The syntheses of unprecedented bis-triazolyl BODIPY dyes displaying high quantum yields are described. The synthetic approach involves a key alkene metathesis step after templating the two bis-triazolyl dipyrromethenes with Zn, promoting the catenane structure at the expense of the mono-macrocyclic structure. The optical properties of the open form, macrocyclic, and [2]-catenane derivatives are compared. Interestingly, if the fluorescence of both the open and the macrocyclic structure displayed excellent fluorescent properties in dichloromethane, the fluorescence is quenched for the catenane analogue. However, the fluorescence of the catenane can be restored in toluene. A putative explanation for the strong solvent effect is proposed.
Triazole-Appended Dipyrromethenes (TADs) constitute a highly tunable and versatile family of ligands. Thus, well designed 1:1 / Zn:L complexes incorporating a macrocyclic TAD member were proven very efficient in the carbonation of epoxides at low CO2 pressure (1 bar) and 100 [Formula: see text]. Interestingly, the non-macrocyclized analogue was catalytically inactive in the presence of Zn(OAc)2 and dimerized instantly. Hence, engineering a structure preventing the dimerization was proven critical to restore the catalytic activity of the zinc complex.
A graphical resume of the hydrothermal decomposition of d-glucose at 150 °C in the presence of ammonium sulfate.
The synthesis and characterization of unusual silver triazolylidene-containing dipyrromethene complexes are described. The carbeneTAD-N3C-Hobtained from its parent Triazole-Appended Dipyrromethene (TAD-N-4) is an excellent ligand for the complexation of silver, thanks to the proximity between the dipyrromethene scaffold and the triazolylidene. The effect of silver salt stoichiometry on the structure of the complexes was clearly evidenced by(1)H-NMR spectroscopy and mass spectrometry. Furthermore, an unexpected argentophilic interaction was proved by different analytical techniques, including X-ray diffraction analysis and fluorescence spectroscopy. The potentiality of using the unprecedented DPM-triazolydene silver complexes for the preparation of dipyrromethene-based metallocomplexes displaying unusual coordination mode was further demonstrated with palladium.
The acidic hydrothermal dehydration of D-glucose into humins was studied. In addition to the well-known intermediates such as 5-hydroxymethylfurfural, which have been identified during the decomposition of D-glucose into humins, water-soluble oligomers of D-glucose (WSO) were identified. After isolation and characterization, the role of the WSO in the formation of humins was investigated. On this basis, we were able to propose a slight modification of the commonly admitted humins structure.
Secondary phosphine oxides were synthesized using a two-step procedure: a basic hydrolysis of oxazaphospholidine SP-2 to form the secondary phosphinate RP-4, followed by the stereoselective nucleophilic attack of organometallic reagents to obtain the expected enantioenriched secondary phosphine oxides.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An efficient and environmentally benign procedure for the synthesis of N‐alkyl‐5‐methylpyrrolidin‐2‐ones from biosourced levulinic acid, alkyl amines, and formic acid without any additive, catalyst or solvent is described.
Access to a series of 5-methylpyrrolidone derivatives is described directly using the biosourced levulinic acid in the absence of any additive, catalyst or solvent.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An efficient enantioselective strategy for the synthesis of variously substituted phosphine oxides has been developed, incorporating the use of (1S,2S)-2-aminocyclohexanol as the chiral auxiliary. The method relies on three key steps: 1) Highly diastereoselective formation of P(V) oxazaphospholidine, rationalized by a theoretical study; 2) highly diastereoselective ring-opening of the oxazaphospholidine oxide with organometallic reagents that takes place with inversion of configuration at the P atom; 3) enantioselective synthesis of phosphine oxides by cleavage of the remaining P-O bond. Interestingly, the use of a P(III) phosphine precursor afforded a P-epimer oxazaphospholidine. Hence, the two enantiomeric phosphine oxides can be synthesized starting from either a P(V) or a P(III) phosphine precursor, which constitutes a clear advantage for the stereoselective synthesis of sterically hindered phosphine oxides.
D-Glucosamine was successfully employed as a chiral auxiliary for the enantioselective synthesis of phosphine oxides. The influence of the anomeric position was also investigated and revealed the excellent ability of the α-anomer to perform this transformation in a highly selective fashion. The methodology employed consisted of three steps: diastereoselective formation of the oxazaphospholidine followed by subsequent selective cleavage of P-N and P-O bonds by reaction with two Grignard reagents. P-epimers oxazaphospholidines were prepared switching from a P(v) to a P(III) precursor, thus allowing for the synthesis of enantiomeric phosphine oxides. In addition, the chiral auxiliary could be recovered and efficiently recycled.
The design of new molecular scaffolds for the selective recognition or transport of anions is often critical, because subtle changes in the substitution pattern may drastically impact the targeted properties. Herein, detailed spectroscopic and X-ray crystal-structure analyses were used to investigate the effect of the substitution pattern of a new series of N2O2 or N-4 anion sensors. Our study evidences two distinct in-in and in-out conformations depending on the nature of the substituent (e. g., phenol vs. aniline). Interestingly, because of intramolecular hydrogen bonds involving the -OH or the -NH2 functions, the dipyrrin subunit only acts as a scaffold and does not participate in the anion binding. Furthermore, the nature of the meso substituent was not critical, as similar binding affinities were measured for meso-C6H5 or meso-C6F5 ligands. Hence, the meso position can be further modified without any noticeable changes to the electron density on the dipyrromethene subunit.
A d-glucosamine-based phosphine/Pd(OAc)2 complex has been applied to the Suzuki-Miyaura coupling reaction of aryl bromides with arylboronic acids using the supported aqueous phase catalysis, SAPC, concept. The recyclability of the catalyst was investigated and revealed a very high activity during the 4 runs.
The selective functionalization of BINOL derivatives with 3-(dimethylamino)prop-1-yn-1-yl is described. The corresponding La and Yb complexes were evaluated toward the epoxidation of α,β-unsaturated ketones. The Yb-complexes display the highest catalytic activity and selectivity, affording the expected chiral epoxides in quantitative yields and up to 90% ee in homogeneous conditions, and 93% ee when supported on silica gel.