"Use of 4,5-dihydropyridazinones in the synthesis of heterocycles and their derivatives"

Abstract

The present investigation deals with the base-catalyze condensation of Q-methoxybenzaldehyde with 6-aryl-4,5-dihydro­ pyridazin-3(2H)-ones(115) to give the corresponding products 6- aryl-4(Q-methoxyphenylmethyl)pyridazin-3(2H)-ones(116) which were synthesised easily by the reaction of Q-methoxy benzaldehyde with 13-aroylpropionic acid under Perkin conditions to give the corresponding lactones followed by the reaction of hydrazine hydrate with these lactones in the presence of alkali.

Treatment of 6-aryl-4-(Q-methoxyphenylmethyl) pyrida­ zin-3(2H) ones(116) with phosphorus oxychloride produced 6- aryl-4-(Q-methoxyphenylmethyl)3-chloropyridazines (117) which react with thiourea to give 6-aryl-4-(Q-methoxyphenylmethyl) pyridazin-3 (2H)-thiones (118).

The latter thiones were prepared from the action of P2 S5 in xylene on the corresponding pyridazin-3(2H)-ones (116).

6-Aryl-4-(Q-methoxyphenylmethyl)pyridazin-3(2H)-thiones (118) react with hydrazine hydrate by fusion to give the corresponding pyridazine derivatives (119), the latter compounds react with benzaldehyde to give the corresponding derivatives (120). However treatment of 6-aryl-4-(Q-methoxyphenylmethyl)3-chlor­ opyridazines (117) with hydrazine hydrate by fusion yielded the corresponding derivatives (121) which are different from (119).

6-Aryl-4-(Q-methoxyphenylmethyl) pyridazin-3(2H)-thiones(ll8) in the mercapto form react with dimethyl sulphate in presence of sodium hydroxide to give the corresponding 3-methyl­ thiopyridazine derivatives (122), however it react in the thione form (118) with dimethylsulphate in presence of anhydrous potassium carbonate to give (123).

Treatment of6-aryl-4-(Q-methoxyphenylmethyl)pyridazin- 3(2H)-thions . (118) with ethylchloroacetate in presence of anhydrous potassium carbonate yielded the mercaptopyridazine derivatives (124 ).

The latter esters (124) react with hydrazine hydrate to give the corresponding hydrazide derivatives (125).

Finally 6-aryl-4-(Q-methoxyphenylmethyl)pyridazin-3(2H)­ thiones (118) reacts with thiourea to give the corresponding derivatives (126), which reacts with benzaldehyde to give (127).