Trifluoroacetamide → 4-Nitrophenol
Reaction equation
S.N1C=CC=CC=1.Br[C:9]1[CH:10]=[CH:11][C:12]([N+:16]([O-:18])=[O:17])=[C:13](O)[CH:14]=1.FC(F)(F)C(N)=[O:22]>>[N+:16]([C:12]1[CH:11]=[CH:10][C:9]([OH:22])=[CH:14][CH:13]=1)([O-:18])=[O:17]Participants
4
Procedure
Subunit containing the base of FIG. 30C. 3-Bromophenol was nitrated to produce 5-bromo-2-nitrophenol. This was reduced with hydrogen sulfide/pyridine to the aminophenol, and the amino group masked as the trifluoroacetamide. A second nitration produced the 4-nitrophenol species which was treated with ammonia to cleave the trifluoroacetamide. This was reacted with cyanogen bromide to produce the aminobenzoxazole which is protected as the trifluoroacetamide. The nitro group was reduced with pyridine hydrogen sulfide and the amine treated with ethyl chloroformate to generate the carbamate. Nitration, nitro reduction, and heating provided the fused imidazolone. Ammonolysis of the trifluoroacetamide gave the aminobenxoxazole which was protected as the beta(trimethylsilyl)ethylcarbamate. This was coupled with the pyranoid glycal as in Example 4Aii to produce the subunit with the glucose moiety. Following complete desilylation, the amino group was protected as the trifluoro- or trichloroacetamide as per Example 1. The glucosyl subunit may be converted into the morpholine containing subunit by the method of Example 2C except that two equivalents of sodium periodate is employed in the oxidation step.