Unusual formation of cyclic-orthoesters by Pd(II)-mediated cyclization–carbonylation of propargylic acetates
作者:Keisuke Kato、Yasuhiro Yamamoto、Hiroyuki Akita
DOI:10.1016/s0040-4039(02)01438-7
日期:2002.9
The oxidative cyclization-methoxycarbonylation of propargylic acetates 1 in the presence of (CH3CN3)(2)PdCl2/p- benzo-quinone in methanol under carbon monoxide atmosphere (balloon) afforded (E)-cyclic-orthoesters 5 in moderate yields. (C) 2002 Elsevier Science Ltd. All rights reserved.
A facile access to spiro furanone skeleton based on Pd(II)-mediated cyclization–carbonylation of propargylic esters
mediated by Pd(II) afforded cyclic orthoesters, which were hydrolyzed into γ-acetoxy-β-ketoesters. Based on the NMR experiments, it was presumed that the cyclization reaction was initiated by a nucleophilic attack of carbonyl oxygen to the alkyne carbon coordinated to palladium(II). When the γ-acetoxy-β-ketoesters were treated with a basic condition, Knoevenagel–Claisen type condensation took place, and