描述了乙烯基氮丙啶和乙烯基环丙烷的双核,应变诱导的开环反应。先前报道的[NDI] Ni 2(C 6 H 6)络合物(NDI =萘啶-二亚胺)通过C–N氧化加成与N-甲苯磺酰基-2-乙烯基氮丙啶反应生成二镍金属环产物。基于该化学计量反应性,[NDI] Ni 2(C 6 H 6)配合物被证明是将乙烯基环丙烷重排为环戊烯的高活性催化剂。值得注意的是,与非催化热重排相比,2-苯基-1-乙烯基环丙烷在受阻较小的C–C键处进行区域选择性活化。DFT计算提供了对Ni-Ni键沿催化途径稳定关键中间体和过渡态的能力的了解。
Photochemically Promoted Aza-Diels–Alder-Type Reaction: High Catalytic Activity of the Cr(III)/Bipyridine Complex Enhanced by Visible Light Irradiation
作者:Noriyoshi Arai、Takeshi Ohkuma
DOI:10.1021/acs.joc.7b00838
日期:2017.7.21
Aza-Diels–Alder-type cycloaddition reactions between a range of N-arylimines and functionalized alkenes were effectively catalyzed by the Cr(III)/bipyridine complex under irradiation of blue light, to give the corresponding 1,2,3,4-tetrahydroquinoline derivatives in high yields with excellent diastereoselectivity. Typically, the reaction of benzylideneaniline with 1-vinyl-2-pyrrolidinone proceeded
A cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ is reported, which uses nonmetallic quinone DDQ as an oxidant in the allylation of N-benzylanilines under mild conditions. C–C bond with high selectivity and activity was constructed in this reaction and homoallylic amines were obtained with yields of up to 99%.
Cross-dehydrogenative coupling strategy for phosphonation and cyanation of secondary N-alkyl anilines by employing 2,3-dichloro-5,6-dicyanobenzoquinone
has been developed firstly under mild reaction conditions. Based on detailed optimization of reaction conditions, the substrate generality of N-alkyl anilines and various hydrogen phosphonates has been investigated, and a series of versatile α-aminophosphonates and α-aminonitriles were therefore furnished in good to excellent yields. A plausible collective reaction mechanism through dehydrogenation to
during the formation of iminesfrom aldehydes 1 and amines 2, is employed to promote the one-pot Mannich reaction of trimethylsilyloxyfuran 3a without addition of extra solvent or catalyst. This clean and quick reaction allows the obtention of a series of 5-substituted γ-butenolides 4 with good yields and modest diastereomeric ratio. A large panel of substituents is tolerated ranging fromaliphatic chains
Mechanistic Studies of Hydride Transfer to Imines from a Highly Active and Chemoselective Manganate Catalyst
作者:Frederik Freitag、Torsten Irrgang、Rhett Kempe
DOI:10.1021/jacs.9b05024
日期:2019.7.24
highly active and chemoselective manganese catalyst for the hydrogenation of imines. The catalyst has a large scope, can reduce aldimines and ketimines, and tolerates a variety of functional groups, among them hydrogenation sensitive examples such as an olefin, a ketone, nitriles, nitro groups and an aryl iodo substituent or a benzyl ether. We could investi-gate the transfer step between imines and the
我们介绍了一种用于亚胺加氢的高活性和化学选择性锰催化剂。该催化剂适用范围广,可还原醛亚胺和酮亚胺,可耐受多种官能团,其中对氢化敏感的例子如烯烃、酮、腈、硝基和芳基碘取代基或苄基醚。我们可以详细研究亚胺和氢化物配合物之间的转移步骤。我们发现配体的双重去质子化是必不可少的,过量的碱不会导致转移步骤中的更高速率。我们将实际的加氢催化剂鉴定为 K-Mn-双金属物种,并且可以通过 X 射线分析获得氢化物转移后形成的 K-Mn 配合物的结构。核磁共振实验表明氢化物转移是一个明确定义的反应,这是亚胺的一级,双金属(K-Mn)氢化物的一级,并且速率与钾碱的浓度无关。我们提出了一种外球机制,其中质子似乎不参与速率确定步骤,导致底物中的瞬态带负电荷的氮原子与 HOtBu(2-methylpropan-2-ol)迅速反应以产生胺。这是基于几个观察结果,例如反应速率不依赖于 HOtBu 浓度,没有可观察到的锰酰胺