Pyridin-4-ones, 2,3-dihydro

When JV-acetyldihydroveratramine (XXXII) is treated with phosphorus oxychloride in pyridine one of the hydroxyls is replaced with chlorine and the other is eliminated with the formation of a double bond to form the compound C29H40ONCI (L). The unsaturated nature of this compound is indicated not only by the fact that it can be oxidized to an a-glycol, isolated as its diacetate, C33H4 06NC1 (LII), with osmium tetroxide, but also by the fact that it can be catalytically reduced to the dihydro compound, C29H42ONCI (LI), without loss of halogen (61). 

Oxazolo[4,5-6]pyridin-2(3 H)-one IR, 6, 653 <76HCA1593) Oxazolo[4,5-fi]pyridin-2(3H)-one, 3-(4-chlorophenyl)-3a,7a-dihydro-6-methyl-X-ray, 6, 647 <79CPB2261) Oxazolo[4,5-6]pyridin-2(3H)-one, 3-(4-chlorophenyl)-3a,7a-dihydro-7a-methyl-X-ray, 6, 647 <79CPB2261) 5H-Oxazolo[3,2-a]pyridin-3(2H)-one, 2-phenyl-6,7,8,8a-tetrahydro-X-ray, 6, 646 <77MI42902) Oxazolo[5,4-d]pyrimidin-4-amine, A7-methyl- H NMR, 6, 650 <70BCJ3909)... 

Pyridin-4-one, 3,5-dichloro-2,6-dimethyl-tautomerism, 2, 111 Pyridin-4-one, 1,4-dihydro-polymers, 1, 297 Pyridin-4-one, 2-dimethylamino-synthesis, 2, 419... 

Thieno[3,2-c]pyridine-4(5H)-thione, 6,7-dihydro-synthesis, 4, 762 Thieno[2,3-c]pyridin-4-ones synthesis, 4, 1007, 1008 Thieno[2,3-c]pyridin-7-ones synthesis, 4, 1007 Thieno[3,2-c]pyridin-7-ones synthesis, 4, 1007... 

Tile same methodology as mentioned for the preparation of (9) was applied for the synthesis of 8-nitro-l,6-naphthyridines. Heating diethyl N- 3-nitropyridin-4-yl)aminomethylenemalonate (12) in diphenyl ether yields ethyl 8-nitro-l,6-naphthyridin-4(lH)-one 3-carboxylate (13) (63JCS4237, 30%) and acid treatment of 4-( y, y-diethoxypropylamino)-5-nitro-2-(/3,/3 -trifluoroethoxy)-pyridine (14) gives in a similar way 8-nitro-5-(/3, /3-triflu-oroethoxy)-l,2-dihydro-l,6-naphthyridine (15, 76%). Subsequent oxidation with chloranil, acid hydrolysis, and methylation with methyl iodide gives 8-nitro-6-methyl-l,6-naphthyridin-5(6H)-one (16,63%) (81JHC941). 

Ravindranath and co-workers studied the electrochemical behavior of 5-amino-2-phenyl-4-arylazo-l,2-dihydro-3//-pyrazol-3-one (90UC864) and 5-methyl-4-arylazo-2-(pyridin-2-ylcarbonyl)-2,4-dihydro-3//-pyrazol-3-(Mie (90IJC895). Similar studies were undertaken by Jain and Damodharan of pyrazol-3-ones 408a-f (95CJC176) (Scheme 94). The underlying rationale for this study on the electrochemical reduction of these biologically important pyrazol-3-ones is that it can lead to information on the reaction routes and mechanisms of biological redox reactions. 

Polymorphic forms of I and II of 3- 2-[4-(6-fluorobenzo[r/ isoxazol-3-yl)-3,6-dihydro-2//-pyridin-l-yl]ethyl -2-methyl-6,7,8,9-tetrahydro-4//-pyrido [1,2-n]pyrimidin-4-one was characterized by IR spectroscopy (99MIP1). 

