3.4- Dihydro - 1/7-pyrano pyridine

A-(3,5-Bis(trifluoromethyl)benzyl]-8-oxo-5-p-totyl-8//-pyrano[3,4-h]pyridine-6-carboxamide (47, X=0) and ethanolamine gave iV-[3,5-bis(trifluoromethyl) benzyl -7-(2-hydroxyethyl)-8-oxo-5-/ -totyl-7,8-dihydro-l,7-naphthyridine-6-carboxamide (47, X = NCH2CH2OH) (reactants, MeOH, THF, 20°C, 16 h then to dryness solid, diazabicycloundecane, MeCN, PhMe, reflux, 1 h 70%) analogs likewise.243 944 cf 556 1252... 

Methyl 1-met hy I-3-oxo-3,4-dihydro-1 //-pyrano 3,4-r pyridine-5-carboxylate (39) with methanolic ammonia gave 5-(l-hydroxyethyl)-2,7-naphthyridine-l,3(2ff,7fl)-dione (40) (20°C 78%)206... 

A microwave-assisted, diversity-oriented, inverse electron-demand [4+2] cycloaddition of functionalized 1,2,4-triazines with alkyne dienophiles was carried out (Hajbi et al., 2008). 2,3-Dihydrofuro[2,3-b]pyridines and 3,4-dihydro-2H-pyrano-[2,3-b]pyridines on functionalization at the 3 and 4 positions have close structural similarity with well-known potent serotonineigic ligands like quinolines, substituted pyridines, and chromanes. 

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