New Results on the Triplet Photoreactivity of β,γ-Unsaturated Aldehydes: Diastereoselective Synthesis of Cyclopropanecarbaldehydes

Abstract

A comparative study on the triplet photoreactivity of a series of β,γ-unsaturated aldehydes and methyl ketones has been carried out. Aldehydes 14 and 20 were found to undergo the oxa-di-p-methane rearrangement yielding the corresponding cyclopropane carbaldehydes 15 and 21 diastereoselectively. Decarbonylations and 1,3-carbonyl migrations have been observed in some cases, although these reactions do not take place via a Norrish Type I mechanism.

Keywords

β,γ-unsaturated carbonyl compounds - oxa-di-p-methane rearrangement - decarbonylation - cyclopropanecarbaldehydes - 1,3-formyl migration.

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12

Aldehydes 15a-b and 21a-d undergo spontaneous oxidation in the presence of atmospheric oxygen. The combustion analyses quoted correspond to the carboxylic acids resulting from oxidation.