Enantiospecific synthesis of polhydroxylated indolizidines related to castanospermine: 1 (6R,7S,8aR)-6,7-dihydroxyindolizidine and (6R,7R,8S,8aR)-6,7,8-trihydroxyindolizidine.

Enantiospecific syntheses of (6R,7S,8aR)-6,7-dihydroxy-indolizidine (3) and (6R,7R,8S,8aR)-6,7,8-trihydroxy-indolizidine (4) from methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (7) are reported. The two synthetic indolizidines (3) and (4) have been tested against a wide range of enzymes.     

A general enantioselective approach to jasmonoid fragrances: synthesis of (+)-(1R,2S)-methyl dihydrojasmonate and (+)-(1R,2S)-magnolione

Methyl dihydrojasmonate 1 and magnolione 3 are of both academic and industrial interest. In this paper, we describe a flexible, high-yielding route to diastereomerically pure (+)-cis-(1R,2S)-methyl dihydrojasmonate 1 and the first synthesis of (+)-cis-(1R,2S)-magnolione 3, both with enantiomeric excesses up to 93%. The two syntheses diverged from the same advanced intermediate 5, readily available from the enantioenriched hydroxymethyl delta-lactone (-)-(3aS,4S,6aR)-6. The olfactory properties of (1R,2S)-1 and (1R,2S)-3 are reported.     

(+)-(1S,2S,5R)-8-联苯薄荷醇的合成

以(R)-( )-pu legone为起始原料,经1,4-加成,还原两步反应合成了手性辅助试剂( )-(1S,2S,5R)-8-联苯薄荷醇及其差向异构体(-)-(1R,2S,5R)-8-联苯薄荷醇,总产率95%。其结构经1H NMR,13C NMR,IR,MS和X-射线衍射仪表征。     

Heterotricyclodecane XX (+)-(1S, 3S, 6S, 8S)- und (−)-(1R, 3R, 6R, 8R)-2, 7-Dioxa-twista-4,9-dien

(+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene. A synthesis and the determination of the sense of chirality of (+)-(1S, 3S, 6S, 8S)- and (?)-(1R, 3R, 6R, 8R)-2,7-dioxa-twista-4,9-diene ((+)- 5 and (?)- 5 , respectively) is described.     

Total synthesis of (S)-(+)-curcudiol, and (S)-(+)- and (R)-(-)-curcuphenol.

A highly enantioselective synthesis of the versatile chiral synthons possessing one stereogenic center, (S)- and (R)-4-aryl-5-hydroxy-(2E)-pentenoate (3) was achieved based on the enzymatic reaction of (+/-)-3 with commercially available lipases MY-30 or OF-360 from Candida rugosa. Application of (S)-3 and (R)-3 to the total syntheses of(S)-curcuphenol (1), (S)-curcudiol (2), and (R)-curcuphenol (1), respectively, is described.     

Novel stereocontrolled synthesis of the tricyclic lactone (1R,3R,6R,9S)-6,9-dimethyl-8-oxo-7-oxatricyclo[4.3.0.03,9]nonane

The stereocontrolled synthesis of (1R,3R,6R,9S)-6,9-dimethyl-8-oxo-7-oxatricyclo[4.3.0.0^3,9]nonane 1 from (R)-(−)-carvone has been accomplished by application of a 13-step sequence with 12% overall yield. The absolute stereochemistry of the unsaturated acid 8a has been established by X-ray analysis of the chiral amide 8c.     

雌舞毒蛾引诱剂: (＋)-(7R,8S)-7,8-环氧-2-甲基十八烷的不对称全合成

由雌舞毒蛾释放的性引诱剂由于在害虫防治方面的需求不断增加, 已有许多文献对其合成方法进行报道. 以正十一醛和环戊酮为起始原料, 用L-脯氨酸催化的不对称羟醛缩合反应构筑手性中心, 后经拜耶-维利格氧化, 维梯希烯化等步骤, 为雌舞毒蛾性引诱剂(＋)-(7R,8S)-7,8-环氧-2-甲基十八烷提供了一条简便高效的不对称合成新途径, 总收率为37.8%.     

A novel asymmetric route to succinimides and derived compounds: synthesis of the lignan lactone (+)-hinokinin

A novel approach to chiral succinimides and derived compounds has been developed that involves chiral lithium amide desymmetrisation of an N-ortho-tert-butylphenyl succinimide to generate a putative atropisomeric intermediate enolate, alkylation of which enables access to the lignan lactone (+)-hinokinin.     

Enantiospecific synthesis of (6R,7S,8aR)-dihydroxyindolizidine and (6R,7R,8S,8aR)-trihydroxyindolizidine from D-glucose.

Enantiospecific syntheses of (6R,7S,8aR)-dihydroxyindolizidine (1) and (6R,7R,8S,8aR)-trihydroxyindolizidine (2) from readily available methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (5) are described.     

