Studies on Phenylalkanethiolamine. VI. Synthesis and Configuration of 2-Phenyl-3, 4-dimethylthiomorpholine

Racemic and optically active N-(2-mercaptoethyl)ephedrines, 2-phenyl-3, 4-dimethyl-tetrahydro-4H-1, 4-thiazines, and their diastereomers were prepared, and their configurations were investigated. 2-Phenyl-3, 4-dimethyltetrahydro-4H-1, 4-thiazine, was obtained either by chlorination of N-(2-hydroxyethyl)ephedrine with thionyl chloride followed by cyclization with sodium sulfide, or by dehydration N-(2-mercaptoethyl)-l-and d-ψ-ephedrines with 80% sulfuric acid. Both reactions led to formation of threo-2-phenyl-3, 4-dimethyltetrahydro-4H-1, 4-thiazine. erythro-2-Phenyl-3, 4-dimethyltetra-hydro-4H-1, 4-thiazine was prepared from erythro-1-phenyl-2-methylaminopropanethiol and cthylene dibromide. When N-(2-mercaptoethyl)ephedrine was heated, formation of ephedrine due to partial splitting of 2-mercaptoethyl group was observed.