Synthesis of a,b-unsaturated amides by Z-selective HWE reactions

HWE reactions of (ArO)₂P(O)CH₂CONR¹R² with RCHO gave a,b-unsaturated amides in a Z-selective manner. Diphenylphosphonoacetamide derivative (Ar = Ph) gave the a,b-unsaturated amides with moderate to high Z-selectivity.¹ Introduction of o-t-Bu groups to the diphenylphosphono group greatly improved the Z-selectivity, especially in the case of Weinreb amides.² As a result, a wide range of Z-a,b-unsaturated amides have become available. These amides are useful as building blocks for a variety of purposes.

1) Ando, K. Synlett 2001, 1272-1274.

2) Ando, K.; Nagaya, S.; Tarumi, Y. Tetrahedron Lett. 2009, 50, 5689-5691.