3-Pyridinecarboxylic acid [(3R,10R)-6β,7β,10-triacetoxy-5aβ-acetoxymethyl-3,4,5,5a,6,7,8,9-octahydro-9α-hydroxy-2,2,9-trimethyl-3β,9aβ-methano-2H-1-benzoxepin-5α-yl] ester