Catalytic C-C bond-forming multi-component cascade or domino reactions: pushing the boundaries of complexity in asymmetric organocatalysis

N-Heterocyclic carbene-catalyzed synthesis of functionalized 3-hydroxypyrrolidinones via a domino aza-Michael/aldol reaction

The reaction features a transition-metal-free approach, mild reaction conditions, as well as a simple procedure.

Synthesis of 4-quinolones, benzopyran derivatives and other fused systems based on the domino ANRORC reactions of (ortho-fluoro)-3-benzoylchromones

This method provides a valuable one-pot shortcut for the synthesis of 4-quinolones, benzopyran derivatives and other fused systems from (ortho-fluoro)-3-benzoylchromones.

Organocatalytic diastereoselective synthesis of chiral decalines through the domino Claisen–Schmidt/Henry reaction

General and operative domino Claisen–Schmidt/Henry (CS/H) reaction has been revealed to obtain highly substituted chiral decalines in good yields with excellent ees and des by using push–pull enamine catalysis.

Enantioselective construction of spiro-1,3-indandiones with three stereocenters via organocatalytic Michael-aldol reaction of 2-arylideneindane-1,3-diones and nitro aldehydes

Asymmetric domino reaction between 2-arylideneindane-1,3-dione and nitro aldehyde has been developed for the construction of an enantioenriched spiro-1,3-indandione framework with three stereocenters.

Synergistic Cu–amine catalysis for the enantioselective synthesis of chiral cyclohexenones

An unprecedented utilization of 1,3-acetonedicarboxylic acid as a 1,3-bis-pro-nucleophile and a reactive acetone surrogate in enantioselective catalysis has been reported.

Organocatalytic cascade reaction for the asymmetric synthesis of novel chroman-fused spirooxindoles that potently inhibit cancer cell proliferation

The enantioselective preparation of bioactive chroman-fused spirooxindoles is described. Compound 7e induced apoptosis and cell cycle arrest in MCF-7 cells by interfering with the p53–MDM2 interaction.

Organocatalytic asymmetric Michael addition of aldehydes and ketones to nitroalkenes catalyzed by adamantoyl l-prolinamide

A series of adamantoyl l-prolinamides have been synthesized.

Strategies for the asymmetric functionalization of indoles: an update

During the past four years, the research of new synthetic methodologies for the rapid construction of enantiomerically pure substituted indole has had a fruitful and important growth.

Gold and silver catalysis: from organic transformation to bioconjugation

A summary of gold (including AuNPs, Au(i) and Au(iii) complexes) and silver(i) catalysis and their application in bioconjugation reactions.

l-Cysteine functionalized magnetic nanoparticles (LCMNP): a novel magnetically separable organocatalyst for one-pot synthesis of 2-amino-4H-chromene-3-carbonitriles in water

Magnetic nanoparticles were functionalized with l-cysteine using a new and efficient method and introduced as a novel magnetically separable organocatalyst.

Synthesis of functionalized tryptamines by Brønsted acid catalysed cascade reactions

A new solvent-free Brønsted acid catalysed cascade reaction has been established, allowing access to highly substituted tryptamines under mild conditions.

Stereoselective synthesis of epoxyisoprostanes: an organocatalytic and “pot-economy” approach

An efficient and direct synthetic route to epoxyisoprostane EC methyl ester has been accomplished in 8 steps (10% overall yield) from readily available starting materials using a series of asymmetric organocatalytic reactions and one-pot operations.

Diversity oriented synthesis of tri-substituted methane containing aminouracil and hydroxynaphthoquinone/hydroxycoumarin moiety using organocatalysed multicomponent reactions in aqueous medium

One-pot multicomponent reaction of aldehyde, 1,3-dimethyl-6-aminouracil and 2-hydroxy-1,4-naphthoquinone/4-hydroxycoumarin using a bifunctional thiourea-based organocatalyst in aqueous medium has been reported.

