Strategy for Employing Unstabilized Nucleophiles in Palladium-Catalyzed Asymmetric Allylic Alkylations
作者:Barry M. Trost、David A. Thaisrivongs
DOI:10.1021/ja806781u
日期:2008.10.29
unstabilized anions in palladium-catalyzed asymmetric allylic alkylations (AAA). The "hard" 2-methylpyridyl nucleophiles studied are first reacted in situ with BF3.OEt2; subsequent deprotonation of the resulting complexes with LiHMDS affords "soft" anions that are competent nucleophiles in AAA reactions. The reaction is selective for the 2-position of methylpyridines and tolerates bulky aryl and alkyl substitution
A Stereoselective Synthesis of Phosphinic Acid Phosphapeptides Corresponding to Glutamyl-γ-glutamate and Incorporation into Potent Inhibitors of Folylpoly-γ-glutamyl Synthetase
作者:David M. Bartley、James K. Coward
DOI:10.1021/jo0507439
日期:2005.8.1
Radical addition of H3PO2 to N-/C-protected vinyl glycine led to the corresponding H-phosphinic acid in excellent yield. The non-nucleophilic H-phosphinic acid was converted to a nucleophilic PIII species, RP(OTMS)2, which was used in two approaches to the target phosphinicacid containing pseudopeptide. New methodology was developed that led to excellent yields in the reaction of RP(OTMS)2 with unactivated
将H 3 PO 2自由基加到N- / C-保护的乙烯基甘氨酸中可得到相应的H-次膦酸,产率极高。将非亲核性H-次膦酸转化为亲核性的P III物种RP(OTMS)2,该物质以两种方法用于含有伪肽的目标次膦酸。开发了一种新的方法,可导致RP(OTMS)2与未活化的亲电试剂(包括无环均烯丙基溴)的反应获得优异的收率。然而,途中目标假肽,RP(OTMS)的阿尔布蜀夫反应2与环状高烯丙基溴,(ř)-3-(溴甲基)-环戊-1-烯导致重排的烯丙基次膦酸而不是所需的均烯丙基衍生物,即假定的谷氨酸替代物。将RP(OTMS)2共轭添加到含有手性助剂的α-亚甲基戊二酸酯中只会导致适度的非对映选择性。通过快速色谱纯化提供假肽的两种非对映异构体的保护衍生物。整体脱保护后,(S)-H-Glu-γ-[Ψ(P(O)(OH)(CH 2))]-(S)-Glu-OH与(S)-H-Glu-γ偶联-[Ψ(P(O)(OH)(CH 2
A Short Synthesis of (?)-Carbovir
作者:Stefan Hildbrand、Thomas Troxler、Rolf Scheffold
DOI:10.1002/hlca.19940770506
日期:1994.8.10
(–)-Carbovir ((–)-1) was synthesized via the cyclic carbonate 2 in four steps starting from enantiomerically enriched (–)-(S)-(cyclopent-2-enyl)methanol ((–)-3).