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31.9.2.1.4.9.1 Variation 1: N-Dealkylation of N-Alkylarenesulfonamides

DOI: 10.1055/sos-SD-031-00644

Shcherbakova, I.Science of Synthesis, (200731820.

N-Dealkylation as deprotection of N-alkylarenesulfonamides is often part of the synthetic strategy in medicinal chemistry[‌197‌] and the most widely used protecting group is tert-butyl. Deprotection is executed with trifluoroacetic acid[‌198‌] or, avoiding strong acidic conditions, with boron trichloride in dichloromethane at room temperature.[‌197‌] However, removal of alkyl groups other than tert-butyl by these methods is problematic. Nickel-catalyzed N-deallylation proceeds on treatment of N-allylarenesulfonamides with diisobutylaluminum hydride and is effective for basic, neutral, or acidic nitrogen.[‌199‌] Oxidative sonochemical N-dealkylation of a number of N-alkylarenesulfonamides is reported in the presence of (diacetoxyiodo)benzene and iodine, although yields are moderate and the scope of the reaction is limited.[‌200‌] Novel N-dealkylation of N-alkyl- or N,N-dialkylarenesulfonamides, e.g. 155, with periodic acid catalyzed by trichromium(III) heptaacetate dihydroxide results in good to excellent yields of the arenesulfonamides 156, is effective for a wide range of alkyl groups and for the benzyl group, and tolerates a variety of functional groups (Scheme 66).[‌201‌]

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