Direct Arylation of Thiophenes in Continuous Flow

Synthetic methodologies involving direct C-H functionalization are promising to improve sustainability in organic synthesis. However, these newly developed strategies may have a scarce appeal for larger scale applications due to the high catalyst loading, harsh conditions or their typically long reaction times that affect severely the process productivity. Flow chemistry technology is a recognized tool to improve both the efficiency and scalability in organic synthesis that can overcome these issues. In the present paper we studied an "in flow" method for the direct arylation of thiophene derivatives with aromatic bromides to promptly afford heteroaromatic biaryls, which are recurrent motifs both in biologically active molecules and in functional materials. By using a packed-bed reactor containing potassium carbonate as the solid base and an automated system, we could develop a reliable methodology for thiophene arylation in flow with yields up to 90 % within a residence time of 30-60 minutes. This strategy is suitable for a wide variety of substrates and allowed the reaction to be carried out at gram-scale reaching a productivity value of 1.1 g h(-1)

SYNTHESIS OF NITROGEN-CONTAINING COMPOUNDS VIA NITRENE-TRANSFER CATALYSED BY PORPHYRIN COMPLEXES

In this Ph.D. thesis several aspects around the topic of metal porphyrins-catalysed nitrene transfer reactions were investigated. It is worth to remark the importance of this sustainable synthetic methodology, it affords valuable nitrogen-containing compounds using cheap starting materials and, if organic azides are employed as nitrene source, molecular nitrogen is the only by-product of the reaction. The scope of ruthenium porphyrin-catalysed amination reaction was extended to the synthesis of important compounds from a biological and pharmaceutical point of view. New strategies to obtain amino acid derivatives and indoles by C-N bond formation were developed. In particular, the reported synthesis of the latter compounds was the first example of intermolecular reaction between an alkyne species and an organic azide affording the indole motif instead of triazoles; thus, it was demonstrated that a great control on the reaction selectivity can be achieved using metal porphyrin catalysts. The optimisation of these transformations was carried out also by studying the mechanism of the catalytic reaction. The generality of a previously performed mechanistic investigation concerning ruthenium porphyrin catalysed allylic amination was assessed. The point of view of Resonance Raman allowed the study of the catalytic system from a different perspective, whilst kinetic and theoretical studies shed some light into the mechanism of ruthenium-porphyrin catalysed aziridination of olefins and benzylic amination to give \u3b1- and \u3b2-aminoesters. The development of new catalysts to improve the catalytic performances and the process sustainability was also considered. Glycoporphyrin complexes, being potentially active compounds in promoting asymmetric synthesis or reactions in aqueous media, seem suitable for the accomplishment of this target. A preliminary study revealed the good catalytic activity in nitrene and carbene transfer reaction of this biocompatible substances, moreover the basis for a catalyst recovery/reuse system were laid

Development of a measurement platformon a light airplane and analysis of airborne measurementsin the atmospheric boundary layer

In the present paper we provide an overview of a long term research project aimed at setting up a suitable platform for measurements in the atmospheric boundary layer on a light airplane along with some preliminary results obtained from fi eld campaigns at selected sites. Measurements of air pressure, temperature and relative humidity have been performed in various Alpine valleys up to a height of about 2500 m a.m.s.l. By means of GPS resources and specifi c post-processing procedures careful positioning of measurement points within the explored domain has been achieved. The analysis of collected data allowed detailed investigation of atmospheric vertical structures and dynamics typical of valley environment, such as morning transition from ground based inversion to fully developed well mixed convective boundary layer. Based on data collected along fl ights, 3D fi elds of the explored variables have been detected and identifi ed through application of geostatistical techniques (Kriging). The adopted procedures allowed evaluation of the intrinsic statistical structure of the spatial distribution of measured quantities and the estimate of the values of the same variable at unexplored locations by suitable weighted average of data recorded at close locations. Results thus obtained are presented and discussed

A mechanistic investigation of the ruthenium porphyrin catalysed aziridination of olefins by aryl azides

A combination of DFT and kinetic studies suggests a mechanism for olefin aziridination by organic azides catalysed by ruthenium porphyrins

Development of a measurement platformon a light airplane and analysis of airborne measurementsin the atmospheric boundary layer

In the present paper we provide an overview of a long term research project aimed at setting up a suitable platform for measurements in the atmospheric boundary layer on a light airplane along with some preliminary results obtained from fi eld campaigns at selected sites. Measurements of air pressure, temperature and relative humidity have been performed in various Alpine valleys up to a height of about 2500 m a.m.s.l. By means of GPS resources and specifi c post-processing procedures careful positioning of measurement points within the explored domain has been achieved. The analysis of collected data allowed detailed investigation of atmospheric vertical structures and dynamics typical of valley environment, such as morning transition from ground based inversion to fully developed well mixed convective boundary layer. Based on data collected along fl ights, 3D fi elds of the explored variables have been detected and identifi ed through application of geostatistical techniques (Kriging). The adopted procedures allowed evaluation of the intrinsic statistical structure of the spatial distribution of measured quantities and the estimate of the values of the same variable at unexplored locations by suitable weighted average of data recorded at close locations. Results thus obtained are presented and discussed

