Stereoselective synthesis of cis-2-aryl- and 2-alkyl-1-chlorocyclopropanecarboxaldehydes

The title compounds were stereoselectively synthesized via a semi-benzilic Favorskii rearrangement of 3-aryl- and 3-alkyl-2,2-dichlorocyclobutanols, obtained by stereoselective reduction of the corresponding cyclobutanones. This synthetic pathway, starting from the synthesis of 3-substituted-2,2-dichlorocyclobutanones can be performed in one day with total yields up to 60% after purification. Reduction of the cyclobutanones yielded only cis-3-substituted cyclobutanols. Taking into account the stereoselectivity of the rearrangement, 1-halocyclopropanecarboxaldehydes, of which very few articles have been published, can be seen as highly interesting building blocks for further elaboration.