Efficient synthesis of spirooxazine-pyrans via rhodium-catalyzed [3+3] cascade spiroannulation of benzoxazines with 1-diazonaphthalen-2(1H)-ones

A redox-neutral access to spirooxazine-pyrans has been realized via Rh( iii )-catalysed [3+3] cascade spirocyclization of benzo[ b ][1,4]oxazines and 1-diazonaphthalen-2(1 H )-ones under extremely mild reaction conditions.