Abstract
Palladium/phenanthroline catalyzed reduction of nitroarenes by in situ‐generated carbon monoxide, from the decomposition of phenyl formate, affords the corresponding nitrosoarenes. The latter are trapped by conjugated dienes to give the corresponding 3,6‐dihydro‐2H‐[1, 2]‐oxazines (hetero Diels‐Alder adducts). Many functional groups are well tolerated. Yields are higher than those obtainable by any previously reported method, including the direct reaction of the diene with the pure nitrosoarene. The reaction can be performed in a single standard glass pressure tube, without the need for autoclaves or high‐pressure CO lines.
Under pressure. No autoclave or CO pressure lines are necessary to obtain oxazines directly from nitroarenes and dienes in yields higher than those previously obtained by any other method and with wide group tolerance.