Pyrrolo -naphthyridin-2-ones

Amino-l,5-naphthyridin-4 (1 //)-one (21) underwent diazotization to 3-diazo-nio-l,5-naphthyridin-4(1//)-one chloride (22) (substrate, Me2NCHO, 0°C, Me2CHCH2CH2ONO [, HCI/btOH [ 75%), which on irradiation gave 177-pyrrolo[3,2-b]pyridine-3-carboxylic acid hydrochloride (23) [substrate, AcOH, H20, 0°C, hv (arc lamp), h %].722... 

Amino-l,5-naphthyridin-4 (1 //)-one gave crude 3-diazonio-l,6-naphthyridin-4(l//)-one chloride (HC1, NaN02, 5°C, 12 h) and thence 3-diazonio-l,6-naphthyridin-4-olate (26) (NaHC03, Et20 70% overall) 726 subsequent irradiation caused ring contraction to pyrrolo [3,2-[Pg.133]

Amino-l,7-naphthyridin-4(l//)-one (10) underwent diazotization to give 4-oxo-3,4-dihydro-l,7-naphthyridin-3-ylidendiazonium chloride hydrochloride (11) (NaN02, HC1, 0°C 80%) and subsequent ring contraction on irradiation to afford pyrrolo[2,3-c]pyridine-3-carboxylic acid (12) (AcOH, H20, hv,... 

Most of the compounds reported in this chapter are the naphthyridines fused with a five-membered ring containing one heteroatom, i.e. pyrrolo-, furo- and thienonaphthyridine compounds. Some other ring systems, which are the few known examples of the numerous possible structures, have only been studied sparsely and they will be presented briefly in Section 8.37.2.8. 

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