Abstract
Thermal decomposition of 2,5-dihydro-1,3,4-oxadiazole 4 in toluene solution in the presence of thiolactams 7 or corresponding lactams 11 result in the chemoselective formation of the N-(dimethoxy)methyl derivatives 8 and 12, respectively. The products of both types are formed via insertion of dimethoxycarbene 2a into the N−H bonds. A reaction mechanism via the intermediate ion pair 14/15 or a complex of type 13 is postulated to explain the formation of the products.