58497-00-0 6alpha,9-Difluoro-11beta,16alpha,17,21-tetrahydroxypregna-1,4-diene-3,20-dione cyclic 16,17-acetal with acetone, 21-propionate 6alpha,9-Difluoro-11beta-hydroxy-16alpha,17-(isopropylidenebis(oxy))pregna-1,4-diene-3,20-dione