The Hosomi–Sakurai Reaction

Key words

titanium catalysis - Lewis acids - allylation - organosilicon - carbonyl groups

Significance

The Hosomi–Sakurai reaction is a powerful synthetic tool used to add a nucleophilic allyl group to ketones and aldehydes under Lewis-acidic conditions. In this original 1976 report of the reaction, Hosomi and Sakurai illustrate a truly remarkable scope, adding allyltrimethylsilane to a variety of carbonyl-containing compounds, using only TiCl₄, with reaction times typically being under ten minutes. The reaction typically worked best with alkyl-derived aldehydes, though ketones and benzaldehyde were amenable to the reaction. In the case of benzaldehyde, BF₃·OEt₂ was used as the Lewis acid.

Comment

The Hosomi–Sakurai reaction initiates by coordination of the oxaphilic Lewis acid to the carbonyl group. Subsequent attack of the olefin forms a silyl-stabilized secondary β-cation. A nucleophilic source of halogen then attacks the TMS group, thereby generating a double bond. Since this report, a wide variety of catalytic and enantio­selective variants of this reaction have been discovered (see Review below).

Review

J. J. Lade, S. D. Pardeshi, K. S. Vadagaonkar, K. Murugan, A. C. Chaskar RSC Adv. 2017, 7, 8011–8033.

Publication History

Article published online:
18 August 2021