Search results for "enamine"

Verbindungen mit potentiell positiv inotroper Wirkung, 1. Mitt. N-Substituierte 3-Amino-2-cyclopentenone aus partiell hydrierten 2-Phenanthrylaminen

1984

Die Darstellung partiell hydrierter 2-Phenanthrylamine und ihre Umsetzung mit 1,3-Cyclopentandion zu N-subst. 3-Amino-2-cyclopentenonen wird beschrieben. Compounds with Potentially Positive Inotropic Activity, I: N-Substituted 3-Amino-2-cyclopentenones from Partially Hydrogenated 2-Phenanthrylamines The synthesis of partially hydrogenated 2-phenanthrylamines and their reactions with 1,3-cyclopentanedione to N-substituted 3-amino-2-cyclopentenones is described.

Electrophilic substitution and cyclization of 2,2′-bis(N-methylindolyl): A simple access to potential protein kinase C inhibitor

1994

A strategy is described for the synthesis of functionalized and cyclized 2,2′-bisindolyl derivatives related to several basic systems of natural products. The starting 2,2′-bis(N-methylindolyl) (8) reacts with a variety of electrophiles and electrophilic dienophiles to furnish the novel, functionalized and cyclized bisindolyl derivatives 9–16. In addition, some reactivity and structural aspects are discussed; an X-ray crystallographic analysis of the 2,2′-bisindolyl 8 provided valuable information for the conformational analyses.

1967

Enamines derived from cyclic ketones behave as difunctional intermediates when treated with phenyl isocyanate to produce dicarboxanilides. Reaction of bis(4-isocyanatophenyl)-methane with 1-N-morpholino-1-cyclopentene in DMSO leads to poly[iminocarbonyl(2-morpholino-1-cyclopenten-1.3-ylene)carbonylimino-p-phenylenemethylene-p-phenylene], a polyamide. The effects of various cyclic enamines and diisocyanates on the polymerization are surveyed. Morpholine and piperidine are more effective than pyrrolidine or dimethylamine when incorporated into cyclopentanone enamines. The molecular weight of the polymer decreases when the ring size of the ketone component is increased. The efficiency of the d…

ChemInform Abstract: Water in Stereoselective Organocatalytic Reactions

2009

In this review, recent advances in asymmetric organocatalytic reactions carried out with variable amounts of water, from substoichiometric to a large excess (reaction medium), are discussed. We also summarize several proposed mechanisms for the different possibilities of the action of water both in the increased activity of the catalyst and in the asymmetric induction. Finally, the application of this catalytic methodology to the enantioselective synthesis of valuable compounds through enamine or iminium catalysis is presented.

Advances towards highly active and stereoselective simple and cheap proline-based organocatalysts

2010

Ten 4-acyloxy-L-prolines were screened as catalysts at loadings of 2–0.1 mol-% for the direct asymmetric aldol reaction in water by using variable amounts of water. Among them, a new catalyst, the L-proline carrying a trans-4-(2,2-diphenylacetoxy) group, and a catalyst previously synthesized by us, the L-proline carrying a trans-4-(4-phenylbutanoyloxy) group, were found to be excellent catalysts for the aldol reaction between cyclohexanone or cyclopentanone and substituted benzaldehydes when employed in only 1 and 0.5 mol-%,respectively, at room temperature without additives. For such catalysts, high turnover numbers were obtained, which are among the highest values obtained for enamine org…

Synthesis of 6,12-Disubstituted Methanodibenzo[b,f][1,5]dioxocins : Pyrrolidine Catalyzed Self-Condensation of 2′-Hydroxyacetophenones

2019

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C–O and two C–C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones.

Water in stereoselective organocatalytic reactions

2009

In this review, recent advances in asymmetric organocatalytic reactions carried out with variable amounts of water, from substoichiometric to a large excess (reaction medium), are discussed. We also summarize several proposed mechanisms for the different possibilities of the action of water both in the increased activity of the catalyst and in the asymmetric induction. Finally, the application of this catalytic methodology to the enantioselective synthesis of valuable compounds through enamine or iminium catalysis is presented.