Access to Substituted Carbazoles in Water by a One-Pot Sequential Reaction of α,β-Substituted Nitro Olefins with 2-(3-Formyl-1<i>H</i>-indol-2-yl)acetates
interesting new multifunctional carbazole scaffolds have been prepared in good to excellent yields by an organocatalytic one-pot two-step sequentialreaction between α-alkyl-β-substituted nitroolefins or α-alkyl-δ-substituted nitro-dienes and 2-(3-formyl-1H-indol-2-yl)acetates in water at room temperature followed by treatment with 2 n HCl under mild conditions. This one-pot, organocatalytic, oxidant-free
Diastereo- and Enantioselective Synthesis of Functionalized Dihydropyrans via an Organocatalytic Claisen Rearrangement/Oxa-Michael Addition Tandem Sequence
rearrangement/oxa-Michael addition tandem sequence with a cinchona squaramide catalyst was described, which afforded a practical and atom-economical approach to access a range of valuable dihydropyrans in good to excellent yields with excellent stereoselectivities. The organo-bifunctional catalyst played a key role in enhancing stereoselectivity in this asymmetrictandem sequence. Moreover, the asymmetric catalytic
Thiophosphoramide catalyzed asymmetric Michael addition of acetone to functionalized nitrostyrenes: a convenient approach to optically active tetrahydropyrans
Thiophosphoramide 5d was found to be an effective organocatalyst for the enantioselective Michael reaction of problematic acetone to various hydroxymethyl nitrostyrenes, affording the multisubstituted tetrahydropyrans with three stereogenic centers. The Michael addition products generated were obtained as a single diastereomer with enantioselectivities ranging from 46% to 74% ee. (C) 2010 Elsevier Ltd. All rights reserved.