The dipolar cycloadditions of ortho-nitrophenyl alkynes with aryl nitrile oxides has been demonstrated. A range of substituents are tolerated on the alkyne. These reactions proceed with excellent levels of regioselectivity. Subsequent functionalization of the isoxazole scaffold has been demonstrated.

New derivatives of d-xylose with aglycons of the most efficient glucose derived inhibitors of glycogen phosphorylase were synthesized to explore the specificity of the enzyme towards the structure of the sugar part of the molecules. Thus, 2-(β-d-xylopyranosyl)benzimidazole and 3-substituted-5-(β-d-xylopyranosyl)-1,2,4-triazoles were obtained in multistep procedures from O-perbenzoylated β-d-xyl...

N-Methylated amides (N,4-dimethylbenzamide and N-methylcyclohexanecarboxamide) were systematically subjected to chemical transformations, namely, N-tosylation followed by nucleophilic substitution. The amide function was converted to the corresponding carboxylic acid, esters, amides, aldehyde, and ketone upon treatment with hydroxide, alkoxide, amine, diisobutylaluminium hydride and Grignard re...

Novel 5α-androstanes containing an isoxazoline moiety condensed to ring A or D were efficiently synthetized by 1,3-dipolar cycloadditions of aryl nitrile oxides to steroidal α,β-unsaturated ketones. During the ring closures, regioisomers in which the O terminus of the nitrile oxide dipoles is attached to the β-carbon of the dipolarophile were formed in a stereoselective manner to furnish exclus...

A first example of organo-N-heterocyclic carbene (NHC) catalyzed click-type fast 1,3-dipolar cycloaddition of nitrile oxides with alkynes was developed for the regioselective synthesis of 3,5-di- and 3,4,5-trisubstituted isoxazoles. Triethylamine (Et(3)N) was employed as an effective base to generate both nitrile oxide and the organo-NHC catalyst in situ. This catalytic approach was used to att...

Isoxazoline analogues of artemisinin were obtained in low yield and low diastereoselectivity from the 1,3-dipolar cycloaddition of nitrile oxides. Alternatively, starting from the aldehyde 7, a number of transformations--Wittig reaction and reduction, Henry reaction and cyanohydrin formation--were achieved in significantly higher yields. In the cases where a new stereocenter was introduced this...

A rapid and simple procedure was devised for the synthesis of multifunctionalized cyclic β-amino esters and γ-amino alcohols via the 1,3-dipolar cycloaddition of nitrile oxides to β-aminocyclopentenecarboxylates. The opening of the isoxazoline reductive ring to the corresponding highly functionalized 2-aminocyclopentanecarboxylates occurred stereoselectively with good yields.