875654-93-6Relevant academic research and scientific papers
Stereoselective double lewis acid/organo-catalyzed dimerization of donor-acceptor cyclopropanes into substituted 2-oxabicyclo[3.3.0]octanes
Novikov, Roman A.,Timofeev, Vladimir P.,Tomilov, Yury V.
, p. 5993 - 6006 (2012)
A new approach for the dimerization of donor-acceptor cyclopropanes (2-arylcyclopropane-1,1-dicarboxylates) under double-catalysis conditions by treatment with 20 mol % of GaCl3 and dimethyl 3,5-dimethyl-1- pyrazoline-3,5-dicarboxylate as a specific organocatalyst has been found. Under these conditions, the starting compounds are regio- and stereospecifically converted into polysubstituted 2-oxabicyclo[3.3.0]octanes. Two new rings, one C-O bond, and two C-C bonds are formed in this process, and four stereocenters are thus created. The reaction mechanism was thoroughly studied by NMR spectroscopy, and a number of intermediates were detected.
A new type of donor-acceptor cyclopropane reactivity: The generation of formal 1,2- and 1,4-dipoles
Novikov, Roman A.,Tarasova, Anna V.,Korolev, Victor A.,Timofeev, Vladimir P.,Tomilov, Yury V.
, p. 3187 - 3191 (2014/04/03)
A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3, they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles due to migration of positive charge from the benzyl center. This type of reactivity has been demonstrated for new reactions, namely, cyclodimerizations of donor-acceptor cyclopropanes that occur as [2+2]-, [3+2]-, [4+2]-, [5+2]-, [4+3]-, and [5+4]-annulations. The [4+2]-annulation of 2-arylcyclopropane-1,1-dicarboxylates to give polysubstituted 2-aryltetralins has been developed in a preparative version that provides exceedingly high regio- and diastereoselectivity and high yields. The strategy for selective hetero-combination of donor-acceptor cyclopropanes was also been developed. The mechanisms of the discovered reactions involving the formation of a comparatively stable 1,2-ylide intermediate have been studied. Old ring, new reactivity: A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3, they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles owing to the migration of positive charge from the benzyl center.
