1,3-Dipolar addition of diazocyclopropane to eudesmane-type methylidene lactones and thermolysis of the resulting spiro-fused pyrazolines
作者:Yu. V. Tomilov、E. V. Revunov、E. V. Shulishov、V. V. Semenov
DOI:10.1007/s11172-012-0039-0
日期:2012.2
Reactions of alanto-, isoalanto-, and alloalantolactones, which are unsaturated eudesmane-type lactones, with diazocyclopropane generated in situ from N-cyclopropyl-N-nitrosourea under the action of sodium methoxide proceed alike, are highly regio- and stereoselective, and always give spiro-fused pyrazolines via cycloaddition to the exocyclic double bond of the methylidene group of the lactone ring
alanto-、isoalanto-和alalalantolactones 是不饱和的eudesmane 型内酯,与在甲醇钠的作用下由 N-环丙基-N-亚硝基脲原位生成的重氮环丙烷的反应类似,具有高度的区域和立体选择性,并且总是通过环加成到内酯环亚甲基的环外双键上,得到螺稠合的吡唑啉。它们在 195–210 °C 下的热解导致分子氮的消除,主要产生含螺戊烷的内酯。次要的热解产物 (10–12%) 是异构的 13-环丙基内酯。