title: Microwave assisted base dependent regioselective synthesis of partially reduced chromenes, isochromenes and phenanthrenes.
abstract: We have reported a microwave assisted base directed regioselective synthesis of partially reduced chromenes, isochromenes and phenanthrenes. Functionalized 4-(piperidin-1-yl)-5,6-dihydro-2H-benzo[h]-chromen-2-one-3-carbonitriles have been used as precursors, which on reaction with functionalized acetophenones in the presence of KOH in DMF under microwave irradiation yield (Z)-2-(2-aryl-5,6-dihydro-4H-benzo[f]isochromen-4-ylidene)acetonitriles. The use of NaH in DMF provides 3-aryl-1-(piperidin-1-yl)-9,10-dihydro phenanthrene-2-carbonitriles in excellent yield regioselectively. The use of cyclohexanone as a nucleophile source yields (Z)-2-(3,4,7,8-tetrahydro-1H-naphtho[2,1-c]chromen-6(2H)-ylidene)acetonitriles. The structure and geometry of isochromene have been proved without any ambiguity by single crystal X-ray diffraction.
authors.affiliation: Department of Chemistry, University of Delhi, North Campus, Delhi, 110007, India. ramendrapratap@gmail.com.
authors.forename: Pratik
authors.initials: P
authors.lastname: Yadav
authors.forename: Surjeet
authors.initials: S
authors.lastname: Singh
authors.forename: Satya Narayan
authors.initials: SN
authors.lastname: Sahu
authors.forename: Firasat
authors.initials: F
authors.lastname: Hussain
authors.forename: Ramendra
authors.initials: R
authors.lastname: Pratap
mesh_terms: D001578:Benzopyrans / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D008872:Microwaves; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D001578:Benzopyrans; D010616:Phenanthrenes