In situ enzymatic screening (ISES) of P,N-ligands for Ni(0)- mediated asymmetric intramolecular allylic amination

Authors

David B. Berkowitz, University of Nebraska - LincolnFollow
Weijun Shen, University of Nebraska - Lincoln
Gourhari Maiti, University of Nebraska - Lincoln

Document Type

Article

Date of this Version

September 2004

Comments

Published in Tetrahedron: Asymmetry 15:18 (September 20, 2004), pp. 2845–2851; Integrating Biocatalysis into Organic Syntheses. Copyright © 2004 Elsevier Ltd. doi:10.1016/j.tetasy.2004.06.052 Used by permission. http://www.sciencedirect.com/science/journal/09574166.

Abstract

An in situ enzymatic screening (ISES) approach to rapid catalyst evaluation recently pointed to Ni(0) as a new candidate transition metal for intramolecular allylic amination. This led to further exploration of chiral bidentate phosphine ligands for such transformations. Herein, a variety of P,N-ligands are examined for this Ni(0)-chemistry, using a model reaction leading into the vinylglycinol scaffold. On the one hand, an N,N-bis(2-diphenylphosphinoethyl)alkylamine (‘PNP’) ligand proved to be the fastest ligand yet seen for this Ni(0)-transformation. On the other, phosphinooxazoline (PHOX) ligands of the Pfaltz–Helmchen– Williams variety gave the highest enantioselectivities (up to 51% ee) among P,N-ligands examined.