A simple and facile method for regio- and stereoselective bromoformyloxylation and bromoacetoxylation of olefins using NH4Br and oxone®

A mild and efficient protocol for the preparation of bromoformates as well as bromoacetates from olefins using NH₄Br and oxone® in nucleophile sources (DMF or DMA) without employing catalyst at room temperature is described. This method is facile, environmentally friendly and cost effective. A variety of terminal, internal and cyclic alkenes reacted smoothly to give the corresponding bromoformate and acetate products in good to excellent yields. Moreover, 1,2-disubstituted olefins provided moderate to excellent diastereoselectivity.     

A simple and efficient L-prolinamide-catalyzed alpha-selenenylation reaction of aldehydes

An efficient and simple l-prolinamide-catalyzed alpha-selenenylation reaction of aldehydes with N-(phenylseleno)phthalimide has been developed for the efficient preparation of alpha-phenylselenoaldehydes. Such compounds are versatile building blocks for the synthesis of alpha,beta-unsaturated aldehydes, allylic alcohols, and amines. [reaction: see text]     

A simple and efficient synthesis of 2-alkylazulenes

The annulation method based on 2H-cyclohepta[b]furan-2-ones was applied for the synthesis of 2-alkylazulenes; 2-R-azulene (R = Et, i-Pr, n-Pr, i-Bu). Tropolone p-toluenesulfonate was used as a starting compound. By the two step synthesis, 1-carboxylic-3-cyanoazulene derivatives were obtained. Treatment of 1-carboxylic-3-cyanoazulene derivatives with aq H₂SO₄ resulted in decarboxylation and elimination of cyano group to give 2-alkylazulenes in good yields.     

A simple and efficient method for synthesis of 5-substituted 2'-deoxyuridine nucleosides using metal-halogen exchange reaction of 5-iodo-2'-deoxyuridine sodium salt

Treatment of the sodium salt of 2'-deoxy-3', 5'-bis-O-(tert-butyldimethylsilyl)-5-iodouridine (3) with n-BuLi effected regioselective lithiation at the 5-position and the following reaction with various electrophiles afforded 5-substituted 2'-deoxyuridines including 1b, the precursor of stable spin-labeled 1a, in good yields.     

Molecular sieves as an efficient and recyclable catalyst for bromolactonization and bromoacetoxylation reactions

Bromolactonization of unsaturated acids and bromoacetoxylation of olefins proceeded smoothly in the presence of molecular sieves and N-bromosuccinimide. The molecular sieves can be recycled and reused, and the halogen carrier can be recovered effectively.     

A simple and efficient synthesis of 2-aryl-substituted benzimidazoles

Sodium hydrogen sulfite was used to promote condensation of o-phenylenediamine with aromatic aldehydes in dimethylformamide to obtain the corresponding 2-arylbenzimidazoles. The procedure is simple and convenient, and it implies inexpensive promoter and is characterized by short reaction time and easy purification of the final products. Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 872–874. The text was submitted by the authors in English.     

CuI catalyzed sulfamidation of arylboronic acid using TsNBr2 at room temperature

An expeditious protocol for amidation arylboronic acid has been developed using TsNBr₂ as the nitrogen source in presence of a CuI as catalyst. Various arylboronic acids could be transformed into corresponding N-arylsulfonamide derivatives within a very short time using CuI as catalyst in presence of DBU at room temperature.     

Metal free synthesis of quinoxalines from alkynes via a cascade process using TsNBr2

A metal free protocol for the synthesis of quinoxalines from alkynes has been developed. The reaction was carried out by treating alkynes with TsNBr₂ in presence of O-phenylenediamines in a mixture of acetonitrile and water (9:1). This one-pot reaction proceeds via an oxidative transformation of alkynes to α,α-dibromoketones in presence of TsNBr₂ and eventually to quinoxalines in presence of 1,2-diamines in a cascade process.     

