Organosamarium halides reactions with aldehydes

Reactions of organosamarium(II) halides with aldehydes are sranewhat more complicated and synthetically less useful than those with ketones. The ability of Sm species to serve as strong reducing agents introduces a number of alternative reaction pathways. For example, reaction of EtSmI with benzalde-hyde provides a mixture of benzyl alcohol, benzoin, hydrobenzoin, and benzyl benzoate in low yields. Die first three products presumably arise from benzaldehyde ketyl, generated by single-electron transfer from the Sm reagent to benzaldehyde. The benzyl benzoate apparently is derived frmn a Tischenko-type condensation reaction between a samarium alkoxide species and benzaldehyde. 

The Sm(OTf)3 reagent mediates the Grignard-type reaction in THF-HMPA. Alkylation, allylation and benzylation of ketones and aldehydes with alkyl, allyl or benzyl halides proceeded via stable organosamarium intermediates [69] (Scheme 29). 

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