Letters in Organic Chemistry - Volume 15, Issue 12, 2018

Synthetic methods for the poly(3-hexylthiophene) polymers (P3HT) preparation were reviewed. Different protocols were reported such as electropolymerization, oxidative method (mainly by FeCl3), Ni-catalyzed methods (McCullough, Rieke, GRIM), Pd- catalyzed methods such as Suzuki and Stille coupling and, the more recent, Direct Arylation Polymerization (DArP). The present review focuses on the synthetic protocols and their relationship to the final key-structural polymer characteristics like regioregularity and molecular weight control which are of importance in the final properties and application of P3HT. An extended literature review was performed covering also very recent advancements. The use of NHC palladium or nickel catalysts, disclosed the door to the preparation of “quasi” living polymers for most of the Ni and Pd catalyzed reactions, enabling a fine tuning of both regioregularity and molecular weight.

Background: Ficus hirta Vahl. is a medicinal plant, used in folk medicine in some countries such as Vietnam for the treatment of hepatitis, nephritis, mastitis, rheumatism, etc. Previous phytochemical investigation of F. hirta revealed the presence of phenolics such as phenylpropanoids, coumarins, furanocoumarins, flavonoids as the main constituents of this species. The aim of this study is to isolate and identify new chemical constituents from Ficus hirta growing in Vietnam. Methods: The crude MeOH extract was partitioned in turn between n-hexane, ethyl acetate and n-butanol. The ethyl acetate and n-butanol extracts were chromatographed on silica gel, Sephadex LH- 20 columns to afford ten compounds. The structure elucidation of isolated compounds was unequivocally determined by spectroscopic means, HR-ESI-MS, 1D and 2D NMR spectroscopy and by in comparison with the published references. Results: A new furanocoumarin glycoside, 5-O-[β-D-apiofuranosyl-(1→2)-β-D-glucopyranosyl]- bergaptol (1), along with nine known compounds, including six phenolics, bergapten (2), umbelliferone (3), 6-carboxy-umbelliferone (4), 6,7-furano-hydrocoumaric acid methyl ester (5), picraquassioside A (6), rutin (7); a nucleoside, adenosine (8); and two saccharides, ethyl-β-D-fructofuranoside (9), ethyl-β-D-glucopyranoside (10) were isolated and identified from the ethyl acetate and n-butanol extracts of the roots of Ficus hirta. Conclusion: A new furanocoumarin glycoside, 5-O-[β-D-apiofuranosyl-(1→2)- β-D-glucopyranosyl]- bergaptol along with nine known compounds were isolated from the roots of Ficus hirta growing in Vietnam.

We have synthesized new N-demethyl-N-substituted derivatives (n-propyl, allyl) of 1- iodocodeine and their 7,8-dihydro analogues starting from codeine. Key intermediates, 1-iodonorcodeine and 1-iododihydronorcodeine were prepared from the corresponding 6-O-acetylated compounds using alpha- chloroethyl chloroformate. 3-O-Demethylation of 1-iodocodeine and 1-iododihydrocodeine with boron tribromide resulted in 1-iodomorphine and 1-iododihydromorphine, respectively. The latter compounds were transformed to their 3,6-di-O-acetyl derivatives. 8-Iodoapocodeine was prepared from 1-iodocodeine by acid-catalyzed rearrangement.

The photochemical isomerization of 1,2,4-oxadiazole derivatives to 1,2,4-triazoles has been studied at B3LYP/6-311G+(d,p) level of theory. The reaction occurred in the presence of Ru(bpy)2Cl2. The irradiation of the Ru complex allowed the substitution of chlorine with the substrate. The irradiation at 760 nm of this new complex led to an electron transfer process that favors the transfer of a hydrogen atom from the hydrazonic NH group to the N atom at the fourth position in the 1,2,4-oxadiazole ring. The resulting radical cation cyclized to give a reaction product through Dewar isomer structure.

A highly efficient and simple protocol for the construction of aromatic and aliphatic thioureas from their respective amines in the presence of cheap, readily available and air-stable iron catalyst in one pot three steps reaction is described. All the reactions were carried out under optimized reaction conditions to get the target products in good to excellent yields and shorter reaction time.

A novel synthesis of 3-(7-methylbenzo[d]oxazol-4-yl) butanoic acid as a possible precursor of (+)-seco-pseudopteroxazole and (+)-pseudopteroxazole is presented. This synthesis was performed from m-cresol where a Fries rearrangement, a nitration reaction and an olefination reaction were the key reactions to achieve the synthesis of 3-(7-methylbenzo[d]oxazol-4-yl) butanoic acid.

We report the synthesis and complexation properties of two new hydroxyquinolinecalixarene derivatives 1 and 2. The complexation studies of the synthesized ligands toward lanthanide cations have been monitored by UV absorption spectrophotometry and conductimetric in acetonitrile. The extraction properties into water to dichloromethane of 1 and 2 toward La(III), Gd(III) and Yb(III) have been also determined.

Hydrosilylation of olefins catalyzed by Cp2TiCl2/Sm (Cp = cyclopentadienyl) under solventfree conditions has been investigated. The mole ratio of Cp2TiCl2/Sm has some influence on the catalytic properties, and the best Cp2TiCl2/Sm ratio for the catalytic hydrosilylation is 1/2. By using this catalytic system, hydrogenation products were also detected in the final reaction mixtures.

A new ring contraction of fused bis-lactams into spirolactams is presented here. In the presence of a triflate catalyst in various solvents under microwave irradiation, this rearrangement allows a clean conversion of some fused bicycles into spirocycles with good yields. The interest of this work thus lies in the use of activated 2,5-diketopiperazines as starting materials and demonstrates the wide range of applications of ring contraction reactions.

In this study, the application of scandium tris[bis(perfluorooctylsulfonyl)amide] as a catalyst in glycosidation reactions was investigated. Besides being a versatile Lewis acid promoter for such reactions, the studied complex could be easily recovered from the reaction mixtures with sufficient activity to repeatedly catalyze the glycosidation reactions.

A new sesquiterpene, litopharbdiol along with five known metabolites of terpenes and sterols were isolated and identified from the methanolic extract of the Red Sea soft coral Litophyton arboreum. The structures of the isolated compounds were elucidated on the basis of their 1D- and 2DNMR and MS spectral data. In parallel, the total extract was evaluated for its in vivo genotoxicity and antigenotoxicity against the mutagenicity induced by the anticancer drug cyclophosphamide (CP). The extract was found to be safe and nongenotoxic at 100 mg/kg b.wt. Moreover, the mice group of CP pretreated with the extract (100 mg/kg b.wt) showed significant reduction in the percentage of chromosomal aberrations induced in bone marrow and mouse spermatocytes.

A prudent and scalable synthesis of (±)-Preclamol is described utilizing Michael addition and in-situ reduction/cyclization of an aryl-α-carbethoxy acetonitrile derivative as a key step.

A highly efficient and milder protocol for the syntheses of novel series of 2-aminothiazoles bearing 5-methylisoxazoline and pyridine-piperazine hybrid molecules has been developed. The target compounds 13a-e were screened for their in vitro cytotoxicity activity against various tumor cell lines including MCF-7 (human breast adenocarcinoma), HCT-116 (colorectal carcinoma), Jurkat (human T-cell leukemia) and THP-1 (human acute monocytic leukemia). The bioactive assay showed that the most of the new compounds exhibited promising results in comparison with the parental Sunitinib. The synthesized compounds could well be used in the future as lead anticancer drugs in drug development studies. The synthesized compounds were fully characterized by IR, 1H NMR, 13C NMR, elemental analysis and mass spectral data.