Synthesis of optically active boroxazolidine, borathiazolidine and boraselenazolidine and their N-borane adducts from the corresponding 2- imino-heteroazolidines

The synthesis from the corresponding 2-imino-heteroazolidines of optically active boroxazolidine, borathiazolidine and boraselenazolidine, derived from ephedrine, and their N-borane adducts is reported. The X-ray diffraction structures of (4R,5R)-(+)-3,4-dimethyl-5-phenyl-2-iminium thiazolidine thiocyanate 9b, (4R,5R)-(+)-3,4-dimethyl-5-phenyl-2-iminium- selenazolidine selenocyanate 9c, (4R,5R)-(+)-3,4-dimethyl-5-phenyl-2- iminoselenazolidine 10b and (4R,5R)-(+)-3,4-dimethyl-5-phenyl-2- boraselenazolidine dimer 15 were elucidated. Compounds were also studied by ¹H, ¹³C and ⁷⁷Se NMR.