Nalmefene Impurity H Catalogue N211338 CAS 738552-29-9 M.W 339.44 M.F C21H25NO3 Specifications FAQs (4R,4aS,7aS,12bS)-3-(But-3-en-1-yl)-7-methylene-1,2,3,4,5,6,7,7a-octahydro-4aH-4,12-methanobenzofuro[3,2-e]isoquinoline-4a,9-diol