Pyrazolines and their pyrazole congeners are important heterocyclic building blocks with numerous applications in the fine chemical industries. However, traditional routes towards these entities based on multistep syntheses generating substantial amounts of waste. Here we report an alternative approach using UV-light to convert tetrazoles pyrazolines via a reagent-free photo-click strategy. Thi...

In the present investigation, series of Bis (heterocycle)s bearing pyrazoline in combination of the imidazole derivatives have been synthesized via 1,3-dipolar cycloaddition reactions of N-(nitrobenzyl)-imidazole nitrile imines with different dipolarophiles. All the newly synthesized compounds were characterized and screened for analgesic-anti-inflammatory activities and were compared with the ...

Density functional theory (DFT) calculations and experiments in tandem led to discoveries of new reactivities and selectivities involving bioorthogonal sydnone cycloadditions. Dibenzocyclooctyne derivatives (DIBAC and BARAC) were identified to be especially reactive dipolarophiles, which undergo the (3+2) cycloadditions with N-phenyl sydnone with the rate constant of up to 1.46 M-1 s-1. Most si...

A novel synthesis of 1,2-disubstituted 1,2-dihydroquinazoline 3-oxides 8 and the first ever examples of 1,3-dipolar trapping of these nitrones to homonuclear dipolarophiles is described. The new dipoles 8 reacted with N-methyl maleimide, generating diastereomeric adducts 14-16. In the reaction between 8 and dimethyl acetylenedicarboxylate, primary cycloadducts 17 and/or stable rearrangement pro...

The dipolar cycloaddition reactivity of N-(1-naphthy1)-1,4- benzoquinoneimine N-oxide and N-phenyl-1,4- naphthoquinoneimine Noxide are investigated, The latter gives the expected adducts with common dipolarophiles such as acrylonitryle, methyl methacrylate, dimethylacetylene dicarboxylate and N-phenylmaleimide. The reactivity of the former nitrone is found to be minimal. It undergoes, how...

Design and synthesis of pseudo-natural products (PNPs) through recombination natural product (NP) fragments in unprecedented arrangements enables the discovery novel biologically relevant chemical matter. With a view to wider coverage NP-inspired biological space, we describe combination this principle with macrocycle formation. PNP-macrocycles were synthesized efficiently stereoselective one-p...

The spirocyclic motif is present in natural products, chiral ligands, and compounds of pharmacological interest. Isothiocyanates as well isocyanides bearing electron-withdrawing groups the ?-position can be deprotonated react formal dipoles on account presence a nucleophilic carbanion an electrophilic atom isothiocyanate or isocyanide functional groups. In last years number procedures involving...

The regioselectivity of 1,3-dipolar cycloaddition reactions between mesoionic compounds with singly-tethered substituents is examined. The results with propitiate dipolarophiles are compared with other singly and doubly-tethered examples according to a model using an asynchronous, concerted transition state. The isolation and reaction of a novel, nonaryl substituted mesoionic compound 7 is repo...