Enantioselective Phase-Transfer Catalytic α-Benzylation and α-Allylation of α-<i>tert</i>-Butoxycarbonyllactones
作者:Min Woo Ha、Heejin Lee、Hye Yeong Yi、Yohan Park、Sori Kim、Suckchang Hong、Myungmo Lee、Mi-hyun Kim、Taek-Soo Kim、Hyeung-geun Park
DOI:10.1002/adsc.201200976
日期:2013.3.11
A new enantioselective α‐benzylation and α‐allylation of α‐tert‐butoxycarbonyllactones was devloped. α‐Benzylation and α‐allylation of α‐tert‐butoxycarbonylbutyrolactone and α‐tert‐butoxycarbonylvalerolactone under phase‐transfer catalytic conditions (50% cesium hydroxide, toluene, −60 °C) in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide (1 mol%) afforded the corresponding α‐substituted
开发了新的对映选择性α-苄基化和α-叔丁氧基羰基内酯的α-烯丙基化。在(S,S)-3存在下,在相转移催化条件下(50%氢氧化铯,甲苯,-60°C),α-叔丁氧基羰基丁内酯和α-叔丁氧基羰基戊内酯的α-苄基化和α-烯丙基化, 4,5-三氟苯基-NAS溴化物(1 mol%)以非常高的化学收率(高达99%)和光学收率(高达ee的99%)提供了相应的α-取代的α-取代的α-叔丁氧基羰基内酯)。非天然α-季高丝氨酸,3-烷基-3-羧基吡咯烷和3-烷基-3-羧基哌啶的不对称合成已成功证明了该方法的合成潜力。