Propargyl Hydrazides as Useful Intermediates Leading to Pyrazoles via Reaction with Certain Electrophiles

Abstract

The reactions of propargyl hydrazides with certain electrophiles successfully led to the regioselective formation of various alkylated hydrazides. Reactions with electrophiles directly afforded the alkylated, chlorinated, brominated, and iodinated pyrazoles.

Sulfonyl Hydrazides in Organic Synthesis: A Review of Recent Studies

“…2‐Propargyl alcohols have numerous applications in organic synthesis. We want to discuss applications of these highly reactive reagents as alkynyl or allenic carbocations ( via a Meyer‐Schuster rearrangement) precursors in direct substitution by nucleophilic sulfonyl hydrazides. In the presence of a Lewis acid, alkynyl carbocations were generated and attacked by amino group.…”

“…64‐1). I 2 or NXS (X=Cl, Br, I) would constitute a novel approach to the synthesis of various halo‐3H‐pyrazoles (Eq. 64‐2,3).…”

Silica-zinc chloride (SiO2-ZnCl2) catalyzed Michael addition reaction of active methylene compounds to β-nitrostyrenes: Synthesis of functionalized pyrazole derivatives

“…Pyrazole derivatives were found with wide range of biological activities including antimicrobial agent 4 , tyrosine kinase-2 inhibitors 5 , insulin-like growth factor−1 receptor (IGF-1R) 6 , ataxia telangiectasia mutated (ATM) kinase inhibitors 7 , T−type calcium channel blockers 8 , p21-activated kinase inhibitors 9 , etc. Biological properties of pyrazole derivatives have inspired chemists to develop various synthetic methods that have been reported for the synthesis of pyrazole derivatives [10][11][12][13][14][15] but still there is a requirement for the new derivatives of pyrazoles to address the new challenging tasks.…”

Expedited Route to Fully Substituted Amino-Pyrazole Building Blocks and Their Further Transformations

“…14−25 Another strategy, recently reported, is based on copper catalyzed N–N bond formation of the pyrazole (Scheme 1, path b). 25 A third approach relies on the cycloaddition of a range of 1,3-dipoles with an alkyne or alkene. Among the dipoles involved, diazo compounds have found numerous applications, as have nitrilimines (generated in situ from halogenated hydrazoyles) and sydnones after CO 2 extrusion (Scheme 1, path c).…”

“…There are only a few strategies used to access the pyrazole scaffold . A first one is the formal intramolecular hydroamination of an alkyne with a tethered hydrazine derivative (Scheme , path a). − Another strategy, recently reported, is based on copper catalyzed N–N bond formation of the pyrazole (Scheme , path b) . A third approach relies on the cycloaddition of a range of 1,3-dipoles with an alkyne or alkene.…”