Solid-phase syntheses of N-substituted carbamates. Reaction monitoring by gel-phase 13C NMR using a 13C enriched BAL-linker

The solid-phase synthesis of N-substituted carbamates using the tris(alkoxy)benzyl (BAL) resin is reported. The incorporation of the primary amine was carried out by reductive amination, which was followed by reaction with an alkyl succinimidyl carbonate prepared in situ from the alcohol and N,N′-disuccinimidyl carbonate (DSC). Final cleavage with trifluoroacetic acid rendered the target compounds. Scope and limitations of these methods are discussed. The reactions were controlled by gel-phase 13C NMR using a 13C enriched BAL resin.