3.5- Dihydro-4/7-2,3-benzodiazepin-4-ones

A well-studied case of tautomerism is that of l,2-diazepin-4-ones tautomers 47a and 47b were characterized by NMR, the former being the most stable (85JOC2141). 3,5-Dihydro-4//-2,3-benzodiazepin-4-ones exist as 48a and not as 4-hydroxy tautomers 48b (74JHC401). 

The reaction of methyl anthranilate and 3-amino-2-chloropyridine in 1,2,4-trichlorobenzene in the presence of KOt-Bu at 50 °C gave 5,1 l-dihydro-6//-pyrido[2,3-Z)]benzodiazepin-6-one and 6-amino-ll//-pyr-ido[2,l-Z)]quinazolin-l 1-one as a by-product (99BMCL3031). 

Chloro-6-phenyl-1 -methyl-3-hydroxy-1,3-dihydro-2H-1,4-benzodiazepine-2-one... 

A suspension of 45 g 3-phenoxycarbonyloxy-1 -methyl-7-chloro-5-pheny -1,3-dihydro-2H-1,4-benzodiazepin-2-one in 450 ml methanol is treated with stirring, with 43 ml of a solution of dimethylamine in methanol (containlng31 gdimethylamine in 100 ml). Stirring ismaintained at 20°C to 25°C during 5 hours. The reaction mixture is filtered, and the filtrate is diluted with 450 ml water. The precipitate thus formed, is 3-(N,N-dimethylcarbamoyloxy)-1-methy -7-chloro-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one, which is collected on a filter, dried and recrystallized from ethyl acetate, and has a melting point of 173°C to 174°C. 

Chemical Name 5-(o-chlorophenyl)-1,3-dihydro-7-nitro-2H-1,4-benzodiazepin-2-one Common Name —... 

A solution of 60 g of chromic anhydride in 40 ml of water was added dropwise to a suspension of 60 g of 2-aminomethyl-1 -methyl-5-chloro-3-(o-fluorophenyl)-indole hydrochloride in 600 ml of acetic acid. The mixture was stirred at room temperature overnight. To the reaction mixture was added 1.1 liters of ether and 1 liter of water and then 800 ml of 28% ammonium hydroxide, in small portions. The ethereal layer separated, washed with water, dried, and concentrated under reduced pressure. The residue (51.8 g) was dissolved in 100 ml of ethanol, and 100 ml of 20% ethanollc hydrogen chloride was added to the solution and the mixture was cooled. The precipitate was collected by filtration to yield 46.5 g of 1 -methyl-7-chloro-5-(o-fluorophenyl)-1,3-dihydro-2H-1,4-benzodiazepine-2-one hydrochloride, melt-... 

Chemical Name 8-Nitro-1,2-dihydro-2-(N-methyl-piperazin-1 -yl)methylene-6-(o-chloro-phenyl)-1 H,4H-imidazo-[ 1,2-a] [ 1,4] -benzodiazepin-1 -one methanesulfonate... 

To a slightly warm suspension of 3-acetoxy-7-chloro-5-(o-chlorophenyl)-1 3-dihydro-2H-1,4-benzodiazepin-2-one thus obtained was added 4N sodium hydroxide solution with stirring. All the solid dissolved and soon a thick white solid precipitated out. The solid was filtered, washed well with water and recrystallized from ethanol. The product was isolated as a solvate with 1 mol of ethanol. When heated it loses the ethanol of solvation and melts at 166°C to 168 C. 

To a suspension of 3.4 g of 3-acetoxy-7-chloro-1,3-dihydro-5-(o-chlorophenyl)-2H-1,4-benzodiazepin-2-one in 80 ml of alcohol was added 6 ml of 4 N sodium hydroxide. After complete solution had taken place a solid precipitated that redissolved upon the addition of 80 ml of water. The solution was acidified with acetic acid to give white crystals. After recrystallization from alcohol the compound melted at192°Cto 194°C. 

Chemical Name 7-Chloro-1 -dihydro-5-phenyl-l (2H)-1,4-benzodiazepin-2-one Common Name Nordiazepam desmethyidiazepam Structural Formula ... 

A) Suspend lOg of 7-chloro-l -dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide in 150 ml of acetic anhydride and warm on a steam bath with stirring until all the solid has dissolved. Cool and filter off crystalline, analytically pure 3-acetoxy-7-chloro-1,3-dihydro-5-phenyl-2H-1 /t-benzodiazepin-2-one, melting point 242°C to 243°C. 

Chemical Name 7-chloro-1,3-dihydro-3-hydroxy-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one... 

Acetoxy-7-chloro-1 -methyl-5-phenyl-l, 3-dihydro-2H-1,4-benzodiazepin-2-one Sodium hydroxide... 

Acetoxy-7[Pg.1610]

This section also discusses l,5-bcnzodiazepin-2-ones, the corresponding thiones and benzo-diazepinediones. The benzodiazepinones exist in the 1,3-dihydro form 4 A rather than as the 1,5-dihydro tautomers 4B, as shown by 1HNMR spectroscopy.251,252 1Z/-1,5-Benzodiazepine-2,4(3//,5Z/)-diones 5 show NH absorptions at ca. 3180 and 3190, and amide carbonyl bands at ca. 1710 and 1660cm 1.253... 

Only one procedure has been reported recently within this category. Thus 7-chloro-l-methyl-5-phenyl-2,3-dihydro-lH-benzodiazepin-2-one 4-oxide (437) with dimethyl acetylenedicarboxylate in methylene chloride at 20° C for 3 days gave a separable mixmre of the primary tricyclic adduct, dimethyl lO-chloro-6-oxo-llb-phenyl-5,6,7, 1 lb-tetrahydroisoxazolo[2,3-t/] [ l,4]benzodiazepine-1,2-dicarboxylate (438), and its rearrangement product, 6-chloro-4-(2-methoxalyl-2-methoxycarbonyl-l-phenylvinyl)-l-methyl-3,4-dihydro-2(lT0-quinoxalinone (439) each product afforded 6-chloro-l-methyl-2(l//)-quinoxalinone (440) on refluxing in ethanol (see also Section 1.7.13). However, the final quinoxaline (440) was best obtained in 75% yield) by simply heating the initial substrate (437) and dimethyl... 

CN (Z)-6-(2-chlorophenyl)-2,4-dihydro-2-[(4-methyl-l-piperazinyl)methylene]-8-nitro-l//-imidazo[l,2-a][ 1,4]benzodiazepin- 1-one... 

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