607. Pyridazines. Part II. The action of grignard reagents on 6-aryl-2,3,4,5-tetrahydro- and -2,3-dihydropyridazin-3-ones

Abstract

By F. G. BADDAR, A. EL-HABASHI, and A. I<. FATEEN 6-Aryl-2,3,4,5-tetrahydropyridazin-3-ones react with phenyl-and 9-anisylmagnesium bromide to give 3,6-diaryl-4,5-dihydropyridazines, which are spontaneously dehydrogenated to 3,6-diarylpyridazines. 6-Aryl-2,3-dihydropyridazin-3-ones, prepared by dehydrogenation of 6-aryl-2,3,4,5-tetrahydropyridazin-3-ones by bromine in acetic acid, react with phenylmagnesium bromide to give (i-aryl-2,3,4,5-tetrahydro-4-phenylpyridazin-3-ones. Thc structures assigned to thc products arc established by ultraviolet, infrared, and n.m.r. spectroscopy. 6-ARYL-2,3,4,5-TETRAHk7DROPYRIDAZIK-3-ONES (Ia, b, c, and d) react with phenyl-and fi-anisyl-magnesium bromide to give 3-aryl-6-phenyl-(IVa, b, c, and d) and 3-P-anisyl-6-arylpyridazines (IVc, e, f, and g), respectively. The product (IVc) obtained by the action of phenylmagnesium bromide on 6-P-anisyl-2,3,4,5-tetrahydropyridazin-3-one (Ic) is identical with that obtained by the action of 9-anisylmagnesium bromide on 2,3,4,,5tetrahydro-6-phenylpyridazin-3-one (Ia) .The infrared spectra of the products lack the bands characteristic of OH, NH, and CO groups. This indicates that the reaction takes place by addition to the carbonyl group followed by elimination of water. Analytical data, however, indicate that these products have lost two hydrogen atoms, i.e., they are pyridazines (IV) rather than 4,5-dihydropyridazines (111). The similarity of these compounds in their ultraviolet spectra (in ethanol) indicates that they all possess identical structures; their spectra are also very similar to that of terphenyl (Table 1).

Synthesis of some new pyridazin‐3‐one derivatives and their utility in heterocyclic synthesis

“…This prompted us to synthesize a new series of heterocyclic pyridazinone derivatives through the reaction of 4-(p-bromophenyl) or 4-(p-methylphenyl)-4-oxo-2-butenoic acid 1a,b [12] with benzylamine in dry benzene and yielded the addition products 2a,b. The latters were reacted with hydrazine hydrate in ethanol to give the unexpected pyridazin-3-one derivatives 3a,b, respectively, rather than the expected 4,5-dihydropyridazin-3(2H)-one derivatives 4a,b.…”

Novel 3‐Arylamino‐ and 3‐Cycloalkylamino‐5,6‐diphenyl‐pyridazines Active as ACAT Inhibitors.

“…General method for the synthesis of compounds 1 a-p A mixture of 3-chloro-5,6-diphenylpyridazine [9] (1 mmol) and the appropriate amine (2 mmol) was heated at 140°C in a sealed tube for a time ranging from 2.5 to 48 hours, depending on the nature of the amine. After cooling, the mixture was poured onto water and extracted with CH 2 Cl 2 (3 × 20 mL).…”

“…The compounds were prepared from 3-chloro-5,6diphenylpyridazine [9] by heating at 140°C in a sealed tube with the appropriate amine in a molar ratio of 1:2. Usual workup gave the desired compounds which were finally crystallized from an appropriate solvent (see Scheme 1).…”

5,6-Diphenylpyridazine Derivatives as Acyl-CoA:Cholesterol Acyltransferase Inhibitors

“…On these bases we report here the synthesis and biological properties of new compounds (2, 3, 5, 7-10) which combine some of the characteristics of the reported ACAT inhibitors, namely a long alkylic side chain linked to a heterocyclic ring by a heteroatom of different nature and the o-diphenyl system. Chemistry 2-Substituted-5,6-diphenylpyridazin-3(2H)-ones (2) were obtained from 1 17 by alkylation with the appropriate bromo derivative in dimethylformamide and in the presence of anhydrous potassium carbonate. Alkaline hydrolysis of the ester 2k-m and subsequent acidification led to the corresponding acids 3a-c.…”