2-Oxabicyclo[2.2.1]heptane-1-carboxylic acid, 4,7,7-trimethyl-3-oxo-,(1R)-1-[1-[(R)-[bis(1-methylethyl)amino]carbonyl]-8-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-2-naphthalenyl]ethyl ester, (1S,4R)-