Microwave-assisted synthesis and antioxidant properties of hydrazinyl thiazolyl coumarin derivatives.

Background: Coumarin derivatives exhibit a wide range of biological properties including promising antioxidant activity. Furthermore, microwave-assisted organic synthesis has delivered rapid routes to N- and O-containing heterocycles, including coumarins and thiazoles. Combining these features, the use of microwave-assisted processes will provide rapid access to a targeted coumarin library bearing a hydrazino pharmacophore for evaluation of antioxidant properties

Results: Microwave irradiation promoted 3 of the 4 steps in a rapid, convergent synthesis of a small library of hydrazinyl thiazolyl coumarin derivatives, all of which exhibited significant antioxidant activity comparable to that of the natural antioxidant quercetin, as established by DPPH and ABTS radical assays

Conclusions: Microwave dielectric heating provides a rapid and expedient route to a series of hydrazinyl thiazolyl coumarins to investigate their radical scavenging properties.

(E)-6-Bromo-3-{2-[2-(2-meth-oxy-benzyl-idene)hydrazin-yl]-1,3-thia-zol-4-yl}-2H-chromen-2-one.

In the title compound, C(20)H(14)BrN(3)O(3)S, the mol-ecule adopts an E configuration about the central C=N double bond. The chromene ring system and the thia-zole ring are approximately planar [maximum deviations = 0.029 (3) and 0.

6-Bromo-3-{2-[2-(diphenyl-methyl-ene)hydrazin-yl]-1,3-thia-zol-5-yl}-2H-chromen-2-one chloro-form monosolvate.

In the title compound, C(25)H(16)BrN(3)O(2)S·CHCl(3), the thia-zole ring is approximately planar [maximum deviation = 0.002 (3) Å] and makes dihedral angles of 10.75 (14) and 87.

(E)-3-(2-{2-[1-(3-Hy-droxy-phen-yl)ethyl-idene]hydrazin-yl}-1,3-thia-zol-4-yl)-2H-chromen-2-one.

In the title compound, C(20)H(15)N(3)O(3)S, the thia-zole ring is approximately planar, with a maximum deviation of 0.003 (1) Å, and makes dihedral angles of 7.44 (6) and 1.

(E)-6-Bromo-3-{2-[2-(2-chloro-benzyl-idene)hydrazin-yl]thia-zol-5-yl}-2H-chromen-2-one dimethyl sulfoxide monosolvate.

In the title compound C(19)H(11)N(3)O(2)SClBr·C(2)H(6)OS, the mol-ecule adopts an E configuration about the central C=N double bond. The chromene ring system and the thia-zole ring are approximately planar, with maximum deviations of 0.027 (2) and 0.

(E)-6-Bromo-3-{2-[2-(4-chloro-benzyl-idene)hydrazin-yl]thia-zol-5-yl}-2H-chromen-2-one.

In the title compound, C(19)H(11)N(3)O(2)SClBr, the chromene ring system and the thia-zole ring are each approximately planar, with maximum deviations of 0.033 (3) Å and 0.006 (3) Å, respectively.

Synthesis and antimicrobial properties of some new thiazolyl coumarin derivatives.

Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10a-d and 15a-h, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans.

3-{2-[2-(Diphenyl-methyl-ene)hydrazin-yl]thia-zol-4-yl}-2H-chromen-2-one.

In the title compound, C(25)H(17)N(3)O(2)S, the coumarin ring system is essentially planar with a maximum deviation of 0.019 (2) Å. A weak intra-molecular C-H⋯O hydrogen bond stabilizes the mol-ecular structure, so that the coumarin plane is approximately coplanar with the thia-zole ring, making a dihedral angle of 2.

(Z)-3-(2-{2-[1-(4-Hy-droxy-phen-yl)ethyl-idene]hydrazin-1-yl}-1,3-thia-zol-4-yl)-2H-chromen-2-one.

In the title compound, C(20)H(15)N(3)O(3)S, an intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. The chromene ring system is inclined at dihedral angles of 14.21 (9) and 9.

3-{2-[2-(3-Hy-droxy-benzyl-idene)hydrazin-1-yl]-1,3-thia-zol-4-yl}-2H-chromen-2-one hemihydrate.

In the title compound, C(19)H(13)N(3)O(3)S·0.5H(2)O, both organic mol-ecules (A and B) exist in E configurations with respect to the acyclic C=N bond and have similar overall conformations. In mol-ecule A, the essentially planar thia-zole ring [maximum deviation = 0.

(E)-1-[1-(6-Bromo-2-oxo-2H-chromen-3-yl)ethyl-idene]thio-semicarbazide.

The title compound, C(12)H(10)BrN(3)O(2)S, exists in an E configuration with respect to the C=N bond. The approximately planar 2H-chromene ring system [maximum deviation = 0.059 (1) Å] is inclined at a dihedral angle of 17.

3-{2-[2-(2-Fluoro-benzyl-idene)hydrazin-yl]-1,3-thia-zol-4-yl}-2H-chromen-2-one.

In the title compound, C(19)H(12)FN(3)O(2)S, the chromene ring system and the thia-zole ring are approximately planar [maximum deviations of 0.023 (3) Å and 0.004 (2) Å, respectively].