Anionic Cyclizations of Pentynones and Hexynones: Access to Furan and Pyran Derivatives
作者:Thomas Nicola、Ralf Vieser、Wolfgang Eberbach
DOI:10.1002/(sici)1099-0690(200002)2000:3<527::aid-ejoc527>3.0.co;2-n
日期:2000.2
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
在用碱处理时,戊炔酮 8a-f 发生所得烯醇化物与炔部分的阴离子加成反应,并以 10-91% 的产率提供 2,5-二取代呋喃 10a-f。所提出的机制涉及 2-亚甲基-二氢呋喃 11 作为中间体,其互变异构化产生观察到的产物。在α-甲基吡啶衍生物8g的情况下,可能形成烯醇化物12和13,随后分别转化为产物10g和14g。从己酮 9a-e 开始,发生类似的反应,以可比的产率形成吡喃衍生物 15 和 16。在相同的反应条件下,正丁基酮 9f 产生两种异构化合物,即 4H-吡喃 16f 和环己烯酮 17。