Synthesis and characterization of novel pyridyl/naphthyl/(diphenyl)methylseleno substituted alkanoic acids: X-ray structure of 2-pyridylselenoethanoic acid, 2-naphthylselenoethanoic acid and 2-(diphenyl)methylselenoethanoic acid

A number of novel and synthetically important pyridyl/naphthyl/(diphenyl)methylseleno substituted alkanoic acids (20–25) have been synthesized using an efficient and operationally simple strategy. Starting substrates, ethyl pyridyl/naphthyl/(diphenyl)methylseleno substituted alkanoates (8–13) were easily prepared by treatment of ethyl chloroalkanoates 7(a–c) with nucleophilic selenium reagent RSeNa+, generated from the cleavage of dipyridyl/dinaphthyl/bis(diphenylmethyl) diselenide (1–6) with sodium borohydride in ethanol. The ethyl pyridyl/naphthyl/(diphenyl)methylseleno substituted alkanoates (8–13) on basic hydrolysis and subsequent acidification afford pyridyl/naphthyl/(diphenyl) methylseleno substituted alkanoic acids (20–25) in excellent yields. These selenoalkanoates (8–13) and selenoalkanoic acids (20–25) have been characterized by elemental analysis and various spectroscopic techniques viz. NMR (1H, 13C and 77Se), IR and mass spectrometry. The molecular structure of 2-pyridylselenoethanoic acid (20a), 2-naphthylselenoethanoic acid (23a) and 2-(diphenyl)methylselenoethanoic acid (24a) has also been established with the help of single crystal X-ray analysis.