One-pot synthesis and conformational features of N,N′-disubstituted ketene aminals

N,N'-Disubstituted ketene aminals are bioisosteres of thioureas and are useful building blocks in many synthetic operations. A convenient one-pot synthesis of N,N'-disubstituted ketene aminals from activated methylene compounds and isothiocyanates is described. Most of these aminals exist in rotameric equilibrium around the central Cdouble bondC bonds in solution, and the rotamers are stabilized by intramolecular hydrogen bonding both in solution and in solid states.