1,4-Tetrahydrothiazine-3-one 20196-21-8 3-Oxothiomorpholine 3-Thiomorpholinone 4-27-00-02550 (Beilstein Handbook Reference) BRN 0107799 EINECS 243-581-8 NSC 27540 Thiomorpholin-3-one Thiomorpholinone