Rh-catalyzed asymmetric hydrogenation of α-aryl-β-alkylvinyl esters with chiral ferrocenylphosphine-phosphoramidite ligand
作者:Chao Dong、Dao-Sheng Liu、Lei Zhang、Xiang-Ping Hu
DOI:10.1016/j.tetlet.2020.152763
日期:2021.2
An enantioselective Rh-catalyzedhydrogenation of E/Z mixtures of trisubstituted vinyl esters has been disclosed. With a combination of [Rh(COD)2]BF4 and a structurally fine-tuning chiral ferrocenylphosphine-phosphoramidite ligand as the catalyst, a variety of E/Z mixtures of α-aryl-β-alkylvinyl esters have been successfully hydrogenated in high yields and with good to high enantioselectivities (up
tributylstannyl enolates derivedfrom aromatic ketones reacted with electron-deficientalkenes and a variety of alkynes to give the corresponding carbostannylated adducts. The reactions with methyl acrylate gave alpha-tributylstannylmethyl-gamma-ketoesters, unlike the known Michael-type reaction of stannyl enolates forming delta-ketoesters. The carbostannylation of alkynes proceeded in an anti addition
Asymmetric Oxidation of Enol Derivatives to α-Alkoxy Carbonyls Using Iminium Salt Catalysts: A Synthetic and Computational Study
作者:Philip C. Bulman Page、Saud M. Almutairi、Yohan Chan、G. Richard Stephenson、Yannick Gama、Ross L. Goodyear、Alice Douteau、Steven M. Allin、Garth A. Jones
DOI:10.1021/acs.joc.8b02354
日期:2019.1.18
We report herein the first examples of asymmetricoxidation of enol ether and ester substrates using iminium salt organocatalysis, affording moderate to excellent enantioselectivities of up to 98% ee for tetralone-derived substrates in the α-hydroxyketone products. A comprehensive density functional theory study was undertaken to interpret the competing diastereoisomeric transition states in this example
Stereoselective aldol condensations of organotin reagents with aldehydes
作者:Sharada S. Labadie、J.K. Stille
DOI:10.1016/0040-4020(84)80016-2
日期:1984.1
reaction requiring isomerization of the C-Sn to the O-Sn enolate. The Pd catalyzed condensation of cyanomethyltributyltin with reactive aldehydes, such as nitrobenzaldehydes, took place at ambient temperatures in polar solvents to give high yields of condensation products. No reaction occurred with aldehydes such as benzaldehyde. Only low stereoselectivity (10-34% ee) was observed when (-) DIOP or (-)BPPM
Thermal and Photochemical Solvolysis of (<i>E</i>)- and (<i>Z</i>)-2-Phenyl-1-propenyl(phenyl)iodonium Tetrafluoroborate: Benzenium and Primary Vinylic Cation Intermediates
in-plane S(N)2 mechanism. The mechanism of the photolysis involves direct, unassisted cleavage of the vinylic, and aromatic, C-I bond in an S(N)1 mechanism. This produces a primary vinyl cation, which is partially trapped prior to rearrangement in methanol. The unrearranged vinyl ethers are mainly formed with retention of configuration via a lambda3-iodonium/solvent complex in an S(N)i mechanism. Thermal
已在不同亲核性的醇溶剂中研究了两种立体异构体 2-苯基-1-丙烯基(苯基)碘鎓四氟硼酸盐的热和光化学溶剂分解。热反应中的产物分布和产物形成速率都与涉及在反式位(甲基或苯基)中的基团辅助的乙烯基Cl键断裂的机制相容,总是导致重排产物。根据溶剂的亲核性,最初形成的阳离子可能会或可能不会进一步重排为更稳定的异构体。反应性较低的 Z 化合物还在亲核性更强的溶剂中通过面内 S(N)2 机制产生一些未重排的乙烯基醚产物。光解的机制涉及乙烯基和芳烃的直接、无辅助的裂解,S(N)1 机制中的 CI 键。这会产生一个主要的乙烯基阳离子,它在甲醇中重排之前被部分捕获。未重排的乙烯基醚主要通过 S(N)i 机制中的 lambda3-碘鎓/溶剂络合物保留构型形成。碘鎓盐的热和光化学溶剂分解是从同一底物生成不同阳离子中间体的互补技术。