WO2000034253A2 - Intermediates and reaction sequence to produce said intermediates useful for the preparation of antineoplastic and antifungal cryptophycin derivatives - Google Patents

Abstract

A process for preparing a compound of the formula (I) wherein G is (C1-C12) alkyl, (C2-C12) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R3 is (C¿1?-C6) alkyl; R?p1¿ is trityl or a suitable silyl protecting group; Rp2 is hydrogen or a suitable carboxy protecting group; and LG is a suitable hydroxy activating group; or a pharmaceutically acceptable salt thereof, useful in the preparation of cryptophycin derivatives. The processes involve an asymmetric crotylboration and, in the preferred embodiment, a subsequent asymmetric allylboration, providing for an efficient method for preparing Fragment A of the cryptophycin molecule. Also disclosed are novel intermediates useful for preparing cryptophycin compounds.

Description

CROTYLBORATION PROCESS TO PRODUCE ANTINEOPLASTIC AND

ANTIFUNGAL AGENTS Cryptophycins are generally 16-membered despipeptides . They were isolated initially from the blue- green algae (cyanobacterium) Nostoc sp . GSV 224; Trimurtulu, G. et al., J. Am. Chem. Soc. 116, 4729 (1994); Schwartz, R.E. et al., J. Ind. Microbiol. 5, 113 (1990). These compounds have been shown to be highly cytotoxic and have displayed very potent in vi tro cytotoxicity against several human tumor cell lines. Cryptophycin derivatives inhibit tubulin polymerization into icrotubules ; Smith, CD. et al . , Cancer Res . 54, 3779 (1994) . Based on in vi tro and in vivo data, primary activity for some cryptophycin derivatives reside in the presence of benzylic epoxide structure in the molecule; Trimurtulu, G. et al . , supra . ; Trimurtulu, G. et al . , J. Am. Chem. Soc. , 117, 12030 (1995). In recent years several syntheses of cryptophycin derivatives have been reported in the literature; Barrow, R.A. et al., J. Am. Chem. Soc. 117, 2479 (1995); Reg, R. et al., J. Org. Chem. 61, 6289 (1996); Sala onczyk, G.M. et al., J. Org. Chem. 61, 6893 (1996); Ali, S.M. et al . , Tetrahedron Lett. 38, 1703 (1997); Leahy, J.W. et al . , J. Org. Chem. 62, 7098 (1997). Moreover, several total synthetic methods of making cryptophycin compounds are reported in the patent literature. See, for example, PCT Intnl. Publ. No. WO 97/07798, published March 6, 1997, PCT Intnl. Publ. No. WO 96/40184, published December 19, 1996, and PCT Intnl. Publ. No. WO 97/23211, published July 3, 1997.

However, even in light of these references, there remains a need for a direct and convenient method for the synthesis of a benzylic epoxide moiety of the cryptophycin derivatives. Recently, Leahy, J.W. et al . , supra, reported the synthesis of cryptophycin A using an asymmetric aldol reaction. Although this protocol provides the desired benzylic epoxide, this involves a multistep reaction for the construction of the desired benzylic epoxide assembly.

The present invention discloses highly efficient, general methods employing at least one and preferably two double asymmetric syntheses for the synthesis of cryptophycin compounds. The first synthesis involves an asymmetric crotylboration for the generation of a benzylic epoxide assembly, while the second synthesis utilizes an asymmetric allylboration to further elaborate the synthesis of cryptophycin compounds.

Retrosynthetic analysis of Cryptophycin 52 is straightforward, providing four convenient subunits, i.e. fragments A to D . The fragments, B, C and D, are conveniently and efficiently synthesized from the commercially available compounds such as D-tyrosine, ( S) - (-) -leucine, and ethylcyanoacetate, respectively, in 2 to 6- steps. However, the synthesis of fragment A is quite challenging.

The present invention provides a novel enantioselective synthetic route for fragment A starting from ( R) - (-) -mandelic acid. The asymmetric crotylboration and allylboration reactions are performed using enantiomerically pure boron reagents which are readily synthesized from easily accessible and economical chiral (+) -3-carene .

The present invention relates to a process for the preparation of a compound of the formula

wherein

G is (C1-C12) alkyl, (C2-C12) alkenyl , (C2-C12) alkynyl, or Ar;

Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group;

R³ is (Ci-Cs) alkyl;

R^pl is trityl or a suitable silyl protecting group;

R^p2 is hydrogen or a suitable carboxy protecting group; and

LG is a suitable hydroxy activating group; or a pharmaceutically acceptable salt thereof;

comprising the steps of:

(a) reacting an -chiral aldehyde of the formula

ORP¹

with a chiral crotylboron reagent to form a compound of the formula

wherein G, R³, and R^pl are as defined above and R^p3 and R^p4 are each isocaranyl or isopinocampheyl ;

(b) reacting a compound of formula (3) with a boron- cleaving agent to form an alcohol of the formula

OH

wherein G, R³ , and R^pl are as defined above;

(c) reacting the alcohol of formula (4) with an alcohol protecting/activating agent to form a compound of the formula

wherein G, R³ , R^pl and LG are as defined above;

(d) oxidizing the compound of formula (5) with an oxidizing agent to provide an aldehyde of the formula

O-LG 6)

wherein G, R , R^pl and LG are as defined above ;

(e) reacting the aldehyde of formula (6) with an allylating agent to provide a homoallylic alcohol of the formula

O OH

I

^LG (7)

wherein G, R³ , R^pl and LG are as defined above;

(f) oxidizing the homoallylic alcohol of formula (7) with an oxidizing agent to provide a hydroxy aldehyde of the formula

O OH

I LG ( 8 )

wherein G, R³ , R^pl and LG are as defined above;

(g) reacting the hydroxy aldehyde of formula (8) with a carboxylic acid, ester or amide forming agent to provide a compound of formula (I), and optionally forming a pharmaceutically acceptable salt thereof .

This invention further provides a process for preparing an alcohol of formula (4) comprising reacting an α-chiral aldehyde of formula (2) with a chiral crotylboron reagent to form a compound of formula (3) and reacting a compound of formula (3) with a boron-cleaving agent to provide an alcohol of formula (4) .

Additionally, this application provides for a process for preparing a cryptophycin compound using a compound of formula (I).

This invention further provides novel intermediates of the formulae (I), (3), (4), (5), (6), (7) and (8) . As used in the application:

(a) the designation " ~~ " refers to a bond that protrudes forward out of the plane of the page;

(b) the designation " " refers to a bond that protrudes backward out of the plane of the page; and

(c) the designation " ^^ " refers to a bond for which the stereochemistry is not designated.

As used herein, the term "pharmaceutically acceptable salt" refers to either acid addition salts or base addition salts.

The expression "pharmaceutically acceptable acid addition salt" is intended to apply to any non-toxic organic or inorganic acid addition salt of the compounds of formulae (I), (II) or any of their intermediates. Illustrative inorganic acids which form suitable salts include hydrochloric, hydrobromic, sulphuric, and phosphoric acid and acid metal salts such as sodium monohydrogen orthophosphate, and potassium hydrogen sulfate. Illustrative organic acids which form suitable salts include the mono-, di- and tricarboxylic acids. Illustrative of such acids are for example, acetic, glycolic, lactic, pyruvic, malonic, succinic, glutaric, fumaric, malic, tartaric, citric, ascorbic, maleic, hydroxymaleic, benzoic, hydroxybenzoic, phenylacetic, cinnamic, salicylic, 2-phenoxy-benzoic , and sulfonic acids such as p-toluenesulfonic acid, methane sulfonic acid and 2-hydroxyethane sulfonic acid. Such salts can exist in either hydrated or substantially anhydrous form.

The expression "pharmaceutically acceptable basic addition salts" is intended to apply to any non-toxic organic or inorganic basic addition salts of the compounds of formula I or any of its intermediates. Illustrative bases which form suitable salts include alkali metal or alkaline-earth metal hydroxides such as sodium, potassium, calcium, magnesium or barium hydroxides; ammonia and aliphatic, cyclic or aromatic organic amines such as ethylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, isopropyldiethylamine, pyridine and picoline.

As used herein, the term "alkyl" refers to a saturated straight or branched chain hydrocarbon group. As used herein, the term "(Cι-C₁₂) alkyl" refers to a saturated straight or branched chain hydrocarbon group of one to twelve carbon atoms. Included within the scope of this term are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl , 2-methylbutyl , 3- methylbutyl, hexyl, heptyl, octyl, nonyl, decyl and the like. Included within the term is the term " (C_:-C₆) alkyl" which refers to a saturated, unsaturated, straight or branched chain hydrocarbon radical of from one to six carbon atoms. Included within the scope of this term are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, 2-methylbutyl, 3-methylbutyl , hexyl and the like. Included within the terms " (Cι-Cι₂) alkyl" and " (Cι-C₆) alkyl" is the terms "(C₁-C₃) alkyl" which refers to a saturated, unsaturated, straight or branched chain hydrocarbon radical of from one to three carbon atoms. Included within the scope of this term are methyl, ethyl, isopropyl, and the like.

"Substituted (Cι-C₆) alkyl " refers to a (Cι-C₆) alkyl group that may include up to three (3) substituents containing one or more heteroatoms . Examples of such substituents are OH, NH₂ , CONH₂, C0₂H, P0₃H₂ and S0₂R²¹ wherein R²¹ is hydrogen, (Cι-C₃) alkyl or aryl.

The term " (C₃-C₈) cycloalkyl" refers to a saturated (C₃-C₈) cycloalkyl group. Included within this group are cyclopropyl, cyclobutyl, cyclohexyl, cyclooctyl, and the like. A "substituted (C₃-C₈) cycloalkyl group" refers to a (C -Cs) cycloalkyl group having up to three (C_ι-C₃ ) alkyl , halo, or OR²¹ substituents. The substituents may be attached at any available carbon atom. Cyclohexyl is an especially preferred cycloalkyl group. The term "-(CH₂)_m- (C₃-C₅) cycloalkyl" where m is an integer from one to three (inclusive) refers to a cyclopropyl, cyclobutyl or cyclopentyl ring attached to a methylidene, ethylidene or propylidene substituent.

The term "(C₂-C₁₂) alkenyl" refers to an unsaturated straight or branched chain hydrocarbon radical of two to twelve carbon atoms and having from one to three triple bonds. Included within the scope of this term are ethenyl, propenyl , isopropenyl, n-butenyl, isobutenyl, pentenyl, 2-methylbutenyl , 3-methylbutenyl , hexenyl , octenyl, nonenyl , decenyl and the like. It is especially preferred that alkenyl have only one double bond.

The term " (C₂-Cι₂) alkynyl" refers to an unsaturated straight or branched chain hydrocarbon radical of two to twelve carbon atoms and having from one to three triple bonds. Included within the scope of this term are ethynyl, propynyl , isopropynyl, 2-methylpropynyl , hexynyl , decynyl , and the like. It is particularly preferred that alkynyl has only one triple bond. The term " (Cι-C₃) alkoxy" refers to a straight or branched alkoxy group containing from one to six carbon atoms, such as methoxy,^' ethoxy, n-propoxy, isopropoxy, n- butoxy, isobutoxy, pentoxy, 2-methylpentoxy, and the like. The term " (Ci-Cs alkoxy) phenyl" refers to a phenyl group substituted with a (Cι-C₆) alkoxy group at any available carbon on the phenyl ring.

The term "halo" refers to chloro, bro o, fluoro, or iodo .

The terms "aromatic group" and "heteroaromatic group" refer to common aromatic rings having 4n + 2 pi electrons in a monocyclic or bicyclic conjugated system. The term "aryl" refers to an aromatic group, and the term "aralkyl" refers to an aryl(Cι-C₆) alkyl) group. Examples of aromatic groups are phenyl, benzyl and naphthyl . Heteroaromatic groups will contain one or more oxygen, nitrogen and/or sulfur atoms in the ring. Examples of heteroaromatic groups include furyl , pyrrolyl, thienyl, pyridyl and the like. When the aromatic or heteroaromatic groups are substituted, they may have from one to three independently selected (Cι-C₆) alkyl , (Cι-C₆) alkoxy or halo, substituents. The aromatic groups may be further substituted with trifluoromethyl , COOR⁵⁷ (wherein R⁵ is hydrogen or (Cι-C₆) alkyl, P0₃H, S0₃H, S0₂R⁵⁷, N(R⁵⁹) (R^δ0) (wherein R⁵⁹ is hydrogen or (Cι-C₆) alkyl and R⁶⁰ is hydrogen, (C_ι-C₆)alkyl, BOC or FMOC) , -CN, -N0₂ , -OR⁵⁷, -CH₂OC(0) (CH₂)m_'NH₂ (wherein m' is an integer from 1 to 6 (inclusive) ) or

-CH₂-0-Si (R⁵⁷) (R⁵⁸) (R⁵⁹) (wherein R⁵⁸ is hydrogen or Cι-C₆ alkyl) . Especially preferred substituents for the aromatic groups include methyl, halo, N(R⁵⁹)(R⁶⁰), and -OR⁵⁷. The substituents may be attached at any available carbon atom.

Especially preferred heterocyclic or substituted heterocyclic groups include

wherein R is hydrogen or (d-C₆) alkyl As used herein, "epoxide ring" means a three- membered ring whose backbone consists of two carbons and an oxygen atom.

The term "0-aryl" refers to an aryloxy or an aryl group bonded to an oxy moiety.

As used herein, the term "TBS" refers to tert- butyldimethylsilyl represented by the formula

As used herein, the term "NHS" refers to N- hydroxysuccinimide represented by the formula

As used herein the term "Ph" refers to a phenyl moiety. As used herein the term "base labile amino protecting group" refers to common amino protecting groups which are known to be base labile. The artisan can consult common works such as Greene, T.W. "Protecting Groups in Organic Synthesis", Wiley (New York, 1981). See particularly Chapter 7 of Greene. An especially preferred base labile amino protecting group is fluorenylmethoxycarbonyl (FMOC) .

The term "silyl protecting group" refers to alkyl and/or aryl-substituted silyl groups, such as tri(C_ι-C₆) alkyl silyl. The term "tri (Cι-C₆) alkyl silyl" refers to a compound of the formula:

(C C₆) alkyl

(C₁-C₆) alkyl Si

(C C₆) alkyl

Examples of silyl protecting groups include tert- butyldimethylsilyl , tert-butyldiphenylsilyl , tri- isopropylsilyl , tri-ethylsilyl and the like.

