Patent ID: 8288515

Claim:
A compound of Formula I wherein R 1 is levulinyl (Lev) or tetrahydropyran (THP); R 2 is â€”O âˆ’ or a salt thereof, â€”OH, â€”OAcyl, or â€”OSO 3 âˆ’ or a salt thereof; R 3 is H, benzyl or a protecting group removable by hydrogenation; R 4 is N 3 (azide), NH 2 , NH-protecting group, or NHSO 3 âˆ’ or a salt thereof; R 5 is C 1 -C 6 alkyl; and R 6 and R 7 are independently selected from â€”CO 2 âˆ’ or a salt thereof, â€”CO 2 H and â€”CO 2 R x where R x is a C 1 -C 6 alkyl, aryl, C 1 -C 4 alkoxy(aryl), aryl(C 1 -C 6 alkyl), or C 1 -C 4 alkoxy(aryl)(C 1 -C 6 alkyl); and wherein said compound has alpha (Î±) stereochemistry at the carbon bearing the â€”OR 5 group.