B. Prabhuswamy

Synthesis of novel 3-[5-ethyl-2-(2-phenoxy-ethyl)-pyridin]-5-substituted isoxazoline libraries via 1,3-dipolar cycloaddition and evaluation of antimicrobial activities

A series of novel 3-[5-ethyl-2-(2-phenoxy-ethyl)-pyridin]-5-substituted isoxazolines were synthesized via 1,3-dipolar cycloaddition of in situ generated nitrile oxide from 4-[2-(5-ethylpyridyl)-ethoxy]-benzaldoxime with alkenes to obtain new heterocyclic libraries containing a pyridine moiety in addition to the isoxazoline ring. The newly synthesized compounds were screened for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Of the compounds studied, compounds 3c and 3f showed significant antibacterial as well as antifungal activity. Compounds 3e and 3g showed moderate activity. The title compounds represent a novel class of potent antimicrobial agents.

Crystal Structures of two Triazole Derivatives

3-Phenyl-4-amino-5-mercapto-1,2,4-triazole(PAMT), C 8 H 8 N 4 S, F.W.=192.24, triclinic, P 1¯, a=6.1698(3)Å, b=7.1765(1)Å, c=9.9894(3)Å, f =81.87(1), g =84.97(2), n =78.81(2), V=428.72(3)Å 3 , Z=2, D cal =1.489 Mgm m 3 , w =0.330 mm m 1 , F 000 =200, u (MoK f )=0.71073 Å, final R1 and wR2 are 0.0871 and 0.2170, respectively. 3-(4-Methylphenyl)-4-amino-5-mercapto-1,2,4-triazole (MAMT), C 9 H 10 N 4 S,F.W.=206.27, triclinic, P 1 , a=5.996(1)Å, b=7.582(2)Å, c=11.143(1)Å, f =73.16(1), g =89.65(2), n =87.88(1), V=484.52(3)Å 3 , Z=2, D cal =1.414 Mgm m 3 , w =2.674 mm m 1 , F 000 =216, u (CuK f )=1.5418 Å, final R1 and wR2 are 0.0656 and 0.1820, respectively. In both of the molecules the triazole rings are planar and oriented at angles of 5.7(1) and 1.4(2) with the respective phenyl rings in MAMT and PAMT. The molecules in the unit cell are stabilized by N-H…N type hydrogen bonds in addition to van der Waals forces.

Crystal and Molecular Structure Analysis of 1,2,4-Triazolo-N-amino-thiols

The compound 4-amino-5-(4-methyl)-4H-[1,2,4]-triazole-3-thiol [AMT], C3H6N4S, crystallizes in the orthorhombic space group Pca21 with cell parameters a = 9.8130(3)Å, b = 8.8600(5)Å, c = 6.5400(5)Å, V = 568.61(6)Å3, and Z = 4. The structure was solved by direct methods using SHELXS-97 and refined using SHELXL-97. The final residual factor is R1 = 0.0465 for 1726 reflections and 75 parameters. The compound 4-amino-5-(4-chlorophenyl)-4H-[1,2,4]-triazole-3-thiol[ACT], C8H7ClN4S, crystallizes in the triclinic space group with cell parameters a = 8.0440(8)Å, b = 11.527(1)Å, c = 11.7780(7)Å, α = 66.537(6)○, β = 72.990(6)○, γ = 76.001(3)○, V = 948.1(1)Å3, and Z = 4. The structure was solved by direct methods using SHELXS-97 and refined using SHELXL-97. The final residual factor is R1 = 0.0644 for 6805 reflections and 254 parameters.

Synthesis and X-ray crystal studies of 6-(2-chlorophenyl)-3-methyl[1,2,4] triazolo[4,5-6][1,3,4]thiadiazole

The compound 6-(2-chlorophenyl)-3-methyl[1,2,4]triazolo[4,5-b][1,3,4]thiadiazole, was synthesised using different reagents and conditions, characterised by spectroscopic techniques and finally confirmed by X-ray crystal structure analysis. The title compound crystallises in monoclinic class under the space group P21/c with cell parameters, a=10.6710 (6)Å, b=7.3660 (4)Å, c=14.3900 (8)Å, β=110.403 (3)°, Z=2 and R1= 0.0396 for 2715 reflections [I>2ΣI]. The structure exhibits inter-molecular hydrogen bonding.

5-Amino-3H-isobenzofuran-1-one (5-aminophthalide).

The title compd., C8H7NO2, serves as an intermediate for the synthesis of citalopram. Crystallog. data are given. The packing of the planar mols. is stabilized by N-H···O and N-H···N H bonds. [on SciFinder(R)]

3-(p-Nitrobenzyl)-1,3-thiazolidine-2,4-dione.

The title compd., C10H8N2O4S, serves as a starting material for the synthesis of antihyperglycemic pharmaceuticals. Crystallog. data are given. The nearly planar thiazolidine-2,4-dione ring is almost perpendicular to the nitrophenyl ring. [on SciFinder(R)]