Synthesis, Spectral, and Antifungal Evaluation of Phosphorylated and Thiophosphorylated Benzothiazole Derivatives

Isothioureas, Ureas, and Their N-Methyl Amides from 2-Aminobenzothiazole and Chiral Amino Acids

In this investigation, the reaction of 2-dithiomethylcarboimidatebenzothiazole with a series of six chiral amino-acids was studied. The reaction proceeds through the isolable sodium salt of SMe-isothiourea carboxylates as intermediates, whose reaction with methyl iodide in stirring DMF as solvent affords SMe-isothiourea methyl esters. The presence of water in the reaction leads to the corresponding urea carboxylates as isolable intermediates, whose methyl esters were obtained. Finally, the urea N-methyl amide derivatives were isolated when SMe-isothiourea or urea methyl esters were reacted with methylamine in the presence of water. The structures of synthesized compounds were established by ¹H and ¹³C nuclear magnetic resonance and the structures of SMe-isothiourea methyl esters derived from (l)-glycine, (l)-alanine, (l)-phenylglycine, and (l)-leucine, by X-ray diffraction analysis. This methodology allows to functionalize 2-aminobenzothiazole with SMe-isothiourea, urea, and methylamide groups derived from chiral amino acids to get benzothiazole derivatives containing coordination sites and hydrogen bonding groups. Further research on the biological activities of some of these derivatives is ongoing.

2-Mercapto Benzothiazole Derivatives: As Potential Leads for the Diabetic Management

BACKGROUND

Results of our previous studies on antiglycation activity, and the noncytotoxicity of 2-mercapto benzothiazoles, encouraged us to further widen our investigation towards the identification of leads against diabetes mellitus.

METHODS

33 derivatives of 2-mercapto benzothiazoles 1-33 were evaluated for in vitro α- glucosidase inhibitory activity. Mode of inhibition was deduced by kinetic studies. To predict the interactions of 2-mercapto benzothiazole derivatives 1-33 with the binding pocket of α-glucosidase enzyme, molecular docking studies were performed on the selected inhibitors.

RESULTS

Compounds 2-4, 6-7, 9-26, 28 and 30 showed many folds potent α-glucosidase inhibitory activity in the range of IC50 = 31.21-208.63 μM, as compared to the standard drug acarbose (IC50 = 875.75 ± 2.08 μM). It was important to note that except derivative 28, all other derivatives were also found previously to have antiglycating potential in the range of IC50 = 187.12-707.21 μM.

CONCLUSION

A number of compounds were identified as dual nature as antiglycating agent and α- glucosidase inhibitors. These compounds may serve as potential lead candidates for the management of diabetes mellitus.

Synthesis of novel inhibitors of β-glucuronidase based on the benzothiazole skeleton and their molecular docking studies

Benzothiazole derivatives (1–20) were evaluated for β-glucuronidase inhibitory activity.

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-2-(1-phenyl-ethyl-idene)hydrazine

The asymmetric unit of the title compound, C₁₅H₁₂FN₃S, consists of two independent mol­ecules with comparable geometries. In one mol­ecule, the 1,3-benzothia­zole ring system (r.m.s. deviation = 0.011 Å) forms a dihedral angle of 19.86 (6)° with the phenyl ring. The corresponding r.m.s. deviation and dihedral angle for the other mol­ecule are 0.014 Å and 22.32 (6)°, respectively. In the crystal, mol­ecules are linked via N—H⋯N, C—H⋯F and C—H⋯N hydrogen bonds into a three-dimensional network. The crystal studied was a non-merohedral twin with a refined BASF value of 0.301 (2).

6-Fluoro-2-(4-methoxyphenyl)imidazo[2,1-b][1,3]benzothiazole

The asymmetric unit of the title compound, C₁₆H₁₁FN₂OS, comprises two independent mol­ecules in which the benzothia­zole rings are essentially planar, with maximum deviations of 0.038 (2) and 0.045 (3) Å. The central benzothia­zole ring makes dihedral angles of 4.87 (13) and 0.64 (12)° and 4.04 (12) and 3.67 (12)° with the two terminal phenyl rings in the two independent mol­ecules. In the crystal, mol­ecules are connected via weak inter­molecular C—H⋯O hydrogen bonds forming supra­molecular chains along the c axis.

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde

The asymmetric unit of the title compound, C(17)H(10)FN(3)OS, consists of two crystallographically independent mol-ecules. In one mol-ecule, the pyrazole ring makes dihedral angles of 6.51 (7) and 34.02 (9)°, respectively, with the terminal 1,3-benzothia-zole ring system and the phenyl ring, while in the other mol-ecule these values are 6.41 (8) and 23.06 (9)°. In the crystal, the molecules are linked by weak π-π [centroid-centroid distance = 3.7069 (10) Å] and C-H⋯π inter-actions.