The term "suitable carboxy protecting group" covers groups well known in the art, see, for example, Protecting Groups in Organi c Synthesis by T. Greene, Wiley- Interscience (1981). Specific examples of carboxy protecting groups include alkyl, allyl, aryl, arylalkyl, and the like. Also included within the term "suitable carboxy protecting group" is the term "suitable activatable carboxy protecting group" . The term "suitable activatable carboxy protecting group" refers to carboxy protecting groups containing activatable ester substituents and are known by one of ordinary skill in the art and disclosed by Greene, T.W., supra. Suitable activatable carboxy protecting groups are those which are activatable ester substituents including N-hydroxy-succinimide, N-hydroxysulfosuccinimide and salts thereof, 2-nitrophenyl , 4-nitrophenyl , 2 , 4-dichlorophenyl , and the like. An especially preferred activatable carboxy protecting group is N-hydroxy-succinimide (NHS) .

The term "suitable hydroxy activating group" refers to any moiety which affords displacement of the hydroxyl moiety and is easily introduced. Examples include tosylate, mesylate, brosylate, nosylate, acetate, trifluoroacetate, carboxylate, and the like.

The terms "Ts" or "tosylate" refer to a p- toluenesulfonate functionality of the formula:

As used herein, the term "cryptophycin compound" refers to a compound of the formula

wherein G and R³ are as defined in formula (I);

R¹ is halogen and R² is OH or glycinate ester; or R¹ and R² may be taken together to form an epoxide ring; or R¹ and R² may be taken together to form a bond;

R⁷ and R⁸ are each independently hydrogen or (Cι-C₆) alkyl; or R⁷ and R⁸ may be taken together to form a cyclopropyl or cyclobutyl ring;

R⁹ is hydrogen, (Cι-C₆) alkyl , (C₂-C₆) alkenyl, (C₂-C₆) alkynyl, - (CH₂)_m- (C₃-C₅) cycloalkyl or benzyl, wherein m is an integer from one to three (inclusive);

R¹⁰ is hydrogen or (Cι-C₆) alkyl ;

R¹¹ is hydrogen, (Ci-Cε) alkyl , phenyl or benzyl;

R¹⁴ is hydrogen or (Ci-Cβ) alkyl ; R⁵⁰ is hydrogen or (=0); Y i s CH , 0 , NR¹² , S , SO , S0₂ , wherein R¹² i s hydrogen or ( Ci-

C₃ ) alkyl ;

R⁶ is (Cι-C₆) alkyl, substituted (Cι-C₆) alkyl , (C₃-

C₈) cycloalkyl, substituted (C₃-C₈) cycloalkyl , a heteroaromatic or substituted heteroaromatic group or a group of formula (IA), (IB) or (IC):

R^6a, R^6b, and R^6c independently are hydrogen, (Cι-C₆) alkyl , halo N(R¹⁸) (R¹⁹) or OR¹⁸;

R¹⁵, R¹⁶, and R¹⁷ independently are hydrogen, halo, (Ci-

C₆) alkyl, OR¹⁸, O-aryl, NH₂ , N(R¹⁸)(R¹⁹), N0₂ , OP0₄H₂, (Ci-C₆) alkoxy phenyl, S-benzyl, C0NH₂ , C0₂H, P0₃H₂, S0₂R²³ , or Z ' ;

R¹⁸ and R¹⁹ independently are hydrogen or (Ci-Cβ) alkyl;

R²³ is hydrogen or (Cι-C₃) alkyl ;

Z is -(CH₂)_n- or (C₃-C₅) cycloalkyl ; n is 0, 1, or 2; and Z ' is an aromatic or substituted aromatic group; or a pharmaceutically acceptable salt thereof. As used herein, the term "Cryptophycin 52" represents the compound of the formula:

As used herein, the term " (=0) " in combination with the carbon on the ring to which it is attached refers to a carbonyl group of the formula

O

As used herein, the term "trityl" refers to a compound of the formula:

A general synthetic procedure is set forth in Scheme A. In Scheme A, all substituents unless otherwise indicated, are as previously defined.

SCHEME A

Deprotection

step 2 OH

(4)

Alcohol Protection

O-LG step 3

(5)

Oxidation

step 4 O-LG

(6)

Allylation

step 5 OH

LG

(7) SCHEME A ( co t

Oxidation

step 6 O OH

I

LG

(8) α, β- Unsaturated Carboxylic Acid Ester Formation

(i) step 7

In Scheme A, step 1, an α-chiral aldehyde of formula (2) is reacted with a chiral crotylboron reagent to form an organoboron of formula (3) .

The chiral crotylboron reagent is any agent which allows for an acyclic diastereo-controlled carbon-carbon bond formation process for the α-chiral aldehyde of formula (2) via an asymmetric crotylboration reaction. See, for example, Brown, H.C. et al . , J. Am. Chem. Soc. 108, 5919 (1986) and Brown, H.C. et al . J. Org. Chem. 54, 1570 (1989). For example, enantiomerically pure crotylboron reagent may be prepared from (+)-3-carene (2a) of 90% enantiomeric excess ("ee"). The hydroboration of ( +) -3-carene (2a) (90% ee and containing about 5% of (+) -2-carene) with borane dimethylsulfide complex (BH₃-SMe₂) in a suitable solvent such as tetrahydrofuran at about 0°C to about room (ambient) temperature provides bis (4-isocaranyl) borane (4-Icr₂BH, 2b); see, for example, Jadhav, P.D. et al . , J. Org. Chem. 50, 3203 (1985) . The reaction of active hydride of 4-Icr₂BH

(2b) with about an equivalent amount of a suitable solvent such as methanol at about 0°C provides enantiomerically pure β-methoxybis (4-isocaranyl) borane (4-Icr₂BOMe, 2c) in quantitative yield. This reaction is illustrated in Scheme Al.

SCHEME Al

Next, the trans-2-butenyl group may be introduced on the boron atom of 4-Icr₂BOMe (2c) in si tu to provide a preferred chiral crotylboron reagent, β-allylbis (4- isocaranyl) borane (4-Icr₂BAll, 2d), as follows. Metallation of trans-2-butene with potassium t-butoxide and n- butyllithium at a temperature ranging from about room

(ambient) temperature to about -100°C, preferably -78°C, in hexane/THF solvent system followed by the reaction with 4- Icr₂BOMe (2c) provides an 'ate' complex which upon reaction with borontrifluoride etherate (BF₃ ^'EE) provides, in si tu , the required β-allylbis (4-isocaranyl ) borane (4-Icr₂BAll, 2d) . This enantiomerically pure allyl boron reagent, generated in si tu , may be reacted with α-chiral aldehyde (2)

at -78°C to provide a boron intermediate of formula (3) which may be used without further isolation or separation or which may be isolated and purified according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallizatio .

In Scheme A, step 2, the organoboron of formula (3) is reacted with a boron-cleaving agent to provide an alcohol of formula (4) .

A suitable boron-cleaving agent is any agent capable of selectively removing the boron moiety while inert to the silyl protecting group.

For example, the organoboron of formula (3) may be subjected to oxidative work up using a suitable base such as sodium acetate, sodium hydroxide, or potassium hydroxide and a suitable oxidizing agent such as hydrogen peroxide. The reaction may be carried out in a suitable organic solvent, such as ethereal solvents or halocarbons and at a temperature ranging from about room (ambient) temperature to

about -100°C. The reaction is then preferably heated to a

temperature ranging from about 40°C to about 100°C and stirred for a period of time ranging from about 2 to about 24 hours. The alcohol of formula (4) may be obtained from a mixture of isomers by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization.

In Scheme A, step 3, the alcohol of formula (4) is reacted with a suitable alcohol protecting/activating agent to form the compound of formula (5) .

A suitable alcohol protecting/activating agent is any agent which provides a suitable alcohol leaving group, such as a tosyl group, to the free alcohol moiety of formula (4) . Examples of suitable alcohol protecting/activating agents are well known in the art as described in T. Greene, supra . , and Advanced Organic Chemistry, Fourth Edition,

Jerry March, John Wiley and Sons (1992) . Examples include tosyl chloride, methanesulfonyl chloride, p- bromobenzenesulfonyl chloride and triflie anhydride. For example, the alcohol of formula (4) is reacted with a suitable alcohol protecting/activating agent, such as tosyl chloride, in a suitable organic solvent, such as tetrahydrofuran, dichloromethane or pentane. A suitable base, such as lithium bis (trimethylsilyl ) amide, n- butyllithium, or pyridine is added and the reaction mixture is stirred at a temperature ranging from about 0°C to about

60°C and stirred for a period of time ranging from about 12 to about 48 hours. The compound of formula (5) may be obtained from a mixture of isomers by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization .

In Scheme A, step 4, the compound of formula (5) is oxidized with an oxidizing agent to provide the aldehyde of formula ( 6 ) .

A suitable oxidizing agent is any agent capable of converting the olefin of formula (5) into the aldehyde of formula (6), while inert to, or much less reactive to, the other moieties present on the compound of formula (5) . Suitable oxidizing agents include ozone, osmium tetroxide/ sodium metaperiodate, ruthenium chloride/sodium periodate, and potassium permanganate, with ozone being preferred. For example, the compound of formula (5) is dissolved in a suitable organic solvent, such as methylene chloride, and cooled to a temperature ranging from about -50°C to about -78°C. A suitable oxidizing agent, such as ozone, and subsequently a suitable reductant, such as zinc dust is added to the solution, followed by a mild acid such as glacial acetic acid. The reaction mixture is then allowed to warm and is stirred for a period of about 1 to about 4 hours. The aldehyde of formula (6) may be obtained from a mixture of isomers by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization.

In Scheme A, step 5, the aldehyde of formula (6) is reacted with a chiral or achiral allylatmg agent to provide the homoallylic alcohol of formula (7) .

A suitable chiral or achiral allylating agent is any agent capable of adding an allyl moiety to the aldehyde moiety of formula (6) . Examples include allyltribuyltin reagent (allyl-Bu₃Sn) , allylmagnesium bromide (allyl-MgBr) , and a chiral metalallyl reagent, with a chiral metalallyl reagent being most preferred. The allylation of the aldehyde of formula (6) with an achiral reagent such as allylmagnesium bromide at -78°C according to methods known in the art provides two homoallylic alcohols, (7) and (7a) in a 1:2 ratio in favor of the undesired homoallylic alcohol (7a) . Yamamoto, Y. et al., Chem. Rev. 93, 2207 (1993); Marshall, J.A., Chem. Rev. 96, 31 (1996) . Similarly, allylation with the allyltributyltin reagent provides a 1:1 ratio of alcohols.

(7) (7a)

The desired homoallylic alcohol (7) may be obtained from the mixture of isomers by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization .

In order to obtain the desired homoallylic alcohol (7) in a higher diastereoselective fashion a chiral metalallyl reagent may be used. For example, an allyl group may be introduced onto the boron atom of 4-Icr₂BOMe (2c) , the same reagent used in Scheme A, step 1, under mild conditions in ethyl ether according to methods analogously known in the art to provide an enantiomerically pure allylboron reagent (2e) as shown in Scheme A2 ; Brown, H.C. et al., J. Am. Chem. Soc. 105, 2092 (1983); Brown, H.C. et al., J. Org. Chem. 51, 432 (1986).

SCHEME A2

allyl-MgX

X = halide

The aldehyde of formula (6) may be reacted with the chiral allylboron reagent of formula (2e) at a temperature ranging from about 25°C to about 100°C to provide the required homoallylic alcohol (7) along with caranyl alcohol as a by-product. A diastereoselectivity of greater than 19 to 1 may be achieved in the reaction. The desired homoallylic alcohol (7) may be obtained from the mixture of isomers by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization .

In Scheme A, step 6, the homoallylic alcohol of formula (7) is oxidized with an oxidizing agent according to the procedure described in Scheme A, step 4, to provide the hydroxy aldehyde of formula (8) .

In Scheme A, step 7, the hydroxy aldehyde of formula (8) is contacted with a carboxylic acid, ester or amide forming agent to provide the compound of formula (I) .

The term "carboxylic acid, ester or amide forming agent" encompasses any suitable means or conditions for forming the carboxylic acid, ester or amide moiety of formula (I) . Included within this definition are the conditions set forth and/or analogously described by W.S. Wadsworth, Organic Reactions, Vol. 25, 73 (1977); W.S. Wadsworth, J. Org. Chem. 50, 2624 (1985) . For the purposes of this disclosure, the term "amide" refers to the "suitable activatable carboxy protecting group" referred to above.

For example, the hydroxy aldehyde of formula (8) may be subjected to a Horner-Emmons-Wadsworth reaction. The Horner-Emmons-Wadsworth reaction is a reaction of a ketone with an ylid to produce an alkene. K. Mori and H. Ueda, Tetrahedron Lett., (1981), 461. S. Hannessian and P. Lavalle, Can. Jour. Chem., (1977), 55, 562. The hydroxy aldehyde of formula (8) is contacted with a suitable R^p2- dialkylphosphonoacetate, such as allyl diethylphosphono- acetate, in a suitable organic solvent such as tetrahydrofuran, halocarbon or toluene. The reaction mixture is stirred for a period of from 3 to 60 minutes and tetramethylguanidine is slowly added. The resulting reaction mixture is then stirred at a temperature ranging from about 20°C to about 60°C for a period of time ranging from about 12 to about 36 hours. The compound of formula (I) may be obtained by isolation and purification according to techniques well known in the art such as extraction, evaporation, chromatography and recrystallization.

Further, when R^p2 is a hydrogen, the ester of formula (8) may be reacted with a hydrolyzing agent to provide a carboxylic acid derivative of formula (8) .

A hydrolyzing agent is any agent that is capable of converting an R^p2 ester moiety of the compound of formula (8) to an acid moiety, while inert to the other substituents on the molecules. Examples of suitable hydrolyzing agents include inorganic bases such as sodium hydroxide and potassium hydroxide, with potassium hydroxide being preferred.

