WO2006102007A2

WO2006102007A2 - Methods for synthesizing alkylated and alkenylated quinone derivatives

Info

Publication number: WO2006102007A2
Application number: PCT/US2006/009576
Authority: WO
Inventors: Thomas E. Cole
Original assignee: San Diego State University Foundation
Priority date: 2005-03-16
Filing date: 2006-03-16
Publication date: 2006-09-28
Also published as: WO2006102007A3

Abstract

The present invention relates to methods for preparing quinone derivatives comprising reacting quinones with organoborane reagents to produce alkylated and alkenylated quinone derivatives. In one embodiment, the present invention provides processes comprising the reaction of mixed diaryl- and dimethylalkyl or alkenylboranes with p-benzoquinone, substituted p-benzoquinones, o-benzoquinones as well as napththquinones, and isomers and substituted derivatives thereof. The invention also provides methods and compositions to treat, prevent or ameliorate cell injury or cell death initiated by the enzyme sphingomyelinase, including but not limited to cell injury or cell death as a direct or secondary result of hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, trauma and the like.

Description

METHODS FOR SYNTHESIZING ALKYLATED AND ALKENYLATED QUINONE

DERIVATIVES

Technical Field

[0001] The present invention relates to the field of organic chemistry and medicine. The invention provides novel methods for the alkylation and alkenylation of quinone compounds. The methods of the invention may also be used to prepare novel hydroquinone and quinone derivatives. The invention also provides methods and compositions to treat, prevent or ameliorate cell injury or cell death initiated by the enzyme sphingomyelinase, including but not limited to cell injury or cell death as a direct or secondary result of hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, trauma and the like.

Background Art

[0002] Neutral sphingomyelinases can hydrolyze sphingomyelin to phosphocholine and ceramide. Various forms are expressed ubiquitously or predominantly in neurons of the CNS. Their activation and the functions of the released ceramides have been associated with signaling pathways in cell growth, differentiation, and apoptosis. Cleavage of sphingomyelin and the products of this reaction have been implicated in multiple pathways, including apoptosis, cellular growth, differentiation, and inflammatory responsiveness.

[0003] Hydroquinone and quinones have found utility as drugs and their precursors. In addition, these compounds have found use as industrial intermediates and items of commercial utility. Hydroquinone and quinone derivatives are found extensively throughout nature, and are an integral part of biological pathways. Examples of the diversity can be found in literature collections (R. H. Thomson Natural Occurring Quinones Volumes I - III). However, there are very few general high yielding synthetic routes for the alkylation or alkenylation of quinone compounds. The majority suffer low yields and formation of a mixture of products (low purity). Summary of Invention

[0004] The invention provides novel methods for the alkylation and alkenylation of quinone compounds. The methods of the invention may also be used to prepare novel hydroquinone and quinone derivatives.

[0005] In one aspect, the invention provides methods for preparing a quinone derivative comprising oxidizing an alkylated or alkenylated hydroquinone intermediate obtained from contacting a compound having formula I

wherein X¹, X², X³ and X⁴ are independently H, optionally substituted alkyl, optionally substituted alkenyl, amino, amido, carbonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, provided at least one of X¹, X², X³ and X⁴ is H; or

X¹ and X² together form an aryl or heteroaryl ring, and at least one of X³ and X⁴ is H; with a borane having formula BR¹R²R³, wherein R¹ and R² are independently aryl or alkyl; and

R³ is a straight or branched alkyl, a cycloalkyl, heterocycloalkyl, or a bridged alkyl, each of which may be optionally substituted with N, O or S, and/or optionally substituted with a carbocyclic, heterocyclic, aryl or heteroaryl; wherein said alkylated or alkenylated hydroquinone intermediate has formula II

wherein X¹, X², X³ and X⁴ are defined as in formula I, provided said H in one of X¹, X², X³ and X⁴, or said H in X³ or X⁴ when X¹ and X² together form an aryl or heteroaryl ring, is an optionally substituted C_2-10 alkyl or alkenyl group defined by R³; thereby providing an alkylated or alkenylated quinone derivative.

[0006] Various borane reagents may be used to practice the methods of the invention. In one embodiment, R¹ or R² in the borane reagent is an alkyl that has a lower migratory aptitude than said straight or branched alkyl in R³. In some examples, R¹ or R² is a primary alkyl and R³ is a secondary or tertiary alkyl. In other examples, R or R is a secondary alkyl and R is a tertiary alkyl. In other examples, R¹ and R² are independently phenyl or methyl. In yet other examples, R³ is ethyl, ethylene, a straight or branched C_3-20 alkyl or C_3-20 alkenyl, cycloalkyl or a bridged alkyl such as norbornyl. In some embodiments, the borane reagent is B-I- hexyldiphenylborane, (2<S)-bicyclo[2.2.1]heptan~2yldimethylborane or B-(E)-I- hexenyldiphenylborane.

