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.
(3+2)-Cycloaddition of Donor–Acceptor Cyclopropanes with Thiocyanate: A Facile and Efficient Synthesis of 2-Amino-4,5-dihydrothiophenes
作者:Daniel B. Werz、Anu Jacob、Philip Barkawitz、Ivan A. Andreev、Nina K. Ratmanova、Igor V. Trushkov
DOI:10.1055/a-1385-2385
日期:2021.6
An easy and efficient route to obtain 2-amino-4,5-dihydrothiophenes is presented. A formal (3+2)-cycloaddition of donor–acceptor cyclopropanes and ammonium thiocyanate catalyzed by Yb(OTf)3 delivers the desired products in good to excellent yields. A broad range of functional groups is tolerated during this process.
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
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.
Sc(OTf)3-Catalyzed [3+3] Annulation of Cyclopropane 1,1-Diesters with β-(Indol-2-yl)-α,β-unsaturated Ketones: Synthesis of Polysubstituted Tetrahydrocarbazoles
作者:Huan-Huan Zhang、Yong-Chun Luo、Wei Chen
DOI:10.1055/s-0034-1380617
日期:——
A Sc(OTf)3-catalyzed cascade reaction consisting of a Friedel–Crafts alkylation followed by a Michael addition between cyclopropane1,1-diesters and β-(indol-2-yl)-α,β-unsaturated ketones allows for the efficient synthesis of polysubstituted tetrahydrocarbazoles under very mild reaction conditions.