Diamine-mediated N2-selective β-selenoalkylation of triazoles with alkenes

Calcium(II)-Mediated Three-Component Selenylation of gem-Difluoroalkenes: Access to α,α-Difluoroalkyl-β-selenides

A calcium-mediated three-component selenylation of gem-difluoroalkenes using alcohols as nucleophiles and N-(phenylseleno)phthalimide as the selenylation agent has been developed for the efficient synthesis of various α,α-difluoroalkyl-β-selenides. This selenylation reaction exhibits broad substrate and functional group tolerance, along with high levels of chemo- and regioselectivity. Additionally, the synthetic utility of the developed transformation in the late-stage functionalization of drug molecules was demonstrated.

Calcium(II)-Mediated Three-Component Selenofunctionalization of Alkenes under Mild Conditions

A mild and general protocol involving amnio- and oxyselenation of diverse alkenes for the efficient synthesis of organo-Se compounds is achieved via an environmentally benign calcium-catalyzed three-component reaction. This selenofunctionalization reaction exhibits excellent substrate/functional group tolerance and high levels of chemo- and regioselectivity. Its utility was exemplified in the late-stage functionalization and even aggregation-induced emission luminogen labeling of organo-Se compounds.

Silver-Catalyzed Cascade Cyclization of Amino-NH-1,2,3-Triazoles with 2-Alkynylbenzaldehydes: An Access to Pentacyclic Fused Triazoles

An operationally simple Ag(I)-catalyzed approach for the synthesis of isoquinoline and quinazoline fused 1,2,3-triazoles was developed by a condensation and amination cyclization cascade of amino-NH-1,2,3-triazoles with 2-alkynylbenzaldehydes involving three new C-N bond formations in one manipulation, in which the group of -NH of the triazole ring serves as a nucleophile to form the quinazoline skeleton. The efficient protocol can be applied to a variety of substrates containing a range of functional groups, delivering novel pentacyclic fused 1,2,3-triazoles in good-to-excellent yields.

N2-Selective β-Thioalkylation of Benzotriazoles with Alkenes

Herein, N²-selective β-thioalkylation of benzotriazoles with unactivated alkenes and styrenes is reported. The N²-selective β-thioalkylation of benzotriazoles is highly stereospecific and works under simple and mild conditions, exhibiting excellent functional group tolerance. The high N²-selectivity is a consequence of the combination of hydrogen bonding and Lewis acid/base activation, which reverses the N²-position to be favored for alkylation.

Synthesis of β-Arylseleno Sulfoximines: A Metal-Free Three-Component Reaction Mediated by Tetrabutylammonium Tribromide

A tetrabutylammonium tribromide-mediated three-component reaction of alkenes, diselenides, and sulfoximines has been established herein, providing direct and metal-free access to diverse β-arylseleno sulfoximine derivatives. This regioselective sulfoximido-selenization protocol proceeds efficiently under mild and ambient conditions with generally good yields. This strategy is featured by step and atom economy, practicability, a broad substrate scope, and gram-scale synthesis.

Recent Developments in N2-Selective Functionalizations of 1,2,3-Triazoles

The widespread use of 1,2,3-triazole compounds in drugs has resulted in a great interest in the efficient synthesis of N2-substituted 1,2,3-triazoles via post triazole functionalization methods. At present, there are many methods for the synthesis of N1-substituted 1,2,3-triazole compounds, but the development of convenient methods for the N2-selective functionalization of 1,2,3-triazoles remains challenging. In general, the greater stability of the N1 tautomer makes the N2 position a non-preferable reactive site, which has limited the application of 1,2,3-triazoles. In this review, we summarized advances in the direct N2-selective functionalization of 1,2,3-triazoles since 2008.

1 Introduction

2 N2-Alkylation

3 N2-Allylation

4 N2-Propargylation

5 N2-Alkenylation

6 N2-Alkynylation

7 N2-Arylation

8 Conclusions and Outlook