Synlett 2021; 32(14): 1397-1405
DOI: 10.1055/s-0040-1706659
account

Developing a Methodology for Catalytic Asymmetric Crotylation of Aldehydes

Aleksandr E. Rubtsov
a   Department of Chemistry, Perm State University, Bukireva 15, Perm 614990, Russian Federation
,
b   Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK
› Author Affiliations
This work was supported by Russian Science Foundation grant 18-73-10156.


Abstract

Asymmetric crotylation has firmly earned a place among the set of valuable synthetic tools for stereoselective construction of carbon skeletons. For a long time the field was heavily dominated by reagents bearing stoichiometric chiral auxiliaries, but now catalytic methods are gradually taking center stage, and the area continues to develop rapidly. This account focuses primarily on preformed organometallic reagents based on silicon and, to some extent, boron. It narrates our endeavors to design new and efficient chiral Lewis base catalysts for the asymmetric addition of crotyl(trichloro)silanes to aldehydes. It also covers the development of a novel protocol for kinetic resolution of racemic secondary allylboronates to give enantio- and diastereomerically enriched linear homoallylic alcohols. As a separate topic, cross-crotylation of aldehydes by using enantiopure branched homoallylic alcohols as a source of crotyl groups is discussed. Finally, the synthetic credentials of the developed methodology are illustrated by total syntheses of marine natural products, in which crotylation plays a key role in setting up stereogenic centers.

1 Introduction

2 Pyridine N-Oxides as Lewis Base Catalysts

3 Bipyridine N,N′-Dioxides as Lewis Base Catalysts

4 Chiral Allylating Reagents

5 Synthetic Applications

6 Concluding Remarks



Publication History

Received: 27 November 2020

Accepted after revision: 09 December 2020

Article published online:
18 January 2021

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