[0007] Various quinone substrates may be used to practice the methods of the invention. Li one embodiment, X¹, X², X³ and X⁴ in said compound having formula (I) are each H. In some examples, X¹ and X² together form a phenyl ring.

[0008] In one embodiment, the alkylated or alkenylated hydroquinone intermediate has formula III, IV, V or VI

VI wherein each of R⁴ and R⁵ maybe H, optionally substituted alkyl, alkenyl, alkynyl, amino, amido, carbonyl, sulfonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, each of which may be optionally substituted by halo, heteroatoms (N, S or O), or one or more optional substituents.

[0009] The methods of the present invention may further comprise isolating said alkylated or alkenylated quinone derivative. The invention may also further comprise purifying said alkylated or alkenylated quinone derivative. For example, the alkylated or alkenylated quinone derivative may be purified by distillation, chromatography or recrystallization.

[0010] In one embodiment, the alkylated or alkenylated quinone derivative obtained using the methods of the invention is avarol, avarone, nakijiquinone, methoxyavarone, ilimaquinone, smenosphosgidine,

or isomers or analogs thereof.

[0011] In another aspect, the present invention provides a method of synthesizing a quinone derivative comprising oxidizing an alkylated or alkenylated hydroquinone intermediate obtained from contacting a compound having formula VII

X¹ and X², or X² and X³, or X³ and X⁴ together form an aryl or heteroaryl ring, and at least one of X¹, X², X³ and X⁴ that does not form a ring is H; with a borane having formula BR¹R²R³, wherein R¹ and R² are independently aryl or alkyl; and

R³ is C_2-1O alkyl, C_2-10 alkenyl, a cycloalkyl, heterocycloalkyl, or a bridged alkyl, each of which be optionally substituted with N, O or S, and/or optionally substituted with a carbocyclic, heterocyclic, aryl or heteroaryl; wherein said alkylated or alkenylated hydroquinone intermediate has formula VIII

wherein X¹, X², X³ and X⁴ are defined as in formula I, provided said H in one of X¹, X², X³ and X⁴, or said H in X¹, X², X³ and X⁴ that does not form a ring, is an optionally substituted C_2-10 alkyl or alkenyl group defined by R³; thereby providing an alkylated or alkenylated quinone derivative.

[0012] In yet another aspect, the present invention also provides a compound having formula III, IV, V or VI

VI

or pharmaceutically acceptable salts thereof, wherein each of R⁴ and R⁵ maybe H, optionally substituted alkyl, alkenyl, alkynyl, amino, amido, carbonyl, sulfonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, each of which may be optionally substituted by halo, heteroatoms (N, S or O), or one or more optional substituents.

[0013] The present invention also provides a pharmaceutical composition comprising a compound having formula III, IV₅ V or VI as defined above, and a pharmaceutically acceptable excipient.

[0014] Furthermore, the present invention provides a method for mediating a sphingomyelinase-mediated condition in a subject, comprising administering to said subject a compound having formula III, FV₅ V or VI as defined above or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. The compounds may be administered to cells or to a mammalian subject. For example, the compounds may be used to treat a cardiovascular disease, ischemia, stroke, or atherosclerosis.

[0015] The present invention also provides a method of reducing apoptosis cell apoptosis in a subject, comprising administering to said subject a compound having formula III, IV, V or VI as defined above or pharmaceutically acceptable salts thereof, or a pharmaceutical composition thereof. [0016] In another aspect, the invention provides the use of a compound having formula III, IV, V or VI as defined above or pharmaceutically acceptable salts thereof in the manufacture of a pharmaceutical composition. In one embodiment, the invention provides the use of a compound having formula III, IV, V or VI or a pharmaceutical composition thereof, for treatment of a sphingomyelinase-mediated condition or for reducing cell apoptosis in a subject. In another embodiment, the invention provides the use of a compound having formula III, IV, V or VI or a pharmaceutical composition thereof, for the manufacture of a medicament for the treatment of a sphingomyelinase-mediated condition or for reducing cell apoptosis. In yet another embodiment, the invention provides the use of a compound having formula III, IV, V or VI or a pharmaceutical composition thereof, for the manufacture of a medicament to inhibit or decrease the activity of a sphingomyelinase.

Detailed Description

[0017] The present invention relates to methods for preparing quinone derivatives comprising reacting quinones with organoborane reagents to produce alkylated and alkenylated quinone derivatives. It is also contemplated that novel alkylated and alkenylated quinones may be prepared using the methods of the invention.

[0018] In one embodiment, the reactions of the invention employ mixed triorganylboranes for the transfer of a single desired organic fragment to the quinone substrate, particularly an alkyl or alkenyl group to provide alkylated and alkenylated quinone derivatives. To minimize loss of potentially valuable organic fragments, two auxiliary ligands are incorporated in the mixed organoborane. These auxiliary ligands include but are not limited to methyl, phenyl or their substituted aryl groups. The phenyl auxiliary ligands do not transfer to the quinone substrate, while small amounts of the methyl groups were found to be incorporated in the hydroquinone product relative to primary alkyl groups.

