Synthesis and characterization of some naphthalene derivatives bearing naphthoxazole and benzothiazole moieties

Depending upon the electronic nature and steric bulk of the substituents already present, it is possible to synthesize a variety of substituted naphthalene derivatives. Starting from methyl-3-hydroxy-2-naphthoate the present work describes the synthetic route to (E)-4-((2-hydroxy-3-(methoxycarbonyl) naphthalene-1-yl) diazenyl) benzene-sulphonic acid) [4] in step-I. Subsequent reduction and condensation with appropriate benzene carboxylic acids it is possible to introduce substituted naphthoxazole ring at position-1,2 [7(a-f)]. Ready hydrolysis of the ester group under mild conditions generates a free carboxylic acid group that can be conveniently condensed with 1-amino-2-thiophenol to afford 3-benzothiophenol substituted derivative of [7(a-f)] identified as [10 (a-f)]. All the synthesis processes were carried out according to the well established protocols. Characterizations were performed by elemental analysis, FT-IR and 1HNMR spectroscopy.