[71338-48-2] · C8H8OSe · (Phenylseleno)acetaldehyde · (MW 199.12)
Solubility: sol common organic solvents; insol water.7
Preparative Methods: reaction of Ethyl Vinyl Ether with Benzeneselenenyl Bromide, followed by hydrolysis;1,7 phenylselenenylation of Acetaldehyde;8 reaction of Vinyl Acetate with Benzeneselenenyl Chloride.9
Handling, Storage, and Precautions: best kept in refrigerator and protected from light. Old material should be redistilled before use.10
(Phenylseleno)acetaldehyde serves as a vinyl cation equivalent.1-6 Aldol condensation with ketones gives keto hydroxy selenides that are convertible, by treatment with Methanesulfonyl Chloride and Triethylamine, into a-vinyl ketones (eq 1).2
The aliphatic reagent (methylseleno)acetaldehyde appears to be less efficient as a vinyl cation equivalent.2 The latent vinyl group can also be released by successive action of Trifluoroacetic Anhydride/triethylamine and Trimethyl Phosphite (eq 2).1 Similar transformations to that shown in eq 1 can be effected with dicarbonyl(cyclopentadienyl)(ethyl vinyl ether)iron tetrafluoroborate11 or (t-butyldimethylsilyl)acetaldehyde.12
Grignard reagents can be converted into (phenylseleno) ketones by reaction with (phenylseleno)acetaldehyde, followed by oxidation of the resulting alcohol (eq 3).7,13 It should be noted, however, that oxidation of hydroxy selenides can be problematic.14
Hydroxy selenides, made using (phenylseleno)acetaldehyde, have been used in radical cyclizations (eqs 4 and 5). The example of eq 4 involves initial use of the reagent in an aldol condensation; in eq 5 the aldehyde is first used to form an iminium species which, on reduction with Sodium Cyanoborohydride, affords the substrate for radical cyclization.
Wittig17 and related8a,18 alkenations give allylic selenides when applied to (phenylseleno)acetaldehyde (eqs 6 and 7).
Steven R. Magnuson & Derrick L. J. Clive
University of Alberta, Edmonton, AB, Canada