Highly stereoselective synthesis of 1-cyanocyclopropane-carboxamides from 3-substituted-2-cyanoacrylamides with N -tosylhydrazones under metal-free conditions

Copper-catalyzed reactions of α,β-unsaturated N-tosylhydrazones with diaryliodonium salts to construct N-arylpyrazoles and diaryl sulfones

Herein, an economical copper-catalyzed reaction of α,β-unsaturated N-tosylhydrazones with diaryliodonium salts to construct both N-arylpyrazoles and diaryl sulfones has been developed. Both the p-toluenesulfonyl anion and the 3-arylpyrazole intermediates were formed in situ from N-tosylhydrazones. Subsequently, the former reacted rapidly with diaryliodonium salts to give diaryl sulfones and aryl iodide intermediates, and the latter reacted with aryl iodide to give N-arylpyrazoles under copper-catalyzed conditions. Using unsymmetrical mesityl phenyliodonium salts as substrates, mesityl p-toluenesulfide was obtained as the major product. This reaction took full advantage of the "waste" part of substrates to form an extra diaryl sulfone.

The intramolecular reaction of acetophenone N-tosylhydrazone and vinyl: Brønsted acid-promoted cationic cyclization toward polysubstituted indenes

In the presence of TsNHNH2, a Brønsted acid-promoted intramolecular cyclization of o-(1-arylvinyl) acetophenone derivatives was developed, leading to polysubstituted indenes with complexity and diversity in moderate to excellent yields. In sharp contrast with either the radical or carbene involved cyclization of aldehydic N-tosylhydrazone with vinyl, a cationic cyclization pathway was involved, where N-tosylhydrazone served as an electrophile and alkylation reagent during this transformation.

A base-promoted cascade reaction of α,β-unsaturated N-tosylhydrazones with o-hydroxybenzyl alcohols: highly regioselective synthesis of N-sec-alkylpyrazoles

An efficient method for the synthesis of N-sec-alkylpyrazoles via a cascade reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed.