A Simple Nickel Catalyst Enabling an
<i>E</i>
‐Selective Alkyne Semihydrogenation
作者:Niklas O. Thiel、Benyapa Kaewmee、Trung Tran Ngoc、Johannes F. Teichert
DOI:10.1002/chem.201903850
日期:2020.2.3
Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom‐economic reducing agent dihydrogen (H2), only few catalysts for the challenging E‐selectivealkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates
立体选择性炔烃半氢化是制备烯烃的有吸引力的方法,烯烃是合成的关键组成部分。对于最具原子经济性的还原剂二氢(H 2 ),仅公开了少数用于具有挑战性的E-选择性炔烃半氢化的催化剂,每种催化剂都具有独特的底物范围特征。在这里,我们表明,市售的镍催化剂促进了多种取代内炔的E-选择性炔烃半氢化。这产生了一个简单且广泛适用的整体方案,用于使用 H 2立体选择性地访问E-烯烃,这可以作为通用的合成方法。
ppm Pd-catalyzed, Cu-free Sonogashira couplings in water using commercially available catalyst precursors
作者:Bo Jin、Fabrice Gallou、John Reilly、Bruce H. Lipshutz
DOI:10.1039/c8sc05618h
日期:——
A newcatalyst that derives from commercially available precursors for copper-free, Pd-catalyzed Sonogashira reactions at the sustainable ppm level of precious metal palladium under mild aqueousmicellar conditions has been developed. Both the palladium pre-catalyst and ligand are commercially available, bench stable, and highly cost-effective. The catalyst is applicable to both aryl- and heteroaryl-bromides
Catalytic and metal-free intramolecular hydroalkoxylation of alkynes
作者:Alexandre Jean、Jacques Rouden、Jacques Maddaluno、Michaël De Paolis、Jérôme Blanchet
DOI:10.1016/j.tetlet.2019.01.020
日期:2019.2
Benzyltrimethylammonium hydroxide act as an efficient metal-free catalyst for the intramolecular hydroalkoxylation of alkynes. Notably, the use of microwave irradiation allowed reaction to operate in only two minutes. Under optimized reaction conditions, linear alkynes bearing aryl and heteroaryl substituents were successfully cyclized with good level of stereoselectivity. (C) 2019 Elsevier Ltd. All rights reserved.