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Solvent-free N-Boc deprotection by ex situ generation of hydrogen chloride gas

  • Verschueren, Rik H; 116326;
  • Gilles, Philippe;
  • Van Mileghem, Seger;
  • De Borggraeve, Wim M; 2838;
Publication Date
Apr 30, 2021
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An efficient, scalable and sustainable method for the quantitative deprotection of the tert-butyl carbamate (N-Boc) protecting group is described, using down to near-stoichiometric amounts of hydrogen chloride gas in solvent-free conditions. We demonstrate the ex situ generation of hydrogen chloride gas from sodium chloride and sulfuric acid in a two-chamber reactor, introducing a straightforward method for controlled and stoichiometric release of HCl gas. The solvent-free conditions allow deprotection of a wide variety of N-Boc derivatives to obtain the hydrochloride salts in quantitative yields. The procedure obviates the need for any work-up or purification steps providing an uncomplicated green alternative to standard methods. Due to the solvent-free, anhydrous conditions, this method shows high tolerance towards acid sensitive functional groups and furnishes expanded functional group orthogonality. / status: published

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