Santana AG, Herrera AJ, González CC. Intramolecular Metal-Free C(sp
3)-H Activation Enables a Selective Mono
O-Debenzylation of Fully Protected Aminosugars.
J Org Chem 2021;
86:16736-16752. [PMID:
34807601 DOI:
10.1021/acs.joc.1c01977]
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Abstract
Carbamate-bearing benzylated aminosugars undergo an I2/I(III)-promoted intramolecular hydrogen atom transfer (IHAT) followed by a nucleophilic attack to provide polycyclic structures. Thus, suitably positioned benzyl ethers are surgically oxidized into the corresponding mixed N/O-benzylidene acetals, which can be conveniently deprotected under mild acidic conditions to grant access to selectively O-deprotected aminosugars amenable for further derivatization. The scope of this strategy has been proven with a series of furanosic and pyranosic scaffolds. Preliminary mechanistic studies, including Hammett LFER and KIE analyses, support a reaction pathway with nucleophilic cyclization as the rate-determining step.
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