Synthesis of phosphocholine ester derivatives and conjugates thereof

A method, comprising the steps of:

• contacting
• with a calcium salt of phosphocholine to form
• and
• reacting said
• with
• to form
• wherein
• X is bromo, chloro, iodo, tosyl, or mesyl;
• R1 is H or alkyl;
• Y is —(CH2)n— optionally substituted at any one or more methylene unit with halo, alkyl, alkenyl, alkynyl, cycloalkyl, alkylcycloalkyl, heterocyclyl, heterocycloalkyl, aryl, aralkyl, aryloxy, heteroaryl, heteroaralkyl, perfluoroalkyl, alkylamido, acyl, acyloxy, alkanesulfonamido, alkoxy, perfluoroalkoxy, alkylamino, carboxamido, carboalkoxy, or carboxyalkyl, or optionally one or more methylene unit is replaced with O, S, or NH, or a combination thereof;
• n is an integer from 0 to 20;
• and
• Z is an electron withdrawing group.