Synlett 2007(17): 2627-2634  
DOI: 10.1055/s-2007-991077
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

Metal-Catalyzed Asymmetric Synthesis of P-Stereogenic Phosphines

David S. Glueck*
6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
Fax: +1(603)6463946; e-Mail: glueck@dartmouth.edu;
Further Information

Publication History

Received 29 March 2007
Publication Date:
25 September 2007 (online)

Abstract

This account summarizes our attempts to develop metal-catalyzed asymmetric syntheses of P-stereogenic phosphines. While such phosphines undergo pyramidal inversion slowly at room temperature, inversion is rapid in metal-phosphido com­plexes (M-PR2). These observations were the basis for catalytic, dynamic kinetic resolution processes in which racemic secondary phosphines [PR(R′)H] were converted into enantioenriched tertiary phosphines [PR(R′)(R′′)] by platinum-catalyzed asymmetric hydrophosphination of acrylonitrile or related Michael acceptors, by ­palladium-catalyzed asymmetric phosphination of aryl iodides using secondary phosphines or phosphine-boranes, and by platinum-catalyzed asymmetric alkylation of secondary phosphines. The key intermediates were diastereomeric phosphido complexes with chiral ancillary ligands (Ln*-M-PRR′). Their relative rates of P-inversion and phosphorus-carbon bond formation controlled the enantioselectivity of product formation, whether the phosphorus-carbon bonds were formed by reductive elimination (for Pd), or by the reaction of a platinum-phosphido complex with an electrophile (an alkene in hydrophosphination, or a benzyl bromide in alkylation). The results of mechanistic studies and their use in the design of improved catalytic reactions are described.

1 Introduction

2 Phosphorus Inversion

3 Platinum-Catalyzed Asymmetric Hydrophosphination

4 Palladium-Catalyzed Asymmetric Phosphination

4.1 Secondary Phosphines

4.2 Secondary Phosphine-Boranes

5 Platinum-Catalyzed Asymmetric Alkylation of Secondary Phosphines

6 Conclusion

39

Anderson, B. J.; Glueck, D. S. unpublished results.