Unexpected reactivity of o-nitrosophenol with RCH(2)Br: C-H bond cleavage and annulation to benzoxazoles and benzoxazines (R = Alkynyl).

A one-pot reaction between two molecules of 5-diethylamino-2-nitrosophenol with one molecule of 2-butynyl bromide gave rise to a new heterocyclic compound (structure shown above) consisting of one benzoxazole and one benzoxazine ring. The reaction works equally well with 1-phenyl-3-chloro-1-propyne. It was also found that 5-diethylamino-2-nitrosophenol reacts with R-CH(2)Br (R = aryl or vinyl) to give benzoxazoles with good functional group tolerance and high yield.