title: Sequential Regioselective C-H Functionalization of Thiophenes.
abstract: Herein, the sequential functionalization of 5-membered ring heterocycles is disclosed. By employing a pH sensitive directing group both directed and nondirected C-H activation pathways are available, providing access to 2,3,4- and 2,4,5-substituted thiophenes. The C-H arylation was performed in water, and using a surfactant greatly improved the yield and mass recovery. The use of a directing group with an on/off switch offers a potentially powerful means of generating diversity around medicinally relevant cores.
authors.affiliation: Global Discovery Chemistry, Novartis Institutes for Biomedical Research , 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Daniels
authors.affiliation: Department of Chemistry and Chemical Biology, Northeastern University , 360 Huntington Avenue, Boston, Massachusetts 02115, United States.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Armand
authors.affiliation: Global Discovery Chemistry, Novartis Institutes for Biomedical Research , 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Kian L
authors.initials: KL
authors.lastname: Tan