[0019] In some embodiments, the alkyl and alkenyl groups used to functionalize quinones include but are not limited to tertiary, secondary and primary alkyl and alkenyl groups. In particular examples, these mixed organoboranes may comprise the alkyl or alkenyl group being transferred and two auxiliary ligands such as aryl or methyl. The mixed diaryl- or dimethylalky- and alkenylboranes for use in the methods of the invention may be prepared using synthetic organoborane chemistry techniques generally known in the art. (See e.g., Carey and Sandburg, Advanced Organic Synthesis Third Edition, Plenum Press, New York 1990, at pages 443-464). [0020] In particular examples, the invention relates to the addition of the alkyl or alkenyl groups to p-benzoquinones, naphthoquinones and the substituted derivatives. These substituted hydroquinone products can readily be converted into the corresponding quinones through a variety of oxidation processes.

[0021] In one aspect, stereochemically defined groups retain their geometry on transfer to the quinone. For example, the regio- and stereochemistry of the alkyl and alkenyl group is retained in the transfer. The preservation of stereochemical structure of alkyl and alkenyl groups is desirable in the production of high purity compounds. Thus, the invention provide the use of organoboranes for alkylation and alkenylation of quinone and hydroquinone compounds that have high selectivity, are stereospecific and cleaner than existing reactions.

[0022] In one embodiment, the present invention provides processes comprising the reaction of mixed diaryl- and dimethylalkyl or alkenylboranes with p-benzoquinone, substituted p- benzoquinones, o-benzoquinones as well as napththquinones, and isomers and substituted derivatives thereof. Examples of mixed organoboranes for use in the methods of the invention include but are not limited to diarylalkylboranes, diarylalkenylboranes, dimethylalkylboranes and dimethylalkenylboranes. The nonmigrating phenyl and aryl groups and low migratory aptitude methyl groups may serve as auxiliary ligands.

[0023] Reagents for coupling two auxiliary ligands to the boron before or after the addition of the alkyl or alkenyl groups include but are not limited to organometallic reagents such as lithium, magnesium or organozirconium reagents. In one aspect, the organic fragment being transferred to the quinone substrate is added to the boron using either hydroboration, exchange or transfer from organometallic reagents, including but not limited to organolithium, organomagnesium and organozirconium reagents.

[0024] In one aspect, the purity of this mixed organoborane is dictated by the method and reaction conditions used to prepare these boranes. In one aspect, the addition of diaryl- or dimethylalkyl- and alkenylborane to an ether solution of the quinone substrate was done slowly to control the react of reaction. The addition of a slight amount of air, in some cases helped catalyzed the addition reaction. A small amount of water is then added to hydrolyze the borinic ester product and form the hydroquinone or catechol product. The diarylborinic acid was removed as an ethanolamine addition complex, while the dimethylborinic acid could readily be distilled from the product along with the ether solvent. The solvent was removed under vacuum, and the hydroquinone product recrystallized from a suitable solvent or purified by chromatography.

[0025] The methods of the invention may be used to prepare useful and novel hydroquinones that have structural similarity to the lipid sphingomyelin. Thus, the invention also provides novel hydroquinones that can act as sphingomyelin and hydroquinone analogs to to inhibit the enzyme sphingomyelinase (SMase). Because the enzymatic activity of the sphingomyelinase (SMase) enzyme is activated under certain metabolic and/or stress conditions, and this enzyme activation results the death of cells (e.g., apoptosis), e.g., the death of heart cells following a heart attack or any other stress conditions, wherein the metabolic and/or stress conditions include but are not limited to hypoxia (ischemia or stroke), radiation, chemotherapy, trauma, poisons, and the like, the compositions of the invention (e.g., as pharmaceutical compositions) can be used to treat, prevent or ameliorate cell death (e.g., apoptosis) initiated by the activation of sphingomyelinase (SMase). Thus, in one aspect, the compositions of the invention can be administered after certain metabolic and/or stress conditions, e.g., after a heart attack (e.g., an ischemic cardiac event) to prevent, ameliorate or diminish the amount of cell death and, in one aspect, help re-establish blood flow in the ischemic area or the prevent or ameliorate the apoptosis cell death reaction.

[0026] While the invention is not limited by any particular mechanism of action, because in vivo sphingomyelinase is activated by a stress event, e.g., hypoxia (ischemia or stroke), radiation, chemotherapy agents, trauma, poisons, etc., and this enzyme activation leads to (initiates) apoptosis, and because the compositions of the invention can inhibit or diminish the action of sphingomyelinase (SMase), the methods and compositions of the invention can be used to treat, prevent or ameliorate cell injury or cell death initiated by sphingomyelinase, including but not limited to cell injury or cell death as a direct or secondary result of hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, trauma and the like.

