ایندول

The addition of aromatic substrates to electron-deficient alkenes, which in many respects may be considered a Friedel– Crafts type alkylation, is a key reaction in synthetic organic chemistry for the formation of new C-C bonds. Indole and many of its derivatives are relevant units in many naturally occurring compounds, because of their pharmacological and biological properties. Due to the increased nucleophilic reactivity of C3 position of indole ring, it is often used for the subsequent transformations leading to different indole alkaloids. Here I report an efficient catalyst that can catalyzes the electrophilic substitution of indole with electron deficient alkenes. First, Cobalt tris(2-guanidinobenzimidazole), tri chloride (Co(GBI)33+, 3Cl-)  is prepared and then the reaction of indole with beta - nitrostyrene has studied. No product was detected, so the reaction conditions such as the solvents and the amount of catalyst were changed, but the results were the same. After that the chloride moiety of the complex were replaced with tetrakis[(3,5-trifluoromethyl)phenyl]borate (Barf-)anion and the reaction has run on different condition. Our results showed that Cobalt tri(2-guanidinobenzimidazole), tetrakis[(3,5-trifluoromethyl)phenyl]borate (Co(GBI)33+, 3BArf- ) catalyzes the reaction of indole with β - nitrostyrene and afforded the product in high yields. It is noteworthy to mention that using lipophilic anions such as BArf- [(B(3,5-C6H3(CF3)2)4-] , the catalyst could be solubilized in nonpolar solvents that do not compete with substrates for the hydrogen bonding sites.

In this research, due to the high importance of crown ethers in complexometric and also in the field of pharmacology, a new method for the preparation of several heterocyclic crowns ethers was proposed using titanium nano-oxide catalysts. To this end, the reaction of 2-methyl-indole with tosylated triethylene glycol, led to the formation of 2-methyl-1- (2- (2- (2- (2-methyl-H1-1 -indole (ethoxy) (ethoxy) ethyl) -1H-indole in DMF solvent and the KOH. After determining the optimum conditions for the preparation of the crowns (room temperature, dichloromethane solvent and the catalytic ratio of 5 mol%), the chronological derivatives of the crown ethers were obtained from the reaction of the 2-methyl-1- (2- (2- (2- (2-methyl-H1-1 -indole (ethoxy) (ethoxy) ethyl) -1H-indole with different derivatives of aldehydes. One of the advantages of this method is the high efficiency, non-toxicity of the catalyst, and its reuse.

A novel D–π–A system having indole moiety 5 was synthesized in four steps، which exhibit interesting solvatochromism ranging from yellow in CHCl3 to red in DMF، violet in acetone، deep purple in DMSO and green in CH3CN. Also the studies on the fluorescence properties of 5 in different solvents revealed that the emission peaks are dependent on the polarity of solvents. The quantum–chemical calculations of 5 was performed using the Gaussian 03 program at the B3LYP/6-31G* level، which revealed that the HOMO is localized on the 3-hydroxy indole donor moiety، while LUMO is localized on the methylidene dimalononitrile acceptor moieties.