Five and six membered cyclic boric esters form 1, 3 oxazolines and 5, 6 dihydro (4H) 1, 3 oxazines on reaction with acetonitrile [1 3]. In this paper it is shown, using 2 substituted 5, 6 benzo 1, 3, 2 dioxaborepanes () as examples, that the analogous conversion of seven
