tert-Butyl substituent as a regiodirecting and novel C-H protecting group in cyclobutenedione-based benzannulation chemistry

The use of tert-butyl and trimethylsilyl substituted cyclobutenediones allowed the synthesis of 2-unsubstituted hydroquinone monoacetates, quinones and 3-unsubstituted quinolizinones in moderate to high yields. The addition of unsaturated carbon nucleophiles occurred regiospecifically at the carbonyl group farthest from the tert-butyl or trimethylsilyl substituent. Very efficient removal of the tert-butyl group was performed under very acidic conditions.