Efficient Copper-Catalyzed Cross-Coupling Reaction of Alkynes with Aryl Iodides
作者:Che-Hung Lin、Yu-Jen Wang、Chin-Fa Lee
DOI:10.1002/ejoc.201000653
日期:——
A copper-catalyzed cross-coupling reaction of alkynes with aryl iodides is described. The system tolerates a broad range of functional groups and enables the use of sterically demanding substrates with only 1.0-2.5 mol-% of Cu 2 O and 1.0-2.5 mol-% of xantphos as the catalyst.
描述了炔烃与芳基碘化物的铜催化交叉偶联反应。该系统可耐受广泛的官能团,并能够使用空间要求严格的底物,只需 1.0-2.5 mol-% 的 Cu 2 O 和 1.0-2.5 mol-% 的黄磷作为催化剂。
Regioselective synthesis of phthalans via Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohols
efficient, regioselective Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohol, which provides a concise access to functionalized phthalan in high yields has been developed. A wide range of substrates possessing terminal, internal, and heteroaromatic alkynes can be efficiently transformed into the targeted phthalans. Substrates with primary, secondary, and tertiary benzyl
Alkaline Earth Catalysis of Alkynyl Alcohol Hydroalkoxylation/Cyclization
作者:Christine Brinkmann、Anthony G. M. Barrett、Michael S. Hill、Panayiotis A. Procopiou、Stephanie Reid
DOI:10.1021/om3008663
日期:2012.10.22
Heavier alkaline earth bis(trimethylsilyl)amides [AeN(SiMe3)(2)}(2)](2) (Ae = Ca, Sr, Ba) are shown to act as effective precatalysts for the regioselective intramolecular hydroalkoxylation/cyclization of a wide range of alkynyl and allenyl alcohols. In the majority of cases, cyclization of alkynyl alcohols produces mixtures of the possible endo- and exocyclic enol ether products, rationalized as a consequence of alkynylalkoxide isomerization to the corresponding allene derivatives. Cyclization rates for terminal alkynyl alcohols were found to be significantly higher than for substrates bearing internal alkynyl substituents, while the efficacy of cyclization was in general found to be determined by a combination of stereoelectronic influences and the thermochemical viability of the specific alkaline earth metal catalysis, which we suggest is determined by the individual M-O bond strengths. Kinetic studies have provided a rate law pertaining to a pronounced catalyst inhibition with increasing [substrate], indicating that turnover-limiting insertion of C-C unsaturation into the M-O bond requires the dissociation of substrate molecules away from the Lewis acidic alkaline earth center.