Cycloaddition reactions of alkynes are elegant, atom-efficient transformations for the synthesis of carbo- and heterocycles, mostly aromatic, involving the construction of challenging skeletons of complex molecules. Therefore significant efforts have recently been devoted to the development of novel methodologies, efficient strategies and different catalytic systems to broaden the scope of thes...

A highly efficient and mild method for azido glycosylation of glycosyl β-peracetates to 1,2-trans glycosyl azides was developed by using inexpensive FeCl(3) as the catalyst. In addition, we demonstrated, for the first time, that FeCl(3) in combination with copper powder can promote 1,3-dipolar cycloaddition (click chemistry) of azido glycosides with terminal alkynes. Good to excellent yields we...

The first study of pseudo-bimolecular cycloaddition reaction dynamics in the gas phase is presented. We used femtosecond time-resolved photoelectron spectroscopy (TRPES) to study the [2+2] photocycloaddition in the model system pseudo-gem-divinyl[2.2]paracyclophane. From X-ray crystal diffraction measurements we found that the ground-state molecule can exist in two conformers; a reactive one in...

1,3-Dipolar cycloaddition reactions of azomethine ylides play an important role in the synthesis of highly substituted pyrollidines which are found in the structures of many important natural products and pharmaceuticals . Using this chemistry, four chiral centers can be created in a single step. The asymmetric version of this reaction has been tried both with achiral azomethine ylides and chir...

The potential energy surfaces of the cycloaddition reactions MO(4)(NC(5)H(5))(2) + C(60)→ MO(4)(NC(5)H(5))(2)(C(60)) (M = Fe, Ru, and Os) have been studied at the B3LYP/LANL2DZ level of theory. It has been found that there should be two competing pathways in these reactions, which can be classified as a [6,5]-attack (path A) and a [6,6]-attack (path B). Our theoretical calculations indicate tha...

The cycloaddition of azomethine ylides to [60]fullerene (C60) has been studied in ortho-dichlorobenzene (o-DCB) by evaluating the impact an ionic liquid (IL) additive. solvent effect addressed activation parameters and boosting microwave (MW) induced dielectric heating. IL additive plays a twofold role stabilizing dipolar ylide intermediate favoring retro-cycloaddition at high temperature regim...

The 1,3-dipolar cycloaddition of azides and activated alkynes has been used for site-selective labeling of biomolecules in vitro and in vivo. While copper catalysis has been widely employed to activate terminal alkynes for [3 + 2] cycloaddition, this method, often termed "click chemistry", is currently incompatible with living systems because of the toxicity of the metal. We recently reported a...

The 1,3-dipolar cycloaddition reaction (1,3-DC) has offered the opportunity to produce a wide range of heterocyclic compounds [1,2]. These compounds were used to prepare new molecules of crucial importance for both pharmaceutics and industry sector [3]. The application of 1,3-DC reactions in natural product synthesis is heavily dependent upon an understanding of the regioselectivity and chemios...

The cycloaddition of azides to alkynes is one of the most important synthetic routes to 1H-[1,2,3]-triazoles. Here a novel regiospecific copper(I)-catalyzed 1,3-dipolar cycloaddition of terminal alkynes to azides on solid-phase is reported. Primary, secondary, and tertiary alkyl azides, aryl azides, and an azido sugar were used successfully in the copper(I)-catalyzed cycloaddition producing div...