The development of photoredox reactions of 1,3-dipolarcycloaddition of nitrones with alkenes is reported. It offers an efficient synthetic method to obtain isoxazolidine derivatives under mild conditions in synthetically useful yields. The nitrones are cyclized with oxidizable styrenes and aliphatic alkenes via a polar radical crossover cycloaddition reaction through photocatalytic reaction without
Rhodium-Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight-Membered Heterocycles
作者:Chunxiang Wang、Dongping Wang、Hao Yan、Haolong Wang、Bin Pan、Xiaoyi Xin、Xincheng Li、Fan Wu、Boshun Wan
DOI:10.1002/anie.201407394
日期:2014.10.27
N‐aryl‐substituted nitrones were employed as five‐atom couplingpartners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic CHactivation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight
arylnitrones and diazo compounds by C–H activation/[4 + 1] annulation with a C(N2)–C(acyl) bond cleavage is reported, and 2,3-disubstituted NH indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh(III)-catalyzed synthesis of homologous series, this method
Gold-Catalyzed Oxidative Arylations of 3-Butyn-1-ols and 2-Propyn-1-ols with Nitrones to Yield Distinct Fused Indoles Bearing a Heterocyclic Ring
作者:Rajkumar Lalji Sahani、Rai-Shung Liu
DOI:10.1021/acscatal.9b01491
日期:2019.7.5
The catalytic formation of various fused indoles from the nitrone oxidations of 1-substituted n-yn-1-ols (n = 2, 3) is described. For 3-butyn-1-ols, the oxidations yield tetrahydropyrano[4,3-b]indoles, whereas 2-propynols deliver tetrahydro-[1,2]oxazino[5,4-b]indoles efficiently. When styryl nitrones were tested on 2-propyn-1-ols, dihydrooxazolo[3,4-a]indoles were produced efficiently. We postulate
描述了由1-取代的n -yn-1-ols(n = 2,3)的硝酮氧化催化形成各种稠合吲哚的方法。对于3-丁炔-1-醇,氧化产生四氢吡喃并[4,3- b ]吲哚,而2-丙炔醇有效地递送四氢-[1,2]恶嗪基[5,4- b ]吲哚。当在2-丙炔-1-醇上测试苯乙烯基硝酮时,可以高效地生产二氢恶唑并[3,4- a ]吲哚。我们假定这些稠合的吲哚的形成是由共同的机理引起的,该机制涉及在这些稠合的吲哚之前,初始的烯基金中间体的[3,3]-σ位移以提供羰基化作用。
Rhodium(III)‐Catalyzed Asymmetric Access to Spirocycles through C−H Activation and Axial‐to‐Central Chirality Transfer
作者:Lingheng Kong、Xi Han、Song Liu、Yun Zou、Yu Lan、Xingwei Li
DOI:10.1002/anie.202000174
日期:2020.4.27
Axial-to-central chirality transfer is an important strategy to construct chiral centers, where the axiallychiral reagents are mostly limited to atropomerically stable ones. Reported herein is a RhIII -catalyzed enantioselective spiroannulative synthesis of nitrones. The coupling proceeds via C-Harylation to give an atropomerically metastable biaryl, followed by intramolecular dearomative trapping