An Efficient and Simple Synthesis of 3,4,5,6-Tetrahydro-2H-1,2-oxazines by Sodium Cyanoborohydride Reduction of 5,6-Dihydro-4H-1,2-oxazines - Zimmer, Reinhold; Arnold, Thomas; Homann, Kai; Reissig, Hans-Ulrich (Synthesis, 1994)