yl group; wherein X is a F or Cl and R??? is an alkyl, aryl or acyl group; wherein X is a F or Cl and R is an H, alkyl, aryl or acyl group; and wherein X is a F or Cl and R is an H, alkyl, aryl or acyl group.DETAILED DESCRIPTIONIt has been determined that by changing the substitution pattern on the aromatic ring of the pre-Grewe intermediate from methoxy, o-hydroxyl and m-bromo (as disclosed by Ri