Heterocycle formation via palladium-catalyzed intramolecular oxidative C-H bond functionalization: an efficient strategy for the synthesis of 2-aminobenzothiazoles.
N-arylthioureas are converted to 2-aminobenzothiazoles via intramolecular C-S bond formation/C-H functionalization utilizing an unusual cocatalytic Pd(PPh(3))(4)/MnO(2) system under an oxygen atmosphere at 80 degrees C. This method eliminates the need for an ortho-halo substituted precursor, instead achieving direct functionalization of the ortho-aryl C-H bond. Mechanistic observations, including a large intramolecular primary kinetic isotope effect of 5.9, reveal a reaction pathway inconsistent with an electrophilic palladation mechanism.
Joyce
Laurie L
LL
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
Batey
Robert A
RA