A complementary method to obtain N-acyl enamides using the Heck reaction: extending the substrate scope for asymmetric hydrogenation

• Published in: Tetrahedron letters Vol. 45; no. 50; pp. 9277 - 9280
• Main Authors: Harrison, Paul, Meek, Graham
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 06-12-2004
• Subjects: Asymmetric hydrogenation; Heck reaction; N-Acyl enamides; Heck reaction; Asymmetric hydrogenation; N-Acyl enamides
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2004.10.063

A series of
N-acyl enamides were prepared using the Heck reaction. Asymmetric hydrogenation provided protected amines in up to 99% ee.
A method to prepare
N-acyl enamides is reported that is complementary to the existing protocols. Heck reaction of a variety of aryl trifluoromethanesulfonates with commercially available
N-vinylacetamide occurred in a highly regioselective fashion to provide these valuable synthetic intermediates. This method permits the formation of
N-acyl enamides containing functionality that would not be tolerated by the existing methods. Asymmetric hydrogenation using [diphosphine RhCOD]BF
4 complexes provided optically active protected amines in up to 99% ee. De-acylation occurs without affecting the amine enantiopurity.