a]²⁵o = -36.6 (c 0.96, CHCb);

¹H NMR (600 MHz, CDCb, mixture of carbamate rotamers) d 4.86-4.78 (m, 1H); 4.73 (q, J = 13 Hz, 1H), 3.68 (ddd, J= 10.8, 10.8, 1.1 Hz, 1H), 2.84 (s, 3H), 1.65-1.61 (m, 1H), 1.48 (s,

9H), 1.46-1.41 (m, 3H), 1.39-1.30 (m, 1.5H), 1.28-1.26 (m, 0.5H), 1.23 (s, 3H), 1.19 (d, 7= 7.5 Hz, 3 H), 1.14-1.05 (m, 1H), 0.95 (d, J= 6.8 Hz, 3H), 0.89 (s, 9H); ¹³C NMR (175 MHz, CDCb, mixture of carbamate rotamers) d 181.0, 180.8, 180.3, 180.0, 174.0, 173.4, 156.5, 156.2, 155.4,

80.5, 80.4, 80.1, 79.8, 79.2, 79.1, 74.3, 74.2, 54.5, 54.3, 54.1, 46.7, 37.7, 37.5, 37.4, 37.2, 37.1,

34.6, 31.2, 30.9, 28.5, 26.1, 26.0, 25.9, 25.7, 22.3, 21.8, 21.6, 21.2, 21.1, 21.0, 20.9, 15.8, 15.6, 15.1, 15.8, 15.6, 15.1;

HRMS (ESI) m/z for CiiH^NNaO? [M+Na]⁺ calcd 468.2932, found 468.2945. allyl N-(N-((S)-2-((6S,9S,llS,13S,17S,E)-9-(tert-butyl)-13-hydroxy-17-(hydroxy-methyl)- 2,2,5,6,11 4,14,19-octamethyl-4,7,15-trioxo-3,8-dioxa-5,16-diazaicos-18-en-20-amido)-3-(4- methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl-L-isoleucinate (5.9)

amino alcohol in CH2CI2 (4 mL) was added. The resulting yellow solution was stirred at 23 °C for 12 h, at which the reaction mixture was concentrated under reduced pressure. Purification via flash column chromatography on silica gel (25: 1 CLLCh/MeOH, v/v) gave amide 5.9 (0.483 g, 71 % for 2 steps) as a white foam.

R/0.26 (25: 1 CLLCh/MeOH, v/v); [a]²⁵o = -54.6 (c 0.13, CHCh);

¾ NMR (700 MHz, CDCh, mixture of carbamate rotamers) d 7.08 (d, J= 8.5 Hz, 2H), 6.78 (d, J= 8.5 Hz, 2H), 6.49 (d, J= 8.2 Hz, 1H), 6.34-6.20 (m, 1H), 5.92-5.83 (m, 1H), 5.40 (q, J= 6.9 Hz, 1H), 5.30 (dd, j= 17.0, 1.4 Hz, 1H), 5.23 (dd, j= 10.5, 1.4 Hz, 1H), 5.20 (qd, j= 8.2, 1.5 Hz, 1H), 4.94 (d, J= 10.4 Hz, 1H), 4.86-4.79 (m, 1H), 4.79-4.65 (m, 2H), 4.63-4.56 (m, 2H), 3.76 (s, 3H), 3.75-3.68 (m, 1H), 3.63-3.56 (m, 1H), 3.55-3.47 (m, 1H), 3.47-3.39 (m, 1H), 3.08-3.01 (m, 1H), 2.94 (s, 3H), 2.89-2.84 (m, 1H), 2.82 (s, 3H), 2.72 (s, 3H), 2.00-1.94 (m, 1H), 1.92 (s, 3H), 1.82-1.71 (m, 1H), 1.71-1.63 (m, 1H), 1.61-1.50 (m, 3H), 1.45 (s, 9H), 1.43 (d, J= 7.5 Hz, 3H), 1.37 (t, J= 12.7 Hz, 1H), 1.30-1.24 (m, 4H), 1.24-1.18 (m, 3H), 1.15-1.07 (m, 3H), 1.05-0.96 (m, 2H), 0.94 (d, J= 6.6 Hz, 3H), 0.91 (d, J= 6.6 Hz, 3H), 0.89 (s, 9H), 0.86 (d, J= 7.5 Hz, 3H); ¹³C NMR (175 MHz, CDCh,, mixture of carbamate rotamers) d 178.3,

