9.10- Dimethoxy-2- -6,7-dihydro-4//-pyrimido

Chemical Name 2-[(l,l-Dimethylethyl)amino]-6,7-dihydro-9,10-dimethoxy-4H-pyrimido[6,l-a]isoquinolin-4-one... 

Photolysis of 6-azidoquinazolinc in anhydrous dioxane and potassium methoxide in methanol yields 8,9-dihydro-5,7-dimethoxy-5//-pyrimido[5,4-c]azepine (16%) as an unstable colorless solid which, on acid hydrolysis, undergoes ring opening to give the pyrimidinecarbaldehyde. ... 

Aryloxy-9,10-dimethoxy-6,7-dihydro-4//-pyrimido[6,1 -a]isoquinolin-4-ones formed in the reaction of 2-chloro derivative and phenols in the presence of K2CO3 in DMF at 90 °C for 2. 5 h or in boiling 2-PrOH for 6-24 h (00MIP20). When 2-isobutylphenol was used the reaction was carried out in the presence of BuLi in THF at —78 °C. 

However, under the same conditions, 6-azidoquinazoline (32) yields the acid-sensitive 5.7-dimethoxy-8,9-dihydro-5//-pyrimido[5,4-c]azcpine (34 16%) by a 1,4-addition of methanol to the initially formed 7-methoxy-9//-pyrimido[5,4-c]azepine (33).153... 

Reaction of 2-cyanomethylpyridine with iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)-iV -(4-methylphenyl)carbodiimides, and with (1,1,2,2,2-pentachloro- and l,l-dichloro-2,2,2-trifluoroethyl)isocyanates or A-methoxycarbonyl-l,2,2,2-tetrachloro-, — l-chloro-2,2-trifluoroacetaldehyde imines afforded 3-aryl-4-cyano-l-(4-methylphenyl)imino-3-trifluoromethyl-2,3-dihydro-17/-pyrido[l,2-f]pyrimidines and 4-cyano-3-trichloro-, 4-cyano-3-trifluoro-17/-pyrido[l,2-4pyrimidin-l-ones, respectively <2004CHE47>. Refluxing 2-cyanomethylpyridine and iV-(l-aryl-l-chloro-2,2,2-trifluoroethyl)isocyanates in benzene furnished l-aryl-4-cyano-l-trifluoromethyl-l,2-dihydro-3//-pyrido[l,2-4pyrimidin-3-ones. However, when the solution of the isocyanate was added dropwise to the solution of 2-cyanomethylpyridine, and the reaction mixture was then treated with NEt at room temperature, the isomeric 3-aryl-4-cyano-3-trifluoromethyl-2,3-dihydro-l//-pyr-ido[l,2-dpyrimidin-l-ones were obtained. Reaction of l-(acetyl- and benzoylmethylene)-6,7-dimethoxy-l,2,3,4-tetra-hydroisoquinolines with PhCONCS yielded 1-acetyl-, 1 -benzoyl-9,10-dime thoxy-3-pheny 1-6,7-dihydro-2//-pyrimido[6,l- ]isoquinoline-2-thiones <2003SL2369>. 

Catalytic hydrogenation of 3,4-dihydro-2//-pyrimido[2,l-a]isoquinoline-2,4-diones (93) and 3,3-diethyl-9,10-dimethoxy-3,4,6,7-tetrahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione (94) over Pt02 and Pd/C catalysts gave l,3,4,6,7,llb-hexahydro-2/7-pyrimido[2,l-a]isoquinoline-2,4-diones (95) [69YZ649 71JPP71/09466]. From the mother liquid of compounds 93 (R = H, R1 = Et and R = R1 = Et) 3-ethyl-2-hydroxy-6,7-dihydro-and -8,9,10,1 l-tetrahydro-4//-pyrimido[2,l-a]isoquinolin-4-ones, and 3,3-diethyl-l,3,4,llb-tetrahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione, also could be isolated as minor products. Reduction of 3,3-diethyl-l,3,4,6,7,llfo-hexahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione (95, R = R1 = Et, R2 = H) with LAH in tetrahydrofuran at 70°C for 9 h afforded 3,3-diethyl-l,3,4,6,7,llb-hexahydro-2//-pyrimido[2,l-a]isoquinoline (96). 

A solution of 9,10-dimethoxy-2-chloro-6,7-dihydro-4H-pyrimido[6,l-a]isoquinolin-4-one (3.0 g) and t-butylamine (10 ml) in chloroform (75 ml) is heated under reflux for 16 h. The solvent is evaporated under reduced pressure and the residue triturated with a dilute solution of sodium hydroxide to give a white precipitate of 9,10-dimethoxy-2-t-butylamino-6,7-dihydro-4H-pyrimido[6,l-a]isoquinolin-4-one. 

The alkylation of 2-(substituted amino)-9,10-dimethoxy-6,7-dihydro-4H-pyrimido[6,l-a]isoquinolon-4-ones usually led to a mixture of 2-(disubstituted amino)-6,7-dihydro and 2-(substituted imino)-3-alkyl-2,3,6,... 

Diazotization of 4-(p-aminophenyl)-9,10-dimethoxy-6,7-dihydro- and -l,3,4,6,7,llh-hexahydro-2//-pyrimido[6,l-fl]isoquinolines, followed by treatment with 30% H3PO2, gave deaminated products (55CPB259). 

Acylation of 2-[(2,4,6-trimethylphenyl)amino]-9,10-dimethoxy-6,7-dihydro-4//-pyrimido[6,l-a]isoquinolin-4-one with acetyl chloride gave a 2-acetamido derivative (84JMC1470). (Earlier the starting compound was described as a 4-amino-2-oxo-2// derivative, which afforded a mixture of 3-acetyl-4-[substituted imino]-2,3,6,7-tetrahydro-2-oxo-2// and 4-acetamido-... 

Hydrogenation of ethyl A -[2-(2-pyridyl)ethyl]carbamate in ethanol over Raney Ni at 130°C and 120 atm gave perhydropyrido[l,2-c]pyrimidin-1-one (67YZ663). Cyclization of ethyl Y-[2-(l,2,3,4-tetrahydro-2-quinolyl)ethyl]carbamate at 190-200°C afforded 2,3,4,4a,5,6-hexahydro-l//-pyrimido[l,6-a]quinolin-l-one (60YZ1414), whereas that of l-(2-benzamidoethyl)-6,7-dimethoxy-3,4-dihydroisoquinoline in boiling toluene with phosphoryl chloride led to 4-phenyl-9,10-dimethoxy-6,7-dihydro-2//-pyrimido[6,l-fl]isoquinoline (63YZ1043). 

Hydrogenation of l-acylamidinomethylene-l,2,3,4-tetrahydroisoquino-line (48, R = Me, R = Ph) over Pd/C gave 2-amino-4-phenyl-9,10-dimethoxy-6,7-dihydro-4H-pyrimido[6,l-a]isoquinoline via 49 (R = Me, R = Ph) (90CB493). When an ethanolic solution of l-[(benzoylamidino) methylenejtetrahydroisoquinoline (48, R = Me, R = Ph) was evaporated... 

The reactions of l-aminocarbonylmethylene-3,4-dihydro- and 1,2,3,4-tetrahydroisoquinolines with N,A -dimethylcarboxamide diethyl acetals, triethyl orthoformate, and diethyl carbonate yielded 6,7-dihydro-2//-pyrimido[6,l-a]isoquinolin-2-ones [81KFZ(5)44 82KGS1095 84JMC1470] and 9,10-dimethoxy-3,4,6,7-tetrahydro-2//-pyrimido[6,l-fl]isoquinoline-... 

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