Direct functionalization of 4,5-dichloropyridazin-6-one

Direct functionalization of 4,5-dichloropyridazin-6-one with some nucleophiles in seven solvents gave regioselectively 5-halo-4-substituted-pyridazin-6-ones as main product. Reaction of 4,5-dichloropyridazin-6-one with 2-mercaptopyrimidine (2 equivalents) also afforded 4,5-di(pyrimidin-2-ylsulfanyl)pyridazin-6-one as the main product.     

Synthesis of 4,5-dichloro-1-(4,5-dichloropyridazin-3-yl)pyridazin-6-one

This paper presents the synthesis of 4,5-dichloro-1-(4,5-dichloropyridazin-3-yl)pyridazin-6-one from 4,5-dichloropyridazin-6-one.     

Reaction of 4,5-dichloro-3-nitropyridazin-6-one with dimethylchloromethyleneammonium chloride

3,4,5-Trichloropyridazin-6-one, 3,4,5,6-tetrachloropyridzine and 4,5-dichloro-3-(N,N-dimethylamino)-pyridazin-6-one were synthesized from 4,5-dichloro-3-nitropyridazin-6-one and dimethylchloromethylene-ammonium chloride selectively.     

Alkylation of 4,5-dichloropyridazin-6-one with α,ω-dibromoalkanes or 4,5-dichloro-1-(ω-bromoalkyl)pyridazin-6-ones

Alkylations of 4,5-dichloropyridazin-6-one (1) with dibromoalkanes 2 or 3 in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide were investigated under restricted condition. Reactions of 1 with 2 or 3, except for 2b and 3b , in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide gave only the N-alkylation products 3 and/or 4. Alkylation of 1 with 2b or 3b in the presence of potassium carbonate yielded the N-alkylation products 3b and/or 4b and the O-alkylation product 5 as the main product, whereas treatment of 1 with 2b or 3b in the presence of tetrabutylammonium bromide/potassium hydroxide afforded selectively the N-alkylation products 3b and/or 4b.     

Retro-ene reaction. II. Reaction of 4,5-dichloro-1-hydroxy-methylpyridazin-6-one with alkyl halides and carboxylic acid chlorides

1-Alkyl-4,5-dichloropyridazin-6-oncs and (4,5-dichloro-6-oxopyridazin-1-yl)methylcarboxylates were synthesized from 4,5-dichloro-1-hydroxymethylpyridazin-6-one and the corresponding alkyl halides or carboxylic acid chlorides. Also the reaction mechanisms via a fragmentation of retro-ene type are discussed.     

A Novel Photochemical Reaction of 4-Bromo-3-methyl-1- phenyl-4,5-dihydro-pyrazol-5-one

UV-Irradiation of 4-bromo-3-methyl-l-phenyl-4,5-dihydro-pyrazol-5-one (1) in the presence of various aromatic hydrocarbons gave different types of photoproducts depending on the nature of the hydrocarbons via an electron-transfer mechanism. In the presence of naphthalene or phenanthrene a photochemical homocoupling reaction of 1 occurred to form 2 or 2 and 3, respectively.     

Reaction of 6-methyl-6-p-tolyl-4-ethoxy-5,6-dihydro-pyran-2-one1 with perchloric acid

6-Methyl-6-p-tolyl-4-ethoxy-5,6-dihydro-pyran-2-one (1) undergoes decarboxylative elimination with perchloric acid in ether to give 4-p-tolyl-3-penten-2-one (3), the structure of which has been confirmed through an unambiguous synthesis.

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Reaktion von 6-Methyl-6-p-tolyl-4-ethoxy-5, 6-dihydro-pyran-2-on mit PerchlorsäureKurze Mitteilung

Zusammenfassung Die Titelverbindung (1) ergibt mit Perchlorsäure unter decarboxylierender Eliminierung 4-p-Tolyl-3-penten-2-on (3). Die Struktur von3 wurde mittels eines eindeutigen Syntheseweges festgelegt.

     

A Convenient Synthesis of 7,9,9-Trimethyl-1-oxaspiro[4,5]-6-decen-2-one

The allylic lactone 1 was prepared from the reaction of lithium 3-lithiopropanoate (5) with isophorone (3) followed by mild acid treatment of the hydroxy acid adduct.     

Isothiazoles VI: 4,5-dihaloisothiazolidin-3-one 1-Oxides

A useful and facile procedure for preparing 4,5-dihaloisothiazolidin-3-one 1-oxides is reported. Chlorination or bromination of various 4-isothiazolin-3-one 1-oxides yielded the title compounds.     

Reaction of 3-methoxy-17-methylmorphinan-6-one with formaldehyde

Reaction of 3-methoxy-17-methylmorphinan-6-one ( 1 ) and formaldehyde with the presence of calcium hydroxide in aqueous dioxane gave 7,7-bis(hydroxymethyl)-3-methoxy-17-methyl-5-methylenemorphinan-6β-ol ( 2a ). Catalytic reduction of 2a yielded the 5α-methyl compound, 2b . Tosylation of 2a,b followed by lithium triethylborohydride reduction gave either 7α-methyl-6β,7β-oxetanes 4a,b or 7,7-dimethyl-6β-ols 5a,b , depending on reaction conditions. The C-6 ketones 6a,b were prepared by oxidation of 5a,b . One compound in this series, 6a , had antinociceptive activity.     

A Ring-Enlargement Reaction Yielding 1,2,5-Benzothiadiazonin-6-one 1,1-Dioxides

At room temperature or under reflux in MeCN, 3-amino-2H-azirines 2 and 3,4-dihydro-2H-1,2-benzothiazin-3-one 1,1-dioxide ( 4 ) give 1,2,5-benzothiadiazonin-6-one 1,1-dioxides 5 in fair-to-good yield (Scheme 2). The structure of this novel type of heterocyclic compounds has been established by X-ray crystallography of 5a (Fig.). A ring expansion via a zwitterionic intermediate of type A ' is proposed as the reaction mechanism of the formation of 5 .     

Reaction of 3-carbomethoxy-4,5-dihydro-6H-1,2-oxazinen-oxide with acetylenes

Conclusions The reaction of 3-carbomethoxy-4,5-dihydro-6H-1,2-oxazine N-oxide with acetylenes leads to the formation of the derivatives of a new heterocyclic system, namely 2-oxa-1-azabicyelo[4,1,0]heptane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.2, pp.473–474, February, 1973.     

Bromination of 6-dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one

Bromination of 6-dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one (I) with molecular bromine was studied at different ratios of reactants and varied reaction time. A number of tri-, tetra-, penta-, and hexabromo derivatives was obtained, which were characterized by ¹H, ¹³C, IR, UV spectroscopy and elemental analysis. The molecular structure of (2R,3R,4S,5S,6R)-2-dibromomethyl-2-methyl-3,4,5,6-tetrabromocyclohexan-1-one (V) was revealed using XRD. It was shown that 2-bromo-6-dibromomethyl-6-methylcyclohexyl-2,4-dien-1-one (III) upon standing for six months at room temperature dimerized quantitatively via Diels-Alder reaction to form IX. Dimer IX was investigated by the methods of cyclic voltammetry (CVA) and rotating disk electrode (RDE) in a solution of DMF on glassy carbon electrode.