amount of InCl3 and aceticanhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation
through a cascadereaction between 2‐isocyanoethylindole and alkylidene malonates catalyzed by a chiral N,N′‐dioxide/MgII catalyst. Fused polycyclic indolines containing three stereocenters were afforded in good yields with excellent diastereo‐ and enantioselectivities through a Michael/Friedel–Crafts/Mannich cascade. When 2‐substituted 2‐isocyanoethylindoles were used, spiroindoline derivatives were obtained
Stereospecific Copper(II)-Catalyzed Tandem Ring Opening/Oxidative Alkylation of Donor–Acceptor Cyclopropanes with Hydrazones: Synthesis of Tetrahydropyridazines
Aerobic copper(II)-catalyzed tandem ringopening and oxidative C–H alkylation of donor–acceptorcyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89–98% enantiomeric excess)
Catalytic asymmetric synthesis of hydrothiazole derivatives was developed via a well-organized formal [2 + 1 + 2] cycloaddition reaction triggered by asymmetric addition of isocyanide to alkylidene malonate. Various chiral hydrothiazole derivatives were readily provided in good yield with high enantioselectivity (up to 98% yield, 98.5:1.5 er) utilizing a chiral Mg(OTf)2/N,N'-dioxide complex as the
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.