Recent developments in the synthesis of 11β-aryl-estrone derivatives

An industrial synthesis of 11β-aryl-estrone derivatives is described, based on the 1,4-addition of the aryl side-chain, as a cuprate, on to a mixture of allylic 5(10) alpha and beta epoxides, followed by hydrolysis and subsequent aromatization.     

FT–IR microspectroscopy study of blends of ester functionalized ethylene–propylene copolymer with (vinylidene fluoride-hexafluoropropene) elastomer

An ethylene—propylene (EPR) copolymer functionalized with (1,2-dicarboethoxy)ethyl groups has been blended with a vinylidene fluoride—hexafluropropene elastomer (NML). The existence of intermolecular interactions involving mainly the carbonyl groups of the side chains of the functionalized copolymer and the methylene hydrogens of the fluoroelastomer through hydrogen bonding was shown by means of FT—IR spectroscopy. The structure and composition of some microdomains in the mixture was examined by means of FT—IR microspectroscopy.     

1-Arylsulfonylamino-1,2,3-triazole derivatives from functionalyzed 1,2-cyclohexanediones

The heterocyclization reaction of arylsulfonylhydrazones from alkyl substituted 1,2-cyclohexanediones is sensitive to the steric requirements of the alkyl groups. A mechanism for the cyclization in acidic medium is also reported.     

X-ray structure and circular dichroism of pure rotamers of bis[guanosine-5'-monophosphate(-1)](N,N,N',N'-tetramethylcyclohexyl-1,2-diamine)platinum(II) complexes that have R,R and S,S configurations at the asymmetric diamine

The use of a sterically hindered diamine ligand (Me(4)DACH) has allowed for the first time, the isolation and characterization, both in the solid state (X-ray crystallography) and in solution (circular dichroism), of pure DeltaHT rotamers of [Pt(Me(4)dach)(5'-GMP)(2)] (compounds 1 and 2 for R,R and S,S configurations of the Me(4)DACH ligand, respectively). Comparison of the CD spectra obtained for each rotamer, which differ only in the chirality of the Me(4)DACH ligand (R,R or S,S) or in the chirality of the HT conformation (Delta or Lambda), allowed us to conclude that, in the 200-350 nm range, the contributions to the overall CD spectrum that stem from diamine chirality and diamine-induced chirality of platinum d--d transitions or from sugar chirality are negligible relative to the exciton chiral coupling that occurs for pi-pi* transitions of the cis guanines. Accurate molecular structures of 1.10 D(2)O and 2.14 D(2)O (conventional crystallographic agreement indexes R(1) convergent to 2.07 % and 2.18 %, respectively) revealed that the crystallized rotamers have a DeltaHT conformation that is in agreement with all previously reported X-ray structures of [Pt(diamine)(nucleos(t)ide)(2)] complexes. This conformation allows the 5'-phosphate to be located in proximity to the Me(4)DACH ligand so that (P)O...HC(N) hydrogen-bond interactions exists in both complexes. For both structures, the canting of the guanine planes on the coordination plane is right-handed (R; canting angle (Phi) of 80.9 degrees and 73.2 degrees, respectively); this indicates that the canting direction is driven by the HT conformation chirality (Delta for both compounds) and not by the chirality of the carrier ligand (different for the two compounds). Density functional theory analysis of the conformational space as a function of Phi indicated a good agreement between the computed and experimental structures. The increase in energy for Phi values below 65 degrees and 55 degrees (for 1 and 2, respectively) is mainly due to the short intramolecular contacts between C(8)H and the cis N-Me groups on the same side of the platinum coordination plane.     

The stereocontrolled synthesis of orthogonally protected (R)-α-methyltryptophan

An expedient and highly stereocontrolled route to (R)-α-methyltryptophan and its orthogonally protected analogs has been developed via a four-step conversion from L-alanine in good overall yields. The stereochemistry of the products is confirmed by X-ray diffraction analysis, NMR spectroscopy and optical rotations.     

Unexpected 1,2,3-triazole formation in the reaction of diethylaluminum azide with α′-amino-α,β-unsaturated ketones

4-Acyl-1H-1,2,3-triazoles are formed from diethylaluminum azide and α′-(N,N-dibenzylamino)-α,β-unsaturated ketones by [3+2] cycloaddition of azide, followed by 1,5 hydride transfer to the β carbon of the triazoline side chain and fragmentation of the tertiary amino group promoted by coordination of the latter to the Lewis acid. The structure of a triazole product is confirmed by X-ray crystallography.     

Synthesis of periphery-functionalized dendritic molecules using polylithiated dendrimers as starting material

A general method for the functionalization of Si-Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further functionalization, e.g., into pyridyl alcohols. The latter were successfully applied as catalyst precursors in a ruthenium-mediated ring-closure metathesis reaction.     

Model for the study of the impact of atmospheric heavy metals on soil microbial biomass

In the Castelporziano (Rome) protected area the inputs of atmospheric heavy metals on the soil-plant system were evaluated by the analysis of stem-flowing water from Quercus ilex L. The heavy metals detected in the soil under the canopies exhibited higher concentrations near to the tree trunks, highlighting the tree's capacity to concentrate such polluting substances. Microbial biomass, its specific respiration and the biomass calculated as a percentage of total soil organic matter, were utilised as indicators of the state of the soil and consequently also its quality with respect to heavy metal contamination.