178.1, 173.6, 173.4, 172.0, 171.5, 170.8, 167.9, 167.8, 158.8, 156.4, 134.1, 133.7, 132.6, 132.3, 131.9, 130.6, 128.1, 120.0, 118.8, 114.1, 80.5, 80.0, 79.1, 79.0, 75.4, 75.2, 65.5, 60.6, 55.3, 54.5, 54.2, 50.7, 49.8, 46.2, 37.9, 37.7, 37.4, 36.9, 34.7, 34.6, 33.4, 31.3, 31.1, 30.7, 30.1, 28.6, 26.2,

26.1, 25.7, 25.2, 25.2, 24.4, 15.9, 15.1, 14.6, 13.5, 10.8;

HRMS (ESI) m/z for CssHsTNsNaOii [M+Na]⁺ calcd 1024.6193, found 1024.6175. allyl N-(N-((S)-2-((E)-3-((S)-2-((3S,5S,7S)-7-((N-(tert-butoxycarbonyl)-N-methyl -L- alanyl)oxy)-3-hydroxy-2,5,8,8-tetramethylnonan-2-yl)-4,5-dihydrooxazol-4-yl)-2- methylacrylamido)-3-(4-methoxyphenyl)propanoyl)-N-methyl-L-alanyl)-N-methyl-L- isoleucinate (5.10)

15 amorphous solid.

R/0.18 (25: 1 CLLCh/MeOH, v/v); [a]²⁵o = -89.6 (c 0.50, CHCh) ;

¾ NMK (700 MHz, CDCh, mixture of carbamate rotamers) d 7.08 (d, J= 8.5 Hz, 2H), 6.78 (d, J= 8.5 Hz, 2H), 6.44 (d, J= 8.2 Hz, 1H), 6.15 (d, J= 8.2 Hz, 1H), 5.92-5.83 (m, 1H), 5.41 (q, j = 6.9 Hz, 1H), 5.30 (dd, J= 17.0, 1.4 Hz, 1H), 5.23 (dd, J= 10.5, 1.4 Hz, 1H), 5.21 (q, J= 6.8 Hz, 1H), 4.94 (d, J= 10.4 Hz, 1H), 4.92-4.88 (m, 1H), 4.88-4.84 (m, 1H), 4.80 (d, J= 10.0 Hz, 1H), 4.63-4.56 (m, 2H), 4.43-4.36 (m, 1H), 3.91-3.84 (m, 1H), 3.76 (s, 3H), 3.67-3.58 (m, 1H), 3.09-3.02 (m, 1H), 2.98 (s, 3H), 2.89-2.84 (m, 1H), 2.85-2.78 (m, 3H), 2.76 (s, 3H), 2.00-1.94 (m, 1H), 1.88 (s, 3H), 1.70-1.63 (m, 1H), 1.59-1.49 (m, 2H), 1.45 (s, 9H), 1.41 (d, J= 7.5 Hz, 3H), 1.38-1.32 (m, 1H), 1.31-1.24 (m, 4H), 1.23-1.16 (m, 6H), 1.02-0.96 (m, 2H), 0.95 (d, J = 6.6 Hz, 3H), 0.92 (d, J= 6.6 Hz, 3H), 0.89 (s, 9H), 0.86 (d, J= 7.5 Hz, 3H); ¹³C NMR (175

