cis-2,3-Disubstituted cyclopropane 1,1-diesters were found to be much more reactive than their corresponding trans-isomers in the AlCl3-promoted [3 + 2]-annulations with isothiocyanates. The reaction with the cis-cyclopropanes proceeded to completion within minutes, providing a variety of densely substituted diastereomerically pure 2-iminodihydrothiophenes in moderate to excellent yields.
Scandium(III) Triflate-Catalyzed Reaction of Aroyl-Substituted Donor–Acceptor Cyclopropanes with 1-Naphthylamines: Access to Dibenzo[<i>c</i>,<i>h</i>]acridines
作者:Murugesan Thangamani、Kannupal Srinivasan
DOI:10.1021/acs.joc.0c02105
日期:2021.1.1
The reaction of aroyl-substituted donor–acceptor (D–A) cyclopropanes with two equivalents of 1-naphthylamines in the presence of a catalytic amount of scandium(III) triflate provides access to dibenzo[c,h]acridines. The key steps of the transformation are the formation of nucleophilic ring-opening products from the D–A cyclopropanes and 1-naphthylamines and their subsequent fragmentation and cyclization
AlCl<sub>3</sub>-Catalyzed [3+2] Annulations of<i>cis</i>-2,3-Disubstituted Cyclopropane 1,1-Diesters with Cyclic Ketones: Diastereoselective Construction of Spirotetrahydrofurans
作者:Gaosheng Yang、Tingting Wang、Jun Chai、Zhuo Chai
DOI:10.1002/ejoc.201403325
日期:2015.2
The stereoselective [3+2] annulations of cis-2,3-disubstituted cyclopropane1,1-diesters with cyclic/acyclic aliphatic ketones were effected by AlCl3 to provide highly functionalized spirotetrahydrofurans in moderate to excellent yields under very mild conditions.
Lewis Acid-Mediated Transformations of<i>trans</i>-2-Aroyl-3-aryl- cyclopropane-1,1-dicarboxylates into 2-Pyrones and 1-Indanones
作者:Gopal Sathishkannan、Kannupal Srinivasan
DOI:10.1002/adsc.201300861
日期:2014.3.10
Abstracttrans‐2‐Aroyl‐3‐arylcyclopropane‐1,1‐dicarboxylates upon treatment with aluminium(III) chloride (AlCl3) underwent ring‐opening, fragmentation, recombination and lactonization to give highly substituted 2‐pyrones. Alternatively, when treated with titanium(IV) chloride (TiCl4), the cyclopropane diesters underwent a Nazarov cyclization to afford 1‐indanones with high diastereoselectivity.magnified image
Stereoselective cyclopropanation of α-bromochalcone with diethyl malonate promoted by K2CO3
A new Michael-initiated cyclopropanation reaction using alpha-bromochalcones as Michael acceptor was developed. Compared to previous works using arylidenemalonates as Michael acceptor, this novel protocol could improve the synthesis of trans-isomers of diethyl 2-benzoyl-3-phenyl-cyclopropane-1,1-dicarboxylates. More importantly, this method also provided the first access to the cis-isomers of these densely substituted cyclopropanes with the Michael-initiated ring closure (MIRC) strategy, albeit with a poor diastereoselectivity. (C) 2013 Published by Elsevier Ltd.