HBTM-2.1 promotes the catalytic asymmetric intermolecular Michael-lactonisation of arylacetic acids and trifluoromethylenones in the presence of pivaloyl chloride, giving C(6)-trifluoromethyldihydropyranones with high diastereo- and enantiocontrol (up to 95 : 5 dr and >99% ee) that are readily derivatised to diverse synthetic building blocks containing trifluoromethyl-stereogenicity. Kinetic studies indicate the reaction is first order with respect to both in situ formed mixed anhydride and catalyst concentration, with a primary kinetic isotope effect observed using α,α-di-deuterio 4-fluorophenylacetic acid, consistent with rate determining deprotonation of an intermediate acyl isothiouronium ion.
HBTM-2.1在有
庚酰氯存在的情况下,促进了芳基
乙酸和三
氟甲烯酮的催化不对称分子间迈克尔-内酯化反应,生成高二者立体选择性和对映选择性的C(6)-三
氟甲基二氢
吡喃酮(达到95 : 5的dr和>99% ee),这些产物可以方便地转化为含有三
氟甲基手性基团的多样合成构件。动力学研究表明,反应对原位生成的混合酸酐和催化剂浓度均为一级反应,同时在使用α,α-二
氘基
4-氟苯乙酸的实验中观察到了主要的动力学同位素效应,这与中间体酰基异
硫尿阳离子的去质子化作为速率限制步骤一致。