MHz, CDCh,, mixture of carbamate rotamers) d 178.3, 178.1, 173.3, 171.9, 171.5, 170.8, 167.8, 158.8, 156.3, 133.7, 132.7, 132.6, 131.8, 130.5, 130.4, 128.1, 120.0, 118.8, 114.0, 80.5, 79.1, 79.0, 75.3, 75.2, 65.5, 65.0, 60.6, 55.3, 54.5, 54.2, 47.6, 46.2, 37.9, 37.4, 36.9, 34.7, 34.6, 33.4, 31.1, 30.7, 28.6, 28.5, 28.5, 26.2, 26.1, 25.7, 25.2, 24.3, 21.0, 20.7, 20.6, 15.9, 15.2, 14.6, 13.5, 10.8;

HRMS (ESI) m/z for CsiHseNsO [M+H]⁺ calcd 984.6267, found 984.6239. Oxazoline dimethyl-apratoxin F (5.2)

high vacuum for 1 h to remove the residual 2,64utidine.

To a solution of above crude trimethyl silyl ether in THF (0.5 mL) at 0 °C, tetrabutylammonium fluoride (54 pL, 54 pmol, 1 M solution in THF) was added and the reaction was stirred at 0 °C for 30 min. The reaction was quenched with saturated aqueous NaHCCh (0.2 mL) at 0 °C and the mixture was warmed to 23 °C. The aqueous layer was extracted with CH2CI2 (10 x 1 mL) and the combined organic layers were dried over Na2S0₄, filtered, and concentrated under reduced pressure.

To a solution of above crude amine in THF (0.15 mL) at 23 °C, morpholine (13 pL, 150 pmol) and Pd(PPh₃)₄ (2.5 mg, 1.8 pmol) was added sequencially and the reaction was stirred at 23 °C for 30 min. The crude residue was concentrated under reduced pressure and azeotropically dried with toluene (2 x 0.5 mL) and then place under high vacuum for 2 h.

To a solution of above crude linear precursor in CH2CI2 (20 mL, 0.001 M) at 0 °C, z-PnNEt (9.1 pL, 52 pmol) was added, followed by PyAOP (9.3 mg, 17.9 pmol). After stirring at 23 °C for 48 h, the reaction mixture was concentrated under reduced pressure. Purification via preparative thin layer chromatography (50: 1 CftCh/MeOH, v/v) yielded cyclic depsipeptide oxa-apratoxin F (5.7 mg, 39 % for 4 steps) as a white amorphous solid.

R/0.19 (25: 1 CTLCL/MeOH, v/v); [a]²⁵o = -63.7 (c 0.50, CHCh);

¾ NMR (700 MHz, CDCh, mixture of rotamers) d 7.14 (d, J= 8.6 Hz, 2H), 6.80 (d, J= 8.6 Hz, 2H), 6.26 (dd, j= 10.4, 1.0 Hz, 1H), 6.25 (d, j= 9.2 Hz, 1H), 5.35 (ddd, 7=10.2, 10.2, 4.4 Hz, 1H), 5.23 (d, J= 11.6 Hz, 1H), 4.86 (dd, J= 12.2, 3.7 Hz, 1H), 4.82 (q, 7=7.7 Hz, 1H), 4.74 (q,

