The dictyostatins are powerful microtubule-stabilizing agents that have shown antiproliferative activity against a variety of human cancer cell lines. Two highly active analogs of dictyostatin, 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, were prepared by a new streamlined total synthesis route. Three complete carbon fragments were prepared to achieve maximum convergency. The...

A new method is presented to prepare strained lactams. Esterification of the C-terminus of a dipeptide with β-nitrostyrene or quinoline-type auxiliaries is followed by lactam formation by an intramolecular aza-Michael-acyl-transfer reaction cascade. Ultimately, the cyclic tetrapeptide cyclo[Phe-Tyr-Ala-Gly] has been prepared.

Esterification of several types of monoand disubstituted phenols with various monoand dialkanoyl chlorides was performed in phase-transfer catalysis conditions, using tetrabutylammonium chloride in a mixture of aqueous NaOH and dichloromethane. The process is particularly efficient (almost quantitative yields) as well as rapid (only 5 min reaction time, at a temperature of 0 C).

Beech sawdust was reacted with phthalic (PA) and maleic (MA) anhydrides for chemical modification. The influence of reaction time and anhydride amount was investigated. IR spectra gave evidence of wood esterification. Thermogravimetric investigation of chemically modified wood indicated a better thermal stability (mainly for wood treated with phthalic anhydride) in comparison with the untreated...

The title compound, C(18)H(33)N(3)O(5), was prepared from N-tert-butoxy-carbonyl-4-piperidone using a nine-step reaction, including condensation, methyl-ation, oximation, hydrolysis, esterification, ammonolysis, Hoffmann degradation, tert-butoxy-carbonyl protection and methyl-ation. The E configuration of the methyl-oxime geometry of the compound is confirmed.

In this work preparation of sulfonic acid functionalized magnetite encapsulated zirconia (Fe3O4@ZrO2-SO3H) has been reported. Structural, chemical, and magnetic properties of the magnetically supported catalyst have also been investigated by Fourier transform infrared (FT-IR) spectroscopy, wide angle X-ray diffraction spectroscopy (WXRD), thermal gravimetric analysis (TGA), energy dispersive X-...

All-trans retinoic acid (10) was synthesized by β-ionone (5) through knoevenagel condensation, reduction and hydrolysis reaction. Then, hydroxyl-pinacolone retinoate (11) prepared the esterification with 1-hydroxy- 3, 3-dimethylbutan-2-ketone. This route not only reduces synthesis steps but also helps to increase yield. The structure of product characterized 1 H NMR 13 C NMR.

In this study, ultrasound was used to accelerate two-stage (esterification–transesterification) catalytic synthesis of biodiesel from cooking oil, which originally had a high acid value (4.35 mg KOH/g). the first stage, acid-catalyzed esterification reaction conditions were developed with 9:1 methanol/oil molar ratio, sulfuric dosage at 2 wt %, and temperature 60 °C. Under irradiation for 40 mi...

Interest in the synthesis and application of thymol esters has increased recent years due to numerous applications associated with its biological activities. The enzymatic octanoate by esterification octanoic acid was explored using soluble lipases immobilized lipase biocatalysts solvent-free systems. Candida antarctica B form most active biocatalyst for this reaction. Different feeding strateg...

An efficient solventless one-pot procedure for the synthesis of imidazolium-based ionic liquid under microwave irradiation is described in which 1-methylimidazole was modified by organosilane (3-chloropropyl triethoxysilane). This ionic liquid 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride (TMICl) is immobilized on Mechanically activated Fly Ash (MFA) by co-condensation method to d...