Carbonylation of Cyclopentane in the Presence of Aprotic Organic Superacids.

The systems MeCOBr·nAlBr3 as well as CHBr3·nAlBr3 and CCl4·nAlBr3 (n =1-4.5) have been shown to initiate carbonylation of cyclopentane under mild conditions to give, after alcoholic work-up, the corresponding ester of cyclopentylcarboxylic acid with good yields and high selectivity.