Cyclohexyl-Fused, Spirobiindane-Derived, Phosphine-Catalyzed Synthesis of Tricyclic γ-Lactams and Kinetic Resolution of γ-Substituted Allenoates
摘要:
A C-2-symmetric chiral phosphine catalyst, NUSIOC-Phos, which can be easily derived from cyclohexyl-fused spirobiindane, was introduced. A highly enantioselective domino process involving pyrrolidine-2,3-diones and gamma-substituted allenoates catalyzed by NUSIOC-Phos has been disclosed. Diastereospecific tricyclic gamma-lactams containing five contiguous stereogenic centers were obtained in high yields and with nearly perfect enantioselectivities. A kinetic resolution process of racemic gamma-substituted allenoates was developed for the generation of optically enriched chiral allenoates.
Ambulation of Incipient Proton during Gas-Phase Dissociation of Protonated Alkyl Dihydrocinnamates
作者:Sihang Xu、Yong Zhang、Ramu Errabelli、Athula B. Attygalle
DOI:10.1021/acs.joc.5b01390
日期:2015.10.2
m/z 167 and 168 ions obtained for di- and tri-deuterio isotopologues showed peak pairs at m/z 134, 135 and 135, 136, at 1:2 and 1:1 intensity ratios, respectively, confirming the benzenium ion intermediate achieves complete randomization before the proton transfer. Additionally, protonated higher esters of alkyl dihydrocinnamates undergo a cleavage of the O–CH2 bond to form an ion/neutral complex,
在气相中活化后,质子化的二氢肉桂酸烷基酯发生醇损失。然而,遵循的机理不是在烷氧基上质子化之后简单地除去链烷醇分子。氘化荷氢二氢肉桂酸甲酯的m / z 166离子质谱图在m / z 133和134处显示两个强度比为1:5的峰,以确认初始质子是可移动的。最初连接到羰基的质子迁移到环并随机化,然后环质子之一随后转移到烷氧基以消除醇。而且,质子化的二氢肉桂酸甲酯经历了一次以上的H / D交换。从m记录的光谱分别获得二氘和三氘同位素的/ z 167和168离子在m / z 134、135和135、136处分别以1:2和1:1的强度比显示峰对,确认苯并鎓离子中间体已完全完成质子转移前的随机化。此外,烷基二氢肉桂酸酯的质子化高级酯会经历O-CH 2键的裂解,形成离子/中性络合物,该离子/中性络合物在活化后会解离生成碳正离子和二氢肉桂酸,或重排生成质子化的二氢肉桂酸和烯烃。通过非特定的质子转移。
Facile and Convenient Method of Deuterium Gas Generation Using a Pd/C-Catalyzed H2–D2 Exchange Reaction and Its Application to Synthesis of Deuterium-Labeled Compounds
The Pd/C-catalyzed H(2)-D(2) exchange reaction using a H(2)-D(2)O combination provided a general, efficient and environmentally friendly route for the preparation of deuterium gas (D(2)). H(2) sealed in a reaction flask was converted into nearly pure D(2), which could be used for the Pd/C-catalyzedone-potreductive deuteration of various reducible functionalities and the chemoselective one-pot deuterogenation
Cyclohexyl-Fused, Spirobiindane-Derived, Phosphine-Catalyzed Synthesis of Tricyclic γ-Lactams and Kinetic Resolution of γ-Substituted Allenoates
作者:Mingyue Wu、Zhaobin Han、Kaizhi Li、Ji’en Wu、Kuiling Ding、Yixin Lu
DOI:10.1021/jacs.9b07418
日期:2019.10.16
A C-2-symmetric chiral phosphine catalyst, NUSIOC-Phos, which can be easily derived from cyclohexyl-fused spirobiindane, was introduced. A highly enantioselective domino process involving pyrrolidine-2,3-diones and gamma-substituted allenoates catalyzed by NUSIOC-Phos has been disclosed. Diastereospecific tricyclic gamma-lactams containing five contiguous stereogenic centers were obtained in high yields and with nearly perfect enantioselectivities. A kinetic resolution process of racemic gamma-substituted allenoates was developed for the generation of optically enriched chiral allenoates.