Synthesis of 6- [4- [substituted - amino] phenyl] - 4,5 -dihydropyridazin-3 [H] ones as potential positive inotropic agents

A series of 6-[4-[substituted-amino]phenyl] pyridazinones and related compounds were synthesized and evaluated as inhibitors of cardiac cyclic AMP phosphodiesterase. Compounds 2c, 2d, 2h showed potent inhibitory activity and were found more potent than milrinone

Synthesis and reactions of 4,6-diaryl-2,3,4,5-tetrahydropyridazin-3-ones

The hitherto unknown 4,6 - diaryl - 2,3,4,5,- tetrahydro - pyridazin - 3-ones III a - e were synthesised from the alpha- aryl, beta-aroylpropionic acids II a-e either by their reaction with hydrazine hydrate or by their conversion to alpha, gamma-diaryl- delta beta, gamma - butenolides [XI], and treatment of the latter with hydrazine hydrate, III afforded 3-chloropyridazin derivative [IV] on its reaction with POCl[3], PCl[5]. The 3-chloropyridazine was treated either with sodium azide producing the tetrazolopyridazine derivative [V] or with acylhydrazines to give the triazolopyridazine derivatives [VI] a-c. 3-Acylpyridazines [VII] a and b were obtained on treatment of III with acetyl chloridies. Ill a was converted to its corresponding thione [VIII], also reacted with benzyl- amine giving 3-N-benzyIpyridazine [IX]. Ill a was dehydrogenated to the corresponding dihydropyridazinone [X]

Synthesis of some 1, 3, 4-oxadiazole derivatives having pyridazinyl-moiety as antimicrobial agents

Some derivatives of pyridazine are reported to exhibit broad spectrum biologic effect [1,2]. Moreover substituted 1,3,4-oxadiazoles have been mentioned to exert wide variety of application in medicine and agriculture[3,4]. On the basis of these findings we wish to report here the synthesis of some substituted [pyridazin-3-yl] thiomethyl, -1,3,4-oxadiazole derivatives and the evaluation of some of their antimicrobial activity. The starting material in this work is ethyl S-[substituted- pyridazin-3-yl] thioglycolate [II] which was obtained either by the reaction of the corresponding 3-thiopyridazine [I[a]] with ethyl chloroacetate [5] or the reaction of the corresponding 3-chloropyridazine [I[b]] with ethyl thioglycolate[6]. II [Ar = Ph, 'Ar = H] showed i.r. absorption bands at 1740 cm[-1] [ester c=o] and 1445 cm[-1] [S-CH2]. The [1] H-NMR spectrum of [II] showed signals at sigma1.2 [CH[3],t, 3H], sigma 4,2 [CH[2]m,4H] and sigma 7.5-8. 2 [Ar-H, m, 7H]. The hydrazides III were prepared by treating the ethyl ester [II] with hydrazine hydrate. Ill [Ar=Ph, R=H] showed i.r absorption bands at 3400-3210 cm[-1] [NH], 1660 cm[-1] [CONH amide 1] and 1390 cm[-1] [S-CH[2]]. The [1]H-NMR spectrum of compound III [Ar=Ph, R=H] showed signals at sigma 4.0 [CH[2],s, 2H], sigma 4.4 [NH, bs, 2H], sigma 7.5-8.2 [Ar-H, m, 7H] and sigma 9.4 [NH, s, 1H]. Mass spectrum of III [Ar=Ph, R=H] showed the following ion fragments m/z [Peak/relative abundance]: 260/20.3 [M[+]], 243/3.8, 201/3.16, 147/7.59, 105/14.87, 103/17.6, 77/100, 73/17.09, 56/29.11, 55/31.01 and 51/14.56