7= 6.7 Hz, 1H), 4.41-4.34 (m, 1H), 4.34-4.30 (m, 0.4H), 4.43-4.36 (m, 0.6H), 4.08 (dd, 7= 8.0, 6.7 Hz, 0.4H), 4.03-3.98 (m, 0.6H), 3.90-3.81 (m, 1H), 3.77 (s, 3H), 3.21 (dd, 7= 12.7, 10.1, 1H), 3.11 (s, 3H), 2.91 (s, 1H), 2.90-2.86 (m, 1H), 2.79 (s, 3H), 2.59 (s, 2H), 2.14-2.08 (m, 1H), 2.02-1.95 (m, 1H), 1.93 (d, 7= 1.3, 3H), 1.83-1.77 (m, 1H), 1.49-1.43 (d, 7= 7.8 Hz, 3H), 1.35-1.28 (m, 3H), 1.27 (d, J= 6.8 Hz, 3H), 1.12 (s 3H), 1.08 (s, 1H), 1.03 (d, J= 6.8 Hz, 3H), 0.99-0.96 (m, 2H), 0.97 (d, J= 6.5 Hz, 3H), 0.88 (s, 9H), 0.82(t, J= 7.4 Hz, 3H), 0.65 (d, J= 6.5 Hz, 3H); ¹³C NMR (175 MHz, CDCb, mixture of rotamers) d 173.5, 172.6, 172.5, 172.2, 171.1, 170.5, 170.3, 169.8, 169.6, 168.3, 158.8, 158.7, 130.8, 130.6, 128.7,128.6, 114.2, 113.9, 77.9, 73.4, 72.8, 72.7, 56.3, 55.7, 55.5, 55.4, 55.0, 54.4, 52.9, 50.3, 42.6, 39.5, 38.2, 37.2, 35.2, 35.2, 24.7, 34.3, 33.8, 33.6, 30.8, 20.0, 29.8, 29.0, 26.3, 26.2, 25.5, 25.0, 24.2, 23.5, 23.3, 20.6, 20.3, 18.2, 17.1, 15.6, 15.1, 15.0, 14.5, 14.2, 14.0, 13.6, 12.8, 10.6, 9.7;

HRMS (ESI) m/z for C45H71N5O9 [M+H]⁺ calcd 826.5325, found 826.5304.

The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated. The term“comprising” and variations thereof as used herein is used synonymously with the term“including” and variations thereof and are open, non-limiting terms. Although the terms“comprising” and“including” have been used herein to describe various embodiments, the terms“consisting essentially of’ and “consisting of’ can be used in place of“comprising” and“including” to provide for more specific embodiments of the invention and are also disclosed. Other than in the examples, or where otherwise noted, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood at the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches

Claims

CLAIMS What is claimed is:

1. An apratoxin analog of Formula (1):

Formula (1), or a pharmaceutically acceptable salt thereof, wherein

R^m is selected from hydrogen, Ci-salkyl, Ci-xalkenyl, Ci-xalkynyl, aryl, heteroaryl, C3-8cycloalkyl, Ci-8heteroaryl; -(CFbCFbOjn-Q, wherein n is an integer selected from 0-300, and Q is a protein conjugating moiety;

X¹ is selected from O, S, and N-R^x, wherein R^x is selected from hydrogen, Ci-salkyl, Ci-xalkenyl, C2-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

X² is selected from O and S;

X³ is a group of the formula -(CR^10aR^10b)m-, wherein m is selected from 0-6;

R¹ is selected from hydrogen, Ci-salkyl, Ci-xalkenyl, C 2-sal kynyl, aryl, heteroaryl, C3-scycloalkyl, and Ci-sheteroaryl;

R^2a is selected from ^ar;

C(0)OR^2ar, OCOR²

cyano, and nitro, wherein R^2ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-scycloalkyl, or Ci-sheterocyclyl;

C(0)OR^2br, OC(0)R^2br; C(0)N(R^2bt)2, 0C(0)N(R^2br)2, N(R^2br)C(0)N(R^2br)2, F, Cl, Br, I, cyano, and nitro, wherein R^2br is in each case independently selected from hydrogen, Ci-salkyl, C2- 8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-scycloalkyl, or Ci-sheterocyclyl; or R^2a and R^2b together form a carbonyl, an imine of formula (=N R^abr), or olefin of formula

(=CR^2arR^2br);

R³ is selected from hydrogen, Ci-salkyl, C2-salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3- scycloalkyl, or Ci-sheterocyclyl;

R^4a is selected from ^r;

C(0)0R^4ar, OCOR⁴

cyano, and nitro, wherein R^4ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^4b is selected from

