Conversion of Digitoxin (2) Into synthetically Useful Derivatives of Digitoxose (1) (2,6-Dideoxy-D-ribo-Hexose)

Abstract

An efficient procedure is described for the conversion of digitoxin (2) into 1,3,4-tri-O-benzoyl-2,6-dideoxy-β-D-ribo-hexopyranose (4). This conversion allows digitoxin (2) to become a viable source of 2,6-dideoxy sugars since the tribenzoate 4 is readily converted into synthetically useful derivatives. One type of derivative, exemplified by t-butyl 2,6-dideoxy-β-D-ribo-hexopyranoside (17), is an unprotected glycoside and thus easily permita structural modification at C-3 and C-4. A second type of derivative formed from 4 is one capable of glycosidic coupling at the anomeric carbon atom. Examples of this latter type are 3,4-di-O-benzoyl-2,6-dideoxy-α-D-ribo-hexopyranoayl chloride (7) and ethyl 3,4-di-O-benzoyl-2,6-dideoxy-1-thio-O-D-ribo-hexopyranoside (13).