The aminopropylated Silica-Gel hydrochloride (APSG.HCl) proved to be an efficient catalyst for the rapid conversion of carbonyl compounds in the corresponding acetals with high yields and in mild and selective conditions. In addition to the obvious advantages offered by heterogeneous catalysis, the present method results very useful when the presence of a weakly-acidic function chemically bonded on
Copper nanoparticle-catalyzed cross-coupling of alkyl halides with Grignard reagents
作者:Ju Hyun Kim、Young Keun Chung
DOI:10.1039/c3cc46419a
日期:——
A cross-coupling reaction between alkyl bromides and chlorides and various Grignardreagents was carried out in the presence of commercially available copper or copper oxide nanoparticles as a catalyst and an alkyne additive. The catalytic system shows high activity, a broad scope, and good functional group tolerance.
Nickel-catalyzed cross-coupling of unactivated alkyl halides and tosylate carrying a functional group with alkyl and phenyl Grignard reagents
作者:Surya Prakash Singh、Jun Terao、Nobuaki Kambe
DOI:10.1016/j.tetlet.2009.07.094
日期:2009.10
primary and secondaryalkylGrignardreagents undergo cross-coupling with alkyl bromides, iodide, and tosylate carrying a functional group such as amide, ester, and ketone at 0 °C in THF. The present procedure provides a simple, convenient, and practical method for construction of carbon chains in the presence of various functional groups. PhMgBr also gave the corresponding coupling product in a moderate
Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf)2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic
Cross-coupling of alkylhalides 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,