[0027] Additionally, because the invention is not limited by any particular mechanism of action, the methods and compositions of the invention can be used to treat, prevent or ameliorate cell injury or cell death (whether or not initiated by sphingomyelinase or any related enzyme), including but not limited to cell injury or cell death as a direct or secondary result of hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, trauma and the like independent of any effect on the activity of sphingomyelinase (SMase).

[0028] In one embodiment, the compounds prepared using the methods of the invention are alkylated and alkenylated hydroquinone and quinone compounds that have structural similarity to sphingomyelin. For example, in one aspect, the sphingomyelin like substituted hydroquinones of the invention can inhibit nSMase at μM concentrations. Examples of hydroquinone and quinone derivatives which may be prepared using the methods of invention are described in Table 1.

Table 1

V VI

[0029] In Formula III- VI, each of R⁴ and R⁵ may be H, optionally substituted alkyl, alkenyl, alkynyl, amino, amido, carbonyl, sulfonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, each of which may be optionally substituted by halo, heteroatoms (N, S or O), or one or more optional substituents known in the art.

[0030] It is contemplated that the methods of the present invention may be used to prepare exemplary hydroquinone and quinone compounds including but not limited to nakijiquinones and analogs thereof, such as those described in Table 2. Nakijiquinone C is a natural product inhibitor of the receptor tyrosine kinase (RTK) Her-2/Neu, which is involved in breast cancer. Analogs of this natural product were found to inhibit two other receptor tyrosine kinases VEGFR-3 and Tie-3. Some of these are involved in tumor angio genesis with several of them showing low-micromolar inhibitory activity against four RTKs. See J Med Chem 2003, 46, 2917.

Table 2

Analogs

[0031] It is also contemplated that the methods of the present invention may be used to prepare exemplary hydroquinone and quinone compounds including but not limited to a family of quinone sesquiterpenes represented by avarol, avarone, nakijiquinone, methoxyavarone, ilimaquinone and smenospongidine, and analogs thereof, such as those described in Table 3 (See, e.g., J. Am. Chem Soc. 2002, 124, 12261). It is further contemplated that the methods of the present invention may be used to prepare other useful marine natural products which exhibit a variety of structural motifs and possess remarkable biological activity, and may be useful antifungal, anticancer and/or antiviral agents. Table 3

avarol avarone nakijiquinone A

smenospongidine

[0032] It is contemplated that the alkylated and alkenylated quinones, which may be prepared using the methods of the invention, may inhibit the cleavage of sphingomyelin to affect multiple biological pathways, including apoptosis, cellular growth, differentiation, and inflammatory responsiveness. It is also contemplated that alkylated and alkenylated quinones prepared using the methods of the invention may be used for reducing apoptosis and atherosclerosis. It is also contemplated that the compounds prepared using the methods of the invention, as inhibitors of nSMase, may be useful in treating strokes, surgery procedures and reducing toxicity to chemotherapy agents. It is further contemplated that the present invention provides for compositions and methods for treating a subject suffering from any condition associated with the overactivity, including the overproduction, of neutral sphingomyelinase. Pharmaceutical Compositions, Dietary Supplements and Kits

[0033] In one aspect, the alkylated and alkenylated quinone derivatives of the invention are be formulated as pharmaceutical compositions to inhibit a sphingomyelinase, or related enzymes, e.g., a neutral sphingomyelinase. In one aspect, the invention provides pharmaceutical compositions comprising alkylated and alkenylated quinone derivatives, and a pharmaceutically acceptable excipient. While the invention is not limited by any particular mechanism of action, the methods and compositions of the invention can be used to treat, prevent or ameliorate cell injury or cell death initiated by sphingomyelinase or related enzyme(s), including but not limited to cell injury or cell death as a direct or secondary result of cell stress or trauma, e.g., hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, force trauma and the like. Additionally, because the invention is not limited by any particular mechanism of action, the methods and compositions of the invention can be used to treat, prevent or ameliorate cell injury or cell death (whether or not initiated by sphingomyelinase or any related enzyme), including but not limited to cell injury or cell death as a direct or secondary result of hypoxia (ischemia or stroke), radiation, chemotherapy agents, poisons, biological warfare agents, extremes in temperature (hot or cold), pressure, trauma and the like independent of any effect on the activity of sphingomyelinase (SMase) or any related enzyme.

[0034] The invention provides parenteral formulations comprising a pharmaceutical composition of the invention. The invention provides enteral formulations comprising a pharmaceutical composition of the invention. The invention provides methods for treating sepsis comprising providing a pharmaceutical composition of the invention; and administering an effective amount of the pharmaceutical composition to a subject in need thereof, thereby treating the desired condition, as described herein.

[0035] The pharmaceutical compositions or dietary supplements used in the methods of the invention may be administered by any means known in the art, e.g., parenterally, topically, orally, or by local administration, such as by aerosol or transdermally. The pharmaceutical compositions can be formulated in any way and can be administered in a variety of unit dosage forms depending upon the condition or disease and the degree of illness, the general medical condition of each patient, the resulting preferred method of administration and the like. Details on techniques for formulation and administration are well described in the scientific and patent literature, see, e.g., the latest edition of Remington's Pharmaceutical Sciences, Maack Publishing Co, Easton PA ("Remington's").

