1H-Naphtho[2,1-b]pyran-1,5,6,10-tetrol,3-ethenyldodecahydro-3,4a,7,7,10a-pentamethyl-, 1,5,6,10-tetraacetate,(1R,3R,4aS,5S,6S,6aS,10R,10aS,10bS)-