Low-molecular-mass bioregulators. II. Synthesis of methyl (±)-tetradeca-2E,4,5-trienoate — The sex pheromone ofAcanthoscelides obtectus

A preparative method has been developed for obtaining methyl (±)-tetradeca-2E,4,5-trienoate — the racemate of the sex pheromone of the dried-bean beetle. Using methyl 4-chlorotetradec-5-ynoate as an example, a detailed study has been made of the dependence of the regiochemistry of reduction on the activity of a zinc-copper couple, the methods of its activation, and the acidity of the proton donor.Institute of Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 96–102, January–February, 1990.     

Pheromone synthesis. Part 249: Syntheses of methyl (R,E)-2,4,5-tetradecatrienoate and methyl (2E,4Z)-2,4-decadienoate,the pheromone components of the male dried bean beetle,Acanthoscelides obtectus (Say)

The enantiomers of methyl (E)-2,4,5-tetradecatrienoate (1), a component of the male pheromone of Acanthoscelides obtectus, were synthesized from the enantiomers of 1-undecyn-3-ol (6), which were obtained via asymmetric acetylation of (±)-1-trimethylsilyl-1-undecyn-3-ol (4) with vinyl acetate as catalyzed by lipase PS (Amano). The ortho ester Claisen rearrangement of 6 with triethyl orthoacetate was the key-step to generate the chiral allenic system. A new synthesis of (±)-1 was also executed starting from (±)-6. Three different syntheses of methyl (2E,4Z)-2,4-decadienoate (2), another component of the male pheromone of A. obtectus, were achieved by means of either palladium-catalyzed Heck reaction or a Claisen and an Al₂O₃ catalyzed thermal rearrangements.     

A chemoenzymatic asymmetric synthesis of methyl (6S,13R)-6,13-dihydroxytetradeca-(2E,4E,8E)-trienoate,a component of Mycosphaerella rubella

The first asymmetric synthesis of (6S,13R)-6,13-dihydroxytetradeca-(2E,4E,8E)-trienoate has been developed. The key steps of the synthesis were the use of an efficient lipase-catalyzed acylation, a chiral template-driven enantiocontrolled allylation for introducing the stereogenic centers, and a cross-metathesis for controlling the C-8 olefin geometry.     

A facile asymmetric route to (-)-aphanorphine

8O-methylaphanorphine was synthesized from 4-methoxyphenylacetaldehyde in 36% overall yield and in nine steps, featuring the formation of ring B via a Friedel-Crafts alkylative cyclization with the concomitant stereospecific introduction of the benzylic quaternary carbon center. The current work constitutes an efficient enantioselective formal synthesis of 3-benzazepine marine alkaloid (-)-aphanorphine.     

A crystallization-induced asymmetric transformation to prepare (R)-4-chlorophenylalanine methyl ester

A second order asymmetric transformation of racemic 4-chlorophenylalanine methyl ester was achieved via salt formation with (2S,3S)-(−)-tartaric acid in the presence of salicylaldehyde to afford the desired (R)-enantiomer of 4-chlorophenylalanine methyl ester in good yield and high enantiomeric purity.     

A stereoselective synthesis of (-)-viridiofungin A utilizing a TiCl(4)-promoted asymmetric multicomponent reaction

A stereoselective synthesis of (-)-viridiofungin A is described. The convergent synthesis utilized a unique highly diastereoselective multicomponent reaction between optically active phenyldihydrofuran and an α-ketoester to provide two chiral centers including a quarternary carbon center in a single step. Other key steps include an acyloxycarbonium ion-mediated tetrahydrofuran ring-opening reaction and a Julia-Kocienski olefination.     

A new route to (2S,4R)- and (2R,4S)-4-hydroxypipecolic acid

Both enantiomers of cis-4-hydroxypipecolic acid have been prepared by asymmetric synthesis using (S)- or (R)-glycidol as the chiral source, and involving a stereoselective hydrogenation of a six-membered cyclic imine. The latter is obtained by reduction and cyclization of a cyano β-hydroxy ketone.     

Desymmetrization of meso-methylenecyclopropanes by a palladium-catalyzed asymmetric ring-opening bis(alkoxycarbonylation) reaction

Desymmetrization of various meso-methylenecyclopropanes was accomplished by a palladium-catalyzed asymmetric ring-opening bis(alkoxycarbonylation) reaction employing a chiral bioxazoline ligand. The reaction proceeded smoothly in the presence of copper(I) triflate under carbon monoxide and oxygen at ambient pressure to give the corresponding optically active α-methyleneglutarates with up to 60% ee. Desymmetrization of protected meso-(3-methylenecyclopropane-1,2-diyl)dimethanols was also carried out to give enantioenriched highly oxygen-functionalized α-methyleneglutarates.     

Stereodirectional synthesis of the main component of pheromone (9Z,12E)-tetradeca-9,12-dienyl acetate by cross-coupling

By cross-coupling of alkynyl cuprate with crotyl halides was synthesized (9Z,12E)-tetradeca-9-12-dienyl acetate, the main component of pheromones of several insect species Lepidoptera. The assignment of the chemical shifts of diene system was performed by¹H and¹³NMR spectroscopy. The study was carried out under financial support of the Russian Foundation for Basic Research (grant no. 96-03-32801).     

A new synthetic route to (−)-cassine via asymmetric aminohydroxylation

(−)-Cassine has been synthesized by a new route, asymmetric aminohydroxylation followed by reductive amination.     

