Adenosine, 2-chloro-N,N-bis[(1,1-dimethylethoxy)carbonyl]-5′-O-[2-ethoxy-1-[[2′-(methoxycarbonyl)[1,1′-biphenyl]-4-yl]methyl]-2-oxo-1-(2H-tetrazol-5-yl)ethyl]-3′-C-methyl-, 2′,3′-bis(1,1-dimethylethyl carbonate)