Pyrimido naphthyridines

Thermal isomerization of l//-pyrimido[l,2-a]quinolin-l-ones (185) into benzo(6)-l,8-napthyridin-4(li/)-ones (186) (94AJC1263), did not occur whereas 6-substituted 4//-pyrido[l,2-a]pyrimidin-4-ones gave 1,8-naphthyridin-4( l//)-ones [77JCS(P1)789]. 

Pyrimido[l,2-a][l,8]naphthyridines synthesis, 2, 599 Pyrimido[5,4-c]oxadiazine purine synthesis from, 5, 591 Pyrimido[4,5-6][ l,4]oxazine synthesis, 3, 312 Pyrimido[2,1 -6]pteridine structure, 3, 284 Pyrimido[5,4-g]pteridine structure, 3, 284 Pyrimidopurines, 5, 566 Pyrimido[4,5-c]pyridazine, aryl- H NMR, 3, 335... 

Ethyl acetoacetate, ethyl ethoxymethylenemalonate, ethyl acetoacetate, and ethyl cyanoacetate afford 2-(ethoxycarbonylvinylamino)-l,8-naph-thyridines (84). Some of these compounds have been successfully cyclized to pyrimido [ 1,2-u]-1,8-naphthyridines (85).4 5... 

Chlorination of 3-(perhydroazepino)propionitrile (408) at temperatures up to 150°C and subsequent distillation in vacuo afforded perchlori-nated pyrimido[l,2-o]azepine (409) (70LA45). In addition to hexachloro-1,8-naphthyridine (411), the perchloropyrimidoazepine 409 was obtained in 3-14% yield in the chlorination of 3-piperidinopropionitriles 410 (72GEP 2024908). 

Chloronicotinoyl chloride 95 was used as the starting compound in the synthesis of hetaryl annulated 1,6-naphthyridines. Its reactions with 4,5-dihydro-1//-imidazolines 96a or tetrahydropyrimidines 96b gave the corresponding A-acyl derivatives 97a,b, which underwent cyclization with potassium Arf-butoxide to yield imidazo- 98a or pyrimido[l,2-gr[[l,6]naphthyridinones 98b, respectively. Compounds 98a,b exhibit antiallergic and anti-inflammatory activitives (1990JHC189, 1990USP5070086). 

Aryl azides undergo indolization upon photolysis, and several examples are known (Scheme 8) [67-70]. Thus, p-phenyl-substituted (Me, OMe, Cl) azidopyrimi-dines 11 were converted to the corresponding 9H-pyrimido[4,5- ]indole (equation 1) [67, 68]. The azide precursor is in equilibrium with the ring-opened 8-phenyltetrazolo[l,5-c]pyrimidine (10) (in trifluoroacetic acid). Similarly, Da Settimo and colleagues synthesized the new ring system 67/-indolo[2,3- ][l,8]naphthyridine 12 by photolysis in trifluoroacetic acid of the equilibrium mixture of 4-phenyltetrazolo[l,5-fl][l,8]naphthyridines... 

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