[3 + 2]-Cycloaddition of in Situ Generated Nitrile Imines and Acetylene for Assembling of 1,3-Disubstituted Pyrazoles with Quantitative Deuterium Labeling

Владимир Владимирович Воронин, Мария Сергеевна Ледовская, Евгений Гордеев, Константин Сергеевич Родыгин, Валентин Павлович Анаников

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49 Scopus citations

Abstract

A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylene from CaC 2 and water. Partitioning of the reactants improves the yields of desired pyrazoles up to 99% and simplifies their isolation to a simple procedure of solvent evaporation. The approach requires no complex equipment and utilizes inexpensive, safe, and easy to handle calcium carbide as a starting material. A model deuterium incorporation is carried out according to the developed methodology, producing a series of novel 4,5-dideuteropyrazoles with excellent deuterium enrichment. Theoretical calculations on reaction mechanism and characterization of possible intermediate structures were performed.

Original languageEnglish
Pages (from-to)3819-3828
Number of pages10
JournalJournal of Organic Chemistry
Volume83
Issue number7
DOIs
StatePublished - 6 Apr 2018

Scopus subject areas

  • Organic Chemistry

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