Synthesis of Bicyclic Guanidines from Pyrrolidin-2-one.

Abstract The syntheses of three bicyclic guanidines as model compounds for the guanidine alkaloid ptilomycalin A are described. The guanidines are prepared from pyrrolidin-2-one via an N-acyliminium ion coupling reaction with silyl enol ethers and a direct guanylation with bis-Boc-thiourea and HgCl2 as the key steps.