[0036] Pharmaceutical formulations or dietary supplements may be prepared according to any method known to the art for the manufacture of pharmaceuticals. Such drugs can contain sweetening agents, flavoring agents, coloring agents and preserving agents. A formulation can be admixtured with nontoxic pharmaceutically acceptable excipients which are suitable for manufacture.

[0037] Furthermore, the invention provides kits comprising compositions of the invention (e.g., the pharmaceutical compositions or dietary supplements of the invention), including instructions on practicing the methods of the invention (e.g., directions as to indications, dosages, routes and methods of administration).

[0038] In one aspect, invention provides a pharmaceutical composition or dietary supplements comprising compositions of the invention formulated as a tablet, gel, geltab, pill, implant, liquid, spray, powder, food, feed pellet, as an injectable formulation or as an encapsulated formulation. In one aspect, compositions of the invention can be chemically modified to produce a protected form that possesses better specific activity, prolonged half-life, and/or reduced immunogenicity in vivo, e.g., the composition can be chemically modified formulated or modified by glycosylation, pegylation (modified with polyethylene glycol (PEG), activated PEG, or equivalent), encapsulation with liposomes or equivalent, encapsulated in nanostructures (e.g., nanotubules, nano- or microcapsules), or combinations thereof, or equivalents thereof, e.g., as described by Wang (2005) MoI Genet Metab. 86(l-2):134-140. Epub 2005 JuI 11. In one aspect, the polypeptide is chemically conjugated with activated PEG, or, 2,4-bis(0-methoxypolyethyleneglycol)-6-chloro-s-triazine, e.g., as described by Ikeda (2005) Amino Acids 29(3):283-287. Epub 2005 Jun 28.

[0039] The invention also provides biocompatible matrices such as sol-gels encapsulating a composition of the invention for use as pharmaceutical composition, e.g., including silica-based (e.g., oxysilane) sol-gel matrices. The invention also provides nano- or microcapsules comprising a composition of the invention for use as pharmaceutical composition or dietary supplements.

[0040] The pharmaceutical compositions and dietary supplements used in the methods of the invention can be administered by any means known in the art, e.g., parenterally, topically, orally, or by local administration, such as by aerosol or transdermally. The compositions and dietary supplements of the invention can be formulated as a tablet, gel, geltab, pill, implant, liquid, spray, powder, food, feed pellet, as an injectable formulation or as an encapsulated formulation. The pharmaceutical compositions and dietary supplements can be formulated in any way and can be administered in a variety of unit dosage forms depending upon the condition or disease and the degree of illness, the general medical condition of each patient, the resulting preferred method of administration and the like. Details on techniques for formulation and administration are well described in the scientific and patent literature, see, e.g., the latest edition of Remington's Pharmaceutical Sciences, Maack Publishing Co, Easton PA ("Remington's") (e.g., Remington, The Science and Practice of Pharmacy, 21st Edition, by University of the Sciences in Philadelphia, Editor).

[0041] Pharmaceutical formulations and dietary supplements can be prepared according to any method known to the art for the manufacture of pharmaceuticals and dietary supplements. Such drugs and dietary supplements can contain sweetening agents, flavoring agents, coloring agents and preserving agents. A formulation (which includes "dietary supplements") can be admixtured with nontoxic pharmaceutically or orally acceptable excipients which are suitable for manufacture. Formulations may comprise one or more diluents, emulsifϊers, preservatives, buffers, excipients, etc. and may be provided in such forms as liquids, powders, emulsions, lyophilized powders, sprays, creams, lotions, controlled release formulations, tablets, pills, gels, on patches, in implants, etc.

[0042] Pharmaceutical formulations and dietary supplements for oral administration can be formulated using pharmaceutically acceptable carriers well known in the art in appropriate and suitable dosages. Such carriers enable the pharmaceuticals and dietary supplements to be formulated in unit dosage forms as tablets, pills, powder, dragees, capsules, liquids, lozenges, gels, syrups, slurries, suspensions, etc., suitable for ingestion by the patient. Pharmaceutical preparations and dietary supplements for oral use can be formulated as a solid excipient, optionally grinding a resulting mixture, and processing the mixture of granules, after adding suitable additional compounds, if desired, to obtain tablets or dragee cores. Suitable solid excipients are carbohydrate or protein fillers include, e.g., sugars, including lactose, sucrose, mannitol, or sorbitol; starch from corn, wheat, rice, potato, or other plants; cellulose such as methyl cellulose, hydroxypropylmethyl-cellulose, or sodium carboxy-methylcellulose; and gums including arabic and tragacanth; and proteins, e.g., gelatin and collagen. Disintegrating or solubilizing agents may be added, such as the cross-linked polyvinyl pyrrolidone, agar, alginic acid, or a salt thereof, such as sodium alginate.

