Alkylation of protected erythromycin (I) at the 6-hydroxyl group with propargyl bromide provided ether (II). Hydrolysis of the cyclohexylidene ketal group of (II) with concomitant desilylation with AcOH gave (III). The oxime function of (III) was then hydrolyzed using either sodium bisulfite and formic acid or sodium nitrite and HCl to afford the title ketone.
Alkylation of protected erythromycin (I) at the 6-hydroxyl group with allyl bromide provided ether (II). Hydrolysis of the cyclohexylidene ketal group of (II) with concomitant desilylation with AcOH gave (III). The oxime function was then hydrolyzed using either sodium bisulfite and formic acid or sodium nitrite and HCl to afford ketone (IV). Dihydroxylation of the allyl group of (IV) by means of N-methylmorpholine-N-oxide and a catalytic amount of OsO4, followed by oxidative cleavage of the resulting glycol (V) with NaIO4 produced aldehyde (VI). Alternatively, aldehyde (VI) was obtained by ozonolysis of the allyl ether (IV).
Alkylation of protected erythromycin (I) at the 6-hydroxyl group with allyl bromide provided ether (II). Hydrolysis of the cyclohexylidene ketal group of (II) with concomitant desilylation with AcOH gave (III). The oxime function of (III) was then hydrolyzed using either sodium bisulfite and formic acid or sodium nitrite and HCl to afford ketone (IV). Dihydroxylation of the allyl group of (IV) by means of N-methylmorpholine-N-oxide and a catalytic amount of OsO4, followed by oxidative cleavage of the resulting glycol (V) with NaIO4 produced aldehyde (VI). Alternatively, aldehyde (VI) was obtained by ozonolysis of the allyl ether (IV).
Condensation of this aldehyde (VI) with hydroxylamine produced the corresponding oxime (VII), which was finally dehydrated to the target nitrile by means of diisopropyl carbodiimide and CuCl.
Finally, condensation of this aldehyde with O-phenyl hydroxylamine yielded the target oxime.
Condensation of this aldehyde (VI) with phenethyl amine (VII) produced the corresponding imine (VIII), which was finally reduced to the target amine by means of NaBH3CN or by hydrogenation over Pd/C.