An efficient and general synthesis of pyrroles

We have discovered that a wide range of 3-alkynyl-hydroxyalkanamine derivatives undergo 5-endo-dig cyclisations when exposed to silver nitrate supported on silica gel. Subsequent in situ dehydration of the resulting and sometimes isolable hydroxy-dihydropyrroles leads to pyrroles in essentially quantitative yields using this recoverable and reusable heterogeneous catalyst.     

An efficient chiral-pool synthesis of botryolide-E

An efficient stereoselective total synthesis of botryolide-E by a chiral-pool approach is described.     

An efficient and versatile chemical synthesis of bioactive glyco-glycerolipids

Synthesis of β-glyco-1,2-diacylglycerols is achieved by a versatile and simple procedure based on trichloro-acetimidate methodology and use of peracetate sugar substrates. The chemical strategy was tested through stereoselective preparation of β-galacto- and β-gluco-lipid derivatives capable to trigger immune system response. The synthetic approach is designed to obtain enantiomerically pure regio- and stereo-isomers including derivatives containing poly-unsaturated fatty acids.     

An efficient synthesis of 4-chromanones

A two step efficient and practical synthesis of a variety of 4-chromanones is described. Phenols undergo a Michael addition to acrylonitriles in the presence of catalytic amounts of potassium carbonate and tert-butanol to generate the corresponding 3-aryloxypropanenitriles in 50-93% yields. Treatment of the resulting aryloxypropionitriles with 1.5 equiv of TfOH and 5 equiv of TFA, followed by an aqueous work up afforded 4-chromanones in moderate to excellent yields.     

An efficient method for the synthesis of lignans

An efficient approach for the synthesis of several types of lignans (dibenzylbutanediols, dibenzylbutanes, substituted tetrahydrofurans, aryldihydronaphthalenes, arylnaphthalenes, and aryltetralins) was developed. The regioselective oxidative coupling of ethyl ferulate was used as the key step.     

A short and efficient general synthesis of luotonin A, B and E

Highly convergent synthesis of three luotonins (A, B, and E) has been achieved from readily available starting materials. The key step in the synthesis is formation of quinazolinone skeleton by the condensation of 3-(1,3-dioxolan-2-yl-quinoline-2-carbaldehyde and anthranilamide.     

An atom efficient and solvent-free synthesis of structurally diverse amides using microwaves

An array of structurally diverse amides was synthesized efficiently by combining (primary and secondary) amines and carboxylic acids in one-pot under solvent-free microwave (MW) conditions. In most cases, no racemization was observed with optically active inputs and chiral amides were obtained in high ee or de.     

Application of matrix solid-phase dispersion to the determination of amitrole and urazole residues in apples by capillary electrophoresis with electrochemical detection

A new method based on matrix solid-phase dispersion (MSPD) extraction was studied for the extraction of amitrole (3-amino-1,2,4-triazole), and its metabolite urazole (3,5-dihydroxy-1,2,4-triazole), in apple samples. The influence of experimental conditions on the yield of the extraction process and on the efficiency of the cleanup step was evaluated. Determination was carried out by capillary electrophoresis (CE) with electrochemical detection, demonstrating the compatibility between MSPD and CE techniques. The method has been successfully applied to different apple varieties. Recoveries in samples spiked at 1.6 and 1.7 μg g⁻¹ for amitrole and urazole were 88 and 82%, respectively. The limits of detection were 0.4 μg g⁻¹ for both compounds using electrochemical detection.     

One-pot general synthesis of metalloporphyrins

A new general one-pot method for the synthesis of various metalloporphyrins has been developed from pyrrole and substituted aldehydes using transition metal salts. This method allows higher working concentrations than those previously reported. Along with the reported metalloporphyrins, some new metalloporphyrins were synthesized in good yield.     

