Synthesis of (+)-α-curcumene, (+)-curcumone, and (-)-methyl citronellate starting from optically pure 5-trimethylsilyl-2-cyclohexenone

Asaoka, Morio; Shima, Kunihisa; Fujii, Naoaki; Takei, Hisashi

doi:10.1016/s0040-4020(01)86178-0

Cited by 50 publications

(15 citation statements)

References 13 publications

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“…, eupalmerin(116), eupalmerin acetate(113), and succinolide, and one c£-methylene-~-lactone 14deoxycrassin. (-)-Eunicenone (120), a rare cembranoid diterpene having the uncommon 11-cis double bond, was found to be the (-)-antipode of a known cembranoid isolated from a South Pacific soft coral.…”

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confidence: 99%

The natural products chemistry of West Indian gorgonian octocorals

1995

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Plexauddae flourish as they do nowhere in the world. Gorgonian corals (order Gorgonacea, phylum Cnidaria) are 4571 4572 A.D. RODRIGUEZ conspicuous members of most tropical and subtropical marine habitats, being the most abundant octocorals found in the West Indies. With over 195 species documented from these two major families, gorgonian octocorals represent an estimated 38% of the known fauna, l Studies of the natural products chemistry of this interesting group of marine invertebrates began in the late 1950's. Since these early investigations, numerous studies of the chemistry of gorgonian corals have been published and summarized. 2-9 This Report documents the exciting chemistry that has been generated through the investigation of gorgonian octocorals from the West Indian region.It includes only research published in refereed journals up to December, 1994. A short communication in Science by Burkholder and Burkholder in 1958, highlighting the occurrence of antibiotic substances in gorgonian corals from Puerto Rico, was used as the starting point for the present review, to This Report is not intended to be comprehensive but instead concentrates on novel marine natural products with interesting biological and pharmaceutical properties. With the exception of several unusual sterols having interesting functionalities, marine sterols, carotenoids, fatty acids, and biopolymers isolated have not been included, since they have been reviewed by specialists, l 1-15 Studies of the chemical ecology aiming at the elucidation of the defensive roles of secondary metabolites from West Indian gorgonians and the value of secondary metabolite composition as a chemotaxonomic tool are discussed. The cited articles were retrieved from computer literature searches by use of Chemical Abstracts (CA Selects), MarinLit, STN International and also NAPRALERT. Terms such as West Indian, Caribbean, gorgonian, sea whip, octocoral, and phylla names were used. The primary focus will be the structural chemistry and biological activities of the metabolites produced by a relatively small group of gorgonians found within a limited geographic area. Wherever possible, every effort was made to record the biological and pharmacological properties of new metabolites. Since marine natural products in general are often the targets of synthetic chemists, we include synthetic work, where available, on novel compounds isolated from these animals.We hope to illustrate the diversity of compounds produced by West Indian gorgonians, while highlighting their specialized ability to biosynthesize secondary metabolites with promising pharmacological activity. 16-19 NATURAL PRODUCTS CHEMISTRYGorgonian metabolites possess novel structures that are largely unknown from terrestrial sources. These animals are now recognized to produce acetogenins, sesquiterpenoids, diterpenoids, prostanoids, and, in some cases, highly functionalized steroids. 7 The chemistry of West Indian gorgonian octocorals will be presented taxonomically according to genus and species (in alphabetic...

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confidence: 99%

The natural products chemistry of West Indian gorgonian octocorals

1995

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“…In view of the fact that the ester could be reduced to the corresponding aldehyde with DIBAL-H, an alterate synthetic approach was adopted in which the double bond of the α,β-unsaturated esters 32-36 were reduced by catalytic hydrogenation, 21 followed by reduction with DIBAL-H to afford the aldehydes 42-46 in very high yield (two steps >80%, Scheme 3). 22 The Henry reaction of aldehydes 42-47 with nitromethane gave the expected nitro alcohol intermediates 48-53 (Scheme 4). This reaction was carried out under a variety of different reaction conditions using different bases (K 2 CO 3 , NaOEt, NaOMe, NaOH and KF), different solvents (MeOH, EtOH, THF, CHCl 3 and i-PrOH), and different temperatures (from room temperature to heating to reflux).…”

