The reaction of beta-tert.- aminoacrylonitriles 1 a-1 c with dimethyl acetylenedicarboxylate (DMAD) to give pyrrolizidine, indolizidine and pyrroloazepine is described.
Jiang, SP., Janousek, Z., & Viehe, HG. (1993). Alpha-cyclization of Tertiary-amines .2. Via (2+2) Cycloaddition of Beta-aminoacrylonitriles With Acetylenedicarboxylate. Societes Chimiques Belges. Bulletin, 102(10), 663-668. https://doi.org/10.1002/bscb.19931021007 (Original work published 1993)