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An increasingly sustainable photochemical synthesis of carbazoles was developed using a catalytic system of Fe(phen)3(NTf2)2/O2 under continuous flow conditions and was demonstrated on gram-scale using a numbering-up strategy. Photocyclization of triaryl and diarylamines into the corresponding carbazoles occurs in general in higher yields than with previously developed photocatalysts.

A continuous flow UV light reactor has been constructed using commercially available equipment, and its efficiency was demonstrated by performing a photocyclodehydrogenation reaction to prepare carbazole derivatives of the drug carprofen.

The photoredox oxidation to N-aryl- and N-alkyl-bearing carbazoles utilizing continuous flow, visible light, and an in situ formed Cu-based sensitizer is reported.

An increasingly sustainable photochemical synthesis of carbazoles was developed using a catalytic system of Fe(phen)

Photochemistry is an important tool in organic synthesis that has largely been underdeveloped in comparison to thermal activation. Recent advances in technology have ushered in a new era in synthetic photochemistry. The emergence of photocatalysis, which exploits sensitizers for the absorption of visible light, has provided organic chemists with a new route to the generation of radical intermediates for synthesis. Of particular interest is the development of Cu-based complexes for photocatalysis, which possess variable photophysical properties and can display complementary reactivity with common photocatalysts based on heavier transition metals such as Ru or Ir. Heteroleptic Cu-based sensitizers incorporating the presence of both a bisphosphine and diamine ligand bound to the copper center are a promising class of photocatalysts. Their synthesis is a single step, often involving only precipitation for purification. In addition, it was shown that the sensitizers could be formed in situ in the reaction mixture, simplifying the experimental setup. The heteroleptic nature of the Cu-complexes also affords opportunities to fine-tune properties. For example, structurally rigidified bisphosphines reinforce geometries about the metal center to extend the excited state lifetime. Variation of the diamine ligand can influence the excited state oxidation/reduction potentials and optical absorbances. The heteroleptic complex Cu(XantPhos)(neo)BF4 has demonstrated utility in the synthesis of helical polyaromatic carbocycles. The synthesis of [5]helicene, a relatively simple member of the helicene family, was improved from the existing UV-light mediated method by eliminating the formation of unwanted byproducts. In addition, the Cu-based sensitizers also promoted the formation of novel pyrene/helicene hybrids for materials science applications. The synthetic methods that were developed were augmented when combined with continuous flow technology. The irradiation of reaction mixtures as they are pumped through small diameter tubing provides a more homogeneous and increased photon flux compared with irradiation in round-bottom flasks or other batch reactors. The value of continuous flow methods is also evident when examining UV-light photochemistry, where the simple and safe experimental set-ups allow for further exploration of high energy light for synthetic purposes. The synthesis of functionalized complex carbazoles was also studied using both a visible light method exploiting a heteroleptic copper-based sensitizer and a UV-light mediated method. It was demonstrated that both the photocatalysis methods and UV light photochemistries were rendered more user-friendly, safe, and reproducible when using continuous flow methods. Interestingly, the two photochemical methods often afford contrasting selectivities as a result of their inherently different mechanisms. It can be expected that the complementarity of the various photochemical methods will be an asset to synthetic chemists as the field continues to evolve.

A photochemical synthesis of [5]helicene employing a copper-based sensitizer 7 has been developed that avoids the disadvantages associated with the traditional UV light mediated method. The visible light mediated synthesis uses common glassware and a simple household light bulb without the competing formation of [2 + 2] cycloadducts, regioisomers, or the overoxidation product benzo[ghi]perylene 3. Preliminary results show that the reaction time can be significantly reduced through the use of a continuous flow strategy.

Currently, the research team is systematically studying the oxide compounds present in the ternary system In2O3-TiO2-MgO in order to analyze its thermoluminescent (TL) response. The oxide Mg1.5InTi0.5O4 present in this system was synthesized by a solid state reaction at 1350 °C in air. The X-ray powder diffraction pattern showed a spinel-type structure for this compound. In this work, this spinel, as well as its TL properties when exposed to beta particles, are being reported for the first time. The glow curve is simple and wide with a TL maximum located at 203 °C at 21.33 Gy. The peak shows a shift to lower temperatures and it increases its intensity, as the irradiation dose increases. The lineal behavior was observed between 10.66 to 341 Gy, and no saturation signs were observed. The relative sensitivity variation was 2.7% and standard deviation after ten consecutive irradiation - TL readout cycles was 1 %. The minimum detectable dose was 5.65 Gy for this spinel-type oxide [3]. These results suggest the possible application of Mg1.5InTi0.5O4 in dosimetry.

