... R-Bromotoluic acid and benzyl (2R,3S)-(-)6-oxo-2,3-diphenyl- 4-morpholinecarboxylate were purchased from Aldrich Chemical Co. and used without further purification. ... 1975, 16 , 1219. Scheme 2 1538 J. Org. Chem., Vol. 61, No. 4, 1996 Notes Page 3. ...