A dienamine-mediated enantioselective 1,3-dipolar cycloaddition catalyzed by a chiral prolinol silyl ether catalyst has been developed. Removal of the benzamide group of the intermediates could furnish chiral C-1 substituted tetrahydroisoquinolines (see scheme) in high yields and excellent stereoselectivities.

Amine-catalyzed enantioselective 1,3-dipolar cycloadditions of aldehydes to C,N-cyclic azomethine imines were developed. The reactions between diversely substituted C,N-cyclic azomethine imines and aldehydes proceeded smoothly in the presence of chiral prolinol silyl ether catalyst and gave the C-1-substituted tetrahydroisoquinolines in a highly stereoselective manner. These tetrahydroisoquinolines could be efficiently transformed to several other useful polycyclic frameworks.

We disclose an efficient route to synthesize 3,4-diunsubstituted coumarins through a cascade organocatalytic reaction. The reaction is catalyzed by using of a combination of benzylamine (10 mol-%) and triethylamine (10 mol-%). Various salicylaldehydes were tested, and the corresponding coumarin products were obtained in good to high yields under mild and metal-free reaction conditions.

Amine catalysis has emerged as a powerful and elegant method to construct diverse chiral scaffolds in asymmetric synthesis. However, amine-based non-asymmetric organocatalysis is still in its infancy. This Focus Review examines recent developments in amine-catalyzed non-asymmetric transformations based on enamine, iminium, di- or trienamine, and oxidative enamine catalysis.

A general, organocatalytic inverse-electron-demand [3+2] cycloaddition reaction between a range of carbonyl compounds and diazoacetates has been developed. This reaction is catalyzed by secondary amines as a “green promoter” to generate substituted pyrazoles with high levels of regioselectivity. It is noteworthy that this [3+2] cycloaddition reaction proceeds efficiently at room temperature with a simple and inexpensive catalyst. Considering the large variety and ready availability of the starting materials (e.g. ketones, β-ketoesters, β-diketones, and aldehydes), as well as the operational simplicity of this process, a convenient, practical, and highly modular pyrazole synthesis has been developed. We believe that this work will arouse more research interest in the organocatalytic synthesis of other biologically active heterocycles. Such studies are currently underway in our laboratory.

An enamine-catalyzed strategy has been utilized to fully promote the Huisgen [3+2] cycloaddition with a broad spectrum of carbonyl compounds and azides, thereby permitting the efficient assembly of a vast pool of highly substituted 1,2,3-triazoles. In particular, the employment of commonly used and commercially available carbonyl compounds has resulted in the introduction of a diverse set of functional groups, such as alkyl, aryl, nitrile, ester, and ketone groups, at the 1-, 4-, or 5-positions of the 1,2,3-triazole scaffold. This approach might be manipulated to access more useful and sophisticated heterocyclic compounds. Most significantly, the reaction process exhibits complete regioselectivity, with the formation of only one regioisomer.