Reaction of 2-(arylmethyleneamino)pyridines 335 and styrenes in the presence of hydroquinone afforded 2,4-diaryl-3,4-dihydro-2/f-pyrido[l,2-n]pyrimidines 336 by means of an inverse electron demand Diels-Alder reaction (95MI10). Reaction of 2-(benzylideneamino)pyridines 337 and chloroacetyl chloride gave 2-aryl-4//-pyrido[l,2-n]pyrimidin-4-ones 338 (97JMC2266). 

Reaction of 2-cyano-3-(4-methoxyphenyl)acroyl chloride and 2-amino-pyridine in boiling benzene in the presence of NEt3 for 5 h gave a 2 1 mixture of 3-cyano-4-(4-methoxyphenyl)-3,4-dihydro-2//-pyrido[l, 2-n]pyr-imidin-2-one and 2- [2-cyano-3-(4-methoxyphenyl)acroyl]amino pyridine (01SUL151). 

It is not obvious how the adsorbed 2,2 -dihydro-2,2 -bipyridine (14) could leave the catalyst without undergoing dehydrogenation either simultaneously or before desorption. This second alternative could however be rationalized if it is assumed that in the preparation of 2,2 -bipyridine the two molecules of pyridine are bonded to one atom of nickel (15). The formation of the carbon-carbon bond could... 

Piperazine NH group of 9-fluoro-10-(l-piperazinyl)-7-oxo-2,3-dihydro-7//-pyrido[l,2,3-<7e]-l,4-benzothiazine-6-carboxylate was reacted with 4-nitrophenylsulfonyl chloride, 2,6-dichloropyrazine, 2,6-dichloropyridine in DMF in the presence of pyridine, and with 4-nitrophenyl isothiocyanate in aqueous acetone in the presence of KOH (01MIP13). A side chain amino group on a 2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazin-7-one skeleton was acylated (OOMIPIO). 

A suspension of 100 g of 7-chloro-6-phenyl-1-methyi-3-hydroxy-1,3-dihydro-2H-1,4-benzodi-azepin-2-one in 700 ml of anhydrous pyridine, kept stirred between 0°C and -t5°C, is slowly treated, during 20 to 30 minutes, with 54.5 ml phenyl chlorocarbonate. The temperature is gradually allowed to rise to 20°-25°C and stirring Is maintained at this temperature during 24 hours. 

To a solution of 10 g of 2-N-methyl-aminoacetamido-3-o-chlorobenzoyl-5-ethylthiophene in 50 ml of pyridine are added 20 ml of benzene and 1.9 g of acetic acid. The resulting mixture is refluxed with stirring for 10 hours in a flask provided with a water-removing adaptor. The reaction mixture is concentrated, and the residue is extracted with chloroform. The chloroform layer is washed with water and then with a sodium hydrogen carbonate solution, then dried over magnesium sulfate. The chloroform is distilled off under reduced pressure, and toluene is added to the residue. Thus is precipitated white crystalline-5-o-chloropheny -7-ethyl-1 -methyi-1,2-dihydro-3H-thieno-[2,3-e] [ 1,4] diazepin-2-one, MP 105°C to 106°C. 

Propionic acid, 2-iodo-3-nitro-, ethyl ester [Propanoic acid, 2-iodo-3-mtro-, ethyl ester], 65 2//-Pyran, 3,4-dihydro-, 51 2//-PYR AN-2-ONE, 49 2H Pyran 2-one, 5 bromo 5,6-dihydro, 50 27/-PYRAN-2-ONE, 5,6 DIHYDRO-, 49 PYRIDINE, 2,3,4,5 TETRAHYDRO, 118 Pyridines, -substituted, 34 a Pyrone-6-carboxyhc acid [2H Pyran-6-Larboxyhc acid 2-oxo ], 51 Pyrroles, 34... 

More versatile seemed the synthesis of 2,3-dihydro-lH-pyridin-4-ones 176, that starts from the acrylic /3-ketoester 174 (Scheme 63). This product, pre-... 

CN ( )-r-[3-(3-chloro-10,l I-dihydro-5//-dibenz[6/ azepin-5-yI)propyl]hexahydrospiro[imidazo[l,2-a]pyridine-3(2//),4 - piperidin]-2-one... 

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