Sequential Cyclosulfonylation and Alkylation as a Versatile Strategy for Dihydropyran Synthesis
作者:Gavin L. Edwards、David J. Sinclair
DOI:10.1055/s-2005-918498
日期:——
Deprotonation of 3,4-dihydro-6-(p-toluenesulfonylmethyl)-2H-pyran (2) with n-BuLi and alkylation of the lithiated allyl sulfone gives good to excellent yields of monoalkylated products 3. No γ-substitution is observed in the monoalkylated products. A second deprotonation allows for the introduction of a second alkyl group. Desulfonylation can be effected with either sodium amalgam or sodium/ethanol in THF.
用 n-BuLi 对 3,4-二氢-6-(对甲苯磺酸甲基)-2H-吡喃(2)进行去质子化反应,并对锂化烯丙基砜进行烷基化反应,可得到收率极高的单烷基化产物 3。在单烷基化产物中没有发现δ-取代反应。第二次去质子化可以引入第二个烷基。在 THF 中,可使用钠汞齐或钠/乙醇进行脱磺化反应。