Patent ID: 6897299

Claim:
A method for preparing a fumarate salt of a compound represented by Formula (II): (wherein R 1 represents a hydrogen atom or a lower alkyl group, and R 2 represents a lower alkyl group), which comprises: carbamating a compound represented by Formula (I): (wherein R 1 represents a hydrogen atom or a lower alkyl group) to give a compound represented by Formula (III): (wherein R 1 represents a hydrogen atom or a lower alkyl group, R 3 represents a carbamate group, and R 4 represents a hydrogen atom or a carbamate group); removing all carbamate groups from the compound represented by Formula (III) to give a compound represented by Formula (IV): (wherein R 1 represents a hydrogen atom or a lower alkyl group); alkylating the nitrogen atom at the 3′-position of the desosamine ring in the compound represented by Formula (IV) to give the compound represented by Formula (II); and converting the compound represented by Formula (II) into a fumarate salt; wherein the compound represented by Formula (I) is carbamated in the presence of a cyclic ether or a carboxylic ester to give the compound represented by Formula (III).