For example, an ester of formula (8) is contacted with a suitable hydrolyzing agent, such as 2 N KOH in a suitable organic solvent, such as 1,4-dioxane at room ( ambient) temperature. The solution is then heated to reflux for a period of time ranging from about 1 to about 6 hours. The reaction is then quenched with a suitable acid, such as 2 N HCl. An acid of formula (8) is isolated by techniques well known in the art, such as extraction, evaporation, and precipitation. The product can be purified by techniques well known in the art, such as chromatography.

When R^p2 is an amide or a "suitable activatable carboxy protecting group", an acid of formula (8) (wherein R^p2 is hydrogen) is treated with a carboxy activating agent to provide an activatable ester of formula (8) .

For example, a compound of formula (8) (where R^p2 is hydrogen) is reacted with a suitable coupling agent, such as a carbodiimide, for example, l-ethyl-3- (3- dimethylaminopropyl) carbodiimide, and a suitable carboxy activating agent, such as N-hydroxysuccinimide, in a suitable organic solvent, such as dry dimethylformamide. The mixture is stirred for a period of time ranging from about 6 to 36 hours at a temperature ranging from about 10°C to about 50°C. The activatable ester of formula (8) is isolated by techniques well known in the art, such as extraction, evaporation, and precipitation. The product can be purified by techniques well known in the art, such as chromatography . Optionally, on those compounds of formula (I) containing basic or acidic functional groups, pharmaceutically acceptable salts of the compounds of formula (I) may be formed using standard techniques. For example, the free base may be dissolved in aqueous or aqueous-alcohol solution or other suitable solvent containing the appropriate acid and the salt isolated by evaporating the solution. Alternatively, the free base may be reacted in an organic solvent containing the appropriate acid and the salt isolated by evaporating the solution. Further, the free base may be reacted in an organic solvent in which case the salt separates directly or can be obtained by concentration of the solution or in a solvent such as water which is then removed in vacuo or by freeze-drying, or by exchanging the cations of an existing salt for another cation on a suitable ion exchange resin.

General synthetic procedures for preparing cryptophycin compounds of formula (II) are set forth in

Barrow, R.A. et al . , J^". Am. Chem . Soc . Ill , 2479 (1995); PCT Intnl. Publ. No. WO 96/40184, published December 19, 1996 PCT Intnl. Publ. No. WO 98/08505, published March 5, 1998 PCT Intnl. Publ. No. WO 97/07798, published March 6, 1998, PCT Intnl. Publ. No. WO 97/23211, published July 3, 1997; PCT Intnl. Publ. No. WO 98/08506, published March 5, 1998; PCT Intnl. Publ. No. WO 98/08812, published March 5, 1998; and PCT Intnl. Publ. No. WO 97/31632, published September 4, 1997. References disclosing intermediates and/or processes for preparing cryptophycin compounds of formula (II) or intermediates thereof include PCT Intnl. Publ. No. WO 98/09955, published March 12, 1998; PCT Intnl. Publ. No. WO 98/09974, published March 12, 1998; PCT Intnl. Publ. No. WO 98/09601, published March 12, 1998; and PCT Intnl. Publ. No. WO 98/09988, published March 12, 1998.

A general synthetic procedure for preparing a cryptophycin compound of formula (IIB) is set forth in Scheme B. In Scheme B, all substituents unless otherwise indicated, are as previously defined. Pg is a protecting group.

SCHEME B

(I) ment

Couple Fragment CD step 1

Carboxy Deprotection step 2

SCHEME B ( cont

Fragment B step 3 Coupling

Non-selective

SCHEME B (cont. )

Halohydrin Formation

(IIB) step 6

In Scheme B, step 1, Fragment A, represented by formula (I), is coupled with Fragment CD to provide Fragment AC'D represented by formula (9) .

Fragment CD is described in Barrow, R.A. et al . J^". Am. Chem. Soc. Ill, 2479 (1995); PCT Intnl. Publ. No. WO 96/40184, published December 19, 1996; and PCT Intnl. Publ. No. WO 97/07798, published March 6, 1997.

For example, Fragment A (I) is coupled to Fragment CD according to coupling procedures which are well known by one of ordinary skill in the art. For example, Fragment A (I) is contacted with about 1.0 to about 1.2 molar equivalents of Fragment CD in the presence of a suitable organic solvent and optionally in the presence of suitable coupling catalyst. Suitable coupling catalysts are well known in the art and include dimethylaminopyridine, N,N'- diisopropylcarbodiimide and 1-hydroxybensotriazole . Other coupling catalysts include (1) carbodiimides (e.g., N,N'- dicyclohexylcarbodiimide and N-ethyl-N' - (γ- dimethylaminopropylcarbodiimide) ; (2) cyanamides (e.g. N,N- dibenzylcyanamide) ; (3) ketenemines; (4) isoxazolium salts (e.g., N-ethyl-5-phenylisoxazolium-3 ' -sulfonate) ; (5) monocyclic nitrogen containing heterocyclic amides of aromatic character containing one through four nitrogens in the ring such as imidazolides , pyrazolides and 1,2,4- triazole; (6) alkoxylated acetylene (e.g. ethoxyacetylene) and (7) nitrogen containing heterocyclic compounds having a hydroxy group on one ring nitrogen (e.g., N- hydroxyphthalimide, N-hydroxysuccinimide and 1- hydroxybenzotriazole) . Suitable organic solvents include DMF, glyme, dioxane, CH₃CN, THF, EtOAc, and halohydrocarbons , such as methylene chloride. The reaction is carried out at a temperature ranging from about -30°C to about 75°C, with a temperature ranging from about 20°C to about 60°C being preferred. The Fragment AC'D compound of formula (9) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and reerystalliz tion.

In Scheme B, step 2, the Fragment AC'D compound of formula (9) is carboxy-deprotected with a suitable carboxy- deprotecting agent to provide the carboxy-deprotected Fragment AC'D of formula (10) .

A suitable carboxy-deprotecting agent for allyl carboxy-deprotection is (Ph₃P) Pd or Pd(0Ac)₂ along with organic base such as morpholine.

For example, the Fragment AC'D compound formula (9) is contacted with from about 1.0 to about 10 molar equivalents of morpholine and a catalytic amount of from about 0.1 mole % to about 0.7 mole % of a metal catalyst such as Pd(PPh₃)₄ or Pd(0Ac)₂, with Pd(PPh₃)₄ being preferred. The reaction mixture is stirred for a period of time ranging from about 1 to about 6 hours during which additional metal catalyst may be added. The solvent is then removed and water is added to the emulsion. The emulsion is then acidified with a cold acid, such as 1:1 HCl water solution. The organic layer is separated and the aqueous layer is extracted with a suitable organic solvent such as ethyl acetate. The combined organic is then washed with water, 5% NaHC0₃ aqueous solution (until pH = 7) and brine and is then dried over Na₂S0₄, filtered and concentrated in vacuo to yield the carboxy-deprotected Fragment AC'D of formula (10), which may be used without further purification. Optionally, the carboxy-deprotected Fragment AC'D of formula (10) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and recrystallization .

In Scheme B, step 3, the carboxy-deprotected

Fragment AC'D of formula (10) is coupled with Fragment B (10a) to provide Fragment ABC'D (11) .

Fragment B is represented by the compound of the formula

wherein R⁶ and R¹⁴ are as defined above and R^p5 is hydrogen,

(Cι-C₆) alkyl or trichloroethyl . The Fragment B amino acids of formula (10a) are commercially available or are readily prepared by methods known in the art . Particularly preferred Fragment B amino acids of formula (10a) include those where R⁶ is a group of formula (IA); R^6a is methoxy; R^6b is chloro; R^6c is hydrogen; R¹⁴ is hydrogen and R^pl is hydrogen; said amino acids being disclosed by PCT Intnl. Publ. No. WO 97/07798, published March 6, 1997, PCT Intnl. Publ. No. WO 96/40184, published December 19, 1996; and Barrow, R.A. et al . , J. Am . Chem . Soc . Ill , 2479 (1995).

For example, the carboxy-deprotected Fragment AC'D of formula (10) is coupled with Fragment B (10a) according to procedures well known and appreciated by one of ordinary skill in the art; R.A. Barrow et al . , J. Am . Chem . Soc . Ill , 2479-2490 (1995); PCT Intnl. Publ. No. WO 97/07798, published March 6, 1997; PCT Intnl. Publ. No. WO 96/4084, published December 19, 1996; and PCT Intnl. Publ. No. WO 98/09955, published March 12, 1998. For example, a solution containing the carboxy-deprotected Fragment AC'D of formula (10) in a suitable organic solvent, such as N, N- dimethylformamide (DMF) is treated with a small excess of pentafluorophenyl diphenylphosphinate (FDPP) , diphenylphosphinic chloride or diphenyl chlorophosphate, about an equimolar amount of Fragment B (10a) and about three equivalents of a suitable coupling agent such as diisopropylethylamine (DIEA) . The Fragment ABC'D compound of formula (11) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and reerystallization .

In Scheme B, step 4, the Fragment ABC'D compound

(11) is cyclized using a cyclizing agent to provide the macrocycle of formula (12) .

The term "cyclizing agent" encompasses any suitable means or conditions for forming the macrocycle of formula (12) . Included within this definition are the conditions set forth and/or analogously described in R.A. Barrow et al . , J. Am . Chem . Soc . 117, 2479-2490 (1995).

The macrocyclization of the Fragment ABC'D compound of (11) may be accomplished by first removing the Pg-protecting group (preferably BOC) from the nitrogen moiety and treating the resultant ester with a suitable cyclizing catalyst, such as 2-hydroxypyridine, to provide the macrocycle of formula (12) . For example, a solution of Fragment ABC'D (11) is treated with a suitable deprotecting reagent, such as trifluoroacetic acid and stirred at a temperature ranging from about -25°C to about 25°C for a period of time ranging from about 30 minutes to about 4 hours. The reaction mixture is then contacted with a suitable base such as K₂C0₃ , NaHC0₃ or NaOH, the organic layer is separated and the aqueous layer is extracted with a suitable organic solvent such as ethyl acetate. The combined organic layer is then washed with water, brine, dried, filtered and concentrated. The macrocycle of formula (12) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and recrystallization.

In Scheme B, step 5, the macrocycle of formula (12) is deprotected using a non-selective deprotecting agent to provide the cryptophycin epoxide of formula (IIB) .

A "non-selective deprotecting agent" is one that removes both the R^pl hydroxy protecting group as well as the LG leaving group. Examples of non-selective deprotecting agents include tetrabutylammonium fluoride; Nakata, T. et al., Tetrahedron Lett. 29, 2219 (1988).

For example, the macrocycle of formula (12) is reacted with a suitable non-selective deprotecting agent, such as a 1.0 M solution of tetrabutylammonium fluoride, in a suitable organic solvent, such as tetrahydrofuran, under an inert atmosphere. The reaction mixture is stirred at a temperature ranging from about -25°C to about 25°C for a period of time ranging from about 1 to 6 hours. The reaction mixture may then be diluted with a suitable organic solvent, such as ethyl acetate and washed with water, NaHC0₃ aqueous solution and water. The combined organic may then be dried, filtered and concentrated. The cryptophycin compound of formula (IIB) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and recrystallization .

Alternatively, as shown in Scheme B, steps 5a and 5b, the R^pl group of macrocycle (12) is removed with a suitable hydroxy deprotecting reagent, such as cesium fluoride in dimethylsulfoxide or hydrogen fluoride in acetonitrile to provide the intermediate compound of formula (13) . The intermediate compound of formula (13) under the reaction conditions undergoes ring closure to provide the macrocycle of formula (12) .

In Scheme B, step 6, the epoxide of formula (IIB) is optionally treated with a halohydrin forming reagent to produce the halohydrin of formula (IIC), where Hal is halogen, preferably chlorine.

A "halohydrin forming reagent" is any agent capable of converting the epoxide moiety of compound (IIB) to the halohydrin moiety of compound (IIC) . Suitable halohydrin forming reactions are disclosed in PCT Intnl. Publ. No. WO 96/40184, published December 19, 1996 and PCT Intnl. Publ. No. WO 98/09988, published March 12, 1998. For example, the epoxide of formula (IIB) is treated with a suitable halo-acid, such as hydrochloric acid in a suitable organic solvent or solvent mixture, such as dimethoxy- ethane/water . The mixture is then stirred at a temperature ranging from about 10°C to about 50°C for a period of time ranging from about 6 to 36 hours. The mixture is then neutralized with a suitable base or buffer, such as potassium carbonate. The halohydrin of formula (IIC) is isolated and purified by techniques well known in the art, such as extraction, evaporation, chromatography and recrystallization .

In Scheme B, step 7, the halohydrin of formula

(IIC) is reacted with a glycinating agent to provide the glycinate ester of formula (IID).

A "glycinating agent" is any agent capable of converting the halohydrin of formula (IIC) into the glycinate ester of formula (IID). Suitable glycinating reactions are disclosed in PCT Intnl. Publ. No. WO 98/08505, published March 5, 1998. For example, the halohydrin of formula (IIC) is coupled with N- ( tert-butoxycarbonyl) glycine (BOC-Gly) under coupling conditions well known in the art. For example, the halohydrin of formula (IIC) is contacted with BOC-Gly, dimethylaminopyridine (DMAP) and 1,3- dicyclohexylcarbodii ide (DCC) . The resulting mixture is stirred at a temperature ranging from 10°C to 50°C for a period of time ranging from 0.5 to 24 hours. The glycinate ester of formula (IID) is isolated and purified by techniques well known in the art, such as extraction, evaporation, chromatography and recrystallization.

It should be noted that since one aspect of the invention represents a convergent synthesis to produce a cryptophycin compound of formula (II), alternate sequences of couplings may be utilized as well. For example, Fragment A may be first coupled to Fragment B to form Fragment AB and Fragment C to Fragment D to form Fragment CD. Fragment AB may then be coupled to Fragment CD to form Fragment ABC'D.

A general synthetic procedure for preparing an α- chiral aldehyde of formula (2) is set forth in Scheme C. In Scheme C, all substituents, unless otherwise indicated are as previously defined.

