Ring expansion and vinylic nucleophilic substitution competing for (tert-alkyl)2CC(Li)–Cl in carbenoid chain processes
作者:Rudolf Knorr、Thomas Menke、Karsten-Olaf Hennig、Johannes Freudenreich、Petra Böhrer、Bernhard Schubert
DOI:10.1016/j.tet.2014.03.004
日期:2014.4
(tert-alkyl)2CC(Li)–Cl as transient intermediates. The chains are longer and the overall reactions much slower in tert-butyl methyl ether (t-BuOMe) than in THF as the solvent. In competition with the fast SNV step of these Cl,Li-carbenoids, the Fritsch–Buttenberg–Wiechell (FBW) ring expansion in t-BuOMe (but less so in THF) generates short-lived cyclohexyne species, which are trapped by the accompanying
乙烯基亲核取代(S Ñ V)未活化的,环状的α的反应,α-dichloroalkenes [(叔烷基)2 ç的CCl 2 ]与芳基锂(RLi的),得到(叔烷基)2 Ç C(Cl)的-R是被认为是类胡萝卜素链反应,涉及不饱和Cl,Li-类胡萝卜素(叔烷基)2 C C(Li)–Cl作为过渡中间体。与作为溶剂的THF相比,叔丁基甲基醚(t -BuOMe)中的链更长,总反应慢得多。与快速的S N竞争这些Cl,Li类胡萝卜素的V阶跃,在t -BuOMe中的Fritsch–Buttenberg–Wiechell(FBW)环膨胀(但在THF中则较少)产生了短寿命的环己炔物种,这些环己炔物种被伴随的RLi物种捕获以产生氯环己烯衍生物[(叔烷基)–(Cl)C C(R)–(叔烷基)]作为FBW链产物。