TIGECYCLINE AND METHODS OF PREPARING INTERMEDIATES

摘要

Methods of preparing and purifying 9-nitrominocycline and 9-aminominocycline and salts thereof used in the process of making tigecycline, are disclosed. In one embodiment, the invention is directed to a method of preparing the compound of formula 1 or a pharmaceutically acceptable salt thereof, comprising: (a) reacting nitric acid with the compound of formula 2, or a salt thereof, to produce a reaction mixture comprising an intermediate; and (b) further reacting the intermediate to form the compound of formula 1, wherein the intermediate is isolated from the reaction mixture, the method further comprising sparging with an inert gas prior to step (a).