SCHEME C

(14) (15)

(16)

Reduction step 3

(2)

In Scheme C, step 1, the (R) - ( - ) -mandelic acid analog of formula (14) is esterified to provide the methyl ester of formula (15) according to techniques known in the art; Petrini, M. et al . , Synt . Commun. 18(8), 847 (1988); Petrini, M. et al . , Synt. Commun. 18(8), 853 (1988). For example, the (R) -(-) -mandelic acid analog of formula (14) may be esterified with methanol in the presence of a suitable catalyst, such as Amberlyst-15 resin. The mixture is stirred at a temperature ranging from about 10°C to about 60°C for a period of time ranging from about 6 to 36 hours. The methyl ester of formula (15) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and recrystallization .

In Scheme C, step 2, the methyl ester of formula . (15) is hydroxyprotected using a suitable trityl or silyl protecting agent to provide the hydroxy-protected methyl ester of formula (16) .

A suitable "hydroxy-protecting agent" is one which provides a trityl or silyl group to protect the free hydroxyl moiety of the methyl ester (15) . The "trityl" and "silyl" groups are as defined above, for example, "silyl protecting group" refers to alkyl and/or aryl-substituted silyl groups, such as tri (Cι-C₆ alkyl) silyl. A preferred "hydroxy-protecting agent" is t-butyldimethylsilylchloride (TBS-C1) .

For example, the reaction is performed under an inert atmosphere and the methyl ester of formula (15), imidazole and a suitable organic solvent, such as dimethylformamide, are charged to the reaction vessel in that order. A suitable hydroxy-protecting agent, such as t- butyldimethylsilylchloride, is then added and the resulting slurry is stirred at temperature ranging from about 10°C to about 60°C for a period of time ranging from about 2-24 hours. The hydroxy-protected methyl ester of formula (16) may be isolated and purified according to techniques and procedures well known in the art such as extraction, evaporation, chromatography and recrystallization .

In Scheme C, step 3, the hydroxy-protected methyl ester of formula (16) is reduced using a suitable reducing agent to provide the aldehyde of formula (2) .

A suitable reducing agent includes alkylated aluminum hydrides. Examples include diisobutylaluminum hydride, bis (dialkylamino) aluminum hydride, either preformed or generated in si tu from alkali-aluminum compounds such as LiAlH₄, NaAlH₄, NaH₂Al (Cι-C₆) alkyl₂ , NaH₂Al (OCH₂CH₂OMe) ₂ LiHAl(OtBu)₂ and the like.

For example, the hydroxy-protected methyl ester of formula (16) is reacted with a suitable reducing agent such as DIBAL under an inert atmosphere, for a period ranging from about 1 to 12 hours. The reaction is carried out in the presence of a suitable organic solvent, such as ethyl ether or toluene while the temperature is maintained at a range of from about -60° or below. A suitable quench, such as a 20% aqueous solution of ammonium chloride, is then added slowly and the reaction mixture is stirred from about 1 to 12 hours. The aldehyde of formula (2) may be isolated by techniques well known in the art, such as extraction, evaporation, and precipitation. The product can be purified by chromatography and recrystallization .

Some preferred characteristics of this invention are set forth in tabular form below wherein the features may be independently selected to provide the preferred embodiments of the invention.

A) G is phenyl;

B) G is p-fluorophenyl ; C) R^pl is t-butyldimethylsilyl;

D) R^p2 is allyl;

E) LG is tosyl;

F) R³ is methyl;

G) R⁸ is ethyl, propyl, isopropyl, butyl, isobutyl or isopentyl;

H) R⁷ is ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, or isopentyl; I) R⁷ is hydrogen, R⁸ is methyl and R³ is methyl; J) R³ is ethyl, propyl, isopropyl, butyl, isobutyl, pentyl or isopentyl; K) R⁹ is methyl, ethyl, propyl, butyl, isobutyl, pentyl, or isopentyl ;

L) R¹⁰ is methyl, ethyl, propyl, butyl, isobutyl, pentyl, or isopentyl ; M) a compound wherein Y is selected from the group consisting of 0, NH, S, SO and SO2 ;

N) R⁶ is substituted benzyl wherein one substituent is a halogen and one methoxy;

0) R⁷ and R⁸ are each methyl; P) the chiral crotylboron reagent is ?-allylbis (4- isocaranyl) borane;

Q) the boron-cleaving agent is H₂0₂;

R) the alcohol protecting agent is tosyl chloride;

S) the oxidizing agent is ozone; T) the carboxylic acid ester forming agent is a Horner- Emmons-Wadsworth reagent;

U) the allylating agent is a chiral metalallyl reagent;

V) the allylating agent is β-allyldiisocaranylborane .

The reaction flasks and other equipment using air and moisture sensitive reactions were assembled hot and cooled under stream of nitrogen gas. Special techniques used in handling air-sensitive materials are described elsewhere.²⁰ Borane-methyl sulfide, terpenes, and other reagents used in the entire reaction sequence were used as obtained. Proton NMR spectra were recorded at 300 or 500 Mhz while ¹³C NMR spectra were recorded at 75 or 125.9 MHz.

Preparation 1

Methyl (K)-(-)-Mandelate (18)

Scheme C, step 1: The reaction was run under a nitrogen blanket. A 2-L 3 -neck RB- flask was charged with solid ( R) - (-) -mandelic acid (17) (300 g, 1.97 mole), Amberlyst 15 (90g, 30% weight load), and MeOH (0.9 L) ] . The mixture was stirred at room (ambient) temperature for 20 h. Upon completion of the reaction, solid Na₂S0₄ (10 g) was added and the mixture was stirred and filtered. The solvent was removed at room (ambient) temperature to provide a crude solid (330 g) . The crude solid was dissolved in 1:1 CH₂Cl₂/EtOAc (200 ml) and filtered through a layer of silica gel and eluted with 1:1 hexane/EtOAc . This operation was done to remove baseline impurity (by TLC) present in the crude ester product. The filtrate was concentrated at room (ambient) temperature to yield the title compound (18) as an off-white solid (321.8 g, 98%). mp 55-56°C. TLC (3:1 hexane/EtOAc) : R_f=0.36.

Preparation 2 Methyl- (2_R) - (-) -2- [ tert-butyldi ethylsilyl)oxy] -2-Phenyl- acetate (19)

Scheme C, step 2: The reaction was performed a under a nitrogen blanket. A three-neck RB- flask equipped with a mechanical stirrer and nitrogen bubbler was charged with solid methyl mandelate (18) (321.8 g, 1.936 mole), imidazole (141.8 g, 2.06 mole), and DMF (1 L) in sequence. To the clear reaction mixture stirred at room (ambient) temperature, TBS-C1 (306.4 g, 2.03 mole) was added portionwise. The resulting off white slurry was stirred at room (ambient) temperature for 6-7 h. Upon completion of reaction, cold water (IL) was added and the reaction mixture was extracted with ethyl ether (EE, IL) . The organic phase was washed with water (3 x 300 ml), then brine (1 x 300 ml) . The aqueous layer extracted with EE (2 x 500 ml), and the organic phase was washed with brine. Combined organic layers were dried over solid Na₂S0₄, filtered, and concentrated to yield the desired product (19) (535 g, clear yellow oil, 98%). TLC (9:1 hexanes/EtOAc) R_f = 0.62. A small amount of compound was purified by preparative TLC. [α]_D ²⁵ = -48.3°(C 0.6, CHC1₃) . IR (CHC1₃) : 2955, 2931, 2858, 1753, 1733, 1472, 1256, 1173, 1128, 1105, 860, 839; 'H NMR (300

MHz, CDC1₃) : 67.55-7.45 (m, 2H) , 7.40-7.30 (m, 3H) , 5.26 (s, 1H) , 3.68 (s, 9H) , 0.13 (s, 3H) , 0.94 (s, 9H) , 0.05 (s, 3H) ;

¹³C NMR (125.7 MHz, CDC1₃): 5172.9, 139.6, 128.7, 128.7, 128.4, 126.8, 74.9, 52.5, 26.1, 18.7, -4.7; MS m/z (M⁺)

281.2. Anal. Calcd. for C₁₅H₂₄0₃Si : C, 64.24; H, 8.63. Found: C, 64.53; H, 8.45.

Preparation 3 ( 2R) - (-) -2-Phenyl-2- [ tert-butyldimethylsilyl) - oxy] acetaldehyde (20)

Scheme C, step 3: The reaction was run in a 2-L 3-neck RB-flask equipped with an addition funnel under a nitrogen blanket. To a cold (-78°C) solution of TBS- protected mandelate methyl ester (19) (88.9 g, 0.32 mole) in ethyl ether (200 ml) was added slowly a DIBAL solution in toluene (1.5 M, 295.0 ml, 0.44 mole) such that temperature of the reaction mixture was around -70-(-65)°C. The mixture was stirred for 3 h. To this mixture 20% aqueous solution of NH4CI (200 ml) was added slowly. This was stirred for 15 minutes. The cold bath was removed and slowly was added 100 ml water. A thick gelatinous precipitate of aluminum was separated. The slurry was filtered quickly through a large Buchner funnel. Quick filtration provides aldehyde in good quality (by proton NMR) . The residual solid was washed with ether (2 x 500 ml) . The combined organic was washed with water until pH was about 7, brine (500 ml), dried over Na₂S0 , filtered, and concentrated (at 35-40°C) to yield the desired aldehyde (74 g, 93% yield) .

Preparation 4 Bis (4-isocaranyl) borane (4-Icr₂BH_/ 99% ee) (2b)

Scheme Al : Reaction was done in a dry, moisture free 1-L RB-flask under a nitrogen blanket. The flask was charged with (+)-3-carene (2a) (158 ml, 1 mole), THF (122 ml, such that the molarity of the total solution was -1.25 M with respect to borane) . The resultant solution was cooled to -5°C and slowly was added a neat solution of BH₃ dimethyl sulfide complex (40 ml, 0.4 mole) dropwise with stirring such that temperature of the reaction was maintained around -5°C. After the addition, the stirring was discontinued and the mixture was left undisturbed overnight. A thick, white solid was filtered under a nitrogen atmosphere and washed with pentane (250 ml) . The solid 4-Icr₂BH was transferred into the same flask and a trace amount of the solvent was removed under vacuum to provide the title compound (2b) as a dry, white, powdered solid (74 g, 65% yield) . Preparation 5 /S-methoxy(4-isocaranyl)borane ( 2c )

Scheme Al : The reaction was done in a dry, moisture free 1-L RB-flask under a nitrogen blanket. To the solid 4-Icr₂BH (2b) (74 g, 258.46 mmol) in a 1-L RB-flask, ethyl ether (200 ml) was added. The resultant white suspension was cooled to 0°C and methanol (10.6 ml, 246.2 mmol) was added via syringe (9.9 ml/hr) with stirring. A temperature of 0°C was maintained during the addition of methanol. The reaction mixture turned clear and colorless and was allowed to stir at room (ambient) temperature for another 2 h at which time boron NMR showed the formation of the desired 4-Icr₂BOMe.

Preparation 6 (3R) -benzyl-3-aminopropanoic acid (TFA salt)

A sample of t-Butyl-3- (R) -benzyl-3-amino-propanoic acid (purchased from Oxford Asymmetry, England, >99% ee) was dissolved in trifluoroacetic acid (TFA) and then let stirred at room (ambient) temperature for 4 h. The trifluoroacetic acid was removed in vacuo to give an oily residue which was then triturated with methanol to give a white solid.

TLC: R_£= (CHCI3/CH3OH/NH4OH: 6:3.2:0.8)

¹HNMR(300 MHz,DMS0-d6) d: 7.93 (bs, 2H) , 7.32 (m, 5H) , 3.63

(t, J = 7.2 Hz, 1H) , 2.91 (dd, J = 5.9 Hz, J = 13.6 Hz, 2H) ,

2.77 (dd, J^" = 8.1 Hz, J^" = 13.6 Hz, 2H)

Anal: Calcd for Cι₂Hι₄N0₄ : C, 49.15; H, 4.81; N, 4.78. Found:

C, 48.87; H, 4.73, N, 4.70.

Preparation 7 (3R) -benzyl-3- (tert-butoxycarbonyl) a ino-propanoic acid.

A sample of the compound of Preparation 6 was dissolved in 1, 4-dioxane/H₂0/2N NaOH (2:2:1) at 0° C (ice bath). To this was then added di-t-butyl-dicarboxylate and the ice bath was removed and the resulting reaction mixture was let stirred at room (ambient) temperature for 18 h. The reaction mixture was then concentrated to ca 10 ml and 25 ml of EtOAc was added. To this was then added 0.5 N NaHS0 to lower the pH of aqueous phase to ca . 2-3. The organic layer was then separated and the aqueous layer was extracted with EtOAc (20 ml x 3 ) . The combined EtOAc layer were then washed with water and brine and dried over NaSθ₄. The solvent was then removed in vacuo to give a pale yellow solid.

TLC: R_f = (CHCI₃/CH3OH/NH4OH: 6:3.2:0.8) IR (cm-¹): 3361, 2985, 1670, 1686, 1526, 1266, 1168, 700. UV (CH₃OH) : 258 nm (e = 158) .

OR: [ ]_D= -136.71

¹HNMR(300 MHz,DMSO-d6) d: 7.20 (m, 5H) , 6.75 (d, J = 8.6 Hz, 1H) , 3.88 (m, 1H) , 2.64 (d, J = 7.0 Hz, 2H) , 2.28 (t, J = 5.1 Hz, 2H)1.27 (s, 9H) . Mass (FAB) : 280 (M⁺+H) .

Anal: Calcd for C15H21NO4 : C, 64.50; H, 7.58; N, 5.01. Found: C, 63.25; H, 7.35, N, 4.99.

Preparation 8 Allyl (2S)-2-[3' (tert-Butoxycarbonyl) amino-2 ' - (R) benzylpropanoyloxy] -4-methylpentanoate .

To a solution of allyl (2S) -2-hydroxy-4-methylpentanoate and (3R) -benzyl-3- ( tert-butoxycarbonyl) amino-propanoic acid (Preparation 7) in 10 ml of dry methylene chloride at 0°C (ice bath), was added dicyclohexylcarbodiimide and then followed by DMAP. The reaction mixture was then stirred at room (ambient) temperature for 3 h (TLC indicated the completion of the reaction) . The reaction mixture was then filtered through a small pad of celite and the filtrate was washed with 5% NaHCθ₃ , brine and dried over a₂S0₄. The solvent was removed in vacuo and the residue was flash chromatographed on Siθ₂ (15% EtOAc/hexane) to give the title compound as a clear oil.

