Reactivity of <i>p</i>‐phenyl substituted β‐enamino compounds using k‐10/ultrasound. I. synthesis of pyrazoles and pyrazolinones

Abstract

Abstract The reactivity of the β‐enamino ketones, 3‐amino‐1‐( p ‐phenyl‐substituted)‐2‐buten‐1‐ones 1a‐d and β‐enamino esters. Ethyl‐3‐amino‐3‐( p ‐phenyl‐substituted)‐2‐propenoates 5a‐d were evaluated by systematic studies of the reactions with hydrazine and methylhydrazine by reactions with solid support K‐10/ultrasound and homogeneous media (reflux in ethanol or dichloromethane) yielding pyrazole rings 2a‐d , N ‐methylpyrazoles 3a‐d, 4a‐d and N ‐methylpyrazolinones 6a‐c and 7a‐c . The regiochemistry of the cyclization showed dependence of the reaction conditions employed as well as the substituent in the aromatic ring.