5c-oxo-(4at,10bt)-1,2,3,4,4a,5,6,10b-octahydro-5λ4-1r,4c-methano-dibenzo[c,e][1,2]thiazine-2r',3t'-dicarboxylic acid dimethyl ester

(6RS,6aRS,7SR,12SR,12aRS)-7,12-epoxy-6a,7,12,12a-tetrahydro-5-methyl-5H-6-thia-5-azabenzanthracene 6-oxide