Clarke JJ, Basemann K, Romano N, Lee SJ, Gagné MR. Borane- and Silylium-Catalyzed Difunctionalization of Carbohydrates: 3,6-Anhydrosugar Enabled 1,6-Site Selectivity.
Org Lett 2022;
24:4135-4139. [PMID:
35653692 DOI:
10.1021/acs.orglett.2c01243]
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Abstract
A novel diastereoselective, Lewis acid catalyzed 1,6-difunctionalization of galactose and mannose derivatives has been developed in one pot, via sequential nucleophile additions. Our studies point to the formation of a 3,6-anhydrosugar intermediate as key to the 1,6-site-selectivity. Starting material-specific reactivity occurs when competitive ring-opening C-O cleavage is possible, owed to basicity and stereoelectronic stabilization differences. Lastly, Mayr nucleophilicity parameter values helped predict which reaction conditions would be most suitable for specific nucleophiles.
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