One-pot synthesis and crystal structure of an unusual amidine derived from heterocyclic ketene aminal derivative

摘要

One-pot reaction of Meldrum's acid (1) and heterocyclic ketene aminal (HKA, 2) in acetone affords an unusual amidine HKA derivative 4. The reaction catalysts were optimized and it was found that L-proline is the best catalyst for the one-pot reaction. The mechanism is discussed. The structure of compound 4 was determined by single crystal X-ray analysis.