A facile method for the synthesis of diverse phenothiazines has been achieved by direct thioamination of aryne intermediates with S-(o-bromoaryl)-S-methylsulfilimines and subsequent intramolecular Buchwald-Hartwig amination. Since various sulfilimines could be prepared easily by odorless copper-catalyzed ipso-thiolation of readily available o-bromoarylboronic acids followed by imination and hydrolysis, this approach enables the synthesis of a wide variety of multisubstituted phenothiazines.