Propanamide, N-[(3E)-5-[(2R,3S,5R)-5-(3,4-dihydro-5-methyl-2,4-dioxo-1(2H)-pyrimidinyl)-3-[[(1,1-dimethylethyl)diphenylsilyl]oxy]tetrahydro-2-furanyl]-5-hydroxy-3-penten-1-yl]-3-(2-propyn-1-yloxy)-