Highly Enantioselective Conjugate Additions of Phosphites to α,β-Unsaturated N-Acylpyrroles and Imines: A Practical Approach to Enantiomerically Enriched Amino Phosphonates

✍ Scribed by Depeng Zhao; Yuan Wang; Lijuan Mao; Rui Wang

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 275 KB
• Volume: 15
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200901901

✦ Synopsis

Abstract

The first highly enantioselective phosphonylation of α,β‐unsaturated N‐acylpyrroles has been developed. Excellent yields (91–99 %) and enantioselectivities (up to >99 % enantiomeric excess (ee)) were observed for a broad spectrum of both phosphites and N‐acylpyrroles under mild conditions. In particular, when diethyl phosphite was employed to test the scope of the N‐acylpyrroles, almost optically pure products (98 to >99 % ee) were obtained for 20 examples of N‐acylpyrroles. Moreover, optically pure α‐substituted β‐ or γ‐amino phosphonates can be obtained by several simple transformations of the pyrrolyl phosphonates. The versatility of the N‐acylpyrrole moiety makes the phosphorus adducts powerful chiral building blocks that enable the synthesis of various phosphonate‐containing compounds. Finally, the present strategy can also be applied to the asymmetric hydrophosphonylation of N‐acylimines with high enantioselectivities (93 to >99 % ee).