[1251536-86-3] C53H44BCuF4N2OP2 (MW 937.23) InChI = 1S/C39H32OP2.C14H12N2.BF4.Cu/c1-39(2)33-25-15-27-35(41(29-17-7-3-8-18-29)30-19-9-4-10-20-30)37(33)40-38-34(39)26-16-28-36(38)42(31-21-11-5-12-22-31)32-23-13-6-14-24-32;1-9-3-5-11-7-8-12-6-4-10(2)16-14(12)13(11)15-9;2-1(3,4)5;/h3-28H,1-2H3;3-8H,1-2H3;;/q;;-1;+1 InChIKey = NQBPVTNKMKBSGT-UHFFFAOYSA-N (copper salt, photochemistry) Solubility: soluble in tetrahydrofuran, dichloromethane, chloroform, methanol, acetonitrile. Form Supplied in: yellow crystalline solid. Analysis of Reagent Purity: 1H NMR (300 MHz, CD2Cl2) δ ppm 8.30 (d, 2H, J = 8.1 Hz), 7.82 (s, 2H), 7.71 (dd, 2H, J = 7.8, 1.5 Hz), 7.52 (d, 2H, J = 8.4 Hz), 7.25 (m, 6H), 7.06 (m, 16H), 6.94 (m, 4H), 2.29 (s, 6H); 19F NMR (CD2Cl2) δ−154.1 (s, 4F). Preparation: the original synthesis is a one-step, single-pot procedure from commercially available starting materials (eq 1).1, 2 (1) Alternatively, complex 1 has been formed in situ from the corresponding phosphine and diamine ligands (eq 2).3 (2) Purification: recrystallization from dichloromethane and diethyl ether. Handling, Storage, and Precautions: none.

The photoredox oxidation to N-aryl- and N-alkyl-bearing carbazoles utilizing continuous flow, visible light, and an in situ formed Cu-based sensitizer is reported.

Synthesis of helically chiral aromatics resulting from fusion of pyrene and [4]- or [5]helicene has been accomplished using photoredox catalysis employing a Cu-based sensitizer as the key step. Photocyclisation experiments for the synthesis of the target compounds were carried out in batch and using continuous flow strategies. The solid-state structures, UV/Vis absorption spectra and fluorescence spectra of the pyrene–helicene hybrids were investigated and compared to that of the parent [5]helicene to discern the effects of merging a pyrene moiety within a helicene skeleton. The studies demonstrated that pyrene–helicene hybrids adopt co-planar or stacked arrangements in the solid state, in contrast to the solid-state structure of the parent [5]helicene. The UV/Vis and fluorescence spectra of the pyrene–helicene hybrids exhibited strong red-shifts when compared to the parent [5]helicene. DFT calculations suggest that the strategy of extending the π surface in the y axis of the helicenes increased their HOMO levels while also decreasing their LUMO levels, resulting in significantly reduced band gaps.

En este trabajo se reportan los principales hallazgos observados en pacientes con alveolitis alergica extrinseca inducida por antigeno aviario, estudiados en los dos ultimos anos. En terminos generales desde los puntos de vista clinico, radiologico, funcional y morfologico, nuestros resultados son similares a los reportados en la literatura. Sin embargo, en nuestra serie destacan: 1) Una gran predileccion por el sexo femenino (5:1) y una alta asociacion con el puerperio. 2) Factor reumatoide positivo a titulos muy elevados en mas de la mitad de los pacientes; incremento de los fenotipos HLA-B 15 y HLA-DR 7 y disminucion de la actividad supresora, que en conjunto sugieren la presencia de fenomenos autoinmu-nes. 3) Datos morfologicos y bioquimicos de fibrosis en el 25% de los casos estudiados, lo que demuestra que esta no es una enfermedad «inocente» como habitualmente se considera.