TLC: R_f = (20% EtOAc/hexane)

IR (cm^"1): 2961, 2933, 1742, 1715, 1497, 1366, 1249, 1170, 1127. UV (CH₃OH) : 258 nm (e = 218) .

OR: [α]_D = +7.55

¹HNMR(300 MHz, CDC13) d: 7.25 (m, 5H) , 5.89 (m, 1H) , 5.20- 5.36 (m, 3H) , 5.10 (dd, J = 3.9 Hz, J = 9.6 Hz, 1H) , 4.65 (d, J = 5.4 Hz, 2H) , 4.15 (bs, 1H) , 2.87 (m, 2H) , 2.62 (dd, J^" = 5.6 Hz, J = 15.4 Hz, 1H) , 2.50 (dd, J = 5.0 Hz, J = 15.4 Hz, 1H) , 1.60-1.85 (m, 3H) , 1.40 (s, 9H) , 0.95 (d, J = 4.3 Hz, 3H) , 0.93 (d, J = 4.3 Hz, 3H) . Mass (FAB) : 434.4 (M++H) .

Anal: Calcd for C₂4H₃₅N0₅: C, 66.49; H, 8.14; N, 3.23. Found: C, 66.32; H, 8.29, N, 3.42.

Preparation 9

Fragment D (24) (25)

Allyl (2S) -2- [ [3- [ tert.-Butoxycarbonyl ) amino] -2 ' dimethylpropanoyl] oxy] -4-methylpentanoate (25) . To a solution of 1 , 1 ' -carbonyldiimidazole ("CDI", 1346 g, 8.30 mol) in 3 L of THF was added a solution of compound (24) (1803 g, 8.3 mol) in 4 L of THF over 30 min. The reaction was stirred for 2 h at which time NMR analysis showed complete reaction of compound (24) . Fragment D (1450 g, 7.54 mol) was added as a solid, and the reaction mixture was heated to approximately 70°C for 16 h. The reaction mixture was cooled to 25°C and concentrated in vacuo to give a suspension. Heptane (4 L) was added, and the mixture was extracted with 0.2 N HCl solution (6 L) to remove imidazole. The aqueous layer was extracted with 2 L of heptane. The combined organic layers were extracted successively with 0.2 N HCl solution (3 L) , deionized water (3 L) , and brine (3 L) . The organic layer was dried over Na₂S0₄ and concentrated in vacuo to give 2984 g of compound (25) as an oil. !H NMR (CDCI3, 500 MHz) δ 0.94 (d, 3H, J = 8.4 Hz), 0.98 (d, 3H, J = 8.4 Hz), 1.27 (d, 6H, J = 5 Hz), 1.45 (s, 9H) , 1.71 (m, 3H) , 3.31 (m, 2H) , 4.66 (m, 2H) , 5.1 (m, 1H) , 5.3 (m, 3H) , 5.9 ( , 1H) . ¹³C NMR (CDCI3, 75 MHz) δ 176.4, 170.7, 156.4, 131.5, 119.1, 78.9, 70.9, 66.0, 48.7, 44.0,

39.6, 28.4, 24.9, 23.1, 23.0, 22.3, 21.6. IR (CHCI3) 3398, 2964, 1739, 1720, 1511, 1472, 1366, 1266, 1252 cm^"1. MS {FD⁺} m/z (relative intensity) 371 (100) .

Preparation 10

( 26 )

To a solution of the (25), obtained in Preparation 9, in 8 L of THF was added Pd(PPh_3)4 (3.0 g, 2.6 mmol). Morpholine (800 ml, 9.15 mol) was then added dropwise over 30 min at 15-25°C, and the reaction was then stirred at that temperature for 1.5 h. The reaction mixture was concentrated in vacuo to an oil, which was dissolved in 6 L of heptane. The heptane solution was extracted with 1 N HCl (9.8 L) . The aqueous layer was back-extracted with 2 L of heptane. The combined organic layers were washed with 3 L of brine, dried over NaS0 , and filtered. The filtrate was stirred at room (ambient) temperature and seeded with 200 mg of compound (26) . The product crystallized, and the slurry was stirred for 64 h (4 h is sufficient) . The slurry was cooled to 0-10°C for 3.5 h and filtered. The filter cake was washed with cold heptane (2 x 500 ml) and vacuum dried at 45-50°C to give 2324 g (93% overall yield from Fragment D) of compound (26) as a white solid, mp 70-73°C.

Preparation 10A

25 26

(R^P=BOC)

(25) -2- [ [3 ' - [ ( ter -Butoxycarbonyl) amino] -2 ' ,2 - dimethylpropanoyl]oxy] -4-methylpentanoic Acid (26)

A three-neck flask with an overhead stirrer was charged with compound (25) (23.92 g, 64.5 mmol), Pd(PPh₃)₄ (149 mg, 0.13 mmol), and dry THF (100 ml) . The mixture was cooled to 8°C under nitrogen. Morpholine (6.8 ml, 77.4 mmol) in 10 ml of THF was add dropwise over 10 min. No exotherm was observed. The cooling bath was removed, and the solution was stirred for 1 h. The solvent was then removed from the reaction mixture under vacuum. The resulting viscous oil was dissolved in 250 ml of hexane, and 70 ml of 0.01 N HCl was added. Then, 1 N HCl (77 ml) was added dropwise over 5 min. A small amount of yellow precipitate formed at the interface. The layers were separated, and the aqueous layer was extracted with 100 ml of hexane. The combined hexane layers were filtered to remove residual palladium complexes, dried over Na₂S0 , and concentrated in vacuo to obtain 21.3 g of (26) as a very viscous oil. (The NMR spectrum showed 6% (by weight) hexane in the oil; corrected yield of (26) = 94%.) [ ]_D = -34.2° (c, 0.032, CHC1₃). ^XH MR (CDCl₃, 500 MHz) δ 0.97 (d, J = 6.3, 3H) , 0.99 (d, J = 6.3 Hz, 3H) , 1.22 (d, J = 9.0 Hz, 6H) , 1.43 (s, 9H) , 1.75 (m, 3H) , 3.31 (m, 2H) , 5.09 (dd, J = 9.7, 3.4 Hz, 1H) , 5.5 (bs, 0.7H), 6.16 (bs, 0.3H), 10.5 (bs, 1H) . ¹³C NMR (CDC1₃, 75 MHz) δ 176.6, 175.6, 156.8, 79.4, 70.6, 48.6, 44.0, 39.6, 28.4, 24.9, 23.1, 22.2, 21.5. IR (CHCI3) 3691, 2963, 1710, 1512, 1151 cm^"1. MS {FD⁺} m/z (relative intensity) 332 (100). Anal. Calcd. for Cι₅H₂₉N0₆ : C, 57.99; H, 8.82; N, 4.23. Found: C, 58.05; H, 8.72; N, 4.13.

TABLE 1 : Preparation of Fragment CD Intermediates

R Condit Lons % Yield

Methyl CDI, 0.1 N THF, 17 h reflux 94

Ethyl CDI , 1 N THF, 72 h reflux 78

Spirocycloper Ltyl CDI, 0.1 N THF , 17 h reflux 55

Spirocyclohe. xyl CDI, 0.1 N THF , 17 h reflux 19

Benzyl CDI, 0.1 N THF , 17 h reflux 21 n-propyl CDI, 0.1 N THF, 17 h reflux 0 n-propyl CDI, 0.4 N PhMe , 17 h reflux 59* i -butyl CDI, 0.4 N PhMe , 17 h refli L1X 52*

* About 50% /wt unknown impurities

Preparation 11

(27) Preparation of 3- (3-Chloro-4-methoxyphenyl) -D-alanine 2,2,2- trichloroethyl ester hydrochloride salt (27) . To a 1000-ml 3-necked flask fitted with a calcium chloride drying tube and a mechanical stirrer and containing a solution of a compound of the formula

(28)

(46.2 g, 100 mmol) in 370 ml of ethyl acetate was added a solution of hydrochloric acid in ethyl acetate { ca . 4.5 M, 800 mmol) . After stirring for 19 h at room (ambient) temperature, the resulting thick white reaction was cooled to 0°C and filtered. The collected solid was washed with cold ethyl acetate (1 x 90 ml) followed by drying in vacuo at 40°C to provide 36.9 g (93%) of compound (27) as a white powder: mp 217-219°C; [a] +3.1° (c, 1.21, MeOH); IR (KBr) 2830 (m) , 1755 (s), 1502 (s), 1282 (s), 1258 (s), 1229 (s), 814 (s) cm^"1; 500 MHz U NMR (DMSO-d₆) δ 8.88 (br s, 3H) , 7.45 (d, 1H, J = 2.0 Hz), 7.28 (dd, 1H, J = 8.5, 2.0 Hz), 7.11 (d, 1H, J = 8.5 Hz), 5.01 and 4.96 (AB quartet, 2H, J = 12.2 Hz), 4.48 (t, 1H, J = 6.6 Hz), 3.84 (s, 3H) , 3.23 (dd, 1H, J = 14.4, 5.9 Hz), 3.17 (dd, 1H, J = 14.4, 7.3 Hz); 125 MHz ¹³C NMR (DMSO-de) d 168.8, 154.7, 131.8, 130.3, 128.4, 121.9, 113.8, 95.2, 75.1, 57.0, 53.8, 35.3. Anal, calcd. for Cι₂Hi₄Cl₅N0₃: C, 36.26; H, 3.55; N, 3.52. Found: C, 36.24; H, 3.59; N, 3.44.

EXAMPLE 1

(35, 45, 5R) -5-phenyl-3-methyl-4-hydroxy-5- [tert- butyldimethylsilyl)oxy] -pent-1-ene

Scheme A, steps 1 and 2 : The reaction was performed in a 5.0 L RB-flask equipped with an overhead stirrer, an additional funnel and connected to a nitrogen bubbler. The flask was charged with solid powdered 95% potassium tert-butoxide (82.7 g, 0.70 mole), distilled THF (550 ml) and the resultant white suspension was cooled to -78°C. To this cold suspension, pre-condensed trans-2- butene (55 g, 0.98 mole) was added and the reaction mixture stirred for 10 minutes. n-BuLi (1.6 M, 437.8 ml, 0.70 mole) was slowly added over the period of 105 min. After complete addition of (n-BuLi), the resultant yellow suspension was stirred for an additional 45 min. The temperature of the reaction mixture was raised to -55°C, and the mixture was stirred for 80 min. The reaction mixture was re-cooled to

-78°C and further stirred for 15 min. Cold (-78°C) 4- Icr₂B0Me (2c) solution (1.34 M, 0.98 mole, 732 ml) in ethyl ether was slowly added over the period of 165 min. The color of the reaction mixture changed to a pale-yellow suspension. The reaction mixture was stirred for 30 min. Next, BF₃ etherate (99. 5 g, 0.7 mole, neat liquid) was added slowly over the period of 45 min and the mixture was stirred for an additional 10 min. Then, a cold (-78°C) solution of aldehyde (20) (100 g, 0.399 mole) in THF (200ml) was added in 50 min. The reaction mixture was stirred for 3

h at -78°C and methanol (20 ml) was added followed by a 3 N NaOAc (392 ml, 1.18 mole) aqueous solution in 60 min and the slow addition of 30% H₂0₂ (210 ml, 1.84 mole) in 90 min. The reaction mixture was allowed to warm to room (ambient) temperature. By then, the reaction mixture had turned colorless to pale-yellow. The reaction mixture was heated at 65°C for 60 min or stirred at room (ambient) temperature

for 8 hours. The reaction mixture was diluted with tert- butyl methyl ether (IL) and the organic layer was washed with water (4 x 500 ml) followed by brine solution (500 ml), dried over anhydrous Na₂S0₄, filtered, and carefully evaporated the solvent on Buchi to yield colorless (or pale viscous liquid (95-100% crude yield) . Flash chromatography of the material on preparative 500 provided 78.8 g (64% yield) of the desired homoallylic alcohol (29) . [α]_D ²⁰ -

-14.67°(c 0.75, CHC1₃) . IR (CHC1₃) : 2957.3, 2930.30, 2858.23, 1471.82, 1463.00, 1258.8, 1091.15, 861.70, 838.21 cm^"1. ^lK

NMR (300 MHz, CDCI3) : δ7.4-7.2 (m, 5H) , 6.07-5.95 (m, IH) ,

5.14-5.01 (m, 2H) , 4.56 (d, IH, J^" = 9 Hz) , 3.55 (m, IH) , 1.1 (d, 3H, J^" = 6 Hz, ) , 0.89 (s, 9H) , 0.05 (s, 3H) , -0.25 (s,

3H) . ¹³C NMR (75 MHz, CDCl₃) : δl41.2, 139.0, 127.9, 127.8, 127.8, 127.1, 126.0, 115.0, 78.9, 76.2, 37.8, 25.4, 17.7, 17.2, -4.9, -5.4. /Anal. Calcd. for Cι₈H₃o0₂Si : C, 70.53; H, 9.86. Found C, 70.05; H, 9.40.

EXAMPLE 2

(35, 45, 51?) -3-methyl-4- [ (p-toluenesulfonyl) oxy] -5- [tert- butyldimethylsilyl)oxy] -5-phenyl-pent-1-ene

Scheme A, step 3: To a 250 ml RB-flask equipped with additional funnel homoallylic alcohol (29) (36.9 g, 0.120 mol), tosyl chloride (32.1 g, 0.169 mol) in freshly distilled THF (100 ml) was added dropwise a solution of lithium bis ( trimethylsilyl ) amide (168.5 ml, 1.0 M, 0.169

mol) at 0°C under nitrogen. The resulting yellow brown slurry was stirred at room (ambient) temperature for 21 h. The reaction mixture was quenched with cold water (200 ml) . The organic layer was separated and the aqueous layer extracted with ether (500 ml) . The combined organic was washed with water until pH = 7, brine (100 ml) , dried over Na₂S0₄, filtered, and concentrated to provide the title compound (30) as a pale orange color thick liquid (53.9 g, 97% yield). TLC (9:1 hexanes/EtOAc ) R_£ = 0.52. IR (CHC1₃). ^λE NMR (500 MHz, CDCl₃) : δ7.47 (d, 2H, J = 8 Hz), 7.16-7.35 (m, 7H) , 5.80-5.90 (m, IH) , 4.98 (m, 2H) , 4.85 (d, IH, J = 5.8 Hz), 4.72 (m, IH) , 2.78 (m, IH) , 2.40 (s, 3H) , 0.96 (d, 3H, J^" = 6.9 Hz), 0.87 (s, 9H) , 0.04 (s, 3H) , -0.30 (s, 3H) .

