Aristoxazole analogues. Conversion of 8-Nitro-1-naphthoic acid to 2-Methylnaphtho[1,2- d ]oxazole-9-carboxylic acid: Comments on the chemical mechanism of formation of DNA adducts by the aristolochic acids

2-Methylnaphtho[1,2-d]oxazole-9-carboxylic acid was obtained by reduction of 8-nitro-1-naphthoic acid with zinc-acetic acid. This naphthoxazole is a condensation product between an 8-nitro-1-naphthoic acid reduction intermediate and acetic acid and is a lower homologue of aristoxazole, a similar condensation product of aristolochic acid I with acetic acid that was previously reported. Both oxazoles are believed to arise via a common nitrenium/carbocation ion mechanism that is likely related to that which leads to aristolochic acid-DNA-adducts.