A direct and efficient α-selective glycosylation protocol for the kedarcidin sugar, L-mycarose: AgPF6 as a remarkable activator of 2-deoxythioglycosides

Lear, Martin J. and Yoshimura, Fumihiko and Hirama, Masahiro (2001) A direct and efficient α-selective glycosylation protocol for the kedarcidin sugar, L-mycarose: AgPF6 as a remarkable activator of 2-deoxythioglycosides. Angewandte Chemie International Edition, 40 (5). pp. 946-949. ISSN 1433-7851

Full content URL: http://dx.doi.org/10.1002/1521-3773(20010302)40:5<...

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Abstract

Without the stereodirecting ability of 2-substituents, strategies to prepare 2-deoxyglycosides selectively in high alpha- or beta-anomeric forms rely heavily on indirect sequences from glycals or latent 2-deoxysugars. As such, these require a
subsequent reductive step that would be unsuitable for many complex natural products and for any viable total synthesis program. A case in point is that of the kedarcidin chromophore and its alpha-linked 2,6-dideoxysugars, L-mycarose
and L-kedarosamine. In particular, direct and efficient alpha-selective methods for allo-configured systems are especially difficult to realise. Herein we describe a direct, potent, and mild protocol to efficiently generate alpha-L-mycarosides from thioglycosides by using AgPF6, which is exemplified by the alpha-mycosylation of an advanced kedarcidin substructure. Although the present method is applicable to other 2-deoxy systems, such as the synthesis of alpha-L-kedarosaminides, normal 2-oxythioglycosides remain inert to AgPF6 and can be used as acceptors armed with strategic anomeric linkages.

Keywords:Natural enediynes, 2-Deoxy sugars, Stereoselective glycosylation
Subjects:F Physical Sciences > F160 Organic Chemistry
Divisions:College of Science > School of Chemistry
ID Code:17127
Deposited On:16 Apr 2015 13:26

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