Enantioselective α-Chlorination Reactions of in Situ Generated C1 Ammonium Enolates under Base-Free Conditions
作者:Lotte Stockhammer、David Weinzierl、Thomas Bögl、Mario Waser
DOI:10.1021/acs.orglett.1c02256
日期:2021.8.6
esters can be carried out with high levels of enantioselectivities utilizing commercially available isothiourea catalysts under base-free conditions. The reaction, which proceeds via the in situ formation of chiral C1 ammonium enolates, is best carried out under cryogenic conditions combined with a direct trapping of the activated α-chlorinated ester derivative to prevent epimerization, thus allowing
活化芳基乙酸酯的不对称 α-氯化可以在无碱条件下使用市售的异硫脲催化剂以高水平的对映选择性进行。该反应通过原位形成手性 C1 烯醇化铵进行,最好在低温条件下进行,同时直接捕获活化的 α-氯化酯衍生物以防止差向异构化,从而实现高达 er 99 的对映选择性: 1.