Lewis Acid Mediated (3 + 2) Cycloadditions of Donor–Acceptor Cyclopropanes with Heterocumulenes
作者:Alexander F. G. Goldberg、Nicholas R. O’Connor、Robert A. Craig、Brian M. Stoltz
DOI:10.1021/ol302494n
日期:2012.10.19
Isocyanates, isothiocyanates, and carbodiimides are effective substrates in (3 + 2) cycloadditions with donor–acceptor cyclopropanes for the synthesis of five-membered heterocycles. These reactions exhibit a broad substrate scope, high yields, and well-defined chemoselectivity. Discussed herein are the implications of Lewis acid choice on the stereochemical outcome and the reaction mechanism.
Reactivity of donor–acceptor cyclopropanes towards nucleophiles and electrophiles is determined by the specific philicity of the carbon atoms originating from the strong polarization of the central C–C bond. Herein, we report that vitamin B12 catalysis enables the transformation of an initially electrophilic center into a nucleophilic radical that reacts with SOMOphiles. This radical-based strategy
供体 - 受体环丙烷对亲核试剂和亲电试剂的反应性由源自中心 C-C 键的强极化的碳原子的特定亲水性决定。在此,我们报道维生素 B 12催化能够将最初的亲电中心转变为与 SOMophiles 反应的亲核自由基。这种基于自由基的策略逆转了标准的区域选择性,从而补充了经典方法。
Ring opening of DA-cyclopropanes with electron rich arene/heteroarene: synthesis of 2-(2,2-diarylethyl)malonates
作者:Ranadeep Talukdar、Amrita Saha、Deo Prakash Tiwari、Manas K. Ghorai
DOI:10.1016/j.tet.2015.12.001
日期:2016.2
strategy for nucleophilic ring opening of donor-acceptor (DA)-cyclopropanes with electronrich arenes to provide 2-(2,2-diarylethyl)malonates in excellent yields is described. The reaction was found to be successful with heteroarenes as the nucleophile as well. Reaction of enantiopure DA-cyclopropane with arene/heteroarene as the nucleophiles afforded the corresponding 2-(2,2-diarylethyl)malonates with
Diastereoselective Synthesis of Functionalized Tetrahydrocarbazoles via a Domino-Ring Opening–Cyclization of Donor–Acceptor Cyclopropanes with Substituted 2-Vinylindoles
作者:Ranadeep Talukdar、Deo Prakash Tiwari、Amrita Saha、Manas K. Ghorai
DOI:10.1021/ol501763n
日期:2014.8.1
synthetic approach for the synthesis of highly functionalized tetrahydrocarbazoles via DROC of various functionalized DA-cyclopropanes with 2-indolylnitroethylene and indole-substituted alkylidene malonate is described. The tetrahydrocarbazoles were obtained with excellent diastereoselectivity having cis alignment of the 1,4-appendages across the six-memberedcarbocyclic ring.
Sc(OTf)<sub>3</sub>-Catalysed [3+3] Annulation of Cyclopropane 1,1-Diesters with Mercaptoacetaldehyde: A Facile Strategy for the Synthesis of Tetrahydrothiopyranols
作者:Hua-Peng Wang、Huan-Huan Zhang、Xiu-Qin Hu、Peng-Fei Xu、Yong-Chun Luo
DOI:10.1002/ejoc.201500282
日期:2015.6
A catalytic [3+3] annulation of cyclopropane1,1-diesters with in-situ-generated mercaptoacetaldehyde for the synthesis of polyfunctionalized tetrahydrothiopyran derivatives has been developed. A ring-opening/aldol cascade reaction catalysed by Sc(OTf)(3) (10 mol-%) gave a series of tetrahydrothiopyranols in good yields. Simple derivatization of the products gave some useful compounds.