Selenium-catalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with amines to 1,2,3-thiadiazol-5-ylureas

A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of CO and O_2. This approach is featured with cheap and easily available raw materials,cheap and reusable catalyst selenium, one-pot procedure, high atomic economy, simple operations and no emission of corrosive wastes.

Synthesis, Crystal Structure and Antitumor Activity of 4-(tert-butyl)-5-(1H-1,2,4-triazol-1-yl)-N-(2-hydroxy-3,5-diiodinebenzyl)-thiazol-2-amine

The title compound, 4-（tert-butyl）-5-（1 H- 1,2,4-triazol- 1 -yl）-N-（2-hydroxy-3,5-diio- dinebenzyl）thiazol-2-amine, was synthesized via the reduction of 4-（tert-butyl）-5-（1H-l,2,4- triazol-l-yl）-N-benzylidene-thiazol-2-amine with NaBH4, and its crystal structure was determined by single-crystal X-ray diffraction. The compound crystallizes in monoclinic system, space group P21/c with a = 7.91944（19）, b = 10.5250（3）, c = 24.4985（6） A, Z = 4, V = 2041.66（9） A3, Mr = 599.22, Dc = 1,949 Mg/m3, S = 1.120, p = 3.203 mm-1, F（000） = 1152, the final R = 0.0283 and wR = 0.0592 for 3490 observed reflections （I 〉 2σ（I））. X-ray analysis displays that the crystal water takes part in three intermolecular hydrogen bonds of O（2）-H（2A）…O（1）, O（2）-H（2B）…N（I） and N（5）-H（5）…O（2）, and an octatomic ring R^（8） is formed via intramolecular hydrogen bond of O（I）-H（IA）…N（4）. Furthermore, the I…I contacts are involved in stabilizing the overall three-dimensional network structure. The preliminary biological test shows the title compound has good antitumor activity with the IC50 value of 26 μM against the Hela cell line.

Synthesis,Crystal Structure and Antitumor Activity of(E)-N-(4-Fluorobenzylidene)-3-(methylthio)-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazol-4-amine

The crystal structure of the title compound（E）-N-（4-fluorobenzylidene）-3-（methylthio）-5-（3,4,5-trimethoxyphenyl）-4 H-1,2,4-triazol-4-amine（C_（19）H_（19）FN_4O_3S,Mr = 402.44） was synthesized,and its structure was characterized by 1 H-NMR,13 C-NMR,ESI-MS and single-crystal X-ray diffraction.The crystal belongs to the triclinic system,space group P1 with a = 9.228（13）,b = 10.364（14）,c = 10.641（14） ？,α = 85.323（3）,β = 75.172（2）,γ = 80.903（3）°,μ = 0.20 mm^（-1）,M_r = 402.44,V = 970.64（10） ？~3,Z = 2,D_c = 1.377 g/cm^3,F（000） = 420,R = 0.0484 and wR = 0.1474 for 3181 observed reflections with I 〉 2σ（I）.In addition,the preliminary bioassay indicated that the title compound 5 exhibits better inhibitory activity against Hela than 5-fluorouracil.

Syntheses, Crystal Structures and Antibacterial Activities of Copper(Ⅱ) and Zinc(Ⅱ) Complexes Based on (E)-4-fluoro-2-((3-morpholinopropylimino)methyl)phenol

Two Schiff base complexes [Cu（L）2] （1） and [Zn（L）2]·3H2O（2） of （E）-4-fluoro-2-（（3-morpholino propylimino）methyl）phenol （HL） have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Crystal data for 1： triclinic, space group Pī with a=4.8000（10）, b=11.109（2）, c=13.921（3）,α=66.55（3）,β=80.35（3）,γ=81.09（3）°, V=668.2（2）3 , Z=1, Dc=1.477g/cm 3 , F（000）=311, and the final R=0.0744 and wR=0.1601 for 2301 observed reflections with I 〉 2σ（I）. And those for 2： monoclinic, space group P21 /c with a=14.789（3）, b=11.713（2）, c=18.846（4）,β=107.85（3）°, V=3107.4（11）3 , Z=4, D c=1.389 g/cm 3 , F（000）=1368, and the final R=0.0749 and wR=0.1348 for 5423 observed reflections with I 〉 2σ（I）. Both 1 and 2 are four-coordinated complexes, with a square-planar geometry of copper（Ⅱ） in 1 and a slightly distorted tetrahedral geometry of zinc（Ⅱ） in 2. An asymmetric unit consists of only one half of a Cu ion and one L ligand in 1, while an asymmetric unit is composed of one Zn ion, two L ligands and three water molecules in 2. Non-classical C-H···O and C-H F hydrogen bonds play important roles in the formation of a 1D chain of 1, but O-H O and O-H N hydrogen bonds play dominant roles in the self-assembly of a 3D network of 2. The antibacterial activities of 1 and 2 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli and E. cloacae have been evaluated by MTT method.

Improvement in the synthesis of 2-(5-amino-1,2,4-thiadiazol-3- yl)-2-(Z)-methoxyiminoacetic acid 2-benzothiazolyl thioester

2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-(Z)-meth-oxyiminoacetic acid 2-benzothiazolyl thioester(III),an important intermediate of the fourth generation cephalos-porins,was efficiently synthesized by reacting 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid(I)with 2,29-dibenzothiazole disulfide(II)in the presence of triphenylphosphine.Effects of reaction time,temperature,solvents,catalysts and feeding molar ratio on the yield and quality of products were investigated,and an im-proved procedure suitable for industrial production was established.Using 1,2-dichloroethane as solvent,triphe-nylphosphine as reducer,and triethylamine as catalyst,n(I):n(II):n(triphenylphosphine)51.0:1.0:1.0,the product was obtained at room temperature in 98.1%yield.The purity of the product without further purification is 98.7%determined by HPLC method.This procedure could be a suitable alternative to the traditional processes because of its easy handling,high yield and low cost.

Heterocyclization of thiocarbonohydrazides:Facile synthesis of 5-unsubstituted-1,3,4-thiadiazoles

2-（Hydrazinecarbothioyl）-N-substituted hydrazinecarbothioamides react with 2,3,5,6-tetrachloro-1,4-benzoquinone in high yields in a novel fast and facile method to give 5-unsubstituted-1,3,4-thiadiazole-2-amine derivatives.The synthesized compounds were characterized by spectroscopic methods and confirmed by using X-ray crystallography.A rationale for the formation of the products is presented.