Terpenoid biosynthesis off the beaten track: unconventional cyclases and their impact on biomimetic synthesis

Terpene and terpenoid cyclizations are counted among the most complex chemical reactions occurring in nature and contribute crucially to the tremendous structural diversity of this largest family of natural products. Many studies were conducted at the chemical, genetic, and biochemical levels to gain mechanistic insights into these intriguing reactions that are catalyzed by terpene and terpenoid cyclases. A myriad of these enzymes have been characterized. Classical textbook knowledge divides terpene/terpenoid cyclases into two major classes according to their structure and reaction mechanism. However, recent discoveries of novel types of terpenoid cyclases illustrate that nature's enzymatic repertoire is far more diverse than initially thought. This Review outlines novel terpenoid cyclases that are out of the ordinary.

Asymmetric synthesis of tetrahydropyridines via an organocatalytic one-pot multicomponent Michael/aza-Henry/cyclization triple domino reaction

A low loading of a quinine-derived squaramide efficiently catalyzes the triple-domino Michael/aza-Henry/cyclization reaction between 1,3-dicarbonyl compounds, β-nitroolefins, and aldimines to provide tetrahydropyridines bearing three contiguous stereogenic centers in good yields, excellent enantiomeric excesses, and up to high diastereomeric ratios.

The ever-expanding role of asymmetric covalent organocatalysis in scalable, natural product synthesis

Following the turn of the millennium, the role of asymmetric covalent organocatalysis has developed into a scalable, synthetic paradigm galvanizing the synthetic community toward utilization of these methods toward more practical, metal-free syntheses of natural products. A myriad of reports on asymmetric organocatalytic modes of substrate activation relying on small, exclusively organic molecules are delineating what has now become the multifaceted field of organocatalysis. In covalent catalysis, the catalyst and substrate combine to first form a covalent, activated intermediate that enters the catalytic cycle. Following asymmetric bond formation, the chiral catalyst is recycled through hydrolysis or displacement by a pendant group on the newly formed product. Amine- and phosphine-based organocatalysts are the most common examples that have led to a vast array of reaction types. This Highlight provides a brief overview of covalent modes of organocatalysis and applications of scalable versions of these methods applied to the total synthesis of natural products including examples from our own laboratory.

Synthesis of Novel Spiro[Cyclopropane-Indazole] Derivatives Via Magnesium-Mediated Conjugate Addition of Bromoform

A novel series of 2,2-dibromo-3-aryl-1'-phenyl-6’,7'-dihydrospiro[cyclopropane-1,5'-indazol]-4'(1' H)-ones derivatives were prepared in moderate to good yields by conjugate addition of bromoform to ( E)-5-arylmethylene-1-phenyl-6,7-dihydro-1 H-indazol-4(5 H)-ones in the presence of magnesium under N2. The structures of all the products were characterised by 1H NMR, 13C NMR, IR spectroscopy, elemental analysis and mass spectrometry.

One-step synthesis of diazaspiro[4.5]decane scaffolds with exocyclic double bonds

Unactivated yne-en-ynes reacted with a range of substituted aryl halides in the presence of Pd(OAc)2-PPh3 to afford diazaspiro[4.5]decane with exocyclic double bonds. Three carbon-carbon bonds are formed in this domino reaction, which involves highly regioselective C-C coupling and spiro scaffold steps.

Asymmetric synthesis of highly functionalized tetrahydropyrans via a one-pot organocatalytic Michael/Henry/ketalization sequence

A diastereo- and enantioselective Michael/Henry/ketalization sequence to functionalized tetrahydropyrans is described. The multicomponent cascade reaction uses acetylacetone or β-keto esters, β-nitrostyrenes, and alkynyl aldehydes as substrates affording tetrahydropyrans with five contiguous stereocenters. Employing a bifunctional quinine-based squaramide organocatalyst, the title compounds are obtained in moderate to good yields (27-80%), excellent enantiomeric excesses (93-99% ee), and high diastereomeric ratios (dr > 20:1) after one crystallization.