C(0)0R^4br, OCOR⁴

cyano, and nitro, wherein R^4br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^5ais selected from R^5ar, OR^5ar, N(R^5ar)2, SiR^5ar ₃, SR^5ar, S0₂R^5ar, S0₂N(R^5ar)2, C(0)R^5ar;

C(0)0R^5ar, OCOR^5ar; C(0)N(R^5ar)2, 0C(0)N(R^5ar)2, N(R^5ar)C(0)N(R^5ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^5ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^5b is selected from R^5br, OR^5br, N(R^5br)2, SiR^5br ₃, SR^5br, S0₂R^5br, S0₂N(R^5br)2, C(0)R^5br;

C(0)0R^5br, OCOR^5br; C(0)N(R^5br)2, 0C(0)N(R^5br)2, N(R^5br)C(0)N(R^5br)2, F, Cl, Br, I, cyano, and nitro, wherein R^5br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^5br);

R^6a is selected from R^6ar, OR^6ar, N(R^6ar)2, SiR^6ar ₃, SR^6ar, S0₂R^6ar, S0₂N(R^6ar)2, C(0)R^6ar;

C(0)0R^6ar, OCOR^6ar; C(0)N(R^6ar)2, 0C(0)N(R^6ar)2, N(R^6ar)C(0)N(R^6ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^6ar is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^6b is selected from R^6br, OR^6br, N(R^6br)2, SiR^6br ₃, SR^6br, S0₂R^6br, S0₂N(R^6br)2, C(0)R^6br;

C(0)0R^6br, OCOR^6br; C(0)N(R^6br)2, 0C(0)N(R^6br)2, N(R^6br)C(0)N(R^6br)2, F, Cl, Br, I, cyano, and nitro, wherein R^6br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^6a and R^6b together form a carbonyl, an imine of formula (=NR^6ar), or olefin of formula (=CR^6arR^6br); R^7a is selected from R^7ar, OR^7ar, N(R^7ar)2, SiR^7ar ₃, SR^7ar, S0₂R^7ar, S0₂N(R^7ar)2, C(0)R^7ar;

C(0)0R^7ar, OCOR^7ar; C(0)N(R^7ar)₂, 0C(0)N(R^7ar)₂, N(R^7ar)C(0)N(R^7ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^7ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^7b is selected from R^7br, OR^7br, N(R^7br)₂, SiR^7br3, SR^7br, S0₂ R^7br, S0₂N(R^7br)₂, C(O) R^7br; C(0)0 R^7br, OCO R^7br, C(0)N(R^7br)₂, 0C(0)N(R^7br)₂, N(R^7bt)C(0)N(R^7br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^7br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^8a is selected from R^8ar, OR^8ar, N(R^8ar)₂, SiR^8ar ₃, SR^8ar, S0₂R^8ar, S0₂N(R^8ar)₂, C(0)R^8ar;

C(0)0R^8ar, OCOR^8ar, C(0)N(R^8ar)₂, 0C(0)N(R^8ar)₂, N(R^8ar)C(0)N(R^8ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^8ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^8b is selected from R^8br, OR^8br, N(R^8br)₂, SiR^8br ₃, SR^8br, S0₂R^8br, S0₂N(R^8br)₂, C(0)R^8br;

C(0)0R^8br, OCOR^8br, C(0)N(R^8br)₂, 0C(0)N(R^8br)₂, N(R^8br)C(0)N(R^8br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^8br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^9a is selected from R^9ar, OR^9ar, N(R^9ar)₂, SiR^9ar ₃, SR^9ar, S0₂R^9ar, S0₂N(R^9ar)₂, C(0)R^9ar;

C(0)0R^9ar, OCOR^9ar, C(0)N(R^9ar)₂, 0C(0)N(R^9ar)₂, N(R^9ar)C(0)N(R^9ar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^9ar is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^9b is selected from R^9br, OR^9br, N(R^9br)₂, SiR^9br ₃, SR^9br, S0₂R^9br, S0₂N(R^9br)₂, C(0)R^9br;

