Zr(OBut)4 As an effective promoter for the Meerwein–Ponndorf–Verley alkynylation and cyanation of aldehydes: development of new asymmetric cyanohydrin synthesis
作者:Takashi Ooi、Tomoya Miura、Keisuke Takaya、Hayato Ichikawa、Keiji Maruoka
DOI:10.1016/s0040-4020(00)01040-1
日期:2001.1
Zr(OBut)4 Can serve as an effective promoter for the Meerwein–Ponndorf–Verley alkynylation of aldehydes and also facilitate MPV type cyanide transfer to aldehyde carbonyls with commercially available acetone cyanohydrin under mild conditions. Based on this finding, a new procedure for asymmetric cyanohydrin synthesis has been developed employing (4R,5R)-2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4
Zr(OBu t)4可以作为Meerwein-Ponndorf-Verley醛烷基化的有效促进剂,并在温和的条件下用市售丙酮氰醇促进MPV型氰化物转移至醛羰基。基于这一发现,开发了一种新的合成不对称氰醇的方法,该方法采用了(4 R,5 R)-2,2-二甲基-α,α,α',α'-四苯基-1,3-二氧戊环-4, 5-二甲醇(TADDOL,6)作为手性配体。例如,用Zr(OBu t)4顺序处理6(1当量)CH 2 Cl 2溶液(1当量)和丙酮氰醇(2当量)在室温下1小时,随后与3-苯基丙醛在-40°C下反应7.5小时,形成相应的氰醇5g [R = Ph(CH 2)2 ],分离出的产率为63%,ee为85%。已经用各种醛作为底物阐明了该方法的范围和局限性。