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Synthesis 2017; 49(15): 3237-3246
DOI: 10.1055/s-0036-1588427
short review
© Georg Thieme Verlag Stuttgart · New York

Reactions of Allylmagnesium Halides with Carbonyl Compounds: Reactivity, Structure, and Mechanism

Nicole D. Bartolo
a   Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, USA   Email: kwoerpel@nyu.edu
,
Jacquelyne A. Read
a   Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, USA   Email: kwoerpel@nyu.edu
,
Elizabeth M. Valentín
a   Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, USA   Email: kwoerpel@nyu.edu
b   Department of Chemistry, Susquehanna University, 514 University Avenue, Selinsgrove, PA 17870, USA
,
K. A. Woerpel  *
a   Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, USA   Email: kwoerpel@nyu.edu
› Author AffiliationsAcknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund, for partial support of this research (57206-ND1). Additional support was provided by the National Institutes of Health, National Institute of General Medical Sciences (GM-61066). J.A.R. thanks the NYU Department of Chemistry for support in the form of a Margaret Strauss Kramer Fellowship.
Further Information

Publication History

Received: 25 April 2017

Accepted: 28 April 2017

Publication Date:
28 June 2017 (online)

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We dedicate this paper to Professor Dr. Herbert Mayr on the occasion of his 70th birthday.

Abstract

The additions of allylmagnesium reagents to carbonyl compounds are important methods in synthetic organic chemistry, but the mechanisms of these reactions are likely to be distinct from mechanisms followed by other organomagnesium reagents. Additions to alkyl aldehydes and ketones are likely to be concerted, proceeding through six-membered-ring transition states. These highly reactive reagents appear to react at rates that approach the diffusion limit, so chemoselectivity is generally low. Furthermore, reactions of allylmagnesium halides with carbonyl compounds are unlikely to follow stereochemical models that require differentiation between competing transition states. This Short Review discusses the current state of understanding of these reactions, including the structure of the reagent and unique aspects of the reactivity of allylmagnesium reagents.

1 Introduction

2 Reactions with Carbonyl Compounds

2.1 Reactivity of Allylmagnesium Halides

2.2 Selectivity of Addition

3 Structure of Allylmagnesium Reagents

3.1 Schlenk Equilibrium and Aggregation

3.2 Spectroscopic Studies

3.3 X-ray Crystallographic Studies

3.4 Computational Studies of Structure

4 Reaction Mechanism

4.1 Substrate-Dependent Mechanisms

4.2 Concerted Mechanisms

4.3 Single-Electron Transfer Mechanisms

4.4 Open, SE2′-Like Transition State

4.5 Computational Studies of Mechanism

5 Conclusion

Key words

Grignard reaction - allylation - allylmagnesium reagents - reaction mechanism - stereoselectivity