C(0)0R^9br, OCOR^9br, C(0)N(R^9br)₂, 0C(0)N(R^9br)₂, N(R^9br)C(0)N(R^9br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^9br is in each case independently selected from hydrogen, Ci-salkyl, C₂- salkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^10a, when present, is in each case independently selected from R^10a, OR^10a, N(R^10a)₂, SiR^10a3, SR^10a, SO₂R^10a, SO₂N(R^10a)₂, C(O)R^10a; C(O)OR^10a, OCOR^10a, C(O)N(R^10a)₂, OC(O)N(R^10a)₂, N(R^10a)C(O)N(R^10a)₂, F, Cl, Br, I, cyano, and nitro, wherein R^10a is in each case independently selected from hydrogen, C i-xalkyl, C₂-xalkenyl, C₂-xalkynyl, aryl, Ci-xheteroaryl, C3-8cycloalkyl, or Ci-8heterocyclyl;

R^10b, when present, is in each case independently selected from R^10br, OR^10br, N(R^10br)2, SiR^10br3, SR^10br, SO₂R^10br, SO₂N(R^10br)2, C(O)R^10br; C(O)OR^10br, OCOR^10br, C(O)N(R^10br)₂,

OC(O)N(R^10br)₂, N(R^10br)C(O)N(R^10br)₂, F, Cl, Br, I, cyano, and nitro, wherein R^10br is in each case independently selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci- sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

R^lla is selected from R^llar, OR^llar, N(R^llar)₂, SiR^llar ₃, SR^llar, S0₂R^llar, S0₂N(R^llar)₂, C(0)R^llar; C(0)0R^llar, OCOR^llar, C(0)N(R^llar)₂, 0C(0)N(R^llar)₂, N(R^llar)C(0)N(R^llar)₂, F, Cl, Br, I, cyano, and nitro, wherein R^llar is in each case independently selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^llb is selected from

C(0)0R^llbr, OCOR^l

cyano, and nitro, wherein R^llbr is in each case independently selected from hydrogen, Ci-salkyl, C₂-8alkenyl, C₂-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

