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 C=C bonds in solution, and the rotamers are stabilized by intramolecular hydrogen bonding both in solution and in solid states.