2-methylpropan-2-yl {[(3R)-1-[7-(but-2-ynyl)-1-({4-[(2-{[7-(but-2-ynyl)-3-methyl-8-[(3R)-3-({[(2-methylprop-2-yl)oxy]carbonyl}amino)hexahydropyridin-1-yl]-2,6-dioxopurin-1-yl]methyl}quinazolin-4-yl)methyl]-4-methyl-4,4a-dihydroquinazolin-2-yl}methyl)-3-methyl-2,6-dioxopurin-8-yl]hexahydropyridin-3-yl]amino}methanoate