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.
Friedel–Crafts-Type Reactions with Electrochemically Generated Electrophiles from Donor–Acceptor Cyclopropanes and -Butanes
作者:Simon Kolb、Nils L. Ahlburg、Daniel B. Werz
DOI:10.1021/acs.orglett.1c01890
日期:2021.7.16
describe a general electrochemical method to functionalize donor–acceptor (D–A) cyclopropanes and -butanes with arenes utilizing Friedel–Crafts-type reactivity. The catalyst-free strategy relies on the direct anodic oxidation of the strained carbocycles, which leads after C(sp3)–C(sp3) cleavage to radical cations that act as electrophiles for the arylation reaction. Broad reaction scopes in regard to
Lewis Acid-Catalyzed Isomerization of 2-Arylcyclopropane-1,1-dicarboxylates: A New Efficient Route to 2-Styrylmalonates
作者:Alexey O. Chagarovskiy、Olga A. Ivanova、Eduard R. Rakhmankulov、Ekaterina M. Budynina、Igor V. Trushkov、Mikhail Ya. Melnikov
DOI:10.1002/adsc.201000636
日期:2010.12.17
A facile efficient approach to the 2-styrylmalonates via the Lewis acid-catalyzedisomerization of 2-arylcyclopropane-1,1-dicarboxylates has been developed. The efficiency of this method was demonstrated for a representative series of such cyclopropanes. The isomerization proceeds chemo-, regio- and stereoselectively to afford E-styrylmalonates in good yields.
Stereospecific assembly of tetrahydroquinolines <i>via</i> tandem ring-opening/oxidative cyclization of donor–acceptor cyclopropanes with <i>N</i>-alkyl anilines
An aerobic copper-catalyzed tandem reaction of N-alkyl anilines with donor–acceptor cyclopropanes is presented for the construction of tetrahydroquinolines via a sequential stereospecific ring opening and oxidative cyclization. The catalyst plays a dual role as a Lewis acid as well as being a redox catalyst. The use of air as an oxidant and the broad substrate scope are the important practical features
Ag(I)-Catalyzed Indolization/C3-Functionalization Cascade of 2-Ethynylanilines via Ring Opening of Donor–Acceptor Cyclopropanes
作者:Raju Karmakar、Arun Suneja、Vinod K. Singh
DOI:10.1021/acs.orglett.6b01057
日期:2016.6.3
A AgSbF6-catalyzed cascade involving the ringopening of donor–acceptorcyclopropanes (DACs) preceded by the cyclization of N-protected 2-ethynylaniline is described. The method discloses a step-economy route to 2,3-disubstituted indole, where a Ag catalyst is found to trigger the cascade by activating both alkyne and DACs. Various functionalities at different ends of both substrates offer rapid access