COCH3 XI chloro-7-inethoxyphenothiazine (VIb, mp 174.5-175'), IVa and IYb yielded, respectively, 3-chlorophenothiazine (Va, mp 201-201.5) 5f6 and 3-chloro-7- methoxyphenothiazine (Vb, n1. p. 202-203'). To permit mixture melting point and infrared comparison, an authentic sample of 2-chloro-7-methoxyphenothiazine (VIb) was prepared as shown in Scheme 11.