2- Phenyl-l,7-naphthyridine

In this method the nitro group in the aliphatic nitro compound is usually present on a carbon atom, which is also activated by CO-functioiiality (aldehyde, ester, arylketoiie). A successful application of this method is the Borsche modification of the Friedlander synthesis, involving condensation of A-(3-amino-4-picolylidene)-p-toluidine (17) with [Pg.289]

Phenyl-l,6-naphthyridine-l,7-diamine gave selectively 2-(7V -rert-butylureido)-3-phenyl-l,6-naphthyridin-7-amine (25) (substrate, NaH, MejNCHO, N2, 20°C, 10 min Bu NCO/Me2NCHO added dropwise 20°C, 4 h 66%) analogs likewise.220... 

Bromo-4-pyridinecarbaldehyde (33) with phenylacetamide gave 3-phenyl-l,7-naphthyridin-2( 1 //)-one (34) [reactants, tris(dibenzylideneacetone)dipalla-dium, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, CS2CO3, PhMe, N2, 100°C, 18 h 75%].117... 

Phenylethynyl-2-pyridinecarbaldehyde (41, R = Ph) with ammonia gave 6-phenyl-l,7-naphthyridine (42, R = Ph) (NH3/EtOH, 80°C, sealed, 2 h 31%) 3-(oct-l-ynyl)-2-pyridinecarbaldehyde (41, R = C6H13) likewise gave... 

Bromo-2-phenyl-l,8-naphthyridin-4(177)-one gave 2-bromo-5-ethoxy-7-phenyl-1,8-naphthyridine (14) (NaH, Me2SO then EtI, 80°C 32%).263... 

Azido-7-methyl-2-phenyl-l,8-naphthyridine (19, R = N3) gave 7-methyl-2-phenyl-l,8-naphthyridin-4-amine (19, R = NH2) (Pd/C, MeOH, H2, 20°C 22%).221 Also a better example.1445... 

Dichloro-1,7-naphthyridine 2-Diethylamino-3-phenyl-l,7-naphthyridin-4-amine JV,JV-Diethyl-5-hydroxy-8-oxo-7,8-dihydro-l,... 

Morpholino-5-phenyl-1,8-naphthyridin-2-amine 7-Morpholino-6-phenyl-1,8-naphthyridin-2-amine 7-Morpholino-2-phenyl-l,8-naphthyridin-2(l//)-one 7-Morpholino-6-phenyl-l,8-naphthyridin-2(l//)-one... 

It was reported that the Niemeiitowski synthesis of 4-hydroxy-3-iiitro-7-pheiiyl-l,8-iiaphthyridiii-2(lH)-oiie (25) from ethyl 2-amiiio-6-pheiiyhii-cotiiiate (23) and ethyl nitroacetate (24) in the presence of sodium was unsuccessful, producing only traces of (25), while condensation of ethyl 2-amino-6-phenylnicotinate (23) with the less reactive ethyl acetate resulted in the formation of 4-hydroxy-7-phenyl-l,8-naphthyridin-2(lH)-one in good yield [66JCS(C)315]. It seems that the more reactive nitroacetate tends to precipitate rapidly from the reaction mixture as its sodio derivative, which explains the low yield of (25). 

Tlie products of nitration of 2-amino-5-phenyl-l,8-naphthyridin-7(8H)-one (63) vary depending on whether the reaction is carried out with nitric acid in sulfuric acid or in acetic anhydride (74GCI499). In sulfuric acid the phenyl ring was found to be nitrated more easily than the naphthyridine ring, yielding a mixture of 3- and 4-nitrophenyl derivatives (64) in acetic... 

Catalytic reduction of 3-nitro-7-phenyl-l,8-naphthyridin-2(lH)-one (136) with palladium on carbon in 2-ethoxyethanol gave the l,2-di(l,8-... 

Dimethyl-2-phenylethynyl-3-pyridinecarboxamide (52) gave 2,4-dimethyl-7-phenyl-l,6-naphthyridin-5(6//)-one (53) (EtONa, EtOH, reflux, 3 h ... 

Diazotization of 3-phenyl-l,6-naphthyridine-2,7-diamine (24) in an excess of hydrochloric acid gave mainly 7-chloro-3-phenyl-l,6-naphthyridin-2-amine (25) along with three separable byproducts (10M HC1, — 10°C, HC1 gasj, substrate), — 10°C, 5h 20°C, 8h 4°C, 2 days 61%) analog likewise.564... 

Ethoxalylmethyl-2-methoxy-5-nitropyridine (3, R = H) gave 3-hydroxy-6-methoxy-3,4-dihydro-1,7-naphthyridin-2( 1 //)-one (4, R = H) (Pt02, EtOH, H2, 3 atm, 2 h 75%),152,234 that underwent subsequent dehydration to afford 6-methoxy-l,7-naphthyridin-2(l //)-one (TsCl, pyridine, 150°C, sealed , 4 h 79%) 234 similarly, 4-oc-ethoxybenzyl-2-methoxy-5-nitropyridine (3, R=Ph) gave 3-hydroxy-6-methoxy-4-phenyl-3,4-di hydro-1,7-naphthyridin-4(l//)-... 

Phenyl-3,10-diazatricyclo[5.3.1.03 8]undercane-2,9-dione with methanesulfonic acid gave methyl 8-oxo-6-phenyldecahydro-l,7-naphthyridine-6-carboxylate (46) (reactants, MeOH, reflux, 12 h 97%).124,195... 

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