关键词： asymmetric synthesis   alpha-monofluoromethylbenzylamine   alpha-difluoromethylbenzylamine   regioselective hydrogenolysis   diastereomerically pure bis(alpha-methylbenzyl)amine derivative   partially fluorinated methyl group   opposite asymmetric induction  

摘要： Asymmetric synthesis of alpha-monofluoromethyl- and alpha-difluoromethylbenzylamines through regioselective hydrogenolysis is described. Hydrogenolysis of diastereomerically pure bis(alpha-methylbenzyl)amine derivatives having partially fluorinated methyl group at benzylic position also proceeded with a high regioselectivity as well as in the case of alpha-trifluoromethyl group. Moreover, opposite asymmetric induction was observed in reduction of chiral imines derived from partially fluorinated acetophenone and alpha-phenylethylamine. (c) 2005 Elsevier B.V. All rights reserved.

关键词： ALLYLIC ALCOHOLS   ALPHA   β-UNSATURATED KETONES   KINETIC RESOLUTION   DIASTEREOSELECTIVE EPOXIDATION   HYDROGEN-PEROXIDE   ZINC ALKYLS   AMINO-ACID   DIETHYLZINC   REAGENTS   ENONES  

摘要： [GRAPHICS] We have developed a one-pot procedure for the asymmetric synthesis of a synthetically challenging class of acylic secondary epoxy alcohols with three contiguous stereocenters from simple achiral starting materials. The epoxy alcohols are synthesized via a tandem catalytic asymmetric vinylation of an aldehyde coupled with a diastereoselective epoxidation reaction. A vinylzinc reagent generated in situ undergoes enantioselective addition to an aldehyde in the presence of a zinc catalyst to provide an allylic zinc alkoxide. This species is then epoxidized by addition of dioxygen and a titanium tartrate catalyst to give epoxy alcohols with excellent enantioselectivities, in most cases, and with diastereoselectivities up to 4.5:1 in favor of the threo-diastereomer. The system described herein represents a significant advance in terms of synthetic efficiency and selectivity.

关键词： Alteromonas/chemistry   Anti-Bacterial Agents/chemical synthesis*   Catalysis   Mupirocin/analogs & derivatives   Mupirocin/chemical synthesis*   Pyrans/chemical synthesis   Stereoisomerism  

摘要： The isolation and characterization of the pyran-containing pseudomonic acidshave led to the commercial success of Bac-troban,a topical antimicrobial medication for *** active ingredient,pseudomonic acid A(mupirocin,1,Figure 1),displays poor oralabsorptivity and low metabolic ***,there has been significant interest in thedevelopment of improved,less toxic analogues that could also be suitable as *** A(2)and derivative 3 are rare marine natural products recently isolated fromthe bacterium Alteromonas rava *** 73390.

关键词： asymmetric synthesis   heterocycles   amino acids   epoxidation   imidazoisoquinolinones  

摘要： Reaction of isoquinolines 1 with N-arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo [2, 1-a]isoquinolin-3-ones 5 via intermediate N-acylisoquinolinium salts 3. Addition reactions to the enamine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1-a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo [2,1-a]isoquinolin-3-ones 10 or 12 or of the polycyclic 1,4-dioxane 13 in high stereoselectivity. The regioselectivity of the oxiran ring opening depends on the kind of nucleophile and the conditions. Reaction of dihydroisoquinoline with O-TBDMS-mandelic acid chloride 15 leads to a tetrahydrooxazolo[2,3-a]isoquinoline 17 with opposite facial selectivity as compared with dihydroimidazo [2,1-a]isoquinolin-3-ones 5. (C) Wiley-VCH Verlag GmbH Co.

关键词： N-苯甲酰基-(2R,3S)-3-苯基异丝氨酸异丙酯   紫杉醇   氨羟化   不对称合成   抗癌剂  

摘要： 用反式肉桂酸异丙酯为原料,N-溴代苯甲酰胺为助氧化供氮试剂,分别在配体3、4存在下进行锇催化的不对称氨羟化反应,一步制得抗癌药紫杉醇的C13片段N-苯甲酰基-(2R,3S)-3-苯基异丝氨酸异丙酯,收率分别为41.2%和43.6%,对映体过量(ee)均为97%。

关键词： 手性氨基烷基酚   不对称合成   立体选择性   手性诱导  

摘要： 综述了近几年来手性氨基烷基酚合成的最新研究进展,包括通过无溶剂不对称Mannich反应、亚胺的不对称还原反应合成以及Bettibase衍生物的合成等。

关键词： 不对称反应   手性配体   不对称合成   手性催化剂   金属配合物   有机合成   有机配体  

摘要： 不对称合成是有机合成领域的热点,本文综述了以有机配体———金属配合物为手性催化剂的不对称合成的最新进展。

关键词： amino alcohol   enantioselective synthesis   tert-butane-sulfinimine   Grignard reagents   nucleophilic addition  

摘要： Facile and highly stereoselective synthesis of 1,2-amino alcohols has been achieved by the addition of [(dimethylphenylsilyl)methyl] magnesium chloride to the tert-butanesulfinimines, followed by Fleming-Tamao oxidation of the silicon moiety.

关键词： asymmetric synthesis   additions   pyrrolidine   carbanions   reductive lithiation  

摘要： Based on the use of phenyl thioether (3S)-7 as a synthetic equivalent to the N- and alpha-dianions (3S)-2a, a new carbanionic approach to trans-(2R,3S)-2-substituted 3-aminopyrrolidines (10) is described. Application of the method to the asymmetric synthesis of 1-aminopyrrolizidine alkaloid (+)-absouline is also reported.

关键词： alkylation   asymmetric catalysis   Heck reaction   palladium   total synthesis  

摘要： The interesting biological properties of the hamigerans wherein hamigeran B is a potent antiviral agent with low cytotoxicity to host cells make these deceptively simple looking structures challenging synthetic targets. A strategy to hamigeran B evolved wherein the three contiguous stereo-centers are established ultimately from a Pd catalyzed asymmetric allylic alkylation (AAA). The latter involves an asymmetric allylation of a non-stabilized ketone enolate in 77 % yield and 93 % ee. By using this process, (S)-5- allyl-2-isopropyl-5-methyl-1-trifluoromethanesulfonyloxycyclopentene becomes available in four steps from 2-methylcyclopentanone. Introduction of the aryl unit by cross-coupling proceeded intermolecularly but failed intramolecularly. On the other hand, reductive removal of the triflate permitted a Heck reaction to effect intramolecular introduction of the aryl ring. The unusual conformational properties of this molecular architecture are revealed by the regioselectivity of the beta-hydrogen elimination in the Heck reaction and the diastereoselectivity of the reduction establishing the stereochemistry of the carbon bearing the isopropyl group. The successful route consists of 15 steps from 2-methylcyclopentanone and dimethylorcinol illustrating the efficiency of the route based upon the Pd AAA.