Thiazine (or oxazine) derivatives and preparation thereof

Abstract From the Canadian patent

Abstract of the Disclosure:, Thiazine (or oxazine) derivatives of the formula I: I, wherein R1 and R2 are both H or form a naphthalene ring together with the benzene ring; R3 and R4 are both H or one, of them is halogen and another is H; X is S or O; R5 and R6 are each i) H, ii) lower alkyl, iii) cycloalkyl iv) substi-, tuted phenyl, v) naphthyl vi) lower alkyl which is substi-, tuted by substituted or unsubstituted phenyl or vii) S-, containing heterocyclic group; one of Z1 and Z2 is O and another is H2; A is lower alkylene; R7 and R8 are each i) H ii) lower alkyl, iii) lower alkenyl, iv) lower alkynyl or v), lower alkyl which is substituted by substituted or unsubstituted phenyl, or both …