Many compounds in medicinal chemistry contain an azaindole with a free NH-moiety. During the synthesis of these compounds, an arylsulfonyl group is often used as stable blocking group for this functionality. After removal of this group by a methanol/cesium carbonate system described for the deprotection of N-arylsulfonyl-indoles we found considerable amounts of N-methylated by-products due to the reactivity of the methyl-arylsulfonate formed in the reaction. We could prevent this type of side reaction by replacing methanol with trifluoroethanol.We will present the rationale for choosing trifluoroethanol and a range of examples where this deprotection method has successfully been applied.

Clean deprotection of 1-arylsulfonyl-azaindoles using a trifluoroethanol/base system

246th National Meeting (2013)

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