IUPAC nomenclature of organic chemistry

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry. To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked over. However, th

Rh-catalyzed C-H Bond Heteroarylation with Hypervalent Iodine Reagents and Pd-Catalyzed Tethered Functionalizations of Carbon-Carbon Multiple Bonds.

Ashis Kumar Das

Transition metal-catalyzed C-H activation is a powerful tool for the synthesis of organic building blocks, materials, and natural products. Over the last decade, directing-group-assisted metal-catalyzed C-H functionalization has attracted increasing interest as a means to target specific C-H bonds. Moreover, a large variety of electrophiles has been employed in this kind of processes. In this thesis, we describe a novel C-6 selective C-H heteroarylation of pyridine-2-ones using indoleBX reagents as coupling partners under Rh(I)-catalysis. The reaction worked efficiently also with other analogous heterocyclic substrates and with a quinoline-N-oxide. We were able to obtain 6-(indol-3-yl)pyridinone and 8-(indol-3-yl)quinolone after cleavage of the directing group or rearrangement of the N-oxide moiety. 1,2-Amino alcohols are important structural motifs in organic chemistry that can be observed in natural products, pharmaceutically and biologically active molecules. The palladium-catalyzed difunctionalization of C-C multiple bonds has been broadly investigated as an efficient strategy to access such substructures. This transformation has been reported using either Pd(0)/Pd(II) or Pd(II)/Pd(IV) catalytic cycles, in which the nucleophilic functionalization of a putative Pd(II)-alkyl intermediate is achieved prior to beta-hydride elimination. As a further topic of this thesis, we developed new methods for the synthesis of amino alcohols whereby the Pd-catalyzed difunctionalization of alkynes and alkenes was combined with the tethering approach previously established in our laboratories. We first investigated the Pd-catalyzed enantioselective hydroalkoxylation of propargylic amines. The latter were tethered in situ with a trifluoroacetaldehyde hemiacetal. Best results were obtained with commercially available DACH-Phenyl Trost ligand. Aryl iodides were required as an additive in catalytic amount for successful outcome. A large variety of chiral oxazolidines were obtained in good to excellent yields and ee, followed by a diastereoselective reduction to give protected enantioenriched amino alcohols. A possible mechanism for this transformation relies on a Pd(0)/Pd(II) catalytic cycle involving oxidative addition of aryl iodide with a subsequent oxypalladation/protodemetallation (or reductive elimination) reaction. This is necessary to generate the active complex, not as the start of a cross-coupling event. The use of a commercially available DACH-Ph Trost ligand to produce high enantioselectivity in an unprecedented DYKAT process was critical to success.The Pd-catalyzed amino acetoxylation of cinnamyl alcohols was next taken into consideration towards the synthesis of valuable amino diol derivatives. In this case, preformed substrates were used, where the alcohol moiety was tethered to N-nucleophilic groups. Conditions involving Pd(II)/Pd(IV) catalysis and employing PIDA as a strong oxidant were employed. The use of this hypervalent iodine reagent was key to the success of the transformation. Amino acetoxylated products were obtained in moderate to good yields and dr. The scope of this reaction remains mostly limited to cinnamyl derived substrates. The reaction conditions did not tolerate substituents on the alpha, beta, and gamma positions of the allylic chains. Alkyl chain containing unsaturated alcohols delivered Aza-Wacker-type products.

EPFL2022

Standard-Free Quantification of Dicarboxylic Acids: Case Studies with Salt-Rich Effluents and Serum

Sasa Bjelic, Christian Ludwig, Daniil Salionov

The present study evaluates the ionization efficiency (IE) of linear and branched C2–C14 dicarboxylic acids (DCAs) by electrospray ionization (ESI) under different conditions. The influence of the concentration of organic modifier (MeOH); mobile phase additive; and its concentration, pH, and DCA structure on IE values is studied using flow injection analysis. The IE values of DCAs increase with the increase of MeOH concentration but also decrease with an increase of pH. The former is due to the increase in solvent evaporation rates; the latter is caused by an ion-pairing between the diacid and the cation (ammonium), which is confirmed by the study with different amines. The investigation of DCA ionization in the presence of different acidic mobile phase additives showed that a significant improvement in the (−)ESI responses of analytes was achieved in the presence of weak hydrophobic carboxylic acids, such as butyric or propanoic acid. Conversely, the use of strong carboxylic acids, such as trichloroacetic acid, was found to cause signal suppression. The results of the IE studies were used to develop the liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method that provided instrumental limits of detection in the range from 6 to 180 pg. Furthermore, upon applying the nonparametric Gaussian process, a model for the prediction of IE values was developed, which contains the number of carbons in the molecule and MeOH concentration as model parameters. As a case study, dicarboxylic acids are quantified in salt-rich effluent and blood serum samples using the developed LC-HRMS method.

2022

Copper-Catalyzed Alkynylation of Hydrazides: An Easy Access to Functionalized Azadipeptides

Julien Aymeric Borrel, Eliott Hugo Joran Le Du, Jérôme Waser

We report a copper-catalyzed alkynylation of azadipeptides using ethynylbenziodoxolone (EBX) reagents. Nonsymmetrical ynehydrazides could be obtained in 25–97% yield using azaglycine derivatives as nucleophiles. The transformation is compatible with most functional groups naturally occurring on amino acid side chains and allows the transfer of silyl-, alkyl-, and aryl-substituted alkynes. The obtained α-alkynyl azaglycine products could be further functionalized by nucleophilic attack or cycloaddition on the triple bond.

2022

Rh-catalyzed C-H Bond Heteroarylation with Hypervalent Iodine Reagents and Pd-Catalyzed Tethered Functionalizations of Carbon-Carbon Multiple Bonds.

Ashis Kumar Das

EPFL2022