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.