{(R)-1-[6-[2,2-Bis-(4-hydroxy-phenyl)-ethylamino]-9-((1R,2S,3R,4S)-2,3-dihydroxy-4-propionylamino-cyclopentyl)-9H-purin-2-yl]-pyrrolidin-3-yl}-carbamic acid tert-butyl ester trifluoroacetate