A highly stereoselective, modular route to (E)-vinylsulfones and to (Z)- and (E)-alkenes

A recently discovered radical fragmentation of 2-fluoro-6-pyridinoxy derivatives allows a new highly stereoselective and convergent route to (E)-vinylsulfones from allylic alcohols. Reductive desulfonylation or nickel-catalyzed couplings furnish di- and trisubstituted (E)- and (Z)-alkenes.     

A new asymmetric synthesis of the anti-tumor alkaloid (R)-(+)-crispine A

We report a novel, facile, and asymmetric approach for the synthesis of the anti-tumor alkaloid (+)-crispine A via a highly diastereoselective N-acyliminium cyclization reaction as a key synthetic step.     

A dirhodium(II)-carbenoid route to (-)- and (+)-Geissman-Waiss lactone: synthesis of (1R,7R,8R)-(-)-turneforcidine.

(-)- and (+)-Geissman-Waiss lactone, 4b, was efficiently prepared via the intramolecular C-H insertion reaction of the chiral nonracemic diazoacetates (-)-5a and (+)-5b catalyzed by dirhodium(II) tetrakis[methyl (5R and 5S)-3-phenylpropanoyl-2-imidazolidinone-5-carboxylate]. The cyclization was found to proceed with excellent regioselectivity and cis-diastereoselectivity. The bicyclic lactone (-)-4b was successfully used in the synthesis of the necine base, (-)-turneforcidine 2.     

Uncatalyzed asymmetric diels-alder addition of cyclopentadiene to (E)- and (Z) - (R) -4,5-di-O-isopropylidene-pent-2-enonates

The uncatalyzed Diels-Alder addition of cyclopentadiene to the acrylic ester derivatives {=1} proceeds with high diastereo- and enantioface selectitivity.     

Modified synthesis of methyl (1R,2R,3E,5R)-3-(hydroxyimino)-5-methyl-2-(1-methylethyl)-cyclohexanecarboxylate from (R)-4-menthen-3-one

A modified stereospecific synthesis of potentially biologically and pharmacologically active methyl (1R,2R,3E,5R)-3-(hydroxyimino)-5-methyl-2-(1-methylethyl)cyclohexanecarboxylate from (R)-4-menthen-3-one was developed using sequential 1,4-conjugate addition of Norman reagent catalyzed by CuI?CBF₃?Et₂O?CCuCl₂ and ozonolysis?Creduction of the intermediate (R,R,R)-vinylmenthone by hydroxylamine hydrochloridein MeOH.     

A stereoselective route to alkenyl sulfides through the palladium-catalyzed cross-coupling reaction of 9-alkyl-BBN with 1-bromo-1-phenylthioethene or (E)- and (Z)-2-bromo-1-phenylthio-1-alkenes

The reaction of 9-alkyl-9-BBNs with 1-bromo-1-phenylthioethene or (E)- and (Z)-2-bromo-1-phenylthio-1-alkenes takes place readily in the presence of Pd(PPh₃)₄ and sodium hydroxide to afford stereodefined vinylic sulfides in excellent yields.     

Synthesis of optically active forms of methyl (E)-2,4,5-tetradecatrienoate,the pheromone of the male dried bean beetle

Both enantiomers of methyl (E)-2,4,5,-tetradecatrienoate were synthesized with 125–127% the rotatory power of the natural product which was isolated as the pheromone of Acanthoscelides obtectus. The absolute configuration of the levorotatory natural pheromone was confirmed to be R.     

A concise asymmetric route to Nuphar alkaloids. A formal synthesis of (-)-deoxynupharidine

[reaction: see text] A stereocontrolled route to Nuphar alkaloids is described that employs a formal [3 + 3] cycloaddition strategy to assemble the piperidine nucleus. The addition of Pd-TMM complexes to aziridine 10 was found to be sluggish; however, the addition of a functionalized allyl Grignard reagent followed by a Mitsunobu condensation reaction provided 11 in high yield. The employment of this route in the formal synthesis of (-)-deoxynupharidine 1 is described.     

A new and general synthetic pathway to strychnos indole alkaloids: total syntheses of (-)-dehydrotubifoline and (-)-tubifoline by palladium-catalyzed asymmetric allylic substitution

[see reaction]. A novel procedure for the synthesis of an indole skeleton was developed. Treatment of a cyclohexenol derivative having a silyloxymethyl group at the 2-position with N-tosyl-o-bromoaniline in the presence of Pd2dba3*CHCl3 and (S)-BINAPO gave compound 6a with 84% ee in 75% yield. Compound 6a was converted into 11, which was treated with Pd(OAc)2 and Me(2)PPh in the presence of Ag2CO3 to give indoline derivative 12. From 12, we succeeded in the total syntheses of (-)-dehydrotubifoline and (-)-tubifoline.     

昆虫性信息的结构鉴定与合成 XXVII: (5R, 6S)-(-)-及(5S, 6R)-(+)-淡色库蚊产卵引诱性信息素的立体选择性合成与手性亚砜不对称加成的立体化学

从R-(-)-正十三烯-3-醇2所得的R-(+)-醛5, 与R-(+)亚砜化合物6的不对称醇醛缩合得7a和7b(30:1). 7a经一系列转化得1a, 从(5S, 6R)-14出发, 经两次构型翻转[5S,6R)-15→(5S, 6S)-16和(5S, 6S)-17→(5R, 6S)-14], 得1a的对映体1b. 光学活性α-苄氧基醛5与手性亚砜的不对称醇醛缩合, 受手性亚砜的1,3-不对称诱导控制, 而不是受醛5的1,2-不对称诱导控制.