Patent ID: 6303764
Filing Date: 2001-10-16
Classification: C07K,C12N,C12P

Abstract:
A method of preparing a 4,7-di-O-alkyl chromogenic ketoside of N-acetylneuraminic acid (Neu5Ac), said method comprising, in order, the following steps:(a) alkylating Neu5Ac on the C1 carboxyl and C2 (anomeric) hydroxyl to provide an alkyl ester alkyl ketoside derivative of Neu5Ac;(b) protecting the 8- and 9-hydroxyl groups of the alkyl ester alkyl ketoside derivative of Neu5Ac to form a protected alkyl ester alkyl ketoside derivative of Neu5Ac;(c) alkylating the 4- and 7-hydroxyl groups of the protected alkyl ester alkyl ketoside derivative of Neu5Ac by contacting the derivative with an alkyl halide to form a 4,7-di-O-alkyl protected alkyl ester alkyl ketoside derivative of Neu5Ac;(d) selectively deprotecting the 8- and 9-hydroxyl groups and dealkylating the 2-hydroxyl group of the ketoside product obtained in step (c) and derivatizing the resulting 2-, 8-, and 9-hydroxyl groups;(e) activating the anomeric carbon of the product obtained in step (d) to form a 4,7-di-O-alkyl alkyl ester derivative of Neu5Ac, derivatized at the 8- and 9-hydroxyls, and activated at the anomeric carbon;(f) contacting the product obtained in step (e) with a suspension of a chromogenic moiety in a solvent to form a chromogenic ketoside of a 4,7-di-O-alkyl alkyl ester derivative of Neu5Ac, derivatized at the 8- and 9-hydroxyls; and(g) obtaining a 4,7-di-O-alkyl chromogenic ketoside of Neu5Ac from the derivatized chromogenic ketoside obtained in step (f).