Couturier M, Tucker JL, Proulx C, Boucher G, Dubé P, Andresen BM, Ghosh A. 5,5-Dimethyl-1,4,2-dioxazoles as versatile aprotic hydroxamic acid protecting groups.
J Org Chem 2002;
67:4833-8. [PMID:
12098295 DOI:
10.1021/jo0256890]
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Abstract
5,5-Dimethyl-1,4,2-dioxazoles are readily installed by transketalization of 2,2-diethoxypropane, where both the NH and OH moieties are protected in a nonprotic form. The dioxazoles are stable to a wide variety of reaction conditions and readily revert back to the hydroxamic acid by treatment with Nafion-H in 2-propanol. The method is applicable to primary, secondary, tertiary, and aromatic hydroxamic acids, and the acidity of the protons adjacent to the dioxazole allows alpha-functionalization.
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