A method of preparing a compound of Formula: including any stereoisomers, tautomers, solvates, hydrates, or salts thereof; wherein, m is 0 to 10; n is 1 to 4; R a and R b are each independently at each occurrence H or alkyl, or R a and R b together are oxo (=O); p is 1, 2, or 3; X is O or CHR 3; each R 3 is independently at each occurrence hydrogen, (C 1 -C 3)alkyl, hydroxy, or hydroxy(C 1- C 3)alkyl, wherein any hydroxy or hydroxyalkyl can be O-substituted with a monosaccharide, a disaccharide, an oligosaccharide, or a hydroxy-protecting group; provided that one R 3 comprises a moiety -OC(=O)(CH(R s)) s SH or -NHC(=O)(CH(R s)) s SH, wherein R s is H and s is 1, which moiety is attached at the C-2 or C-3 position; Y is C(R 4 R 5), O, NH or S; R 4 and R S are each independently H, alkyl, or J; the carbon atom bearing X and Y is in the R or the S configuration; each NR is independently NH or N(C 2 -C 3)alkyl, or an NR, together with an R c or R e bonded to a carbon atom bearing the NR, can form a 4-7 membered ring, or each R c, R c', R e and R e' is independently at each occurrence H, alkyl, aryl, heteroaryl, cycloalkyl, or heterocyclyl, or a sidechain of a naturally occurring amino acid which can be unblocked or blocked with a protecting group; or R c and R c' or R e and R e', or both, together with a carbon atom to which they are attached, form a cycloalkyl or heterocycloalkyl; wherein any alkyl, aryl, heteroaryl, cycloalkyl, or heterocyclyl is substituted with 0-3 J; J is halogen, trifluoromethyl, cyano, nitro, (C 1-6)alkyl, (C 1-6)alkoxy, cycloalkyl, carboxy; acetamido, hydroxy, hydroxy(C 1-6)alkyl, trifluoromethoxy, sulfamoyl, carbamoyl, sulfonamido, alkylsulfonyl, or arylsulfonyl; and R 1 and R 2 are each independently a peptide residue or a glycopeptide residue; the method comprising: contacting a compound of Formula: and a compound of Formula: wherein R d is alkyl, aryl, aralkyl, carboxyalkyl or carboxamidoalkyl; to provide the compound of formula. m is 0 to 10; n is 1 to 4; R a and R b are each independently at each occurrence H or alkyl, or R a and R b together are oxo (=O); p is 1, 2, or 3; X is O or CHR 3; each R 3 is independently at each occurrence hydrogen, (C 1 -C 3)alkyl, hydroxy, or hydroxy(C 1- C 3)alkyl, wherein any hydroxy or hydroxyalkyl can be O-substituted with a monosaccharide, a disaccharide, an oligosaccharide, or a hydroxy-protecting group; provided that one R 3 comprises a moiety -OC(=O)(CH(R s)) s SH or -NHC(=O)(CH(R s)) s SH, wherein R s is H and s is 1, which moiety is attached at the C-2 or C-3 position; Y is C(R 4 R 5), O, NH or S; R 4 and R S are each independently H, alkyl, or J; the carbon atom bearing X and Y is in the R or the S configuration; each NR is independently NH or N(C 2 -C 3)alkyl, or an NR, together with an R c or R e bonded to a carbon atom bearing the NR, can form a 4-7 membered ring, or each R c, R c', R e and R e' is independently at each occurrence H, alkyl, aryl, heteroaryl, cycloalkyl, or heterocyclyl, or a sidechain of a naturally occurring amino acid which can be unblocked or blocked with a protecting group; or R c and R c' or R e and R e', or both, together with a carbon atom to which they are attached, form a cycloalkyl or heterocycloalkyl; wherein any alkyl, aryl, heteroaryl, cycloalkyl, or heterocyclyl is substituted with 0-3 J; J is halogen, trifluoromethyl, cyano, nitro, (C 1-6)alkyl, (C 1-6)alkoxy, cycloalkyl, carboxy; acetamido, hydroxy, hydroxy(C 1-6)alkyl, trifluoromethoxy, sulfamoyl, carbamoyl, sulfonamido, alkylsulfonyl, or arylsulfonyl; and R 1 and R 2 are each independently a peptide residue or a glycopeptide residue; contacting a compound of Formula: and a compound of Formula: wherein R d is alkyl, aryl, aralkyl, carboxyalkyl or carboxamidoalkyl; to provide the compound of formula.