2. The apratoxin analog of claim 1, wherein Q comprises biotin.

3. The apratoxin analog of either of claim 1 or 2, wherein m is 0.

4. The apratoxin analog of either of claim 1 or 2, wherein m is 1.

5. The apratoxin analog of claim 4, wherein R^10a and R^10b are each hydrogen.

6. The apratoxin analog of any of claims 1-5, wherein R^8a, R^8b, R^9a, and R^9b are each hydrogen.

7. The apratoxin analog of any of claims 1-5, wherein R^8a and R^9b together form an (E) olefin.

8. The apratoxin analog of any of claims 1-5 or 7, wherein R^9a is Ci-salkyl.

9. The apratoxin analog of claim 8, wherein R^9a is methyl.

10. The apratoxin analog of any of claims 1-9, wherein R^6a, R^6b, R^7a, and R^8b are each hydrogen.

11. The apratoxin analog of any of claims 1-9, wherein R^6b and R^7a together form an (E) olefin.

12. The apratoxin analog of any of claims 1-9 or 11, wherein R^7b is Ci-salkyl.

13. The apratoxin analog of claim 12, wherein R ^b is methyl.

14. The apratoxin analog of any of claims 1-9 or 12-13, wherein R^7a is Ci-salkyl.

15. The apratoxin analog of claim 14, wherein R^7a is methyl.

16. The apratoxin analog of any of claims 1-9 or 12-15, wherein R^6b is OR and R^6a is hydrogen.

17. The apratoxin analog of claim 16, wherein R^6b is OH or O-Ci-salkyl.

18. The apratoxin analog of any of claims 1-9 or 12-15, wherein R^6a is OR and R^6b is hydrogen.

19. The apratoxin analog of claim 18, wherein R^6a is OH or O-Ci-salkyl.

20. The apratoxin of any of claims 1-19, wherein R^5a is Ci-xalkyl and R^5b is hydrogen.

21. The apratoxin analog of claim 20, wherein R^5a is methyl.

22. The apratoxin of any of claims 1-19, wherein R^5b is Ci-xalkyl and R^5a is hydrogen.

23. The apratoxin analog of claim 22, wherein R^5b is methyl.

24. The apratoxin analog of any claims 1-23, wherein R^4a and R^4b are each hydrogen

25. The apratoxin analog of any of claims 1-23, wherein R³ and R^4b together form a ring; and

R^4a is hydrogen Ci-xalkyl or hydrogen.

26. The apratoxin analog of any of claims 1-25, wherein R³ and R^4b together form a five- membered ring.

27. The apratoxin analog of claim 25 or 26, wherein R^4a is hydrogen.

28. The apratoxin analog of any of claims 1-23, wherein R³ and R^4a together form a ring; and

R^4b is hydrogen Ci-xalkyl or hydrogen.

29. The apratoxin analog of claim 28, wherein R³ and R^4a together form a five-membered ring.

30. The apratoxin analog of claim 28 or 29, wherein R^4b is hydrogen.

31. The apratoxin analog of any of claims 1-24, wherein R³ is Ci-xalkyl or hydrogen.

32. The apratoxin analog claim 31, wherein R³ is methyl.

33. The apratoxin analog of any of claims 1-32, wherein X¹ is O.

34. The apratoxin analog of any of claims 1-32, wherein X¹ is NR^X.

35. The apratoxin analog of claim 34, wherein X¹ is NH or NCi-xalkyl.

36. The apratoxin analog of any of claims 1-35, wherein R^2a is Ci-xalkyl and R^2b is hydrogen.

37. The apratoxin analog of claim 36, wherein R^2a is C2-4 alkyl.

38. The apratoxin analog of claim 37, wherein R^2a is (2S)-but-2-yl or 2-prop-2-yl.

39. The apratoxin analog of any of claims 1-38, wherein R^2b is Ci-xalkyl and R^2a is hydrogen.

40. The apratoxin analog of claim 36, wherein R^2b is C2-4 alkyl.

41. The apratoxin analog of claim 37, wherein R^2b is (2S)-but-2-yl or prop-2-yl.

42. The apratoxin analog of any of claims 1-41, having the structure:

wherein p is an integer from 0-10; X^4a is selected from chemical bond, -C(=0)0-, -C(=0)NH- and -C(=0)-; and X^4b is selected from chemical bond, -0C(=0)-, -NC(=0)-, and -C(=0)-.

43. The apratoxin analog of any claims 1-42, wherein R^llb is hydrogen and R^lla is selected from Ci-salkyl, wherein said alkyl group is unsubstituted or substituted one or more times with OR^z, -OSCkR², COOR^z, N3, an alkynyl; COR^zl; F, Cl, Br, I, or cyano, wherein R^z is Ci-xalkyl or aryl, optionally substituted with one or more electron withdrawing groups, and R^zl is selected from F, Cl, Br, H, Ci-salkyl, and aryl.

44. An apratoxin analog having the formula:

or a pharmaceutically acceptable salt thereof, wherein

R^m is selected from hydrogen, Ci-salkyl, CAxalkenyl, CAxalkynyl, aryl, heteroaryl, C3-8cycloalkyl, Ci-sheteroaryl; -(CH2CH₂0)n-Q, wherein n is an integer selected from 0-300, and Q is a protein conjugating moiety;

A is selected from Ci-salkyl or aryl;

X¹ is selected from O, S, and N-R^x, wherein R^x is selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-8alkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

X² is selected from O and S;

R^2b is selected from R^2br, OR^2br, N(R^2br)2, SiR^2br ₃, SR^2br, S0₂R^2br, S0₂N(R^2br)2, C(0)R^2br;

