A Facile Synthesis of 3,4-Disubstituted Isoxazole Derivatives by Regioselective Cleavage of Pyrano[3,4-<i>C</i>]Isoxazoles with Boron Trihalide
作者:Hyung JinKim、Young JuLee
DOI:10.1080/00397919808004899
日期:1998.10
4-c]isoxazoles 4 were efficiently prepared by the intramolecular nitrile oxide-alkyne cycloaddition following the Michael addition of sodium alkoxide to nitroalkene. Reaction of pyrano[3,4-c]isoxazole 4 with boron trihalide resulted in regioselective benzylic C-O bond cleavage to furnish a 3,4-disubstituted isoxazole (5, 6) in high yield.
摘要 4,5-Dihydro-7H-pyrano[3,4-c]isoxazoles 4 通过分子内腈氧化物-炔烃环加成反应在醇钠与硝基烯烃的迈克尔加成之后有效地制备。吡喃并 [3,4-c] 异恶唑 4 与三卤化硼的反应导致区域选择性苄基 CO 键断裂,以高产率提供 3,4-二取代异恶唑 (5, 6)。