Oligomerization of β-propiolactone (BPL) caused by the Cu 2 O-isonitrile complex in the presence of alkyl halide was studied, and an oligomeric mixture of acrylate derivatives 3 (n= 1, 2 and 3 in Eq.(3)) was isolated in fairly high yields. The complex catalyst showed a distinguished catalytic activity for the oligomerization of BPL. The reaction mechanism involving an intermediate of organocopper (I) isonitrile 4, which is converted into copper (I) ...