Direct α‐functionalization of NH2‐free glycinates with relatively weak electrophiles such as α,β‐unsaturatedesters still remains a big challenge in organic synthesis. With chiral pyridoxal 5 d as a carbonyl catalyst, direct asymmetricconjugated addition at the α‐C of glycinate 1 a with α,β‐unsaturatedesters 2 has been successfully realized, to produce various chiral pyroglutamic acid esters 4 in 14–96 %
aldehydes with alcohols as well as dehydrogentive cross-coupling of primary alcohols to produce esters have been developed using a Rh-terpyridine catalyst. The catalyst demonstrates broad substrate scope and good functional group tolerance, affording esters highly selectively. The high chemoselectivity of the catalyst stems from its preference for dehydrogenation of benzylic alcohols over aliphatic ones. Preliminary
已经使用 Rh-三联吡啶催化剂开发了醛与醇的脱氢交叉偶联以及伯醇的脱氢交叉偶联以生产酯。该催化剂表现出广泛的底物范围和良好的官能团耐受性,可高度选择性地提供酯。该催化剂的高化学选择性源于其对苄醇脱氢的偏好优于脂肪醇。初步机理研究表明,活性催化剂是二聚 Rh( II ) 物种,通过涉及金属-基础-金属协同作用的机制进行操作。
Chiral Ugi-Type Amines: Practical Synthesis, Ligand Development, and Asymmetric Catalysis
作者:Wu-Wei Dong、Yi-Nan Li、Xin Chang、Chong Shen、Chun-Jiang Wang
DOI:10.1021/acscatal.0c04077
日期:2020.11.6
privileged chiral skeleton for chiralligand design bearing central/planar chirality, and such ligands have exhibited tremendous success in various asymmetriccatalysis. However, the current access to enantiopure Ugi’s amine is quite tedious and relies heavily on optical resolution, which impedes its practical applications, to some extent. Herein, we present a facile asymmetricsynthesis of enantioenriched
Pd(II)-catalyzed oxidative Heck-type reaction of triarylphosphines with alkenes via carbon–phosphorus bond cleavage
作者:Ming-Tao Ma、Jian-Mei Lu
DOI:10.1016/j.tet.2013.01.025
日期:2013.3
A Pd(II)-catalyzed oxidative Heck-type reaction of triarylphosphines with alkenes via carbon–phosphorusbondcleavage was reported. Under the optimal reaction conditions, most reactions proceeded smoothly to give the expected coupling products in acceptable to high yields.
Chiral Magnesium(II) Binaphtholates as Cooperative Brønsted/Lewis Acid-Base Catalysts for the Highly Enantioselective Addition of Phosphorus Nucleophiles to α,β-Unsaturated Esters and Ketones
作者:Manabu Hatano、Takahiro Horibe、Kazuaki Ishihara
DOI:10.1002/anie.201300938
日期:2013.4.22
cooperative Brønsted/Lewis acid–base supramolecular catalysts formed in situ from simple chiral magnesium(II) binaphtholate aqua complexes promoted the highly enantioselective 1,4‐hydrophosphinylation of α,β‐unsaturated esters with diaryl phosphine oxides and 1,2‐hydrophosphonylation of α,β‐unsaturatedketones with dialkyl phosphites (see scheme).