The condensation of 2(R)-(2,2-dimethyl-5-oxo-1,3-dioxolan-4(S)-yl)-4,4-dimethylpentanoic acid (I) with 2,2-dimethylpropanal (II), ter-butyl isocyanide (III) and ammonia in methanol gives the intermediate (IV), which, without isolation is treated with hydroxylamine to yield the target compound as a mixture of diastereomers.
The title sulfonamide was obtained by condensation of pentafluorophenyl sulfonyl chloride (I) with 3-hydroxy-4-methoxyaniline (II) in the presence of pyridine.
Condensation of pentafluorophenyl sulfonyl chloride (I) with 3-hydroxy-4-methoxyaniline (II) in the presence of pyridine afforded sulfonamide (III). Treatment of (III) with N,N-diisopropyl dibenzylphosphoramidite (A) and tetrazole gave phosphite ester (IV), which was subsequently oxidized to phosphate (V) by means of tert-butyl peroxide. Finally, hydrogenolysis of the benzyl phosphate ester groups of (V) in the presence of Pd/C and 1,4-cyclohexadiene furnished the title compound.
By condensation of pentafluorophenylsulfonyl chloride (I) with 3-fluoro-4-methoxyaniline (II) in pyridine.