Utilization of Nonionic Bases in Water as a Highly Efficient Organocatalytic System for Michael Addition of β‐Ketoesters

Abstract

Michael addition of various β‐ketoesters with several Michael acceptors in water containing 5 mol% of a nonionic base such as phosphazenes, guanidines, and more classical nitrogen containing derivatives or triphenyl phosphine results in high yield conversion to the corresponding adducts. The study also clearly establishes the benefical use of water as solvent compared to more conventional organic medium.

Keywords:

• Michael addition
• Nonionic bases
• β‐Ketoesters
• Water

Acknowledgments

We gratefully acknowledge Pr G. Buono and Dr J. M. Brunel for fruitful discussions and for kindly providing us with samples of N‐H, N‐Bn, and N‐SO₂Tol iminophosphoranes.

Notes

^aWe have checked the stability of N‐phenyl‐tris(dimethylamino)iminophosphorane in water over a period of 96 hours by ³¹P NMR and found no significant modification of the structure.

^bCommercially available from Fluka.