Synthesis and antimicrobial activities of some new pyrazolines phenyl pyrazolines, flavanones and related compounds

Series of new 2-pyrazolines 4(a-g) and 1-phenyl-2-pyrazolines 5(a-g) have been synthesized from chalcones 3(a-g) by cyclocondensation with hydrazine hydrate and phenyl hydrazine. Chalcones 3(a-g) were synthesized by Claisen-Schmidt condensation of 3,5-di-tert-butyl-4-hydroxy benzaldehyde 1 with different ketones 2(a-g). Some of them exhibited two isomeric forms E & Z. o-Hydroxy chalcones on cyclization gave flavanone 6(a-c) derivatives. The products exhibited antimicrobial activities against Gram+ve bacteria.