Copper-Catalyzed Alkyl–Alkyl Cross-Coupling Reactions Using Hydrocarbon Additives: Efficiency of Catalyst and Roles of Additives
作者:Takanori Iwasaki、Reiko Imanishi、Ryohei Shimizu、Hitoshi Kuniyasu、Jun Terao、Nobuaki Kambe
DOI:10.1021/jo501006u
日期:2014.9.19
Cross-coupling of alkyl halides with alkyl Grignard reagents proceeds with extremely high TONs of up to 1230000 using a Cu/unsaturated hydrocarbon catalytic system. Alkyl fluorides, chlorides, bromides, and tosylates are all suitable electrophiles, and a TOF as high as 31200 h–1 was attained using an alkyl iodide. Side reactions of this catalytic system, i.e., reduction, dehydrohalogenation (elimination)
使用铜/不饱和烃催化系统,烷基卤化物与烷基格氏试剂的交叉偶联可产生高达1230000的极高TON。烷基氟化物,氯化物,溴化物和甲苯磺酸盐都是合适的亲电子试剂,TOF高达31200 h –1使用烷基碘可以达到目的。在没有添加剂的情况下,该催化体系的副反应即还原,脱卤化氢(消除)和卤代烷的均偶联。看来该反应涉及烷基铜中间体的β-氢消除,从而产生烯烃和Cu-H物种,并且该过程既触发副反应又触发Cu催化剂的降解。形成的Cu–H可能促进歧化反应,从而促进烷基卤化物的还原,从而生成烷烃和Cu–X或Cu(0)的生成,这种歧化可以氧化添加到烷基卤化物中以产生烯烃,在某些情况下还可以是均偶联产物。1,3-丁二烯和苯丙炔等不饱和烃类添加剂通过抑制β-氢的消除在实现高效交叉偶联中起着重要作用,