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.
Donor–Acceptor Cyclopropanes as 1,2-Dipoles in GaCl<sub>3</sub>-Mediated [4 + 2]-Annulation with Alkenes: Easy Access to the Tetralin Skeleton
作者:Roman A. Novikov、Anna V. Tarasova、Victor A. Korolev、Evgeny V. Shulishov、Vladimir P. Timofeev、Yury V. Tomilov
DOI:10.1021/acs.joc.5b01179
日期:2015.8.21
A new process for (4 + 2)-annulation of donor–acceptorcyclopropanes (DACs) with unsaturated compounds in the presence of anhydrous GaCl3 has been developed. In this process, DACs act as sources of formal1,2- and 1,4-dipoles to give polysubstituted tetralins in high yields and with high regio- and diastereoselectivity. Alkenes with both aryl and alkyl substituents at the double bond undergo this reaction
Lewis acid catalyzed diastereoselective [3+4]-annulation of donor–acceptor cyclopropanes with anthranils: synthesis of tetrahydro-1-benzazepine derivatives
作者:Zhe-Hao Wang、Huan-Huan Zhang、Dao-Ming Wang、Peng-Fei Xu、Yong-Chun Luo
DOI:10.1039/c7cc04239f
日期:——
A Lewisacidcatalyzed [3+4]-annulation reaction between cyclopropane 1,1-diesters and anthranils has been developed. This annulation consists of a reaction sequence involving ring-opening/aromatization/nucleophilic addition. Thereinto, aromatization is the driving force for this annulation. Using this reaction, a series of 8-oxa-1-azabicyclo[3.2.1]octanes can be prepared conveniently with excellent
A catalytic [1,3] O‐to‐C rearrangement from enyne‐ethers was developed for the rapid synthesis of diverse bridged bicyclic systems. In this reaction, a vinyl oxonium intermediate, generated in situ from enyne‐ether, was the precursor for the [1,3] O‐to‐C rearrangement. This versatile protocol represents the first example of catalytic [1,3] O‐to‐C rearrangement based on ring‐expansion strategy, enabling
GaCl3-Mediated Isomerization of Donor–Acceptor Cyclopropanes into (2-Arylalkylidene)malonates
作者:Yury Tomilov、Roman Novikov、Anna Tarasova
DOI:10.1055/s-0035-1561389
日期:——
A new process for isomerization of donor–acceptor cyclopropanes (2-arylcyclopropanedicarboxylates) by treatment with anhydrous gallium trichloride to give (2-arylalkylidene)malonates in high yields and with good selectivity has been developed. The reaction involves initial formation of a 1,2-dipolar gallium complex.