acetal with tetrahalomethane or trihalomethane at room temperature in the presence of a catalytic amount of Et3B provides 3,3-dihaloacrylate or (E)-3-haloacrylate, respectively. On the other hand, a reaction at −23 °C mainly gives 3,3,3-trihalopropanoate or 3,3-dihalopropanoate.
在催化量的 Et3B 存在下,在室温下用四卤甲烷或三卤甲烷处理乙烯酮甲硅烷基缩醛,分别提供 3,3-二卤代丙烯酸酯或 (E)-3-卤代丙烯酸酯。另一方面,-23 °C 的反应主要产生 3,3,3-三卤代丙酸酯或 3,3-二卤代丙酸酯。
Regioselective Radical Hydroboration of <i>gem</i>-Difluoroalkenes: Synthesis of α-Borylated Organofluorines
作者:Ji-Kang Jin、Wan-Xin Zheng、Hui-Min Xia、Feng-Lian Zhang、Yi-Feng Wang
DOI:10.1021/acs.orglett.9b03173
日期:2019.10.18
hydroboration of gem-difluoroalkenes was developed for the synthesis of α-difluoroalkylborons. The reaction features excellent regioselectivity, broad substrate scope, and good functional group capability. DFT calculations implicated the remarkable α-selectivity was driven from the kinetically and thermodynamically more favorable α-addition step. The resulting α-difluoroalkylborons could be readily converted
Treatment of ketene octyl t-butyldimethylsilyl acetal with tetrabromomethane or tribromomethane in the presence of a catalytic amount of triethylborane gave octyl 3,3-dibromoacrylate or octyl (E)-3-bromoacrylate, respectively.