Carbamic acid,[1-[7-(1-cyclopenten-1-ylmethyl)-1-[(2-cyclopropyl-4-quinazolinyl)methyl]-2,3,6,7-tetrahydro-3-methyl-2,6-dioxo-1H-purin-8-yl]-3-piperidinyl]-,1,1-dimethylethyl ester