Asymmetric Deprotonations: Lithiation of N-(tert-Butoxycarbonyl)indoline with sec-Butyllithium/(−)-Sparteine
摘要:
The asymmetric lithiation of N-Boc indoline (1) with s-BuLi/(-)-sparteine and subsequent substitution provides the 2-substituted N-Boc indolines 3 and 5-11 with excellent enantiomeric ratios and in variable yields. The asymmetric lithiation-substitution sequence with N-Boc-7-chloroindoline (12) provides products 13-19 with good enantiomeric ratios. Mechanistic investigation establishes that the enantioselectivities arise from an initial asymmetric deprotonation to provide the enantioenriched and configurationally stable organolithium intermediates (S)-28 and (S)-29, which react stereoselectively with electrophiles.
Direct Preparation of 7-Allyl- and 7-Arylindolines
作者:Daniele Leonori、Iain Coldham
DOI:10.1002/adsc.200900499
日期:2009.11
allyl halides to the organolithium species derived from lithiation of N-tert-butoxycarbonylindoline with sec-butyllithium (sec-BuLi) and tetramethylethylenediamine (TMEDA) occurs regioselectively by SN2 allylation. In contrast, the organolithium species can be transmetalated to the mixed zinc cuprate that undergoes regioselective SN2′ allylations. Transmetalation to the organozinc chloride allows a Negishi-type
烯丙基卤化物从锂化衍生的有机锂物质加成ñ -叔-butoxycarbonylindoline与秒-丁基锂(秒正丁基锂)和四甲基乙二胺(TMEDA)用S区域选择性地发生Ñ 2烯丙基化。相反,有机锂物质可以被金属转移到经历区域选择性的S N 2'烯丙基化的混合铜酸锌中。使用三苯基膦(PPh 3)作为配体的钯催化,金属转移至有机氯化锌可实现与芳基溴化物的Negishi型交叉偶联反应。该化学方法被用于非常短的7-异戊烯基吲哚和生物碱vasconine的合成。
Nucleophilic Addition of α-Metallated Carbamates to Planar Chiral Cationic η<sup>3</sup>-Allylmolybdenum Complexes: A Stereochemical Study
作者:Philip Kocienski、John Christopher、Richard Bell、Bernhard Otto
DOI:10.1055/s-2004-834917
日期:——
Chiral α-(O-carbamoyl)alkyl- and α-(N-carbamoyl)alkylcopper(I) reagents derived from (-)-sparteine-mediated asymmetric lithiation of hindered carbamates react with cationic η 3 -allylmolybdenum complexes with retention of configuration.
衍生自 (-)-sparteine 介导的受阻氨基甲酸酯不对称锂化的手性 α-(O-氨基甲酰基)烷基-和 α-(N-氨基甲酰基)烷基铜 (I) 试剂与阳离子 η 3 -烯丙基钼配合物反应,并保留构型。