关键词： 谷蠹   不对称环氧化   集结信息素  

摘要： 谷蠹(Rhyzopertha dominica)是世界性储藏产物的主要害虫、在我国仓库中破坏性也占首位.1981年Williams等人首次鉴定和合成了这种信息素.它的两个活性组分是(E)-2-甲基-2-戊烯酸(S)-(+)-1-甲基丁基酯1和(E)-2,4-二甲基-2-戊烯酸(S)-(+)-1-甲基丁基酯2. Williams等人从自然界光学活性体——谷氨酸为原料,经过八步合成1或2,在合成过程中用了剧毒试剂氢化钠.本文报道的不对称合成主要应用Sharpless环氧化动力学拆分以及Wittig反应,以易得的巴豆醛为原料,经过四步得目的化合物,总得率30％。

关键词： .substituents   Valerolactones   asymmetric ring   glutaric   anhydrides   simple alkyl  

摘要： In organic solvents, lipase Amano P catalyzed the asymmetric ring opening of glutaric anhydrides bearing-CH2Cl,-CH2F and -OCH3 groups at position 3 with methanol and 1-butanol to afford the corresponding mono esters in 70-86% e.e. Optically active sigma-valerolactones were synthesized from the mono esters in overall yields of 34-62%. The R-configuration was assigned to the mono esters and the lactones by means of a CD analysis and chemical correlation. This indicates that the lipase preferentially attacked the pro-R carbonyl group of these anhydrides carrying hetero atoms, in keeping with the trend observed for glutaric anhydrides having simple alkyl substituents.

关键词： 双不对称合成   不对称合成  

摘要： 不对称合成反应的研究是有机化学的前沿领域,有关的进展对合成具有光活性的天然产物、药物、多肽和糖类化合物等都有重要的意义。人们不断追求获得更高的立体化学选择性,期望实现对反应产物的立体控制。

关键词： .diastereoselectivity   asymmetric synthesis   smoothly   epimerization   ester enolates   butenyl   aza-Claisen rearrangement   lS phenethyl  

摘要： Aza-Claisen rearrangement of N-2 (E)-butenyl-N-butylpropanamide was found to proceed smoothly at’v135OC in the presence of LDA to furnish syn-N- butyl-2,3-dimethyl-4-pentenamidein- 948 yield and >99% de. The reaction with the corresponding N-(lS)-l-phenethyl derivative yielded (2R, 3s)-N- [(lS)-1-phenethyl) -2,3-dimethyl-4-pentenamidein 83% de. An efficient and generally-applicable two-step procedure for the hydrolysis of N-mono- substituted amides was also developed and the corresponding carboxylic acids were obtained in good yields without any epimerization at thea- position of the acyl group. The amines used for the chiral induction can be recovered in 71% yield.

关键词： .chirality   Diels-Alder   asymmetric synthesis   auxiliaries   enoyl   enantiomerically pure   camphor   bornane   sultam   enolates  

摘要： The readily available enantiomers of bornane[10,2]sultam serve as efficient, versatile and practical chiral auxiliaries. A selection of highly r-face-selective reactions of their N-enoyl derivatives (Diels-Alder additions, dihydroxylations, 1,4-additions) as well as of their 0-metalated N,O-ketene acetals (aldolizations, alkylations, brominations, "aminations") are described. Applications to the syntheses of natural products and, particularly, of enantiomerically pure a-amino acids demonstrate their preparative potential.

关键词： .stereochemical   terpene   dolabellane   isodaucane   araneosene   daucene   isoamijiol  

摘要： The prevalence of a C - common core in diverse C terpenes has been recognised. A bifun%onal C I 2-cyclopentanoid deriva%:% corresponding to this common-core has been prepared from R-(+)-limonene. The enantio- merically pure 2 has been elaborated to several sesqui- and diterpene skeleta. In particular, enantioselective syntheses of isodaucane sesquiterpene, (+)-apha- namol-I, 3 aand dolabellane diterpene, 6-araneosene 26 have been accom- plished for the first time. A general solution to the stereochemical problem associated with this class of compounds has been devised. Syntheses of (-)- daucene 8 and (+)-isoamijiol 17a r e also described.

关键词： 光活性氰酸   不对称合成   稳定性  

摘要： 光学活性芳族氰醇以及由它转变而成的α-羟基酸、α-羟基酯、α-羟基酮和β-羟基胺等光学活性异构体都是重要的农药和医药中间休,从实用观点看,利用催化不对称合成来制取光活性氰醇,更具有重要意义。近年来,环状二肽Cyclo[L(D)-Phe-L(D)-His]用于催化芳族氰醇的不对称合成,由于具有与D-羟腈酶相类似的高活性和高对映选择性。

关键词： 满衍生物   不对称合成  

摘要： 含有色满环(2H-1-苯骈吡喃-3,4-二氢)结构的天然产物有抗氧化,抗病毒,免疫,强壮神经等功能。合成这类中间体结构,很早就为人们所关注。早期根据生源合成理论,将异戊二烯和酚反应,在路易斯酸存在下合成出色满衍生物。此后在这方面作过许多工作。

关键词： 硼氢化物   不对称合成   立体选择性   有机官能团   含氧官能团   手性中心   酮酸   选择性还原   还原反应   丙酸甲酯  

摘要： 综述了硼氢化锌对α-羟基酮、β-羟基酮、α,β-环氧酮、β-酮酸 酯和β-酮酰胺的高立体选择性还原和硼氢化锌在不对称合成中的应用。 硼氢化物试剂可分为有机硼氢化物试剂和无机硼氢化物试剂。有机硼氢化物试剂,特别是手性硼氢试剂,在有机合成中的应用日益增加。无机硼氢试剂,如NaBH_4的新应用广泛地展现了在有机官能团反应中的重要作用。近年来报道的一种新的硼氢化物试剂Zn(BH_4)_2,对含氧官能团酮的还原具有高的立体选择性。本文现就其在不对称合成中的应用作一综述。