tert -Butyl Substituent as a Regiodirecting and Novel C−H Protecting Group in Cyclobutenedione-Based Benzannulation Chemistry
1998; American Chemical Society; Volume: 63; Issue: 9 Linguagem: Inglês
10.1021/jo971565p
ISSN1520-6904
AutoresFuqiang Liu, Lanny S. Liebeskind,
Tópico(s)Asymmetric Hydrogenation and Catalysis
Resumo2-Unsubstituted hydroquinone monoacetates, quinones, and 3-unsubstituted 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 substituent. Thermolysis of the adducts, followed by treatment under acidic conditions to remove the tert-butyl and trimethylsilyl groups in good overall yields, provided access to a variety of "less-substituted" hydroquinone monoacetates, quinones, and quinolizinones. Of the two systems, the tert-butyl-substituted cyclobutenediones proved the most useful.
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