Organocatalytic Sequential Michael Reactions: Stereoselective Synthesis of Multifunctionalized Tetrahydroindan Derivatives

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

A cascade inter-intramolecular double Michael strategy for the synthesis of highly functionalized cyclohexanones from curcumins and arylidenemalonates is reported. This strategy works in the presence of aqueous KOH using TBAB as a suitable phase transfer catalyst at room temperature. The functionalized cyclohexanones are formed as major products in moderate to excellent yields with complete diastereoselectivity in most cases. A triple Michael adduct, tetrahydrochromen-4-one, is also formed as a side product in a few cases with excellent diastereoselectivity.

A Lewis Acid-Promoted Michael Addition and Ring-Expansion Cascade for the Construction of Nitrogen-Containing Medium-Sized Rings

A Lewis acid-promoted annulation of azadienes and cyclobutamines was developed. This reaction proceeded through Michael addition and ring-expansion cascade, affording the corresponding nitrogen-containing medium-sized rings with a broad scope in moderate to high yields. The catalytic asymmetric version of this reaction has also been explored using a chiral base.

Asymmetric Sequential Michael Addition and Cyclization Reactions of 2-(2-Nitrovinyl)phenols Catalyzed by Bifunctional Amino-Squaramides

In this work, we describe the Michael addition–cyclization reaction of 2-(2-nitrovinyl)phenol with two different reactive Michael donors, which lead to chiral benzopyran derivatives. Specifically, bifunctional amino-squaramides with one or two chiral units in the side chains were evaluated as catalysts in these transformations. Furthermore, the utility of selected green solvents as reaction media for these processes was also tested. The best result was achieved with methyl-cyclopentanone-2-carboxylate as the Michael donor in ethyl (–)-l-lactate with quinine-based amino-squaramide as catalyst (yield 72%, dr >99:1, ee 99%).

Merging singlet-oxygen induced furan oxidations with organocatalysis: synthesis of enantiopure cyclopentanones and hydrindanes

A general, flexible and highly effective method for the regio-, diastereo- & enantioselective one-pot synthesis of important carbocycles, namely, enantiopure cyclopentanones and their hydrindane congeners is presented.

Organocatalytic asymmetric Michael addition of 1-acetylcyclohexene and 1-acetylcyclopentene to nitroolefins

Enantioselective organocatalytic Michael addition reactions of 1-acetylcyclohexene, 1-acetylcyclopentene and 1-acetylcyclobutene to nitroolefins have been developed. This is the first report where an α-branched enone has been activated by an amine catalyst for the asymmetric Michael addition reaction to an electrophile. The Michael products have also been cyclized to bicyclic compounds.

Cupreine grafted onto silica as an enantioselective and recyclable catalyst for the 1,4-addition of malonate to trans-β-nitrostyrene

First preparation of silica supported cupreine and its high catalytic performances for the asymmetric Michael addition in some biomass-derived solvents.

Direct amination of γ-halo-β-ketoesters with anilines

The direct amination of α-haloacetoacetates with anilines is described. Compared to existing methods, this simple protocol provides an attractive strategy to prepare diverse γ-anilino-β-ketoesters in one step. Good to excellent yields of the amination products were obtained under robust conditions, providing versatile and useful scaffolds.

Low-loading asymmetric organocatalysis

Asymmetric organocatalysis is now recognized as the third pillar of asymmetric synthesis. Recent years have witnessed increasing interest towards the use of highly active and stereoselective organocatalysts. This critical review documents the advances in the development of chiral organocatalysts which are systematically used in ≤3 mol% loading in all the sub-areas of the field, namely aminocatalysis, Brønsted acids and bases, Lewis acids and bases, hydrogen bond-mediated catalysis, phase transfer and N-heterocyclic carbene catalyses (194 references).

Toward the synthesis of norzoanthamine: building carbocyclic core by a transannular Michael reaction cascade

A 12-step synthesis of the ABC carbocyclic core of norzoanthamine is described. It features an organocatalytic asymmetric intramolecular aldolization to set the stereochemistry of the entire molecule, a fragment coupling by selective alkylation of a bis-enolate, and a transannular Michael reaction cascade for rapid and stereoselective synthesis of the polycyclic core.