[0043] Aqueous suspensions of the invention can an active agent comprising a composition of the invention in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients include a suspending agent, such as sodium carboxymethyl- cellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia, and dispersing or wetting agents such as a naturally occurring phosphatide (e.g., lecithin), a condensation product of an alkylene oxide with a fatty acid (e.g., polyoxyethylene stearate), a condensation product of ethylene oxide with a long chain aliphatic alcohol (e.g., heptadecaethylene oxycetanol), a condensation product of ethylene oxide with a partial ester derived from a fatty acid and a hexitol (e.g., polyoxyethylene sorbitol mono-oleate), or a condensation product of ethylene oxide with a partial ester derived from fatty acid and a hexitol anhydride (e.g., polyoxyethylene sorbitan mono-oleate). The aqueous suspension can also contain one or more preservatives such as ethyl or n-propyl p- hydroxybenzoate, one or more coloring agents, one or more flavoring agents and one or more sweetening agents, such as sucrose, aspartame or saccharin. Formulations can be adjusted for osmolality.

[0044] Oil-based pharmaceuticals are particularly useful for administration of hydrophobic formulations or active agents of the invention (a composition of the invention). Oil-based suspensions can be formulated by suspending an active agent (e.g., a composition of the invention) in a vegetable oil, such as arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin; or a mixture of these. See e.g., U.S. Patent No. 5,716,928 describing using essential oils or essential oil components for increasing bioavailability and reducing inter- and intra-individual variability of orally administered hydrophobic pharmaceutical compounds (see also U.S. Patent No. 5,858,401). The oil suspensions can contain a thickening agent, such as beeswax, hard paraffin or cetyl alcohol. Sweetening agents can be added to provide a palatable oral preparation, such as glycerol, sorbitol or sucrose. These formulations and dietary supplements can be preserved by the addition of an antioxidant such as ascorbic acid. As an example of an injectable oil vehicle, see Minto (1997) J. Pharmacol. Exp. Ther. 281:93-102. [0045] In the methods of the invention, the pharmaceutical compounds and dietary supplements can also be delivered as microspheres for slow release in the body. For example, microspheres can be administered via intradermal injection of drug which slowly release subcutaneously; see Rao (1995) J. Biomater Sci. Polym. Ed. 7:623-645; as biodegradable and injectable gel formulations, see, e.g., Gao (1995) Pharm. Res. 12:857-863 (1995); or, as microspheres for oral administration, see, e.g., Eyles (1997) J. Pharm. Pharmacol. 49:669-674.

[0046] The pharmaceutical compounds, formulations and dietary supplements of the invention can be lyophilized. The invention provides a stable lyophilized formulation comprising a composition of the invention, which can be made by lyophilizing a solution comprising a pharmaceutical of the invention and a bulking agent, e.g., mannitol, trehalose, raffinose, and sucrose or mixtures thereof. A process for preparing a stable lyophilized formulation can include the equivalent of lyophilizing a solution about 2.5 mg/mL protein, about 15 mg/mL sucrose, about 19 mg/mL NaCl, and a sodium citrate buffer having a pH greater than 5.5 but less than 6.5. See, e.g., U.S. patent app. no. 20040028670.

[0047] The compositions (e.g., formulations, including dietary supplements) of the invention can be delivered by the use of liposomes. By using liposomes, particularly where the liposome surface carries ligands specific for target cells, or are otherwise preferentially directed to a specific organ, one can focus the delivery of the active agent into target cells in vivo. See, e.g., U.S. Patent Nos. 6,063,400; 6,007,839; Al-Muhammed (1996) J. Microencapsul. 13:293-306; Chonn (1995) Curr. Opin. Biotechnol. 6:698-708; Ostro (1989) Am. J. Hosp. Pharm. 46:1576- 1587.

[0048] The following examples describing exemplary processes and compositions made by these processes, are offered to illustrate but not to limit the invention.

Example 1 Preparation of l-Hexyl-hydroquinone from i?-l-Hexyldiphenviborane

[0049] A solution of 5-1-hexyldiρhenylborane (7.1 mmol, 1.78 g) in 10 mL of diethyl ether was slowly added to a solution of p-benzoquinone (7.4 mmol, 0.80 g) in 10 mL of diethyl ether. The addition was conducted in a room temperature water-bath to prevent the boiling of the solvent with this exothermic reaction. After the addition was complete approximately 2 mL of water was added to the solution and the mixture was stirred overnight to complete the hydrolysis. The mixture was placed in a separatory runnel along with 5 mL of saturated NaCl solution. The reaction flask was rinsed with an additional 10 mL of diethyl ether, and this was also added to the separatory funnel. The aqueous layer was separated and the solution was washed with an additional 5 mL of NaCl solution. The diethyl ether solution was dried over MgSQ₄ and filtered. The solution was placed in an ice-bath, followed by the slow addition of ethanolamine (7.4 mmol, 0.45 mL), which resulted in a heavy precipitate within a couple of minutes. The solvent was removed under vacuum, and the product was extracted with (3 X 10 mL) of hot petroleum ether. The recrystallization of the product from hot petroleum ether produced 0.81 g (59% yield) of 1-hexyl-hydroquinone as a white solid. ¹H NMR (CDCl₃): δ 6.64 (m, 2H), 6.55 (dd, J= 8.5, 3 Hz, IH), 4.46 (s, IH), 4.40 (s, IH), 2.55 (t, J= 7.5 Hz, 2H), 1.60 (m, 2H), 1.33 (m, 6H), 0.90 (t, J= 7 Hz, 3H); ¹³C NMR (CDCl₃): 5 149.4, 147.5, 130.1, 116.9, 116.1, 113.3, 31.7, 30.0, 29.6, 29.1, 22.5, 14.0.

