Synthesis and tautomerization of hydroxylated isoflavones bearing heterocyclic hemi-aminals
作者:Mykhaylo S. Frasinyuk、Svitlana P. Bondarenko、Volodymyr P. Khilya、Chunming Liu、David S. Watt、Vitaliy M. Sviripa
DOI:10.1039/c4ob02137a
日期:——
presence of excess formaldehyde led principally to 9-(2-hydroalkyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]-oxazin-4-ones 4 and/or the tautomeric 7-hydroxy-8-(1,3-oxazepan-3-ylmethyl)-4H-chromen-4-ones 5. The ratio of these tautomers was dependent on solvent polarity, electronic effects of aryl substituents in the isoflavone and the structure of the amino alcohol. NMR studies confirmed the interconversion
在过量甲醛存在下,羟基化异黄酮与 2-氨基乙醇、3-氨基-1-丙醇、4-氨基-1-丁醇和 5-氨基-1-戊醇的氨甲基化主要生成 9-(2-氢烷基) -9,10-二氢-4H,8H-色并[8,7-e][1,3]-恶嗪-4-酮4和/或互变异构体7-羟基-8-(1,3-oxazepan-3 -基甲基)-4H-色烯-4-酮 5. 这些互变异构体的比例取决于溶剂极性、异黄酮中芳基取代基的电子效应以及氨基醇的结构。 NMR 研究证实了互变异构形式的相互转化。