Pyrazoline enamines-Synthesis and characterization of some conjugated enamino ketones derived from 3-acetyl-4-aryl-2-pyrazolines

摘要

A series of new acyclic and cyclic pyrazoline enamines (3 and 4) have been obtained starting from benzalacetones (1) through the corresponding 2-pyrazolines (2). Structures of the products have been established by spectroscopic data. Enamines are versatile synthetic intermediates, and conjugated enamino ketones exhibit the properties of enamines, ketones, amines and vinylogues of amides. Enamino ketones obtained from simple amines are reported to possess bactericidal, fungicidal and insecticidal activities. Pyrazolines are also. known to exhibit antimicrobial and insecticidal properties. It is therefore expected that pyrazoline enamines would display more potent antimicrobial activity. Further, enamines derived from 2-pyrazolines have not been studied in detail so far. In view of the above, we report herein the hitherto unknown acyclic and cyclic pyrazoline enamines (3 and 4).