Example 2 Preparation of norbornyl-substituted hvdroquinone

[0050] A solution of exo-bicyclo [2.2.1 ]heptan-2yl-dimethylborane (5 mmol, 0.682 g) was dissolved in 5 mL of dimethyl ether was slowly added to a solution of p-benzoquinone (4.9 mmol, 0.53 g) dissolved in 5 mL of ethyl ether. The addition was conducted in a room temperature water bath, a slight exotherm was observed after a few minutes of stirring. After an hour of stirring at room temperature, approximately 1 mL of water was added to the solution, and the mixture was stirred overnight. The reaction mixture was transferred to a simple distillation apparatus under an inert gas along with 5 mL of water. The ether and dimethyl borinic acid were distilled from the aqueous solution. A 1 :1 mixture of toluene/hexane, 60 mL total volume was added to the aqueous solution of hydroquinone product heated to approximately 60 °C and the water portion removed. The hot solution was cooled and the solid hydroquinone product isolated by filtration to yield 0.48 g (47% yield) of the exo- norbornyl- substituted hydroquinone [2-((2S)-bicyclo[2.2.1]heptan-2-yl)-benzene-l,4-diol] as a white solid, mp 135.5-137 °C. ¹H NMR (CDCl₃): δ 6.70 (d, J = 2.9 Hz, IH), 6.65 (d, J = 8.4 Hz, IH), 6.52 (d/d, J = 8.5, 3.0 H, IH), 4.48 (s, IH), 4.41 (s, IH), 2.80 (d/d, J = 8.9, 5.5 Hz, IH), 2.38 (d, J = 3.7 Hz, IH), 2.35 (m, IH), 1.81 (d/d/d, J = 12.0, 9.2, 2.3 Hz, IH), 1.63 (m, IH), 1.59 (m, IH), 1.51 (m, 2H), 1.37 (t/t, J = 10, 2.4 Hz, IH)₅ 1.30 (d/t, J = 10.0, 2.8 Hz, IH), 1.22 (d/pentet, J = 10, 2.5 Hz, IH), ^!3C NMR (CDCl₃): 5 149.42, 147.50, 134.87, 116.12, 113.63, 112.84, 41.23, 40.88, 38.49, 37.08, 36.44, 30.52, 29.22.

[0051] This reaction demonstrates the transfer of a stereochemically defined exo norbornyl group ((2S)-bicyclo[2.2.1]heptan-2-yldimethylborane) with stereochemistry retention to the hydroquinone product. The transfer of a chiral group represents a significant advance for the synthesis of chiral hydroquinones or quinones in which the chiral group is prepared using organoboranes.

Example 3 Preparation of 1-Hexenyl -hydroquinone from ^-(^"E)-1-Hexenyldiphenylborane

[0052] A solution of B-(E)-I -hexenyldiphenylborane (9.1 mmol, 2.26 g) dissolved in 10 mL of diethyl ether was slowly added to a solution of p-benzoquinone (9.3 mmol, 1.0 g) dissolved 10 mL of diethyl ether. The addition was conducted in a room temperature water bath, a slight exotherm was observed after a few minutes of stirring. After an hour of stirring at room temperature, approximately 2 mL of water was added to the solution, and the mixture was stirred overnight to complete the hydrolysis. The mixture was placed in a separatory funnel along with an additional 10 mL of diethyl ether and 5 mL of saturated NaCl solution. The aqueous layer was separated and the organic layer washed with an additional 5 mL of saturated NaCl solution. The dark solution was dried over MgSO4 and filtered. The addition of ethanolamine (9.1 mmol, 0.55 mL) to the solution in an ice-bath resulted in the formation of a precipitate, which was filtered. The solvent was removed under reduced pressure to reveal a black sludge. The product was extracted with hot petroleum ether (3 X 10 mL); no crystals were observed. The purification of the product using flash chromatography afforded 0.96 g (55% yield) of a clear liquid. ¹H NMR (CDCl₃): δ 7.32 (m, 2H), 7.26 (m, 2H), 7.16 (t, J= 7 Hz, IH), 6.36 (d, J= 16 Hz, IH), 6.20 (dt, J= 16, 7 Hz, IH), 2.20 (dt, J= 8, 7 Hz, 2H), 1.45 (m, 2H)₅ 1.39 (m, 2H)₃ 0.92 (t, J= 7.5 Hz₃ 3H); 1³C NMR (CDCl₃): δ 138.1, 131.2, 129.8, 128.8, 128.5, 127.2, 126.8, 126.0, 32.7, 31.5, 22.2, 13.9.

