Non conventional syntheses of heterocyclic compounds. 3. Synthesis of indazole derivatives

The thermal cyclization of a few 2,6-dimethylphenylazo compounds to indazole derivatives is described.     

A highly active fungal β-glucosidase

A highly active thermostable β-glucosidase was purified to homogeneity from a strain ofTrichoderma sp. The enzyme was an extracellular glycoprotein and showed hydrolytic activity toward several β-glucosides. Cellobiose was found to be the substrate of choice for this enzyme. This finding could suggest future technological applications of the purified protein.     

A 13C- and 195Pt-NMR. Study of the Complexes trans-PtCl2 (amine) (CH2CH2)

¹³C- and ¹⁹⁵Pt-NMR. spectra for the complexes trans-PtCl₂(amine)(CH₂?CH₂) have been measured. For amine = (S)-N-methyl-α-methylbenzylamine the two diastereomers present may be distinguished from the values ³J(Pt,C). The ¹⁹⁵Pt-chemical shift is shown to be sensitive to subtle differences stemming from intramolecular non-bonded interactions.     

From chiral and prochiral N-allylpyrroles to stereodefined pyrrole fused architectures: A particular application of the rhodium-catalyzed hydroformylation

We review our recent results on the rhodium-catalyzed hydroformylation of chiral and prochiral N-allylpyrroles as a synthetic route to stereodefined 5,6-dihydro- and 5,6,7,8-tetrahydroindolizines. The indolizine nucleus at different degrees of unsaturation is a building block of natural and synthetic target compounds; thus new approaches, especially if stereoselective and/or stereospecific, are highly desirable. The construction of the indolizine architectures reported here occurs by formation of a C8-C9 bond through intramolecular cyclization of the 4-pyrrolylbutanal intermediate.     

Synthesis and characterization of poly(amidoamine)-platinum(II) complexes. Detailed speciation by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

MALDI and ESI-MS have been applied to the characterization of the reaction products between the labile cis-[Pt(DMSO)₂Cl₂] (1) and trans-[Pt(DMSO)₂Cl(CH₃)] (2) complexes with the simplest poly(amidoamine) ligand (PAMAM, G = 0, 1,2-diaminoethane as core). The comparison of the mass spectra of the starting G₀ and those of the metallo-dendrimers formed upon mixing of the reagents in an equimolecular ratio, and the analysis of the isotopic distribution in the ESI spectra, have revealed the formation of cationic and neutral mononuclear complexes with PAMAM as ligand, e.g., cis-[Pt(DMSO)(PAMAM)Cl]Cl or trans-(C,N)[Pt(DMSO)(PAMAM)Cl(CH₃)], together with various minor components, which have been identified as derivatives from defective structures of PAMAM. The geometry of the main products has been deduced from the values of the protons coupling constants with the isotopically abundant ¹⁹⁵Pt. The metal-to-ligand bond is restricted to the peripheral amino groups of PAMAM which shows sufficient flexibility to involve either one or two branches in the coordination bonding.     

Convenient diastereospecific synthesis of a rociverine precursor and its resolution by lipase-catalyzed transesterification

(±)-1-Cyclohexyl-c-2-hydroxymethyl-r-1-cyclohexanol 3, a precursor of the antimuscarinic drug Rociverine 1, was obtained diastereospecifically in very high yield, from the Grignard reaction between C₆H₁₁MgCl and an appropriately protected 2-(hydroxymethyl)cyclohexanone. The preparation of enantiomerically enriched cis diol (+)-(1R,2S)-3 and the corresponding 2-acetoxymethyl derivative (+)-(1S,2R)-12 was achieved by lipase PPL-catalyzed transesterification of racemic diol (±)-3.     

Efficient Two-Step Synthesis of 11,11′-Dithiobis[1-(2-bromo-2-methylpropionyloxy)undecane], a Conventional Initiator for Grafting Polymer Brushes from Gold Surfaces via ATRP

11,11′-Dithiobis[1-(2-bromo-2-methylpropionyloxy)undecane], a conventional initiator for grafting polymers from gold surfaces, was synthesized in two steps from 11-mercapto-1-undecanol in 88–92% overall yield. Oxidative dimerization of 11-mercapto-1-undecanol with a catalytic amount of sodium iodide and 30% hydrogen peroxide in ethyl acetate proceeded in 96% yield. Esterification with 2-bromoisobutyryl bromide in dichloromethane was clean and almost quantitative (92% yield) with pyridine used as base, whereas triethylamine gave a messy reaction (64% yield). Alternatively, esterification with 2-bromo-2-methyl-propanoic acid in dichloromethane occurred readily under Steglich's conditions with N,N′-dicyclohexylcarbodiimide (DCC) and a catalytic amount of dimethylaminopyridine (DMAP; 88% yield).     

Olive milling wastewater as a medium for growth of fourPleurotus species

Four species of Pleurotus were adapted to grow on olive milling wastewater, and in certain conditions produced high yield of fruit bodies. Some biochemical transformations were observed in the olive milling wastewater owing to the growth of Pleurotus. In particular, the fungi actively excreted large amounts of laccase in the medium, and at the same time the concentration of phenolics and other toxic compounds significantly decreased, as revealed by HPLC analysis and toxicity tests on standard cultures of human cell lines.     

Study of the biological activity of novel synthetic compounds with antiviral properties against human rhinoviruses

Picornaviridae represent a very large family of small RNA viruses, some of which are the cause of important human and animal diseases. Since no specific therapy against any of these viruses currently exists, palliative symptomatic treatments are employed. The early steps of the picornavirus replicative cycle seem to be privileged targets for some antiviral compounds like disoxaril and pirodavir. Pirodavir's main weakness is its cytotoxicity on cell cultures at relatively low doses. In this work some original synthetic compounds were tested, in order to find less toxic compounds with an improved protection index (PI) on infected cells. Using an amino group to substitute the oxygen atom in the central chain, such as that in the control molecule pirodavir, resulted in decreased activity against Rhinoviruses and Polioviruses. The presence of an -ethoxy-propoxy- group in the central chain (as in compound I-6602) resulted in decreased cell toxicity and in improved anti-Rhinovirus activity. This compound actually showed a PI >700 on HRV14, while pirodavir had a PI of 250. These results demonstrate that modification of pirodavir's central hydrocarbon chain can lead to the production of novel derivatives with low cytotoxicity and improved PI against some strains of Rhinoviruses.     

Recording of PIV images on photothermoplastic plates

In this paper we explore the possibility of utilizing commercially available photothermoplastic plates as recording support in Particle Image Velocimetry (PIV), to allow real time analysis of recorded data. An experimental apparatus has been developed which allows holographic recording and reconstruction of simulated PIV images. We show that double exposed photothermoplastic plates can successfully be analysed provided that a suitable recording/reconstruction scheme is used.