关键词： AMINO acid synthesis   ASYMMETRIC synthesis  

摘要： Addition of Ti(Oi-Pr)(3) ester enolates to tert-butanesulfinyl aldimines and ketimines provided beta-substituted, alpha,beta- and beta,beta-disubstituted, alpha,beta,beta- and alpha,alpha,beta-trisubstituted, and alpha,alpha,beta,beta-tetrasubstituted beta-amino acid derivatives in high yields and with high diastereoselectivites. The N-sulfinyl-beta-amino ester products were further employed as versatile intermediates for both standard solution-phase and solid-phase synthetic transformations, including the synthesis of beta-peptide foldamers.

关键词： ASYMMETRIC synthesis   SWAINSONINE  

摘要： The asymmetric synthesis of H-swainsonine via a nonchiral pool route that involves the Sharpless epoxidation to induce chirality is reported. The key steps involve vinyl epoxide aminolysis, ring-closing metathesis, and intramolecular N-alkylation to prepare the indolizidine ring and a highly diastereoselective cis-dihydroxylation using AD-mix-cc. This synthetic strategy also allowed for the diastereoselective synthesis of (+)-1,2-di-epi-swainsonine and (+)-1,2,8-tri-epi-swainsonine.

关键词： asymmetric synthesis   chiral acyl anions   ligand design   bis(sulfoxides)  

摘要： The preparation of various racemic or enantiopure C-2-symmetric bis(sulfoxides) has been developed over the last decades. Numerous applications in organic synthesis (anionic condensation, cycloadditions) as well as in coordination chemistry have been worked out. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).

关键词： ORGANIC compounds   CHEMICAL reactions  

摘要： A simple and efficient asymmetric synthesis of 2H-azirine-2-phosphine oxides 3 is described. The key step is a solid-phase bound achiral or chiral amine-mediated Neber reaction of beta-ketoxime tosylates derived from phosphine oxides 1. Reaction of 2H-azirines 3 and 11 with carboxylic acids 4 gives phosphorylated ketamides 5 and 12. Ring closure of ketamides 5 and 12 with triphenylphosphine and hexachloroethane in the presence of triethylamine leads to the formation of phosphorylated oxazoles 8 and 13.

关键词： Reaction products   Enantioselective synthesis   Mixtures   Carbonyls   Molecular structure  

摘要： [GRAPHICS] A simple, asymmetric synthesis of tetramic acid derivatives is described in this paper. The key step is a carbonyl transfer from carbonyldiimidazole (CDI) to alpha-diimines (I) to form N-alkyl-4-alkylamino-5-methylenepyrrol-2-ones (II). In turn, these compounds can be easily transformed into tetramic acid derivatives (III) in two additional steps.

关键词： 拟除虫菊酯   手性化合物   拆分   差向异构   不对称合成   杀虫剂  

摘要： 拟除虫菊酯是一类与天然除虫菊素结构类似的化合物,具有立体结构,不同立体结构的生物活性差异很大,如何得到生物活性高的单一异构体,是拟除虫菊酯的研究方向。本文介绍了几种获得单一异构体的方法,并对各种方法进行了评述。

关键词： 有机合成化学   手性试剂   手性催化剂   不对称合成  

摘要： 瑞典皇家科学院2001年10月10日宣布将诺贝尔化学奖授于美国.诺尔斯.(Knowle W)、日本野依良治(Ryoji Noyori)和美国.夏普雷斯KB(Sharpless K B),以表彰他们在不对称合成方面所取得的卓越成绩.

摘要： Enantiopure α-substituted propargyllamines are useful syntheticintermediates which are often encountered as a part of biologically active compounds. Surprisingly,while the chemistry of enantiopure α-substituted propargyl alcohols is now well known andpresent in many synthetic strate-gies, the asymmetric preparation and use of their nitrogenatedanalogues is still in its infancy.~1 Important synthetic developments could be expected if a generaland efficient method for the preparation of such intermediates in enantiomerically pure form wasavailable. The use of a nitrogen directing group, as has been already demonstrated in numerous cases(α-aminoaldehydes chemistry for instance~2), could lead to regio- and stereoselectivetransformations of the acetylenic group and deliver important synthetic intermediates, as well asbiologically active derivatives.

摘要： Role of asymmetric catalysis in solid phase organic synthesis is described especially on the soluble polymer supports, namely, poly (ethylene glycol). The review focus only on the recent progress in this area. Some of advantages as well as limitations posed by this soluble polymer system is also described. The popular reactions covered in this review include asymmetric dihydroxylation, epoxidation, reductions and C-C bond formations.

关键词： ACETAL resins   LEWIS acids  

摘要： A streamlined and high-yielding synthesis of aprepitant (1), a potent substance P (SP) receptor antagonist, is described. The enantiopure oxazinone 16 starting material was synthesized via a novel crystallization-induced dynamic resolution process. Conversion of 16 to the penultimate intermediate cis-sec-amine 9 features a highly stereoselective Lewis acid-catalyzed trans acetalization of chiral alcohol 3 with trichloroacetimidate 18 followed by inversion of the adjacent chiral center on the morpholine ring. The six-step process for the synthesis of 9 was accomplished in extremely high overall yield (81%) and with only two isolations.