Synthesis of 4',5- and 3',4',5-Oxygenated Pyranoisoflavones: Alpinumisoflavone and Related Compounds, and a Revised Structure of Derrone
作者:Masao Tsukayama、Yasuhiko Kawamura、Hideo Tahara
DOI:10.3987/com-91-5918
日期:——
Alpinumisoflavone (4', 5-dihydroxy-2".2"-dimethylpyrano[5", 6"-g]isoflavone) (1a) was synthesized by regioselective reduction of 7-(4-hydroxyphenyl)-2, 3-dihydro-5-methoxy-2, 2-dimethyl-4H, 6H-benzo[1, 2-b:5, 4-b'] dipyran-4, 6-dione (15a) with NaBH4 and dehydration of the resultant alcohol, followed by demethylation with BC13. Its angular isomer (4', 5-dihydroxy-2", 2"-dimethylpyrano[6", 5"-h]isoflavone) (2a) was synthesized from 3-(4-hydroxyphenyl)-8, 9-dihydro-5-tosyloxy-8, 8-dimethyl-4H,10H-benzo [1, 2-b:3, 4-b']dipyran-4, 10-dione (27a) in a similar manner.