Synthesis of 3-carbonyl pyrazole-5-phosphonates via 1,3-dipolar cycloaddition of Bestmann–Ohira reagent with ynones

Synthesis of Novel Pyrazole–sucrose Derivatives by 1,3‐dipolar Cycloaddition

“…However, regiochemical assignments of all adduct were deduced from their 13 C-NMR spectra. In particular, the chemical shifts of C-5 are in excellent agreement with those usually obtained when this quaternary carbon is attached to nitrogen atom [19].…”

Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

“…The 1,3‐dipolar cycloaddition of BOR 2 using dipolarophiles such as ynones 36 was investigated by Rastogi et al . Various carbonyl functionalized pyrazole phosphonates 37 were synthesized by conducting the reaction with ynones containing different aryl, heteroaryl and alkyl substituents (Scheme 11b).…”

“…Various carbonyl functionalized pyrazole phosphonates 37 were synthesized by conducting the reaction with ynones containing different aryl, heteroaryl and alkyl substituents (Scheme 11b). Subjecting the ene‐ynone 38 as dipoarophile with BOR 2 under the established conditions provided the pyrazole derivative 39 in which the enone moiety took part in cycloaddition and the triple bond underwent Michael addition with the methoxide base generated in the reaction medium (Scheme 11c) . The anticipated double 1,3‐cycloaddition was not observed which is probably due to the steric inhibition at the triple bond of the cycloadduct.…”

“…To test the reactivity of bis‐ynone 40 , the substrate derived from terephthalic acid was also employed in 1,3‐dipolar cycloaddition with BOR under the similar reaction conditions. Analogous to ene‐ynone, one of the acetylenic unit was engaged in cycloaddition reaction and the other acetylenic part underwent Michael addition to afford the pyrazole derivative 41 (Scheme 11d) …”

Synthesis and Antimicrobial Activity of Pyrazolyl Triazoles

“…Thus molecules with azole motif in different pharmacological agents have made it an indispensible anchor for the articulation of new drugs. The pyrazoles were prepared by the reaction of hydrazines with 1,3-dicarbonyl compounds [6,7] and ynones [8]. Moreover, 1,3-dipolar cycloaddition of nitrile imines and diazoalkanes to alkynes produced pyrazoles [9].…”