Cyclocondensation of Alkylhydrazines and β-Substituted Acetylenic Esters: Synthesis of 3-Hydroxypyrazoles

Article abstract of DOI:10.1021/jo00047a021

Addition of monosubstituted alkylhydrazines to acetylenic esters with either electron-withdrawing or sterically bulky β-substituents afforded 1-alkyl-3-hydroxy-5-substituted-pyrazoles 1 as the major regioisomeric product.By comparison, the classical cyclo