Studies on the synthesis of furans by anionic cyclization of 4-pentynones
作者:Ralf Vieser、Wolfgang Eberbach
DOI:10.1016/0040-4039(95)00785-b
日期:1995.6
The synthesis of 5-substituted 2-carbomethoxymethyl-furans 4 is achieved by base promoted cyclization of the 4-pentynones 3a-e which are easily accessible from the 4-pentynal 1.
Anionic Cyclizations of Pentynones and Hexynones: Access to Furan and Pyran Derivatives
pentynones 8a-f undergo anionic addition reactions of the resulting enolate species to the alkyne moiety and afford the 2,5-disubstituted furans 10a-f in yields ranging from 10-91%. The proposed mechanism involves the 2-methylene-dihydrofurans 11 as intermediates which tautomerize to yield the observed products. In the case of the α-picolyl derivative 8g both possible enolates 12 and 13 are formed which are