Synthesis of (+)-(R)-5-hydroxy-6-hydroxymethyl-7-methoxy-8-methylflavanone

The synthesis of (+)-(R)-5-hydroxy-6-hydroxymethyl-7-methoxy-8-methylflavanone is described. A new chromylation method of β-ketosulfoxide 9 leading to the Michael acceptor 12 has been developed. Dilithium tetrachlorocuprate was shown to be a very efficient catalyst for the conjugate addition reaction of phenyl magnesium bromide to the α,β-unsaturated sulfoxide 12. The instability of the obtained adducts 10 represents a limitation in terms of yield. It was confirmed that the natural flavanone leridol does not possess the structure of title compound 1.     

Enantiospecific synthesis of 1-deoxy-castanospermine, (6S,7R,8R, 8aR)-trihydroxyindolizidine,from D-glucose.

An enantiospecific synthesis of 1-deoxy-castanospermine (2) is described from D-glucose, where the key step involves oxidative bromination of a benzylidene acetal to afford 8-azido-3-O-benzoyl-5-bromo-5,6,7,8-tetradeoxy-1,2-O-isopropylidene-β-L-ido-octose (6).     

从(-)-α-蒎烯合成(IR,3R)-(+)-反式菊酸甲酯

报道了以(-)-α-蒎烯为主要成分的松节油作原料,通过十四步反应合成了(1R,3R)-(+)-反式菊酸甲酯,每步反应的得率都在60%以上,总得率10.8%.反应操作方便,条件温和,对合成路线中的有些反应作了一些比较和讨论.化合物3-9都是新化合物.     

Studies on the identification and synthesis of insect pheromone: XXIV. Synthesis of (7R, 8S)-(+)- and (7S, 8R)-(−)-sex pheromone of gypsy moth and stereochemistry of β-hydroxysilane

Condensation of the epoxy aldehyde 2 or 2 prepared by Sharpless asymmetric epoxydation in 96—97% yield, with trimethylsilane lithiated 3 gave 7 or 7 ′, which after transformation to the corresponding acetoxyl compound 8 or 8 ′ afforded the title compound 1a or 1b via β-acetoxysilane elimination and catalytic homogeneous hydrogenation. The configurations of the stereoisomers 7 and 7 ′ were determined.     

昆虫信息素的结构鉴定和合成XXIV: (TR,8S)-(+)-和(7S,8R)-(-)-午毒蛾性信息素的合成及β-羟基硅烷的立体化学

从Sharpless不对称环氧化反应所得的光学活性环氧醛(e.e.96-97%)与三甲基硅锂试剂反应,得到β-羟基硅烷.它们经转化成乙酰氧基化合物后,再通过β-乙酰氧基硅烷的消除反应和均相催化氢化即得到两个标题化合物.对β-羟基硅烷的各非对映异构体的构型进行了测定.     

(1R,6R)-(+)-鱼腥藻毒素的合成

鱼腥藻毒素(Anatoxin-a)是自兰藻类水华鱼腥藻(Anabaena flos-aquae)中分离的一种氮杂双环胺类生物碱,其化学结构及绝对构型经X光晶体衍射法测定分析为:(1R,6R)(+)-2-乙酰基-9-氮双环[4.2.1]壬-2-烯,简称为AnTX-a。     

Terpenes in organic synthesis. 8. Synthesis of optically active (2R/S, 3S, 7R/S)-(-)-diprionyl acetate from (S)-(+)-3,7-dimethyl-1,6-octadiene

Conclusions A seven-stage synthesis has given optically active (2R/S, 3S, 7R/S)-2-acetoxy-3,7-dimethylpentadecane from the readily available (S)-(+)-3,7-dimethyl-1,6-octadiene, in an overall yield of 36%. The synthetic route utilizes all ten carbon atoms of the starting chiral diene.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1142–1146, May, 1988.     

A stereoselective synthesis of (+)-L-733,060 from ethyl (R)-(+)-2,3-epoxypropanoate

An asymmetric synthesis of neurokinin substance P receptor antagonist (+)-L-733,060 starting from enantiomerically pure ethyl (R)-(+)-2,3-epoxypropanoate (ethyl glycidate) is described. The synthesis relies on a diastereoselective reductive amination, regioselective intramolecular epoxide opening, and in situ cyclization as the key steps.     

Natural product synthesis from (8aR)- and (8aS)-bicyclofarnesols: synthesis of (+)-wiedendiol A, (+)-norsesterterpene diene ester and (−)-subersic acid

Both enantiomers (8aR)-7 and (8aS)-7 of bicyclofarnesol were synthesized from the enzymatic resolution products (1R,4aR,8aR)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aR)-5 (98% ee) and acetate of (1S,4aS,8aS)-1,2,3,4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aS)-6 (>99% ee), respectively. The formal synthesis of (+)-wiedendiol 1 was achieved via a coupling reaction of an ate complex derived from 1,2,4-trimethoxybenzene with allyl bromide (8aS)-8 derived from (8aS)-7. The total synthesis of (+)-norsesterterpene diene ester 2 was achieved, based on the synthesis of (13E,10S)-α,β-unsaturated aldehyde 12, derived from (8aS)-7, followed by the selective construction of the (3E,5E)-diene moiety including a C(2)-stereogenic centre in (+)-2. The total synthesis of (−)-subersic acid 3 was carried out based on a Stille coupling between allyl trifluoroacetate congener 25c, derived from (8aR)-7, corresponding to the diterpene part, and aryl stannane congener 26 in the presence of Pd catalyst and CuI as an additive.