Section: Resultsmentioning

confidence: 99%

“…Increasing the bulk of the naphthyl to a fluorenyl group (20) or a biphenyl (21) caused a drop in activity as did the 3,4,5-triOMe substitution (23). However, the most detrimental substitution was the 2,5-diOMe (22), which was about 10-fold less potent than 19. The unsubstituted phenyl analog 18 was the least active.…”

Section: Pneumocystis Cariniimentioning

confidence: 99%

Novel non-classical C9-methyl-5-substituted-2,4-diaminopyrrolo[2,3-d]pyrimidines as potential inhibitors of dihydrofolate reductase and as anti-opportunistic agents

Gangjee

Yang

Queener

2006

Bioorganic & Medicinal Chemistry

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Six novel C9-methyl-5-substituted-2,4-diaminopyrrolo [2,3-d]pyrimidines 18-23 were synthesized as potential inhibitors of dihydrofolate reductase (DHFR) and as anti-opportunistic agents. These compounds represent the only examples of 9-methyl substitution in the carbon-carbon bridge of 2,4-diaminopyrrolo[2,3-d]pyrimidines. The analogs 18-23 were synthesized in a concise eightstep procedure starting from the appropriate commercially available aromatic methyl ketones. The key step involved a Michael addition reaction of 2,4,6-triaminopyrimidine to the appropriate 1-nitroalkene, followed by ring closure of the nitro adducts via a Nef reaction. The compounds were evaluated as inhibitors of DHFR from Pneumocystis carinii (pc), Toxoplasma gondii (tg), Mycobacterium avium (ma) and rat liver (rl). The biological result indicated that some of these analogs are potent inhibitors of DHFR and some have selectivity for pathogen DHFR. Compound 23 was a two digit nanomolar inhibitor of tgDHFR with 9.6-fold selectivity for tgDHFR.

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“…By using this chemistry, different natural compounds can also be readily accessible. Bisabolanes are interesting compounds that display remarkable biological activity . Total syntheses of bisabolanes using organometallic and organocatalytic strategies have been reported.…”

Section: Discussionmentioning

confidence: 99%

“…Bisabolanes are interesting compounds that display remarkable biological activity. 45 Total syntheses of bisabolanes using organometallic 46 and organocatalytic strategies 47 have been reported. Our approach to bisabolanes is illustrated in Figure 4.…”

Section: Discussionmentioning

confidence: 99%

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

et al. 2014

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Recently, the direct substitution of allylic, benzylic, and tertiary alcohols has been achieved via SN 1-type reactions with catalytic amounts of Brønsted or Lewis acids. When a new stereogenic center is formed most of these transformations produce the desired product as a racemate, as these reactions proceed through carbenium ions. The arsenal of activation modes available in organocatalysis can be used to set up suitable reaction conditions in which chiral nucleophiles (enamine catalysis) or chiral electrophiles (iminium catalysis, chiral counterion catalysis) can easily be generated. Recently, we have used stabilized carbenium ions, directly available or obtained from the corresponding alcohols, in new organocatalytic stereoselective SN 1-type reactions. The commercially available carbenium ion benzodithiolylium tetrafluoroborate can be used for the straightforward organocatalytic stereoselective alkylation of aldehydes. In this account we will illustrate the application of this methodology in the total synthesis of natural products and the preparation of valuable starting materials.

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Synthesis of (+)-α-curcumene, (+)-curcumone, and (-)-methyl citronellate starting from optically pure 5-trimethylsilyl-2-cyclohexenone

Cited by 50 publications

References 13 publications

The natural products chemistry of West Indian gorgonian octocorals

The natural products chemistry of West Indian gorgonian octocorals

Novel non-classical C9-methyl-5-substituted-2,4-diaminopyrrolo[2,3-d]pyrimidines as potential inhibitors of dihydrofolate reductase and as anti-opportunistic agents

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

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