PUB - Publikationen an der Universität Bielefeld

The title compounds, (2S)-N-[5-(4-chlorophenyl)-2,3-dihydro-6H-1,3,4-thiadiazin-2-ylidene]-2- [(phenylsulfonyl)amino]propanamide, C18H17ClN4O3S2, (I), (2R)-N-[5-(4-fluorophenyl)6H-1,3,4-thiadiazin-2-yl]-2-[(phenylsulfonyl)a mino]propan-amide, C18H17FN4O3S2, (II), and (2S)-N-[5-(5-chloro-2-thienyl)-6H-1,3,4-thiadiazin-2-yl]-2-[(phenylsulfo nyl)amino]- propanamide, C16H15ClN4O3S3, (III), are potent inhibitors of matrix metalloproteinases. In all three compounds, the thiadiazine ring adopts a screw-boat conformation. The molecules of compound (I) show a short intramolecular N-Ala-H . . .N-exo hydrogen bond [N . . .N 2.661 (3) Angstrom] and are linked into a chain along the c axis by N-endo-H . . .S-endo and N-endo-H . . .O-Ala hydrogen bonds [N . . .S 3.236 (3) and N . . .O 3.375 (3) Angstrom] between neighbouring molecules. In compound (II), the molecules are connected antiparallel into a chain along the a axis by N-exo-H . . .O-Ala and N-Ala-H . . .N-endo hydrogen bonds [N . . .O 2.907 (6) and N . . .N 2.911 (6) Angstrom]. The molecules of compound (III) are dimerized antiparallel through N-exo-H . . .N-endo hydrogen bonds [N . . .N 2.956 (7) and 2.983 (7) Angstrom]. The different hydrogen-bonding patterns can be explained by an amido-imino tautomerism (prototropic shift) shown by different bond lengths within the 6H-1,3,4-thiadiazine moiety.