title: Synthesis of Functionalized Pyrazoles via 1,3-Dipolar Cycloaddition of α-Diazo-β-ketophosphonates, Sufones and Esters with Electron-Deficient Alkenes.
abstract: 1,3-Dipolar cycloaddition of diazo compounds with olefinic substrates is a promising atom-economic strategy for the construction of functionalized pyrazoles. Over the last few years, our group has been engaged in the synthesis of phosphonyl/sulfonylpyrazoles and pyrazole esters by employing Bestmann-Ohira Reagent (BOR) and its sulfur and ester analogs as 1,3-dipole precursors with various dipolarophiles. This account describes the novel synthetic methods developed in our laboratory, in the perspective of closely related work by others, for the synthesis of phosphonyl/sulfonylpyrazoles, pyrazole esters and the total synthesis of Withasomnine, a natural product, by using 1,3-dipolar cycloaddition as the key step.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India.
authors.forename: T V
authors.initials: TV
authors.lastname: Baiju
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India.
authors.forename: Irishi N N
authors.initials: INN
authors.lastname: Namboothiri
keywords: 1,3-Dipolar cycloaddition; Bestmann-Ohira reagent; Diazo compounds; Pyrazole; Withasomnine