A novel dilithiation approach to 3,4-dihydro-2H-1,3-benzothiazines, 3,4-dihydro-2H-1,3-benzoxazines, and 2,3,4,5-tetrahydro-1,3-benzothiazepines

Research has been conducted on 3,4-dihydro-2H-1,3-benzothiazines, 3,4-dihydro-2H-1,3-benzoxazines, and 2,3,4,5-tetrahydro-1,3-benzothiazepines. The synthesis of these compounds carried out via directed thiophenol and phenol ortho-lithiation and via substituted thiophenol side-chain lithiation is described.