Carbamic acid, (1-oxopropoxy)-, 3-ethenyldodecahydro-6,10,10b-trihydroxy-3,4a,7,7,10a-pentamethyl-1-oxo-1H-naphtho(2,1-b)pyran-5-yl ester, (3R-(3alpha,4abeta,5beta,6beta,6aalpha,10alpha,10abeta,10balpha))-