¹³C NMR (125.7 MHz, CDCl₃): δl44.3, 141.3, 139.2, 135.0, 129.8, 128.6, 128.3, 128.1, 127.9, 115.7, 88.9, 76.0, 38.2, 26.2, 21.9, 18.7, 18.5, -4.3, -4.4.

EXAMPLE 3

(2 , 35, 4K)-2-Methyl-3-[(p-toluenesulfonyl)oxy]-4-[tert- butyldimethylsilyl)oxy] -4-phenyl-l-butanal

Scheme A, step 4: A solution of olefin (30) (52.0 g, 0.113 mol), was dissolved in methylene chloride (500 ml) and clear solution was cooled to -78°C. Ozone gas was bubbled over the solution. The reaction progress was followed by TLC. Zinc dust (36.9 g, 0.564 mol) was added followed by the addition of glacial acetic acid (19.6 ml, 0.339 mol) . The cold bath was removed and the gray suspension was allowed to warm to room (ambient) temperature for 2 h and re-cooled to -78°C and an additional 18.5 g of Zn-dust was added, the cold bath removed, the reaction mixture brought to room (ambient) temperature and stirred for 1 h. The reaction mixture was filtered and the filtrate was washed with water (200 ml), saturated aqueous NaHC0₃ solution (2 x 150 ml) , water (2 x 250 ml) , brine (100 ml) , filtered, dried over Na₂S0₄, and concentrated to provide the desired aldehyde (23) (46.0 g, 89% yield). TLC (5% EtOAc in

hexanes) R_f = 0.19. ^XH NMR (500 MHz, CDC1 ) δ9.75 (s, IH) 7.47 (d, 2H, J = 8 Hz), 7.20-7.36 (m, 7H) , 5.15 (d, IH, J = Hz), 4.71 (m, IH) , 2.65-2.70 (m, IH) , 2.49 (s, 3H) , 0.85- 0.91 (m, 12H) , 0.05 (s, 3H) , -0.15 (s, 3H) . This aldehyde (23) was used for the next step without further purification .

Preparation 12 Synthesis of ?-allyldiisocaranylborane (4-Icr₂Ballyl, 2e) .

Scheme A2 : The reaction was run in a 500 ml RB- flask under a nitrogen atmosphere. Allylmagnesium chloride (1.0 M, 122.6 ml, 122.6 mmol) was slowly added to a 1.0 M β- methoxydiisocaranylborane solution (2c) (136.2 ml) in ethyl ether (-5°C) over the period of 70 minutes. The resultant white suspension was allowed to stir at room (ambient) temperature for 1 h. The mixture was filtered under nitrogen to provide a clear solution of trialkylboron species (4-Icr₂Ballyl , 2e, ^UB NMR: 579-80) . Excess ether was carefully evaporated to make the 1.0 M solution of 4- Icr₂Ballyl which was used for asymmetric allylboration without further purification.

EXAMPLE 4 [45, 55, 65, IR] -4-Hydroxy-5-methyl-6- [ (p- toluenesulfonyl)oxy] -7- [ ( ert-butyldimethylsilyl) oxy] -7- phenyl-hept-1-ene

a) Reaction of Aldehyde (31) with Allylmagnesium Chloride.

Scheme A, step 5: To a cold (-78°C) solution of aldehyde (31) (0.1 g, 0.216 mmol) in ethyl ether (3.0 ml) was slowly added a 1.0 M solution of allylmagnesium chloride (0.28 ml, 0.28 mmol) under nitrogen and the reaction mixture was stirred for 1 h. Methanol (0.2 ml) was added, the cold bath was removed, water/ethyl ether (10 ml each) was added. The organic layer was separated and washed with water, brine, dried over Na₂S0 , filtered and evaporated to provide a mixture of alcohols in 1:2 (24:24a) ratio (0.105 g, 97% yield) in favor undesired alcohol (24a) (by ^λH NMR) .

(b) Reaction of Aldehyde (31) with Allyltributyltin.

Scheme A, step 5: To a cold (-78°C) solution of allyltributyltin in methylene chloride (3.0 ml) was added

SnCl (15 μl, 0.050 mmol) . To this reaction mixture was

added a cold (-78°C) solution of aldehyde (31) (0.115 g, 0.248 mmol) in methylene chloride (1.0 ml). The resultant clear solution was stirred for 90 minutes at -78°C and methanol (0.2 ml) was added. The cold bath was removed and methylene chloride (5.0 ml) was added. The organic layer was separated and washed with water, brine, dried over

Na₂S0 , filtered and concentrated in vacuo to yield 0.120 g (96%) of thick oil representing 1:1 ratio of mixture of alcohols (32) and (24a) (by ^XE NMR) .

(c) Synthesis of Enantio and Diastereomerically Pure

Homoallylic Alcohol (32) by Double Asymmetric Crotylboration Using Allyldiisocaranylborane Reagent (4-Icr₂Ballyl, 2e) .

Scheme A, step 5: To a cold (-78°C) 1.0 M clear solution of Icr₂Ballyl (2e, 12.6 ml, 12.6 mmol) was added slowly the cold (-78°C) solution of aldehyde (31) (4.9 g, 10.6 mmol) under nitrogen. The resultant pale yellow reaction mixture was stirred for 1 h, 3 N ΝaOAc aqueous solution ( 5.5 ml , 16.6 mmol) was added followed by the slow addition of 30% H₂0₂ solution (3.5 ml, 30.6 mmol). The cold bath was removed and the reaction mixture was allowed to warm to room (ambient) temperature and heated at 45°C for 1 h. The organic layer was separated and washed with water, brine, dried over Νa₂S0 , filtered and concentrated in vacuo to yield thick oil (H NMR showed >19:1 diastereoselectivity for the formation of the desired 32) which was purified by flash chromatography to yield 3.4 g (64% yield of 32) of white solid. mp 68°C. TLC (5:1 hexane/EtOAc ) R_f = 0.56.

[α]_D ²⁵ = -26.6°, (c 0.64, CHC1₃). IR (CHC1₃): 2957, 2931, 1600, 1469, 1362, 1189, 1176, 1126, 1097, 921, 876, 837 cm^"1. UV (EtOH) 263 (767), 218 (12452). ^XE NMR (500 MHz, CDCI₃): δ 7.55 (d, 2H J = 8.24 Hz), 7.19-7.30 (m, 7.0 H) , 5.79-5.91 (m, 1 H) , 5.05-5.15 (m, 3H) , 4.90 (m, IH) , 3.80 (m, IH) , 2.85 (brs, IH) , 2.45 (s, 3H) , 2.19 (m, IH) , 2.01-2.11 (m, IH) , 1.25-1.38 (m, IH) , 0.82-0.95 (m, 12H) , 0.85 (s, 3H) , -

0.20 (s, 3H) . ¹³C NMR (125.7 MHz, CDC1₃): 5144.64, 140.79, 135.35, 134.38, 129.95, 128.55, 128.21, 128.12, 127.71, 117.98, 88.41, 77.68, 70.87, 40.28, 38.99, 26.20, 21.95, 18.54, 13.91, -4.31, -4.59. MS m/z (M⁺) 505.2. Anal. Calcd. for C₂₇H₄₀O₅SSi: C, 64.25; H, 7.99. Found C, 64.49; H, 7.82. In another approach, aldehyde (31) (46 g, 98.5 mmol) was subjected to allylboration as described above and the resultant homoallylic alcohol (32) along with caranyl alcohol (2.2 equivalent) as a by-product of the reaction was further subjected to ozonolysis as described below.

EXAMPLE 5

Ozonolysis of Homoallylic Alcohol (32) .

Scheme A, step 6 : The crude reaction product mixture (49.7 g) from the above experiment (Example 4c) was dissolved in methylene chloride and ozonolysis was carried out as described earlier. Zinc dust (32.2 g, 0.49 mol) and glacial acetic acid (17.1 ml, 0.30 mol) treatment to intermediate ozonide provided, after work up, the desired aldehyde (33) along with caranyl alcohol (49 g) . This mixture was not purified and subjected for olefination reaction as described below.

EXAMPLE 6 Fragment A: Allyl (55, 65, 75, 8_R) -5-hydroxy-6-methyl-7- [ (p- toluensulfonyl)oxy] -8- [ (tert-butyldimethylsilyl) oxy] -8- phenyl-oct-2 (E) -enoate

Scheme A, step 7: To a cold (-20°C) solution of the above crude mixture (49.0 g) of aldehyde (33) containing caranyl alcohol in tetrahydrofuran (200 ml) was added allyl diethylphosphonoacetate (24.5 ml, 116.28 mmol). The reaction mixture was stirred for 5 minutes and tetramethylguanidine (14.6 ml, 116.28 mmol) was slowly added. The resultant yellow reaction mixture was stirred at room (ambient) temperature for 17 h. The reaction mixture was diluted with water (150 ml) and extracted with ether (2 x 300 ml) . Combined organic layers were washed with water (5 x 150 ml), brine (100 ml), dried over Na₂S0 , filtered and concentrated in vacuo to yield a dark-yellow, thick oil (103 g) . This mixture was further purified by flash chromatography to provide a pale-yellow oil [19.3 g, 33% from 32, three steps yield]. TLC (3:1 hexane/EtOAc) R_f = 0.50. [α]_D ²⁵ = -35.2°, (c 0.50, CHC1₃). UV (EtOH) 262 (1325), 218 (15669) . ^ NMR (500 MHz, CDC1₃) : 5 7.60 (d, 2H, J = 8.2 Hz), 7.20-7.30 (m, 7H) , 7.03-7.06 (m, IH) , 5.93-5.97 (m, IH) , 5.9 (d, IH, J^" = 15.9 Hz), 5.3 (d, IH, J = 18.5 Hz), 5.2

(d, IH, J^" = 11.8 Hz), 5.1 (d, IH, J^" = 5.3 Hz), 4.8 (m, IH) , 4.6 (d, 2H, J = 5.5 Hz), 3.8 (m, IH) , 3.4 (d, IH, J = 3.5 Hz), 2.5 (m, IH) , 2.4 (s, 3H) , 2.2 (m, IH) , 2.1 (m, IH) , 0.9

(s, 9H) , 0.8 (d,.3H, J = 1 Hz) , 0.08 (s, 3H) ,

-0.18 (s, 3H) . ¹C NMR (125.7 MHz, CDC1₃): 5166.2, 146.6, 145.0, 140.3, 134.2, 132.8, 130.1, 128.7, 128.4, 128.1, 127.5, 123.6, 118.3, 88.5, 76.6, 70.4, 65.3, 40.0, 37.4, 26.2, 21.9, 18.6, 14.8, -4.3, -4.6.

EXAMPLE 7

Synthesis

Scheme B, step 1: To a solution of fragment A _.34) (19.3 g, 32.8 mmol), fragment CD (13.0 g, 39.3 mmol,), dimethylaminopyridine (1.2 g, 9.8 mmol) in methylene chloride (130 ml) was slowly added DCC solid (8.1 g, 39.3 mmol) at 0°C under nitrogen. The turbid reaction mixture was

stirred at 0°C for 10 minutes then at room (ambient) temperature 40 minutes. The reaction mixture was filtered and rinsed with methylene chloride. The filtrate was concentrated and partitioned between EtOAc (300 ml) and water (2 x 50 ml) . The organic was washed with 5% NaHC0₃ aqueous solution (2 x 50 ml) , water 2 x 100 ml) , brine (100 ml), dried over Na₂S0 , filtered, and concentrated to obtain a crude residue (31 g) . The residue was triturated in pentane (100 ml), filtered, rinsed with small amount of 1:4 EtOAc/pentane . The filtrate was concentrated to yield the desired coupled fragment AC'D (26) (28.5 g, wet solid, 97%). TLC (8:5:1.5, hexane/THF/ EtOAc) Rf 0.40. A small amount of the compound was purified by preparative TLC. [α]_D ²⁵ = -34.8°, (c 0.5, CHC1₃) • IR (CHCI3) : 2956, 2931, 1715, 1363, 1260, 1189, 1175, 938, 840 cm^"1. UV (EtOH) 257 (1632). ²H NMR (500 MHz, CDCI3) : δ 7.60 (d, 2H, J = 8.3 Hz) , 7.30 (d, 2H, J = 7 Hz), 7.27-7.30 (m, 5H) , 6.74-6.83 (m, IH) , 5.92- 6.02 ( , IH) , 5.8 (d, IH, J = 15.7 Hz), 5.6 ( m, IH) , 5.35 (d, IH, J = 18.5 Hz), 5.32 (m, IH) , 5.20 (d, IH, J = 10.2 Hz), 5.10 (d, IH, J = 4.3 Hz), 4.9 (m, IH) , 4.7 (m, IH) , 4.6 (d, 2H, J = 5.6 Hz), 3.3 (m, 2H) , 2.55 (m, IH) , 2.44 (s, 3H) , 2.33-2.38 (m, 2H) , 1.70-1.75 (m, 2H) , 1.6 (m, IH) , 1.45 (s, 9H) , 1.2 (d, 6H, J = 7.4 Hz) , 0.96-0.91 (m, 6H) , 0.88 (s, 9H) , 0.83 (d, 3H,_J = 7.1 Hz) , 0.04 (s, 3H) , -0.16 (s,

3H) 13 C NMR (125.7 MHz, CDCl 5176.5, 170.2, 165

156.8, 145.2, 144.4, 140.8, 134.3, 132.8, 130.1, 128.7, 128.2, 128.1, 127.4, 124.3, 118.3, 87.5, 79.4, 77.0, 74.1, 71.4, 65.4, 48.9, 44.2, 40.0, 37.2, 33.4, 28.8, 26.2, 25.1, 23.4, 23.3, 22.8, 22.0, 21.8, 18.6, 12.5, -4.4, -4.5.

