Pyrrolo[2,3-d]pyrimidine derivatives; their intermediates and synthesis

This invention relates to methods and intermediates useful for the synthesis of pyrrolo[2,3-d]pyrimidine compounds. Specifically novel synthetic methods and intermediates for the synthesis of 3-{(3R,4R)-4-methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino}-piperidin-1-yl)-3-oxo-propionitrile and its corresponding citrate salt are disclosed.