Carbamic acid,[1-[7-(1-cyclopenten-1-ylmethyl)-2,3,6,7-tetrahydro-3-methyl-1-[2-[2-[2-(methylamino)-2-oxoethoxy]phenyl]-2-oxoethyl]-2,6-dioxo-1H-purin-8-yl]-3-piperidinyl]-, 1,1-dimethylethyl ester