A simple and efficient synthesis of substituted 2H-1-benzopyran-2-ones using natural acids and their bio evaluation

A simple and efficient route for the synthesis of coumarin derivatives (3a-3g) from reaction between substituted phenols (1a-1g) and methyl acetoacetate (2b) in presence of Citrus limon L. juice, Vitis vinifera L. juice and banana peels extract has been carried out. The homogeneity of the compounds were routinely checked by thin layer chromatography and melting points reported are uncorrected. The compounds (3a-3g) were characterized by using ¹HNMR and FTIR spectral techniques and evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (3a-3g) were also screened for their fungicidal activity against Rhizoctonia solani and Colletotrichum gloeosporioides by poisoned food techniques. Antibacterial activity was also determined against Erwinia cartovora and Xanthomonas citri by inhibition zone method. From activity data, it was found that compounds 3a and 3b were most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compound 3b was found most active against R. solani fungus and Xanthomonas citri bacterium at highest concentration. Compound 3e has shown maximum percentage inhibition i.e. 83.17 against C. gloeosporioides at 2000 µg/mL concentration. Erwinia cartovora bacterium was most susceptible to compound 3 g giving 8.00 mm inhibition zone at 2000 µg/mL concentration. Less reaction time, excellent yields, simple work-up, cost effective and mild reaction conditions are some merits of present protocol.     

A simple and efficient procedure of low valent iron- or copper-mediated Reformatsky reaction of aldehydes

An operationally simple and very efficient procedure of Reformatsky reaction of aldehydes has been carried out in THF in the presence of low valent iron or copper which were prepared in situ employing a bimetal redox strategy through reduction of FeCl3 or CuCl2-2H2O with magnesium.     

A general and efficient aldehyde decarbonylation reaction by using a palladium catalyst

A facile decarbonylation reaction of aldehydes has been developed by employing Pd(OAc)(2). A wide variety of substrates are decarbonylated, without using any exogenous ligand for palladium as well as CO-scavenger.     

A simple and efficient synthesis of 3-cyano-4-phenyl-2-pyridone

A preparatively useful method for the synthesis of 3-cyano-4-phenyl-2-pyridone (I) is described. Reaction of 2-cyano-3-methylcinnamamide (VII) with N,N-dimethylformamide dimethyl acetal affords the corresponding dimethylaminomethylidene amide VIII which in turn, is thermally cyclized to I in DMF solvent. The advantages of this method include mild reaction conditions for short periods to give good yields of I on large scales without chromatographic purification.     

A simple and efficient route to 2-arylimidazo[1,2-a]pyridines and zolimidine using automated grindstone chemistry

A green and efficient mechanochemical method for the synthesis of a series of 2-arylimidazo[1,2-a]pyridines was developed using an electrical grinder. I₂ catalyzed mechanochemical grinding facilitates the cyclocondensation reaction between various aryl methyl ketones and 2-aminopyridines to afford 2-arylimidazo[1,2-a]pyridines in good yields at ambient temperature. The method was successfully used for the gram-scale synthesis of a marketed drug, zolimidine. The noticeable advantages of this environmentally sustainable protocol include mild conditions, simple instrumentation, inexpensive catalyst, atom economy, short reaction time etc.     

A modified Curtius reaction: an efficient and simple method for direct isolation of free amine

The Curtius rearrangement and related reactions are often used to convert carboxylic acids to the corresponding primary amines. However, this reaction often requires harsh conditions for hydrolysis of the isocyanate intermediates to amines, and can also be contaminated by the formation of corresponding ureas due to the reactive nature of the intermediates. We have discovered that by quenching the isocyanate intermediates with sodium trimethylsilanolate, the free amines can be isolated after aqueous workup. This mild and fast procedure provides free amines in one pot with good yields.     

A simple and highly efficient method for the synthesis of chalcones by using borontrifluoride-etherate

Chalcones are secondary metabolites of terrestrial plants, precursors for the biosynthesis of flavonoids and exhibit various biological activities. Condensation of substituted acetophenones (2a-12a) with various aromatic aldehydes (1b-7b) in the presence of BF₃-Et₂O at room temperature gave chalcones in 75-96% yield.     

A simple and efficient large-scale synthesis of 3-hydroxyphthalans via oxa-Pictet-Spengler reaction catalyzed by nanosilica sulfuric acid

Nanosilica sulfuric acid is found to be a new, powerful and reusable heterogeneous catalyst for the rapid synthesis of 3-hydroxyphthalans via condensation of aromatic aldehydes and 3-hydroxybenzyl alcohols under conventional heating and microwave irradiation. Scale-up preparation of these heterocycles is also carried out.     

A simple and efficient synthesis of the valsartan

Valsartan 1, one of the most important agents used in antihypertensive therapy today, was synthesized starting from L-valin methyl ester hydrochloride 2 through four steps in an overall yield of 60%. The key step involves the palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses and is more suitable for industrial production.     

A simple and efficient fluorescent sensor for histidine

A simple coordination complex terpyridine-CuCl(2) is found to be an efficient fluorescent sensor for histidine in aqueous solution with up to 1004 fold fluorescence enhancement.