title: Tandem Approach to Benzothieno- and Benzofuropyridines from o-Alkynyl Aldehydes via Silver-Catalyzed 6-endo-dig Ring Closure.
abstract: An operationally simple silver-catalyzed tandem strategy for the synthesis of benzothienopyridines 7a-t and benzofuropyridines 8a-p by the reaction of o-alkynyl aldehyde 4a-t and 5a-p with tert-butylamine 6 under mild reaction conditions is described. The present methodology provides a facile conversion of easily accessible o-alkynyl aldehydes into medicinally useful heterocycles in good to excellent yields under mild and environmentally friendly reaction conditions with excellent regioselectivity. The developed chemistry has been successfully extended for the selective synthesis of C-4 deuterated benzothienopyridines 7u-v and benzofuropyridines 8q-r. The role of the ethanolic proton in the reaction was validated by deuterium-labeling experiments.
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Sonu
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Departamento de Química, Centro de Investigación y de Estudios Avanzados , Apdo. Postal 14-740, México City 07000, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cruz-Hernández
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Pal
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Saunthwal
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.
authors.forename: Monika
authors.initials: M
authors.lastname: Patel
authors.affiliation: Chapman University School of Pharmacy, Harry and Diane Rinker Health Science Campus , 9401 Jeronimo Road, Irvine, California 92618, United States.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Tiwari
authors.affiliation: Departamento de Química, Centro de Investigación y de Estudios Avanzados , Apdo. Postal 14-740, México City 07000, Mexico.
authors.forename: Eusebio
authors.initials: E
authors.lastname: Juaristi
authors.affiliation: Synthetic Organic Chemistry Research Laboratory, Department of Chemistry, University of Delhi , Delhi 110007, India.|School of Physical Sciences, Jawaharlal Nehru University , New Delhi 110067, India.
authors.forename: Akhilesh K
authors.initials: AK
authors.lastname: Verma