l-Proline catalyzed stereoselective synthesis of (E)-methyl-α-indol-2-yl-β-aryl/alkyl acrylates: easy access to substituted carbazoles, γ-carbolines and prenostodione
作者:Soumen Biswas、Pradeep Kumar Jaiswal、Shivendra Singh、Shaikh M. Mobin、Sampak Samanta
DOI:10.1039/c3ob41573b
日期:——
A simple, mild and robust method for the stereoselective synthesis of (E)-methyl α-(3-formyl-1H-indol-2-yl)-β-aryl/alkyl-substituted acrylates via a condensation reaction of methyl 2-(3-formyl-1H-indol-2-yl)acetate with several alkyl or aryl aldehydes using L-proline (25 mol%) as a catalyst is presented for the first time. In addition, completely metal free based high yielding methods for the syntheses
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
procedure for the direct synthesis of highly functionalized 1-methoxycarbonyl-2-aryl/alkyl-3-nitro-9H-carbazoles has been achieved in water medium via a one-pot domino Michael–Henry/aromatization reaction of methyl 2-(3-formyl-1H-indol-2-yl)acetates with aryl/alky-substituted β-nitroolefins under air using DABCO (30 mol%) as an organocatalyst. In addition, the bench scale synthesis can be performed without
Stereoselective synthesis of highly functionalized tetrahydrocarbazoles through a domino Michael–Henry reaction: an easy access to four contiguous chiral centers
作者:Pradeep Kumar Jaiswal、Soumen Biswas、Shivendra Singh、Biswarup Pathak、Shaikh M. Mobin、Sampak Samanta
DOI:10.1039/c3ra41409d
日期:——
one-step procedure for the synthesis of a series of densely functionalized 1-methoxycarbonyl-2-aryl-3-nitro-4-hydroxy-1,2,3,4-tetrahydro-9H-carbazole derivatives has been achieved via a domino Michael–Henry reaction of methyl 3-formyl-1H-indole-2-acetates with β-nitrostyrenes using DABCO as an organocatalyst. Furthermore, the high enantio-(≤92% ee) and diastereoselective (≤12 : 1 dr) synthesis of the