6.7- Dihydro-4H-pyrimido

Dihydro-4H-pyrimido[6,l-fl]isoquinolin-4-one 148 did not blocked nicotinic acid adenosine dinucleotide phosphate signaling (09NCB220). 

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,... 

Heating pyrimido[6,l-a]isoquinolin-4-one (132) in methanol gave the tetracyclic compound 133 (86CB2553). The reaction of l-amino-2-[(2,3,4-trimethylphenyl)amino]-6,7-dihydro-4H-pyrimido[6,l-a]isoquinolin-4-one hydrochloride (134) with HNO2 or with triethyl orthoesters gave the tetracyclic compounds 135 and 136, respectively [89H(29)1929]. 

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... 

Reaction of 2-chloro-6,7-dihydro-4//-pyrimido[6,1 -a]isoquinolin-4-ones with liquid NH3 in a pressure bomb at 85 °C for 4h, and with primary and secondary amines in boiling CHCI3 (98MIP15), and anilines in boiling i-PrOFI (00MI17) yielded 2-amino-6,7-dihydro derivatives or their 2,3,6,7-tetrahydro-2-imino tautomers. 

Oxo-4//-pyrimido[2,l-a]isoquinoline-3-carboxylic acids and their 6,7-dihydro derivatives were prepared by the hydrolysis of ethyl 4-oxo-4H-pyrimido[2,l-a]isoquinoline-3-carboxylates (97) and their 6,7-dihydro derivatives (98) under acidic (in a boiling mixture of acetic acid and cone, hydrochloric acid) and basic conditions (in 2% sodium hydroxide solution, and in a boiling mixture of 2% sodium hydroxide and ethanol) [78USP4127720 84JAP(K)84/172472 85EUP143001]. 

Stereostructures of perhydropyrido[l,2-c][l,3]oxazines 51 and 52 (06JOC8481, 06TL7923) and (+)-(3R,7R)-7-amino-3-(4-methoxyphenyl)-6,7-dihydro-3H,5H-pyrido[3,2,l-z/]quinazoline-l(2H)-one (06USA2006/ 0004028), the relative configuration of l,llfc-dihydro-2H,4H-pyrimido [6,1 -a] isoqu i nol i n-4-one 53 were determined by X-ray crystallographic analysis (09OL1559). 

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

Cl3H12CIN3O2S, 7-Chloro-l,3,5-trimethyl-5H-pyrimido[5,4-b] 1,4)ben-zothiazine-2,4(1H,3H)-dione, 38B, 398 Cl3H12N2O2S, 5,6-Dihydro-6-(2-oxo-propyl)-4H-pyrrolo[1,2-a]thieno-[3,2-f][1,4-diazepine]-4-one, 45B, 380 Cl3H14N2O2S, 2-Amino-4,5-dihydro-7,8-dimethoxynaphtho[1,2-d]thia-zole, 43B, 483... 

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