Preparation of (2R)-2-acetoxy-D-forosamine for the total synthesis of spinosyns

Abstract

A synthesis of 2-acetoxy-D-forosamine (4) starting from 1,2-O-propylidene-α-D-abequose (3,6-dideoxy-1,2-O-propylidene-α-D-xylo-hexopyranose) (5) was developed by introduction of an azide moiety at C-4 with inversion of configuration. The 2-acetoxy group in 4 allows a β-selective glycosidation of a secondary alcohol moiety which is necessary in the total synthesis of spinosyns.

Stereoselective Synthesis of the Disaccharide Unit of Incednine

“…The synthesis of thioglycoside donor 6 originated from the known azido sugar 9, which was prepared in nine steps (23% overall yield) from commercially available allyl R-D-galactopyranoside (8) according to a literature procedure (Scheme 1). 5 We focused next on the synthesis of glycosyl acceptor 7 (Scheme 2). Persilylation of commercially available D-lyxose (11) in the presence of triethylamine produced 12 in essentially quantitative yield.…”

“…The synthesis of thioglycoside donor 6 originated from the known azido sugar 9 , which was prepared in nine steps (23% overall yield) from commercially available allyl α- d -galactopyranoside ( 8 ) according to a literature procedure (Scheme ) . Removal of the 1,2-propylidene acetal was accomplished by treatment of 9 with aqueous trifluoroacetic acid.…”

Synthesis of the Deoxyaminosugar (+)-d-Forosamine via a Novel Domino−Knoevenagel−Hetero-Diels−Alder Reaction

“…Within our attempts to prepare novel analogues of the spinosynes using multiple Pd-catalyzed transformations, efficient access to forosamine was required. Several syntheses of the 4-aminosugar forosamine ( 2 ) by transformation of glucose derivatives or by epoxidation of sorbic acid and successive reaction with dimethylamine have been published so far. , …”