Carbonylation of Methylcyclopentane and Cyclohexane Initiated by the Aprotic Organic Superacid CBr4·2AIBr3

The aprotic organic superacid CBr₄·2AIBr₃ initiates carbonylation of methylcyclopentane 1 and cyclohexane 2 with CO at atmospheric pressure with formation (after EtOH treatment) of various products in high yields depending on the conditions. The products are esters of 1-methylcyclopentanecarbonic (1a; at −45 °C) and cyclohexanecarbonic (2a; at 0°C) acids and 2-methylcyclohexanone (3; at − 23 °C); the reaction mechanism is discussed.