title: Copper-free palladium-catalyzed Sonogashira coupling-annulation: efficient one-pot synthesis of functionalized pyrano[4,3-b]quinolines from 2-chloro-3-formylquinolines.
abstract: A convenient, one-pot, copper-free, Pd-catalyzed methodology has been described for the synthesis of 1,3-disubstituted pyrano[4,3-b]quinolines from 2-chloro-3-formylquinolines. Formation of annulated products 3 is attributed to the presence of Pd(OAc)2 and PPh3. Further, PPh3 in the reaction mixture promotes the cyclization by reducing the reaction time and increasing the yield of cyclized product.
authors.affiliation: Department of Chemistry, Banaras Hindu University, Varanasi - 221 005, U.P., India.
authors.forename: Atish
authors.initials: A
authors.lastname: Chandra
authors.forename: Bhawana
authors.initials: B
authors.lastname: Singh
authors.forename: Ranjana S
authors.initials: RS
authors.lastname: Khanna
authors.forename: Radhey M
authors.initials: RM
authors.lastname: Singh