作者:Steven M. Allin、William R.S. Barton、W.Russell Bowman、Tom McInally
DOI:10.1016/s0040-4039(02)00763-3
日期:2002.6
A novel synthetic protocol for the synthesis of [1,2-b]-fused bicyclic pyrazoles has been developed using radical cyclisation. The protocol uses cyclisation of pyrazole-1-(ω-alkyl) radicals generated from 1-[ω-(phenylselenyl)alkyl]-pyrazole precursors. The pyrazole natural product, withasomnine (3-phenyl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole), and larger ring analogues have been synthesised in good
使用自由基环化已经开发了用于合成[1,2- b ]-稠合的双环吡唑的新颖合成方案。该协议使用了由1- [ω-(苯基硒基)烷基]-吡唑前体生成的吡唑-1-(ω-烷基)自由基的环化作用。使用该方案可以高收率合成吡唑天然产物withasomnine(3-phenyl-5,6-dihydro-4 H -pyrrolo [1,2- b ] pyrazole)和较大的环类似物。用作中间π自由基氧化剂的偶氮或Et 3 B自由基引发剂可促进Bu 3 SnH介导的氧化环化机理。