Reactions of 1,2-Bis(trimethylsilyloxy)cycloalkenes with the Diethyl Acetals of Aldehydes

Lewis acid-mediated reactions of 1,2-bis(trimethylsilyloxy)cyclobutene with acetals derived from a variety of aldehydes,
followed by treatment with Amberlyst 15 resin in TFA,
yielded 1,3-cyclopentanedione products, but reactions with
3,3-dimethyl-1,2-bis(trimethylsilyloxy)cyclobutene led to 1,2-cyclopentanediones. Reactions of 1,2-bis(trimethylsilyloxy)cyclopentene gave intermediates that did not undergo skeletal
rearrangement with Amberlyst 15 resin in TFA.