سید سجاد سجادی خواه

Stable ylide of di-tert-butyl-2-(2-indolinon-1-yl)-3-(trimethoxyphosphorane ylidene) butanedioate was synthesized by means of catalyst-free reaction of trimethyl phosphite, di-tert-butylacetylene dicarboxylate and 2-indolinone in n-hexane/diethyl ether at ambient temperature. Obtained product was characterized by 1H, 13C, 31P NMR, FT-IR and mass spectroscopy. The crystal structure of the stable ylide was determined by X-ray crystallography. The title compound crystallized in monoclinic, space group P21/c and cell parameters a=15.8079(7) Å, b= 18.7521(13) Å, c =17.4987(10) Å, β= 95.504(6)° and Z=8. The X-ray study showed that adjacent carbonyl group (C291=O291, C191=O191) in the ylide moiety of compound had a resonance with bond of C=P. These results show clearly that environment of C(19, 29) is planar.

In this work, facile and efficient procedures were described for the synthesis of 4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxamides via three-component reaction of aryl aldehyde, acetoacetanilide and 3-amino-1,2,4-triazole. The reactions were performed using p-toluenesulfonic acid monohydrate in refluxing EtOH or trityl chloride under solvent-free conditions at 80 ºC. Comparison of the results shows that both organic catalysts are effective for the synthesis of these fused heterocyclic compounds. Some advantages of these methods are short reaction times, good to excellent yields and easy to operate. Additionally, all products were obtained through simple filtration and no need for column chromatography or tedious work-up, which is an important factor to reduce environmental pollutions.

A simple and efficient method has been presented for the synthesis of tetrahydropyridine derivatives via one-pot reaction of aromatic amines (2 eqv), β-ketoesters (1 eqv) and aromatic aldehydes (2 eqv) in the presence of N,N,N′,N′-tetramethylguanidinium acetate [TMG][Ac]. The reaction was carried out in EtOH under reflux conditions. Some of the advantages of this procedure are green and safe solvent, high atom economy, high yield, and no need to column chromatography for product purification. Moreover, the catalyst is recyclable and can be used up to four times without significant loss of its activity.

A simple and efficient method has been presented for the synthesis of 3,4,5-substituted furan-2-one derivatives. One-pot three-component reaction of aromatic amines, aromatic aldehydes and dialkyl acetylenedicarboxylates in the presence of oxalic acid dihydrate in ethanol as a green solvent leads to furan-2-one dreviatives. Some of the advantages of this procedure are mild conditions, high atom economy inexpensive catalyst and high yields. Moreover, the products were obtained through simple filtering and no need to column chromatography.