16983-23-6 Furo(2',3':5,6)cyclohepta(1,2-c)pyran-2,7(3H,4H)-dione, octahydro-4a,9-dimethyl-3-methylene-, (3aR-(3aalpha,4abeta,8aalpha,9alpha,10abeta))- NSC 136718 Vermeerin