Letters in Organic Chemistry - Volume 12, Issue 3, 2015

A concise and efficient route for the synthesis of indole derivatives having propellane structure at position 3 by simple regioselective one-pot reaction of ninhydrin, malononitrile, tryptamine, and β-dicarbonyl compounds was developed. This protocol provides an alternative method for application in combinatorial and parallel synthesis in drug discovery. The value of this method lies in its simplicity, regioselectivity, and good yields. The structures of new synthesized compounds were corroborated spectroscopically (IR, 1H- and 13C-NMR, and EI-MS). A plausible mechanism for this type of reaction is proposed (Scheme 2).

Bentonite-titana composite was prepared and characterized by XRD, FT-IR and SEM. Results indicate that TiO2 particles have been supported on the bentonite layers and a delaminated structure is formed. Then the bentonitetitana composite as a mild, eco-friendly, non-toxic an efficient heterogeneous catalyst have been used for synthesis of benzopyran derivatives from the three-component condensation reaction of dimedone or barbituric acid, malonoitrile, and aromatic aldehydes under solvent free conditions in good to excellent yield and short reaction times.

In this work, several new derivatives of ferrocenyl bicylic aziridine photochromic compounds have been prepared from the premade ketoaziridines and ferrocene carboxaldehyde in the presence of ammonium acetate in absolute ethanol via one-pot, three-component reaction. The structures of the newly synthesized compounds were established on the basis of IR, NMR and UV-Vis spectral studies. The newly synthesized compounds exhibit interesting photochromic behavior in the solid phase and solution state. The photochromic behavior of the prepared compounds has been investigated by UV-Visible spectral data.

A simple, efficient and environmentally method for the synthesis of phosphonate derivatives have been considered using the reaction of 2&apos-hydroxy acetophenone or 1-(6-hydroxy-2-isopropenyl-1-benzofuran-yl)-1-ethanone, malononitrile or ethyl cyanoacetate and trialkyl phosphites or triaryl phosphite in water as the solvent at room temperature.

The reaction of N-(2,4-dinitrophenyl)pyridinium-d5 chloride with N-(4-methylphenyl)piperazine in refluxing ethanol led to the ring opening of the pyridinium-d5 ring to afford the conjugated triene with a penta-2,4- dienylideneammonium-d5 (PDA-d5) group, namely, triene-Da2Db2Dc. The reaction of triene-Da2Db2Dc with 1,1,2,2- tetracyanoethylene (TCNE) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) in methanol (MeOH) and N,N-dimethylformamide (DMF) selectively activated the C-D bonds at the 2- and 4-positions of the PDA-d5 group. The present selective C-D/C-H exchange reaction may have applications in the development of new organocatalyzed coupling reactions

A variety of pyrazoles, thiazoles, thiadiazoles, thiazolidines, azetidine, thiazolo[3,2-a]pyrimidine and pyrazolo[3,4-b]pyridine systems, based on 3-(1,3-dioxoisoindolin-2-yl)-3-oxopropanenitrile precursor are synthesized in good yields. The mechanistic aspect for the formation of the newly synthesized compounds is discussed and the structure of the synthesized compounds was established based on elemental analysis and spectral data.

PEG-400 was found to be an inexpensive, non-toxic and eco-friendly reaction medium for synthesis of pyramido[2,1-b]benzothiazole derivatives. Utilizing this protocol, we are capable of various pyrimido[2,1-b]benzothiazole derivatives 4a-k and 6a-d were synthesised. The reaction between aminobenzothiazole 1, aromatic aldehydes 2a-k and ethyl acetoacetate 3/ diethyl malonate 5 at room temperature for 1-2 h furnished required compounds with good to excellent yields (85-93%). Here we observed carboxylic acid compounds instead of ester compounds when diethyl malonate was used as the substrate, whereas ethyl acetoacetate showed no signs. The reactions are easy to perform, atom-economic, require less reaction time and allow generation of the biologically potent pyrimido[2,1-b]benzothiazole frameworks from readily accessible starting materials.

Homocoupling of arylboronic acids has been successfully carried out by using the inexpensive hydrophilic palladium( II) complex PdCl2(NH2CH2COOH)2 as catalyst in i-PrOH/H2O (v/v=1:2) under aerobic atmosphere without elevated heating to give rise to symmetrical biaryls in moderate to good yields. The aqueous media, room temperature reaction and the low amounts of catalyst (0.5 mol%) show a practical and environmentally benign protocol. In addition, enhancement of yield was observed in the presence of 0.5 equiv. p-toluenesulfonyl chloride. Furthermore, the byproducts of this reaction were not observed while biaryl is the only product, which results in much more facile in the separation of the product symmetrical biaryls from arylboronic acids.

Naturally occurring organic acids are reported to be highly efficient promoters for the Biginelli reaction under thermal and microwave irradiation using solvent free conditions. Among the various organic acids used, malic acid was found to be the most effective promoter for Biginelli reaction under above reaction conditions. Present protocol is a simple and eco-friendly route for the synthesis of 3, 4-dihydropyrimidin-2(1H)-ones/thiones.

Total synthesis of three Febuxostat metabolites, named 67M-1, 67M-2, and 67M-4,is described in this article. Through condensation of the key intermediate compound A with different side chains, and then oxidation and hydrolysis, we obtained three target compounds with an overall yield of 19.5%-28.0%.

A scalable approach for the cyanosilation of benzaldehydes and acetophenones using indium trichloride, a versatile, user friendly catalyst is developed. Cyanohydrin trimethylsilyl ethers are converted in the same pot to α-fluorophenyl acetonitriles which are efficiently reduced to their corresponding amines using sodium borohydride in presence of cerium trichloride.