title: Synthesis of pyrazolopyridine annulated heterocycles and study the effect of substituents on photophysical properties.
abstract: Pyrazolo[3,4-b]pyridines having 4-chloro-5-chloroethyl side chain are synthesized by the reaction of 5-aminopyrazole and cyclic β-formylester gave aminopyrazolodihydrofuranone intermediate, which on cyclization in phosphorous oxychloride exclusively converted in to 4-chloro-5-chloroethyl pyrazolo[3,4-b]pyridines 4(a-b) in major amount. The side chain with acetic acid, thiourea and aromatic amines are used to form angular ring leads to formation of tricyclic Furo[2,3-d]pyrazolo[2,3-b]pyridines 5(a-b), pyrazolo[3,4-b]thieno[2,3-d]pyridines 6(a-b) and pyrazolo[3,4-b]pyrrolo[2,3-d]pyridines 7(a-n) respectively. The substituents effect at C(4) position on fluorescence properties of pyrazolopyridines has been studied. Moreover the effect of electron donor and halogen substituents on fluorescence properties of pyrazolopyrrolopyridines 7(a-n) has been investigated along with their fluorescent quantum yield.
authors.affiliation: Organic Chemistry Research Center, Department of Chemistry, K. H. T. M. College, Gangapur Road, Nashik, 422002, MS, India.
authors.forename: Shivaraj P
authors.initials: SP
authors.lastname: Patil
authors.forename: Deepak P
authors.initials: DP
authors.lastname: Shelar
authors.forename: Raghunath B
authors.initials: RB
authors.lastname: Toche