Example 8

(37)

Synthesis of Fragment ABCD (37)

Scheme B, steps 2 and 3: To a pale-orange solution of fragment AC'D (35) (28.5 g, 31.6 mmol) in THF (150 ml), Pd(PPh₃)₄ (244 mg, 0.21 mmol) was added at once followed by slow addition of morpholine (3.3 ml, 37.92 mmol) at room (ambient) temperature. The reaction mixture stirred for 90 min and an additional 0.4 mole % of Pd(PPh₃)₄ was added and further stirred for 3 h. The solvent was removed with a rotavapor and water (100 ml) was added. The resultant emulsion was acidified with cold 1:1 HCl:water solution. The organic layer was separated and the aqueous layer was extracted with EtOAc (250 ml) . The combined organic was washed with water (2 x 200 ml) , 5% NaHC0₃ aqueous solution (until pH = 7), water (200 ml), brine (50 ml), dried over Na₂Sθ4, filtered, and concentrated in vacuo to yield a yellowish-orange color, thick liquid (36) (27.2 g, 100% yield) which was without further purification subjected to the coupling reaction as mentioned below.

.4 -

To a cold (0°C) solution of acid (36) (27.2 g, 31.6 mmol) in DMF (100 ml), and diisopropylethylamine (16.6 ml, 94.8 mmol) was slowly added 98% diphenylphosphinic chloride (6.5 ml, 31.6 mmol) . The reaction mixture was allowed to stir at room (ambient) temperature for 90 minutes, then cooled back to 0°C. Solid Fragment B HCl (13.2 g, 31.6 mmol) of the formula

was added slowly. The cooling bath was removed and the reaction mixture was stirred at room (ambient) temperature for 1.5 h. The reaction mixture was diluted with water (200 ml) and extracted with EtOAc (2 x 150 ml) . The combined organic was washed with 1 N HCl solution, water (4 x 200 ml), brine (100 ml), dried over Na₂S0₄, filtered, and concentrated in vacuo to yield a thick, yellowish foam of fragment ABC'D (28) (38.1 g, 100% yield). A small amount of the compound was purified by preparative TLC. [α]_D ²⁵ = -28.4° (0.5, CHCI3) - IR (CHCI3) : 2970, 2933, 1708, 1504, 1259, 1159, 1189, 1176 cm^"1. UV (EtOH) 277 (2764). ²H NMR (500 MHz, CDCI3) 5 7.66 (d, 2H, J = 81 Hz), 7.4 (m, IH) , 7.25-7.30 (m, 6H) , 7.20 (m, IH) , 7.1 (d, IH, J = 8.4 Hz) , 6.8 (d, IH, J = 8.4 Hz) , 6.6 (m, IH) , 5.8 (m, IH) , 5.6 (m, IH) , 5.4 (m, IH) , 5.2 (m, IH) , 5.1 (m, IH) , 4.9 (m, IH) , 4.8 (d, IH, J = 12 Hz) , 4.72 (d, IH, J = 11.9 Hz) , 4.70 (m, IH) , 3.80 (s, 3H) , 3.3 (m, 2H) , 3.19-3.23 (dd, IH, J = 5.7, 5.7 Hz) , 3.05-3.10 (dd, IH, J^" = 7 Hz) , 2.50 (m, IH) , 2.40 (s, 3H) , 2.32-2.36 (m, 2H) , 1.74-1.80 ( , 2H) , 1.60 (m, IH, 1.45 (s, 9H) , 1.20 (s, 3H) , 1.16 (s, 3H) , 0.94 (d, 6H, J = 5.4 Hz) , 0.85 (s, 9H) , 0.82 (d, 3H, J^" = 7.1 Hz) , 0.03 (s, 3H) , -0.15 (s, 3H) . ¹³C NMR (125.7 MHz, CDCl₃) 5177.3, 170.4, 165.8, 154.5, 145.3, 140.8, 139.7, 134.3, 131.6, 130.2, 130.1, 129.9, 129.6, 128.9, 128.2, 125.5, 122.7, 112.6, 94.8, 87.6.

EXAMPLE 9

Synthesis of Macrocycle (38)

Scheme B, step 4: To a cold (-10°C) solution of ABC'D fragment (37, 38.0 g, 31.5 mmol) trifluoroacetic acid

(48.8 ml, 630 mmol) was added slowly and the reaction mixture was stirred for 30 minutes at 0°C and further stirred for 30 minutes at room (ambient) temperature. The reaction mixture was poured over cold (~5°C) aqueous solution of K₂C0₃ (105 g in 100 ml water) . The organic layer was separated and the aqueous layer was extracted with EtOAc (200 ml) . The combined organic layer was washed with

(2 x 200 ml), brine (100 ml), dried over Na₂S0₄, filtered, and concentrated to provide a brownish foam. This foamy material was dissolved in toluene (150 ml), and 2- hydroxypyridine (6.1 g, 63 mmol) was added. The resulting brownish clear solution was stirred at 40°C for 21 h. The reaction mixture was diluted with EtOAc (200 ml) and the organic layer was washed with saturated aqueous aHCθ₃ solution (2 x 50 ml), water (2 x 400 ml), brine (100 ml), dried over Na₂S0₄, filtered and concentrated to yield (28.6 g, 95% yield) a yellowish foam. A small amount of material was purified by preparative TLC. IR (CHC1₃) : 2960, 2932, 1754, 1712, 1681, 1503, 1472, 1259, 1189, 1176, 1067, 873 cm^"1. UV (EtOH) 279 (1987). ^XH NMR (500 MHz, CDCI3): 57.6 (d, 2H, J = 8.2 Hz), 7.18-7.32 (m, 9 H) , 7.09-7.12 (m, IH) , 6.88 (d, IH, J = 8.5 Hz), 6.10-7.11 (m, IH) , 5.63-5.75 (m, 3H) , 5.19 (d, 1 H, J = 4.55 Hz), 4.86 (m, IH) , 4.70-4.81 (m, 2H) , 3.89 (s, 3H) , 3.40-3.49 ( , IH) , 3.15 (m, 2H) , 3.05 (m, IH) , 2.50 (s, IH) , 2.43 (s, 3H) , 2.19-2.30 (m, 2H) , 1.50- 1.78 (m, 3H) , 1.25 (s, 3H) , 1.20 (s, 3H) . 0.81-0.99 (m, 18H) , 0.20 (s, 3H) , -0.18 (s, 3H) . ¹³C NMR (125 MHz, CDCI3) 5178.18, 170.91, 170.32, 165.48, 154.50, 145.30, 142.95, 140.90, 134.27, 131.30, 130.24, 130.19, 128.69, 128.28,

128.00, 127.12, 124.71, 122.99, 112.82, 87.09, 77.70, 77.45, 77.19, 76.61, 74.33, 71.76, 56.56, 54.85, 46.96, 43.23,

39.97, 38.47, 35.76, 35.04, 26.19, 25.10, 23.34, 23.11,

22.98, 22.12, 21.98, 18.57, 12.46, -4.42, -4.53. EXAMPLE 10

Synthesis of (39)

Scheme B, step 5a: A solution of macrocycle (38) (0.19 g, 0.2 mmol) in acetonitrile (3.0 ml) was treated with THF (48% solution, 1.7 ml). The reaction mixture was stirred at room (ambient) temperature overnight. Upon completion of reaction, the mixture was partitioned between water and EtOAc (15 ml each) . The organic layer was washed with water (15 ml), saturated aqueous NaHC0₃ solution (10 ml), dried over Na₂Sθ4, filtered, and concentrated to yield the desired desilylated macrocycle (30) (63 mg of yellow foam, 39%). mp 115-116°C. TLC (1:4 hexanes/EtOAc ) R_£ = 0.43. IR (CHC1₃) : 1751, 1714, 1754, 1680, 1528, 1503, 1485, 1176, 1189, 1151, 1067, 957 cm^"1. UV (EtOH) 277 (3303) . ^lH NMR (500 MHz, CDCl₃) 57.36 (d, 2h, J = 8 Hz) , 7.18-7.27 (m, 9H) , 7.08 (m, IH) , 6.85 (d, 2H, J = 8.5 Hz) , 6.7 (m, IH) , 5.96 (d, IH, J = 7.8 Hz) , 5.80 (d, IH, J = 15.1 Hz) , 5.60 (m, IH) , 4.96 (dd, IH, J = 3.5, 6.5 Hz) , 4.87 (d, IH, J = 6.7 Hz) , 4.81 (m, IH) , 2.40 (s, 3H) , 2.29 (m, 2H) , 1.79 (m, IH) , 1.68 (m, IH) , 1.60 (m, IH) , 1.24 (s, 3H) , 1.18 (s, 3H) , 1.09 (d, 3H, J = 1 Hz) , 0.93 (d, 3H, J =6.5 Hz) , 0.89 (d, 3H, J =6.5 Hz) . ¹ C NMR (125.7 MHz, CDCl₃) 5178.1, 171.1, 170.6, 165.8, 154.4, 145.0, 142.9, 140.5, 134.1, 131.3, 130.4, 130.1, 129.0, 128.9, 128.8, 128.5, 127.9, 124.9, 122.9, 112.8, 85.2, 75.4, 73.6, 71.7, 56.6, 55.0, 47.0, 43.3, 40.2, 39.9, 36.2, 35.7, 25.1, 23.3, 23.1, 21.9, 21.8, 11.9. MS (FID) 841.5. /Anal. Calcd. for C₄3H₅₃N₂0ιιSCl : C, 61.38, ; H, 6.35; N, 3.33. Found: C, 61.63, ; H, 6.47; N, 3.21.

EXAMPLE 11

Synthesis of Cryptophycin 52 (40) Scheme B, step 5: To a solution of desilylated macrocycle (39) (25.2 g, 26.3 mmol) in THF (100 ml) was treated dropwise with a 1.0 M solution of tetrabutylammonium fluoride (15.3 g, 58.5 mmol, 58.5 ml) under nitrogen. The resulting clear light brown solution was stirred at room (ambient) temperature for 3 h. The reaction mixture was diluted with EtOAc (200 ml) and washed with water (3 x 100 ml), 10% NaHC0₃ aqueous solution (100 ml), water (100 ml) . The aqueous layer was extracted with EtOAc (2 x 100 ml) . The combined organic was dried over Na₂S0 , filtered, and concentrated to obtain a crude product (22 g, light yellow foam) which was purified by Si0₂ plug (200 g, 3:1 to 1:4 hexanes/EtOAc) to yield the desired crypto-52 (10 g, 56% yield) . mp TLC (1:4 hexanes /EtOAc ) R_f = 0.6. The ^lϊL and ¹³C NMR spectra are comparable with an authentic sample of Cryptophycin 52. EXAMPLE 12

Cryptophycin 55

To a solution of Cryptophycin 52 (6 mg, 0.009 mol, Example 11 or 22A) in 0.6 ml of 2:1 1 , 2-dimethoxymethane/water was added 2 μl of 12 N HCl . The solution was allowed to stir at room (ambient) temperature for 20 h, neutralized with potassium carbonate, filtered through a 5 μ filter, and evaporated. The acetonitrile-soluble material was purified by reverse-phase HPLC on C18 (250 x 10 mm column) using 4:1 MeOH/H₂0 to obtain 3.0 mg of Cryptophycin 55 (48%).

[α]_D +42.5° (c 1.1, CHC1₃) ; EIMS m/z 704/706/708 (M⁺ <1), 668/670 (1.5/0.5, M⁺-HC1) , 445(6), 226(8), 195/197(16/5), 184(10), 155/157 (33/11), 135(100), 91(99), 77(30); HREIMS m/z 668.2873 (M⁺-HC1, C₃6H₄5N₂0₈ ³⁵C1, Δ-0.8 mu) ; UN (MeOH)λ_ma: (ε) 204(48400), 218 (29200), 284 (1600)nm; IR(ΝaCl) V_max 3410, 3286, 2959, 1748, 1723, 1666, 1538, 1504, 1455, 1257, 1178, 1066, 753 cm^"1. ^XH NMR (CDCl₃)δ unit A 7.35-7.42 (10H/11H/12H/13H/14H; m) , 6.78 (3H; ddd, 15.1/10.6/4.5), 5.78 (2H; dd, 15.1/1.7) , 5.16 (5H; ddd, 11.1/8.3/2.1) , 4.65 (8H; d, 9.7) , 4.01 (7H; bd, 9.7) , 2.69 (4H_b; dddd, - 14.5/4.5/2.1/ 1.7) , 2.50 (6H; bm, Wι_/2 = 15) , 2.38 (4-H_a; ddd, -14.5/11.1/ 10.6) , 1.53 (70H, s) , 1.04 (6Me, d, 7.1) ; unit B 7.21 (5H; d, 2.2) , 7.07 (9H; dd, 8.5/2.2) , 6.85 (8H; d, 8.5) , 5.57 (2NH; d, 7.8) , 4.74 (2H; ddd, 7.8/7.6/5.2) , 3.88 (70CH₃; s) , 3.13 (3H_b; dd, 14.5/5.2) , 3.05 (3H_a; dd, 14.5/7.6) ; unit C 7.21 (3NH; m) , 3.38 (3H_b; dd, 13.5/8.3) , 3.17 (3H_a; dd, 13.5/4.1) , 1.23 (2CH₃; s) , 1.17 (2CH₃' ; s) , unit D 4.93 (2H; dd, 10.1/3.5) , 1.78 (3H_b; ddd,

13.5/10.1/5.0) , 1.72 (4H; bm, Wι_/2 ~ 20) , 1.43 (3H_a; ddd, 13.5/8.8/3.5) , 0.92 (4CH₃; d, 6.6) , 0.92 (5H₃, d, 6.4) . ¹³C NMR (CDC1₃) δ unit A 165.1 (C-1) , 142.4 (C-3) , 138.4 (C-9) , 129.0 (C-ll/13) , 128.3 (C-12) , 128.0 (C-10/14) , 124.6 (C-2) , 76.1 (C-5) , 74.1 (C-7) , 62.0 (C-8) , 38.4 (C-6) , 36.5 (C-4) , 8.6 (6Me) ; unit B 170.3 (C-1) , 154.1 (C-7) , 130.9 (C-5) , 129.6 (C-4) , 129.2 (C-9) , 122.6 (C-6) , 112.3 (C-8) , 56.1 (7- OMe) , 54.3 (C-2) , 35.3 (C-3) ; unit C 177.8 (C-1) , 46.5 (C- 3) , 42.8 (C-2) , 22.9 (2Me) , 23.0 (C-2Me') ; unit D 170.3 (C- 1) , 71.3 (C-2) , 39.7 (C-3) , 24.8 (C-4) , 22.7 (4Me) , 21.6 (C- 5) .