Vibrational spectra and structures of urazole and 4-methylurazole: DFT calculations of the normal modes in aqueous solution and in the solid state,and the influence of hydrogen bonding

Solid-state IR and Raman as well as aqueous solution state Raman spectra are reported for urazole, 4-methylurazole and their deuterated derivatives. DFT calculations, at the B3-LYP/cc-pVTZ level, established that the structures and vibrational spectra of the molecules can be interpreted using models with hydrogen-bonded water molecules, in conjunction with the polarizable continuum solvation method. The vibrational spectra were computed at the optimised molecular geometry in each case, enabling normal coordinate analysis, which yielded satisfactory agreement with the experimental IR and Raman data. Computed potential energy distributions of the normal modes provided detailed vibrational assignments. Solid-state pseudopotential-plane-wave DFT calculations, using the PW91 functional were also carried out, reflecting the importance of intermolecular hydrogen bonding in the solid state.     

An efficient synthesis of diynes using (diacetoxyiodo)benzene

A novel and facile method for synthesis of symmetrical conjugated diynes, using (diacetoxyiodo)benzene as oxidant under palladium-catalyzed conditions is presented, in which diynes are prepared in good yields in a short period of time at room temperature.     

An efficient synthesis of 1,5-benzodiazepine derivatives catalyzed by boric acid

1,5-Benzodiazepine derivatives have been synthesized by the condensation of o-phenylenediamines and ketones in the presence of boric acid as catalyst under mild conditions.This method is simple,environmentally benign and high yielding.     

Improved and efficient synthesis of Maxacalcitol

Maxacalcitol,the 22-oxa-derivative of 1a,25-dihydroxyvitamin D3,has been used as an antihyperparathyroidism and antipsoriatic drug.In this paper,an alternative synthetic route has been developed using commercially available vitamin D2as the starting material.In addition,as a key intermediate,the asymmetric synthesis of 20（S）-alcohol 14 with the chiral auxiliary（R-CBS） was described for the first time.This new synthetic route afforded Maxacalcitol with improved overall yield（13.9%） in eleven steps.     

An efficient, general synthesis of racemic 2-substituted ferrocenecarboxaldehydes

A straightforward, high-yielding route to racemic 2-substituted ferrocenecarboxaldehydes has been developed. The synthesis involves the ortho-lithiation/electrophilic quenching of readily accessible 2-ferrocenyl-4,4-dimethyloxazoline (2c), followed by N-methylation, sodium borohydride-mediated reduction, and acidic hydrolysis.     

An efficient approach for total synthesis of aminopropyl functionalized ganglioside GM1b

A highly efficient protocol for the synthesis of aminopropyl functionalized ganglioside GM1b has been described. The full protected ganglioside GM1b was obtained in 71% yield within 5 h. The key feature of the synthetic approach was the use of sialic acid donor that was with a C-5 trichloroacetamide moiety and with a dibenzyl phosphite residue as leaving group at the anomeric carbon. The sialyl donor gave high yields and excellent α-anomeric selectivities with a wide variety of glycosyl acceptors ranging from C-3 or C-6 hydroxyls of galactoside to C-6 hydroxyl of glucosaminoside by using TMSOTf as catalyst in a mixture solution of acetonitrile and methylene chloride.     

An efficient and general synthesis of 3-substituted propionaldehydes using the Suzuki-Miyaura coupling

An efficient method to prepare 3-substituted propionaldehyde derivatives using a Suzuki-Miyaura coupling is reported. The reaction has been demonstrated on a range of substrates including several where the Heck reaction with allyl alcohol failed to give the desired aldehyde product.     

An efficient synthesis of quinazoline-2,4-dione derivatives with the aid of a low-valent titanium reagent

A facile synthetic method using low-valent titanium reagent (TiCl₄/Zn system) to promote the novel reductive cyclization of 2-nitrobenzamides and triphosgene is described. Sequentially, a series of quinazoline-2,4-diones were synthesized in good yields.     

A simple and efficient synthesis of the valsartan

Valsartan 1, one of the most important agents used in antihypertensive therapy today, was synthesized starting from L-valin methyl ester hydrochloride 2 through four steps in an overall yield of 60%. The key step involves the palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses and is more suitable for industrial production.