Letters in Organic Chemistry - Volume 16, Issue 12, 2019

A new synthesis of the 2,6-naphthyridine alkaloid 4-methyl-2,6-naphthyridine from Antirrhinum majus has been developed. Key steps are a regioselective oxidation of 3-bromo-4,5- dimethylpyridine to the corresponding 4-formyl derivative, and the annulation of the second pyridine ring by Suzuki-Miyaura cross-coupling using (E)-2-ethoxyvinylboronic acid pinacol ester as a masked acetaldehyde equivalent. This protocol g Read More

OctaGel resin is a unique, highly uniformed surface-active resin. Here, we compared the performance of OctaGel with that of known resins on the market, namely polystyrene and ChemMatrix, in Solid-Phase Peptide Synthesis. The synthesis of the ‘difficult’ Aib-ACP (65-74) decapeptide showed that OctaGel has the potential to yield molecules with satisfactory purity. Given its high swelling capacity and large bead size, OctaGel als Read More

Rhazya stricta is a rich indole alkaloid medicinal plant species, that is used in traditional medicine particularly in Middle East countries to treat inflammations, diabetes, rheumatism, and skin disorders. The alkaloid plant extract of R. stricta was fractionated on aluminum oxide column and further purified by different chromatographic methods. The chemical structures of the isolated compounds were elucidated by interpret Read More

Dimethyl 6,6’-bis(bromomethyl)-[2,2’-bipyridine]-4,4’-dicarboxylate (2) was synthesized from dimethyl 6,6’-dimethyl-2,2'-bipyridine-4,4'-dicarboxylate (1) through dibromination and debromination. Debromination of dimethyl 6,6’-bis(dibromomethyl)-[2,2’-bipyridine]-4,4’-dicarboxylate (4) with diethyl phosphite and N,N-diisopropylethylamine in THF afforded target product 2 in 58% overall yield. The biggest advantage of Read More

A series of new N-heterocyclic carbene (NHC) precursors, containing bicyclic pyrrolo[1,2- c]imidazole framework, were prepared from N-(tert-butoxycarbonyl)-L-proline (1-Boc-L-proline). The sequential attachment of nitrogen nucleophiles and subsequent ring closure gave the desired bicyclic NHC precursors in good yields. The structures of these new NHC precursors were determined on the basis of spectroscopic tech Read More

Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A f Read More

Bis(indolyl)methane derivatives (BIMs) were synthesized in moderate to good yields by (thio)urea catalyzed electrophilic substitution of indole (2) with various aldehydes 1. Reactions were performed under conventional and microwave (MW) heating, either using 1,2-dichloroetane as solvent or without solvent. The procedure using microwave heating was also applied to the synthesis of the natural products vibrindole A (3n), arsi Read More

A series of novel ethyl 6-[2-(3-aryl-1-phenyl-1H-pyrazol-4-yl)vinyl]-2-oxo-4-phenyl- 1,2,3,4-tetrahydropyrimidine-5-carboxylates (9a-9d) has been synthesized by adopting a multistep synthetic strategy. The structure of the targets was confirmed on the basis of physical and spectral techniques. The synthetically achieved targets were evaluated for their antioxidant activity by in-vitro DPPH free radical scavenging assay. Of the ch Read More

Disclosed herein is a general approach for the synthesis of chiral thiazolo triazoles 5a-e. An efficient 3-step synthetic strategy has been developed to obtain the fused heterocycles in good yields. The key step involves formation of a secondary carbocation under acidic condition and intramolecular attack of the nitrogen of the 1,2,4-triazolo part leads to the formation of fused bicyclic compound in a regioselective man Read More

Structural elucidation of synthesized 2,6-diphenylspiro[cyclohexane-1,3’-pyrido[1,2- a]pyrimidine]-2’,4,4’-trione has been done by UV, FT-IR, 1H, 13C NMR and mass spectroscopy. The molecule was further subjected to density functional theory (DFT) studies with B3LYP function using 6-31G(d,p) basis atomic set. The title molecule was investigated on the basis of thermodynamic properties, polarizability, hyperpolarizabilit Read More

A series of new 1,2,4-triazole Schiff bases incorporating a chlorinated indole moiety were prepared from the condensation reaction of 4-amino-5-mercapto-3-[(5-chloro-2-methyl-1H-indol-3- yl)methyl]1,2,4-triazole with substituted benzaldehydes in the presence of (+)-tartaric acid as an acidic catalyst. The structures of Schiff bases were elucidated by FTIR, NMR and mass spectral data. The cytotoxic, antibacterial and free radic Read More

Isofebrifugine, as a kind of natural quinazolinone alkaloid with important physiological activities and good pharmacological effects, was isolated from a Chinese medicinal plant, Chang Shan (Dichroa febrifuga). In this paper, the synthesis of a series of novel isofebrifugine analogues was accomplished by employing the N-alkylation of 4(3H)-quinazolinones with benzyl (3aR,7aR)-rel-2- (bromomethyl)hexahydrofuro[3,2-b]py Read More