EXAMPLE 13

Cryptophycin 55 Glycinate Hydrochloride

Preparation of Cryptophycin 55 N- -BOC-glycinate

To a solution of a compound of Example 12 (118 mg, 0.167 mmol), N-t-BOC-glycine (44 mg, 0.251 mmol), and 4- dimethylamino pyridine (2.0 mg, 0.0167 mmol) in 490 ml of anhydrous methylene chloride at room (ambient) temperature was added a solution of 1 , 3-dicyclohexylcarbodiimide (52 mg, 0.251 mmol) in 67 ml of methylene chloride. After stirring for 50 min, the cloudy white reaction mixture was diluted with ethyl acetate-hexanes (3:1, 1 ml), stirred for 10 min, and filtered through a plug of celite, while washing with ethyl acetate-hexanes (3:1) . The filtrate and washings were concentrated in vacuo to a colorless oil. Chromatography (19 g of flash silica gel, 3:l/ethyl acetate-hexanes) afforded 138 mg (96%) of the title compound as a white foam: 500 MHz ^!H NMR (CDCl₃) d 7.34 (s, 5H) , 7.24 (d, IH, J = 2.0 Hz), 7.23-7.19 (m, IH) , 7.10 (dd, IH, .7 = 8.4, 2.0 Hz), 6.88 (d, IH, J = 8.4 Hz) , 6.79-6.70 (m, IH) , 5.77 (d, IH, J = 13 Hz) , 5.50 (d, IH, .7 = 8.0 Hz) , 5.47 (d, IH, J = 9.8 Hz) , 4.97 (dd, IH, J = 11, 2.7 Hz) , 4.89 (t, IH, J = 10 Hz) , 4.83

(d, IH, J = 9.8 Hz) , 4.79-4.72 (m, IH) , 4.68 (br s, IH) , 3.91 (s, 3H) , 3.66 (dd, IH, J^" = 18, 5.3 Hz) , 3.42-3.35 (m, 2H) , 3.21 (dd, IH, J = 13, 4.0 Hz) , 3.17 (dd, IH, J = 15, 5.1 Hz) , 3.08 (dd, IH, J = 15, 7.6 Hz) , 2.66-2.57 (m, 2H) , 2.47-2.38 (m, IH) , 1.95 (ddd, IH, J = 14, 12, 4.7 Hz) , 1.85- 1.77 (m, IH) , 1.75-1.67 ( , IH) , 1.43 (s, 9H) , 1.27 (s, 3H) , 1.20 (s, 3H) , 1.08 (d, 3H, J = 7.0 Hz) , 1.03 (d, 3H, J = 6.7 Hz) , 0.98 (d, 3H, .7 = 6.5 Hz) .

(b) Preparation of Cryptophycin 55 glycinate hydrochloride salt

To a solution of a compound of Example 13, step (a) (122 mg, 0.141 mmol) in 471 ml of methylene chloride at room (ambient) temperature was added a 4.0 M solution of hydrogen chloride in 1,4-dioxane (178 ml, 0.707 mmol). After stirring for 1 h 20 min, the clear, colorless reaction mixture was concentrated in vacuo to provide 120 mg (99%, corrected for 7% wt dioxane) of the title compound as a white foam: 500 MHz ^H NMR (MeOH-d₄) d 7.81 (dd, IH, J = 8.5, 2.2 Hz), 7.46-7.41 (m, 2H) , 7.40-7.36 (m, 3H) , 7.31 (d, IH, J = 2.1 Hz), 7.20 (dd, IH, J = 8.4, 2.1 Hz), 7.01 (d, IH, J = 8.4 Hz), 6.70 (ddd, IH, J = 15, 13, 3.7 Hz), 5.97 (dd, IH, J^" = 15, 1.7 Hz) , 5.55 (d, IH, J = 9.9 Hz) , 5.18 (d, IH, .7 = 9.9 Hz) , 5.14 (dd, IH, J = 10, 2.8 Hz) , 4.84 (t, IH, J = 10 Hz) , 4.52 (dd, IH, J = 11, 3.7 Hz) , 3.87 (s, 3H) , 3.78 (d, IH, J = 18 Hz) , 3.50 (dd, IH, J = 13, 9.8 Hz) , 3.23 (d, IH, .7 = 18 Hz) , 3.20 (dd, IH, J = 14, 3.6 Hz) , 3.13 (dd, IH, J = 13, 2.4 Hz) , 2.80-2.69 (m, 3H) , 2.41-2.32 (m, IH) , 1.99-1.92 (m, IH) , 1.91-1.81 (m, 2H) , 1.25 (s, 3H) , 1.20 (s, 3H) , 1.12 (d, 3H, J = 7.0 Hz) , 1.06 (d, 3H, J = 6.2 Hz) , 1.04 (d, 3H, 6.2 Hz) .

Claims

WE CLAIM :

1. A process for preparing a compound of the formula

wherein

G is (Cι-Cι₂) alkyl, (C₂-C₁₂) alkenyl, (C₂-C₁₂) alkynyl, or Ar;

Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Cι-C₆) alkyl;

R^pl is trityl or a suitable silyl protecting group;

R^p2 is hydrogen or a suitable carboxy protecting group; and

LG is a suitable hydroxy activating group; or a pharmaceutically acceptable salt thereof;

comprising the steps of:

(a) reacting an α-chiral aldehyde of the formula

ORP¹

° (2) with a chiral crotylboron reagent to form a compound of the formula

wherein G, R³ , and R^pl are as defined above and R^p3 and R^p4 are each isocaranyl or isopinocampheyl ;

(b) reacting a compound of formula (3) with a boron- cleaving agent to form an alcohol of the formula

OH

wherein G, R , and R^p are as defined above;

(c) reacting the alcohol of formula (4) with an alcohol protecting/activating agent to form a compound of the formula

O-LG ( 5 :

wherein G, R³ , R^pl and LG are as defined above;

(d) oxidizing the compound of formula (5) with an oxidizing agent to provide an aldehyde of the formula

O-LG ( ,6,,,

wherein G, R³ , R^pl and LG are as defined above;

(e) reacting the aldehyde of formula (6) with an allylating agent to provide a homoallylic alcohol of the formula

wherein G, R³, R^pl and LG are as defined above; (f) oxidizing the homoallylic alcohol of formula (7) with an oxidizing agent to provide a hydroxy aldehyde of the formula

wherein G, R³ , R^p~ and LG are as defined above;

(g) reacting the hydroxy aldehyde of formula (8) with a carboxylic acid, ester or amide forming agent to provide a compound of formula (I), and optionally forming a pharmaceutically acceptable salt thereof.

2. A process according to claim 1 wherein G is phenyl; LG is tosyl; and R^p2 is allyl.

3. A process according to claim 2 wherein R³ is methyl and R^pl is t-butyldimethylsilyl .

4. A process according to claim 1 wherein the compound of formula (I) is allyl (5S, 6S, IS, 8_R) -5-hydroxy- 6-methyl-7- [ (p-toluensulfonyl) oxy] -8- [ ( ert- butyldimethylsilyl) oxy] -8-phenyl-oct-2 (E) -enoate.

5. A process according to claim 1 wherein the chiral crotylboron reagent is 5-allylbis (4- isocaranyl ) borane .

6. A process according to claim 5 wherein the boron-cleaving agent is H₂0₂; the alcohol protecting/activating agent is tosyl chloride; the oxidizing agent is ozone and the carboxylic acid ester forming agent is a Horner-Emmons-Wadsworth reagent.

7. A process according to claim 1 wherein the allylating agent is a chiral metalallyl reagent.

8. A process according to claim 6 wherein the allylating agent is β-allyldiisocaranylborane .

9. A process according to claim 8 wherein the compound of formula (I) is allyl (5S, 6S, IS, 8R) -5-hydroxy- 6-methyl-7- [ (p-toluensulfonyl) oxy] -8- [ (tert- butyldimethylsilyl) oxy] -8-phenyl-oct-2 (E) -enoate.

10. A process for preparing an alcohol of the formula

OH ; 4 )

wherein

G is (C1-C12) alkyl, (C2-C12) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Ci-Cε) alkyl; and

R^p is trityl or a suitable silyl protecting group;

comprising the steps of

(a) reacting an α-chiral aldehyde of the formula

(2:

with a chiral crotylboron reagent to form a compound of the formula

wherein G, R³ , and R^pl are as defined above and R^p3 and R^p4 are each isocaranyl or isopinocampheyl ; and

(b) reacting a compound of formula (3) with a boron- cleaving agent to form an alcohol of the formula (4) .

11. A process according to claim 10 wherein G is phenyl and R^p3 and R^p4 are both isocaranyl.

12. A process according to claim 10 wherein the compound of formula (4) is (3S, AS, SR) -5-phenyl-3-methyl-4- hydroxy-5- [ tert-butyldimethylsilyl ) oxy] -pent-1-ene .

13. A process according to claim 10 wherein the chiral crotylboron reagent is ?-allylbis (4- isocaranyl ) borane .

14. A process according to claim 13 wherein the boron cleaving agent is H₂0₂.

15. A process according to claim 12 wherein the chiral crotylboron reagent is β-allylbis (4-isocaranyl ) borane and the boron cleaving agent is H₂0₂.

16. A compound of the formula

wherein

G is (C1-C12) alkyl, (C -C₁₂) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group;

R³ is (Cι-C₆) alkyl;

R^pl is trityl or a suitable silyl protecting group;

R^p2 is hydrogen a suitable carboxy protecting group; and LG is a suitable hydroxy leaving group; or a pharmaceutically acceptable salt thereof.

17. A compound of claim 16 wherein G is phenyl; LG is tosyl; and R^p2 is allyl.

18. A compound of claim 17 wherein R³ is methyl and R^pl is t-butyldimethylsilyl .

19. A compound of claim 16 wherein the compound is allyl (55, 6S, I S, 8R) -5-hydroxy-6-methyl-7- [ (p- toluensulfonyl) oxy] -8- [ ( ert-butyldimethylsilyl ) oxy] -8- phenyl-oct-2 ( E) -enoate.

20. A compound of the formula

wherein

G is (C₁-C₁₂) alkyl, (C₂-Cι₂) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Ci-Cβ) alkyl; R^p is trityl or a suitable silyl protecting group; and R^p3 and R^p4 are each isocaranyl or isopinocampheyl .

21. A compound of claim 20 wherein G is phenyl; R³ is methyl and R^pl is t-butyldimethylsilyl .

22. A compound of claim 20 wherein R^p3 and R^p4 are each isocaranyl.

23. A compound of claim 21 wherein R^p3 and R^p4 are each isocaranyl

24. A compound of the formula

OH ( 4 : wherein

G is (C₁-C₁2) alkyl, (C₂-Cι₂) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R is (Ci-Cβ) alkyl; and R^pl is trityl or a suitable silyl protecting group.

25. A compound of claim 24 wherein G is phenyl; R³ is methyl and R^pl is t-butyldimethylsilyl .

26. A compound of claim 24 wherein said compound is ( 3 S, AS, 5R) -5-phenyl-3-methyl-4-hydroxy-5- [ tert- butyldimethylsilyl) oxy] -pent-1-ene.

27. A compound of the formula

O-LG

wherein

G is (C₁-C₁2) alkyl, (C₂-Cι₂) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Ci-Cε) alkyl; R^pl is trityl or a suitable silyl protecting group; and LG is a suitable hydroxy leaving group.

28. A compound of claim 27 wherein G is phenyl;

R^pl is t-butyldimethylsilyl and LG is tosyl.

29. A compound of claim 28 wherein R³ is methyl.

30. A compound of claim 27 wherein said compound is (3S, AS, 5R) -3-methyl-4- [ (p-tolunesulfonyl) oxy] -5- [ ert- butyldimethylsilyl) oxy] -5-phenyl-pent-l-ene .

31. A compound of the formula

°- ^G (6) wherein

G is (Cι-Cι₂) alkyl, (C₂-Cι₂) alkenyl, (C₂-Cι₂) alkynyl , or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Ci-Cβ) alkyl; R^pl is trityl or a suitable silyl protecting group; and LG is a suitable hydroxy leaving group.

32. A compound of claim 31 wherein G is phenyl; R^pl is t-butyldimethylsilyl and LG is tosyl.

33. A compound of claim 32 wherein R³ is methyl

34. A compound of claim 31 wherein said compound is ( 2R, 3 S, AR) -2-Methyl-3- [ (p-tolunesulfonyl) oxy] -4- [tert- butyldimethylsilyl) oxy] -4-phenyl-l-butanal .

35. A compound of the formula

wherein G is (C1-C12) alkyl, (C₂-C₁₂) alkenyl, (C2-C12) alkynyl, or Ar; Ar is an aromatic or heteroaromatic group or a substituted aromatic or heteroaromatic group; R³ is (Ci-Cβ) alkyl; R^pl is trityl or a suitable silyl protecting group; and LG is a suitable hydroxy leaving group.

36. A compound of claim 35 wherein G is phenyl; R^pl is t-butyldimethylsilyl and LG is tosyl.

37. A compound of claim 36 wherein R³ is methyl.

38. A compound of claim 35 wherein said compound is [ AS, 55, 65, IR] -4-Hydroxy-5-methyl-6- [ (p- toluenesulfonyl) oxy] -7- [ ( ert-butyldimethylsilyl) oxy] -7- phenyl-hept-1-ene .

39. A compound of the formula

wherein Q¹, Q² and Q are each independently hydrogen, (Ci- C₆) alkyl or halo; R³ is (Cι-C₆) alkyl; R^pl is trityl or a suitable silyl protecting group; and LG is a suitable hydroxy leaving group.

40. A compound of claim 39 wherein G is phenyl; R^pl is t-butyldimethylsilyl and LG is tosyl.

41. A compound of claim 40 wherein R³ is methyl.

42. A compound of claim 39 wherein said compound is represented by the formula