Organic azides : energetic reagents for the intermolecular amination of C-H bonds

This feature article provides an overview of the application of organic azides for the intermolecular amination of sp(3) and sp(2) C-H bonds. The catalytic activity of several metal complexes was reviewed underlining both synthetic and mechanistic aspects of the C-H amination. The majority of the aminated compounds reported in literature have been collected in this paper to provide a compendium of published procedures. In addition, the discussion of involved mechanisms has been included to assist the reader to envisage the future potential of organic azides in the synthesis of aza-derivatives

Selective formation, reactivity, redox and magnetic properties of MnIII and FeIII dinuclear complexes with shortened salen-type schiff base ligands

The reactivity of the shortened salen-type ligands H3salmp, H2salmen and H2sal(p-X)ben with variable para-substituent on the central aromatic ring (X = tBu, Me, H, F, Cl, CF3, NO2) towards the trivalent metal ions manganese(III) and iron(III) is presented. The selective formation of the dinuclear complexes [M2(m-salmp)2], M = Mn (1a), Fe (2a), [M2(m-salmen)2(m-OR)2)], R = Et, Me, H and M = Mn (3a\u2013c) or Fe (4a\u2013c), and (M2(m-sal[p-X]ben)2(m-OMe)2), X = tBu, Me, H, F, Cl, CF3, NO2 and M = Mn (5a\u2013g) or Fe (6a\u2013g), could be identified by reaction of the Schiff bases with metal salts and the base NEt3, and their characterization through elemental analysis, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction of 2a.2AcOEt, 2a.2CH3CN and 3c.2DMF was performed. In the case of iron(III) and H3salmp, when using NaOH as a base instead of NEt3, the dinuclear complexes [Fe2(m-salmp)(m-OR)(salim)2], R = Me, H (2b\u2013c) could be isolated and spectroscopically characterized, including the crystal structure of 2b.1.5H2O, which showed that rupture of one salmp3\u2013 to two coordinated salim\u2013 ligands and release of one salH molecule occurred. The same hydrolytic tendency could be identified with sal(p-X)ben ligands in the case of iron(III) also by using NEt3 or upon standing in solution, while manganese(III) did not promote such a C\u2013N bond breakage. Cyclic voltammetry studies were performed for 3b, 4b, 5a and 6a, revealing that the iron(III) complexes can be irreversibly reduced to the mixed-valence FeIIFeIII and FeII2 dinuclear species, while the manganese(III) derivatives can be reversibly oxidized to either the mixed-valence MnIIIMnIV or to the MnIV2 dinuclear species. The super-exchange interaction between the metal centers, mediated by the bridging ligands, resulted in being antiferromagnetic (AFM) for the selected dinuclear compounds 3b, 4b, 5a, 5e, 5f, 6a and 6e. The coupling constants J (\u20132J \u15c1\ub7\u15c2 formalism) had values around \u201313 cm\u20131 for manganese(III) compounds, among the largest AFM coupling constants reported so far for dinuclear MnIII2 derivatives, while values between \u20133 and \u201310 cm\u20131 were obtained for iron(III) compounds

Synthesis and catalytic activity of μ-​oxo ruthenium(IV) porphyrin species to promote amination reactions

This work describes the synthesis of ruthenium(IV) mu-oxo porphyrin complexes of general formula [Ru-IV(TPP)(X)](2)O which have been applied as catalysts in nitrene transfer reactions using aryl azides (ArN3) as nitrene sources. Collected data indicated that the catalytic efficiency of [Ru-IV(TPP)(OCH3)](2)O was comparable to that of Ru-II(TPP)CO because of their analogous reactivity towards aryl azides to give the same catalytically active bis-imido species Ru-VI(TPP)(ArN)(2). The reaction of [RuIV(TPP)(OCH3)](2)O with Ph3CN3 or (CH3)(3)SiN3 afforded [RuIV(TPP)(N-3)](2)O which was fully characterised, its molecular structure was also determined by single crystal X-ray analysis

Characterization of ten highly polymorphic microsatellite loci for the intertidal mussel Perna perna, and cross species amplification within the genus

The brown mussel Perna perna (Linnaeus, 1758) is a dominant constituent of intertidal communities and a strong invader with multiple non-native populations distributed around the world. In a previous study, two polymorphic microsatellite loci were developed and used to determine population-level genetic diversity in invasive and native P. perna populations. However, higher number of microsatellite markers are required for reliable population genetic studies. In this context, in order to understand P. perna origins and history of invasion and to compare population genetic structure in native versus invaded areas, we developed 10 polymorphic microsatellite markers. Findings Described microsatellite markers were developed from an enriched genomic library. Analyses and characterization of loci using 20 individuals from a population in Western Sahara revealed on average 11 alleles per locus (range: 5–27) and mean gene diversity of 0.75 (range: 0.31 - 0.95). One primer pair revealed possible linkage disequilibrium while heterozygote deficiency was significant at four loci. Six of these markers cross-amplified in P. canaliculus (origin: New Zealand). Conclusions Developed markers will be useful in addressing a variety of questions concerning P. perna, including dispersal scales, genetic variation and population structure, in both native and invaded areas.Peer Reviewe