Phenylselenoacetaldehyde,a Useful Reagent for the Homologative Conversion of Halides to Phenylselenomethyl Ketones

The conversion of primary, secondary and vinylic halides to the two C-atoms homologated phenylselenomethyl ketones 8 is described. The method involves addition of the readily available phenylselenoacetaldehyde 5 to the Grignard reagents 9 and oxidation of the resulting β-hydroxy-selenides 10 (Scheme 3).