[0053] It is understood that the foregoing detailed description and accompanying examples are merely illustrative, and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications, including without limitation those relating to the chemical structures, substituents, derivatives, intermediates, syntheses, formulations and/or methods of use of the invention, may be made without departing from the spirit and scope thereof. U.S. patents and publications referenced herein are incorporated by reference.

Claims

1. A method of synthesizing a quinone derivative comprising oxidizing an alkylated or alkenylated hydroquinone intermediate obtained from contacting a compound having formula

I

2. The method of claim 1, wherein R¹ or R² is an alkyl that has a lower migratory aptitude than said straight or branched alkyl in R³.

3. The method of claim 2, wherein R¹ or R² is a primary alkyl and R³ is a secondary or tertiary alkyl.

4. The method of claim 2, wherein R¹ or R² is a secondary alkyl and R³ is a tertiary alkyl.

5. The method of claim 1 , wherein R¹ and R² are independently phenyl or methyl.

6. The method of claim 5, wherein R³ is ethyl, ethylene, a straight or branched C_3-20 alkyl or C_3-20 alkenyl, cycloalkyl or a bridged alkyl.

7. The method of claim 6, wherein said bridged alkyl is norbornyl.

8. The method of claim 1 , wherein X¹, X², X³ and X⁴ are each H.

9. The method of claim 1 , wherein X¹ and X² together form a phenyl ring.

10. The method of claim 1 , wherein said alkylated or alkenylated hydroquinone intermediate has formula III, IV, V or VI

V VI

wherein each of R⁴ and R⁵ maybe H, optionally substituted alkyl, alkenyl, alkynyl, amino, amido, carbonyl, sulfonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, each of which may be optionally substituted by halo, heteroatoms (N, S or O), or one or more optional substituents.

11. The method of claim 1 , wherein said borane is B- 1 -hexyldiphenylborane, (2S)- bicyclo[2.2.1 ]heptan-2yldirnethylborane or B-(E)- 1 -hexenyldiphenylborane.

12. The method of claim 1, further comprising isolating said alkylated or alkenylated quinone derivative.

13. The method of claim 12, further comprising purifying said alkylated or alkenylated quinone derivative.

14. The method of claim 13, wherein said alkylated or alkenylated quinone derivative is purified by distillation, chromatography or recrystallization.

15. The method of claim 1 , wherein said alkylated or alkenylated quinone derivative is avarol, avarone, nakijiquinone, methoxyavarone, ilimaquinone, smenosphosgidine,

or isomers or analogs thereof.

16. A method of synthesizing a quinone derivative comprising oxidizing an alkylated or alkenylated hydroquinone intermediate obtained from contacting a compound having formula VII

R³ is C_2-1O alkyl, C_2-10 alkenyl, a cycloalkyl, heterocycloalkyl, or abridged alkyl, each of which be optionally substituted with N, O or S, and/or optionally substituted with a carbocyclic, heterocyclic, aryl or heteroaryl; wherein said alkylated or alkenylated hydroquinone intermediate has formula VIII

17. A compound having formula III, IV, V or VI

VI

or pharmaceutically acceptable salts thereof, wherein each of R⁴ and R⁵ may be H, optionally substituted alkyl, alkenyl, alkynyl, amino, amido, carbonyl, sulfonyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl, each of which may be optionally substituted by halo, heteroatoms (N, S or O), or one or more optional substituents.

18. A pharmaceutical composition comprising the compound of claim 17, and a pharmaceutically acceptable excipient.

19. A method for mediating a sphingomyelinase-mediated condition in a subject, comprising administering to said subject the compound of claim 17, or a pharmaceutical composition thereof.

20. The method of claim 19, wherein said subject is cells or a mammalian subject.

21. The method of claim 21 , wherein said condition is a cardiovascular disease, ischemia, stroke, or atherosclerosis.

22. A method of reducing apoptosis cell apoptosis in a subject, comprising administering to said subject the compound of claim 17, or a pharmaceutical composition thereof.

23. The use of a compound according to claim 17 in the manufacture of a pharmaceutical composition.

24. The use of a compound according to claim 17 or a pharmaceutical composition thereof, for treatment of a sphingomyelinase-mediated condition or for reducing cell apoptosis in a subject.

25. The use of a compound according to claim 17 or a pharmaceutical composition thereof, for the manufacture of a medicament for the treatment of a sphingomyelinase-mediated condition or for reducing cell apoptosis.

26. The use of a compound according to claim 17 or a pharmaceutical composition thereof, for the manufacture of a medicament to inhibit or decrease the activity of a sphingomyelinase.