A Bifunctional Copper Catalyst Enables Ester Reduction with H<sub>2</sub>: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
作者:Birte M. Zimmermann、Trung Tran Ngoc、Dimitrios-Ioannis Tzaras、Trinadh Kaicharla、Johannes F. Teichert
DOI:10.1021/jacs.1c09626
日期:2021.10.13
activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered “soft” copper(I) hydrides to previously
采用基于铜 (I)/NHC 配合物和胍有机催化剂的双功能催化剂,促进了以 H 2作为末端还原剂的催化酯还原成醇。这里采用的方法能够通过氢键同时活化酯,并从 H 2形成亲核的氢化铜 (I) ,从而导致氢化物催化转移到酯。由胍亚基介导的质子穿梭进一步促进了还原步骤。这种酯还原的双功能方法首次将通常认为的“软”氢化铜 (I) 的反应性转变为以前不反应的“硬”酯亲电子试剂,并为用催化剂和 H 2替代化学计量还原剂铺平了道路.
A new synthetic route to 1,5-dienes is described. Irradiation of a mixture of allyl bromides and allyl sulfides in the presence of hexamethylditin gives the cross-coupled products selectively.
The Absolute Configuration of the Pyrrolosesquiterpenoid Glaciapyrrol A
作者:Ramona Riclea、Jeroen S. Dickschat
DOI:10.1002/chem.201101139
日期:2011.10.10
unambiguously clarified the relative configuration of natural glaciapyrrol A that was previously only partly solved from the available NMR data. An enantioselective synthesis was carried out resulting in the unnatural enantiomer (11S,12R,15R)‐(−)‐glaciapyrrol A. These data establish the absoluteconfiguration of the natural product as (11R,12S,15S)‐(+)‐glaciapyrrol A.
mechanistic investigation was performed to elucidate the reaction mechanism. For the cyclization of geranyl acetate, it was found that the cleavage of the leaving group is the rate-determiningstep. Furthermore, the studies revealed that trace amounts of acid are required as cocatalyst. A series of control experiments demonstrate that a synergistic interplay between the supramolecular capsule and the
Microwave accelerated selective and facile deprotection of allyl esters catalyzed by Montmorillonite K-10
作者:Anil S. Gajare、Nadim S. Shaikh、Bhushan K. Bonde、Vishnu H. Deshpande
DOI:10.1039/a909265j
日期:——
Carboxylic acids are regenerated from their corresponding substituted allyl esters by Montmorillonite K-10 using microwave irradiation under solvent free conditions to afford enhanced yields and reduced reaction times compared to thermal conditions.