C(0)0R^2br, 0C(0)R^2br; C(0)N(R^2br)2, 0C(0)N(R^2br)2, N(R^2br)C(0)N(R^2br)2, F, Cl, Br, I, cyano, and nitro, wherein R^2br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R³ is selected from hydrogen, Ci-salkyl, C2-8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3- scycloalkyl, or Ci-sheterocyclyl;

C(0)0R^4br, OCOR^4br, C(0)N(R^4br)2, 0C(0)N(R^4br)2, N(R^4br)C(0)N(R^4br)2, F, Cl, Br, I, cyano, and nitro, wherein R^4br is in each case independently selected from hydrogen, Ci-salkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl;

R^7a is selected from R^7ar, OR^7ar, N(R^7ar)2, SiR^7ar3, SR^7ar, S0₂R^7ar, S0₂N(R^7ar)2, C(0)R^7ar;

C(0)0R^7ar, OCOR^7ar; C(0)N(R^7ar)2, 0C(0)N(R^7ar)₂, N(R^7ar)C(0)N(R^7ar)2, F, Cl, Br, I, cyano, and nitro, wherein R^7ar is in each case independently selected from hydrogen, Ci-salkyl, C2- 8alkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; R^7b is selected from R^7br, OR^7br, N(R^7br)2, SiR^7br ₃, SR^7br, SO2 R^7br, S0₂N(R^7br)2, C(O) R^7br; C(0)0 R^7br, OCO R^7br, C(0)N(R^7br)2, 0C(0)N(R^7br)2, N(R^7br)C(0)N(R^7br)2, F, Cl, Br, I, cyano, and nitro, wherein R⁷¹⁵¹ is in each case independently selected from hydrogen, C i-xalkyl, C2- salkenyl, C2-salkynyl, aryl, Ci-sheteroaryl, C3-8cycloalkyl, or Ci-sheterocyclyl; or

45. The apratoxin analog of claim 44, having the structure:

46. The apratoxin analog of claim 44, having the structure:

wherein X⁵ is -(0¾)r-, wherein p is selected from 0-10.

47. The apratoxin analog of any of claims 44-46, wherein R^7a and R^7b together form a cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl ring.

48. The apratoxin analog of any of claims 44-46, wherein R^7a and R^7b are independently selected from hydrogen, S1R3, or Ci-₆alkyl, wherein said Ci-₆alkyl group may be substituted one or more times with groups independently selected from aryl, heteroaryl, heterocycle, cycloalkyl, or halogen.

49. The apratoxin analog of any of claims 44-48, wherein R³ and R^4b together form a five- membered or six-membered ring.

50. The apratoxin analog of any of claims 44-48, wherein R³ and R^4b are independently selected from hydrogen or Ci-₆alkyl.

51. The apratoxin analog of any of claims 44-48, wherein R³ and R^4b are each methyl.

52. The apratoxin analog of any of claims 44-51, wherein R^2b and R³ together form a five- membered or six-membered ring.

53. The apratoxin analog of any of claims 44-51, wherein R^2b is a Ci-₆alkyl group.

54. The apratoxin analog of any of claims 44-51, wherein R^2b is selected from methyl, ethyl, prop-2-yl, prop-l-yl, n-but-l-yl, (S)-but-2-yl, and tert-butyl.

55. The apratoxin analog of any of claims 44-54, wherein R^lla is selected from Ci-₆alkyl, halogen, OR, SO2R, C(0)R; C(0)0R, F, Cl, Br, I, and cyano.

56. The apratoxin analog of any of claims 44-55, wherein R^lla is a Ci-₆alkyl group, substituted one or more times with a group independently selected from halogen, OR, SO2R, C(0)R; C(0)0R, F, Cl, Br, I, and cyano.

57. The apratoxin analog of any of claims 44-56, wherein R^7b is Si(CH3)3.