The detection of free radicals and related species has attracted significant attention in recent years because of their critical roles in physiological and pathological processes. Among the methods for the detection of free radicals, electron spin resonance (ESR) coupled with the use of the spin trapping technique has been an effective approach for characterization and quantification of these s...

Simplification of caprazamycins, which are promising antibacterial nucleoside natural products, was conducted by scaffold-hopping of the structurally complex diazepanone moiety to the isoxazolidine scaffold. The designed isoxazolidine-containing uridine derivatives were synthesized by an intramolecular 1,3-dipolar cycloaddition of alkenyl nitrone as a key step. The lactone-fused isoxazolidine i...

Two diastereoisomers of the title compound, C(25)H(26)N(2)O, have been prepared by cyclo-addition between 1,3,3-trimethyl-2-methyl-eneindoline and C-phenyl-N-phenyl-nitrone. The stereochemistry of the major diastereoisomer, viz. S,R/R,S, is confirmed by the X-ray analysis. The oxazole and the pyrole rings have envelope conformations. The packing is stabilized by weak C-H⋯π inter-actions involvi...

Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza-cyclooctynone (BARAC) proceed with rate constants up to 47.3 M(-1) s(-1), this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne-nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free ener...

Regioselective additions of pyrroles to a variety of optically active nitrones under smooth acidic conditions lead to chiral pyrrolic N-hydroxylamines in good to excellent yields. Depending on the position of the chirality on the nitrone partner, the addition products have been isolated with high diastereoselectivity levels. Reaction of glyoxylate based chiral nitrones either at the C-2 or at t...

The direct C-H annulation of anilines or related compounds with internal alkynes provides straightforward access to 2,3-disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3-diaryl substituted indoles. Herein, we report the rhodium(III)-catalyzed C-H annulation of nitrones with symmetrical diaryl alkynes as an alt...