Unexpected formation of highly functionalized dihydropyrans via addition-cyclization reactions between dimethyl oxoglutaconate and α,β-unsaturated hydrazones
作者:Jason E. Mullins、Jean-Louis G. Etoga、Mariusz Gajewski、Joseph I. DeGraw、Charles M. Thompson
DOI:10.1016/j.tetlet.2009.02.180
日期:2009.5
The condensation between dienophiles and α,β-unsaturated hydrazone azadienes was previously reported to afford piperidines. During an attempt to adapt this reaction to the preparation of piperidine-based conformationally restricted analogs of glutamate, it was discovered that the electrophile, dimethyl oxoglutaconate (DOG) led to highly substituted dihydropyrans in 20–50% yield. The unexpected pyran
先前报道了亲二烯体和 α,β-不饱和腙氮杂二烯之间的缩合得到哌啶。在尝试将该反应用于制备基于哌啶的构象限制性谷氨酸类似物时,发现亲电子试剂,酮戊二酸二甲酯 (DOG) 以 20-50% 的产率生成高度取代的二氢吡喃。出乎意料的吡喃产物可能是腙最初 1,4-加成到氧代戊二酸,随后生成的烯醇氧分子内环化成 α,β-不饱和亚胺离子。进一步操作得到取代的四氢吡喃 6-甲氨基-2,4-二羧酸。