Formation of 3,4-dimethyl-2-pyrones from allene carboxylates and 2-silyloxydienes via 3-carboethoxyethylidene cyclobutanols
作者:Michael E. Jung、Aaron R. Novack
DOI:10.1016/j.tetlet.2005.09.091
日期:2005.11
cyclobutanols 4 with various bases affords good yields of the substituted 3,4-dimethyl-2-pyrones 6. The proposed mechanism involves ring opening of the metal alkoxide 7 to give the carbanion 8, which undergoes proton transfer to give the more stable carbanion 9 and double bond isomerization to give the enolate 10, which then forms the pyrone ring 6 via attack on the ester via 11.
3-碳乙氧基乙叉基环丁醇4分两步制备:通过[2 + 2]将2-甲硅烷基氧二烯1和烯丙基羧酸酯2环加成,然后进行酸性水解。用各种碱处理这些环丁醇4可获得良好的取代3,4-二甲基-2-吡喃酮6的产率。拟议中的机制包括将金属醇盐7开环以产生碳负离子8,该碳负离子8经历质子转移以产生更稳定的碳负离子9并通过双键异构化产生烯醇盐10,然后该烯醇盐10通过对酯的攻击形成吡喃环6。通过11。