TERT-BUTYL SUBSTITUENT AS A REGIODIRECTING AND NOVEL C-H PROTECTING GROUP IN CYCLOBUTENEDIONE-BASED BENZANNULATION CHEMISTRY

2-Unsubstituted hydroquinone monoacetates, quinones, and 3-unsubstitut ed quinolizinones were synthesized in moderate to high yields via tert -butyl and trimethylsilyl substituted cyclobutenediones. The addition of unsaturated carbon nucleophiles proceeded regiospecifically at the carbonyl group most distant from the tert-butyl or trimethylsilyl subs tituent. Thermolysis of the adducts, followed by treatment under acidi c conditions to remove the tert-butyl and trimethylsilyl groups in goo d overall yields, provided access to a variety of ''less-substituted'' hydroquinone monoacetates, quinones, and quinolizinones. Of the two s ystems, the tert-butyl-substituted cyclobutenediones proved the most u seful.