Highly Stereoselective Synthesis of Trisubstituted Cyclohexanols Using a Guanidine-Catalyzed Tandem Henry–Michael Reaction

Critical trends in synthetic organic chemistry in terms of organocatalysis

The utilization of small organic compounds as catalysts has advanced rapidly, and organocatalysis has emerged as a dominant technique complementary to metal-catalyzed organic conversions. The organocatalysis field has enhanced the progression of innovative approaches to make varied chiral molecules. Researchers have placed enormous effort towards designing and blending simpler organocatalysts to synthesize enantioselective molecules in good yields. This work emphasized the impact of enamine, iminium, hydrogen bonding, and phase transfer organocatalysts in organic synthesis. The monograph focused on the crucial methods to construct valuable molecules with high enantiomeric purity.

Catalysts’ evolution in the asymmetric conjugate addition of nitroalkanes to electron-poor alkenes

This review provides a journey of the catalyst usage for the enantioselective conjugate addition of nitroalkanes to electron-poor olefins from the early attempts to the latest achievements. Selected applications are also reported.

Synthesis of spiro-tetrahydrothiopyran-oxindoles by Michael–aldol cascade reactions: discovery of potential P53-MDM2 inhibitors with good antitumor activity

Novel one-pot Michael–aldol cascade reactions were used to efficiently construct spiro-tetrahydrothiopyran-oxindoles with good in vitro antitumor activity.

The chemistry and biology of guanidine natural products

The present review discusses the isolation, structure determination, synthesis, biosynthesis and biological activities of secondary metabolites bearing a guanidine group.

Stereoselective synthesis of spirooxindole derivatives using an organocatalyzed tandem Michael–Michael reaction

A highly efficient and stereoselective method for the synthesis of functionalized spirooxindole derivatives was realized using enamine catalysis.

Organocatalytic 1,4-Addition Reaction of 2-Formyl(thio)esters to Vinylketones: An Efficient Access to Acyclic Chiral Building Blocks with a Quaternary Carbon Stereocenter

2-Formyl(thio)esters were utilized as pronucleophiles to obtain less-accessible acyclic chiral building blocks bearing versatile functional groups on a quaternary carbon atom for enantioselective 1,4-addition to vinylketones. To achieve high enantioselectivity in the present 1,4-addition reaction, thiourea-tertiary amines containing a bulky chiral backbone were developed as catalysts, and several derivatizations of the products were performed to demonstrate the synthetic utility of the products.

Higher-Order Cyclopropenimine Superbases: Direct Neutral Brønsted Base Catalyzed Michael Reactions with α-Aryl Esters

The synthesis and characterization of six new classes of higher-order superbases, including five that incorporate cyclopropenimine functionality, has been achieved. We propose a nomenclature that designates these as the CG2, GC2, PC3, PC1, C3, and GP2 classes of superbases. The pK(BH+) values were measured to be between 29.0 and 35.6 in acetonitrile. Linear correlations of ten superbase basicities vs that of their substituents demonstrated the insulating effect of the cyclopropenimine core. The molecular structures of several of these materials were obtained by single-crystal X-ray analysis, revealing interesting aspects of conformational bias and noncovalent organization. The types of superbasic cores and substituents were each reliably shown to affect selectivity for deprotonation over alkylation. Higher-order cyclopropenimine and guanidine superbase stability to hydrolysis was found to correlate to basicity. Finally, a GC2 base was found to catalyze conjugate additions of α-aryl ester pronucleophiles, representing the first report of a neutral Brønsted base to catalyze such reactions.

Synthesis and characterization of bis(amidate) rare-earth metal amides and their application in catalytic addition of amines to carbodiimides

Five bis(amidate) rare-earth metal amides were successfully employed in guanidination, and the Nd-based catalyst showed the highest reactivity.

(2S,5R)-2-Methylaminomethyl-1-methyl-5-phenylpyrrolidine, a chiral diamine ligand for copper(ii)-catalysed Henry reactions with superb enantiocontrol

Copper(ii)-complexes of a cis-2-aminomethyl-5-phenylpyrrolidine catalyse enantioselective Henry reactions with extraordinarily high stereocontrol.