1,3,2-Dioxaphosphorinan-2-amine, N,N-bis(2-chloroethyl)-4,6-dimethyl-, 2-oxide, cis-, mixt. with trans-N,N-bis(2-chloroethyl)-4,6-dimethyl-1,3,2-dioxaphosphorinan-2-amine 2-oxide NSC294543