Synthesis of linear coumarins via para-Claisen rearrangement of coumarate ester derivatives: total synthesis of suberosin, demethylsuberosin, and ostruthin
作者:Nicholas Cairns、Laurence M. Harwood、David P. Astles
DOI:10.1039/c39860001264
日期:——
Heating 2′-O-prenylated derivatives of 4′-O-benzyl methyl coumarates (3) furnishes the corresponding linear prenylated umbelliferones (1) directly via sequential para-Claisenrearrangement and relactonisation.
Allyl esters of 3-carboxylcoumarins undergo facile decarboxylative coupling at just 25−50 °C. This represents the first extension of decarboxylative C−C bond-forming reactions to the coupling of aromatics with sp3-hybridized electrophiles. Finally, the same concept can be applied to the sp2−sp3 couplings of pyrones and flavones. Thus, a variety of biologically important heteroaromatics can be readily
3-羧基香豆素的烯丙酯在 25−50 °C 下即可轻松脱羧偶联。这代表了脱羧CC键形成反应首次扩展到芳香族化合物与sp 3杂化亲电子试剂的偶联。最后,相同的概念可以应用于吡喃酮和黄酮的 sp 2 -sp 3偶联。因此,多种生物学上重要的杂芳族化合物可以很容易地官能化,而不需要更标准的交叉偶联反应通常需要的强碱或化学计量的有机金属化合物。
Cairns, Nicholas; Harwood, Laurence M.; Astles, David P., Journal of the Chemical Society. Perkin transactions I, 1994, # 21, p. 3101 - 3108
作者:Cairns, Nicholas、Harwood, Laurence M.、Astles, David P.