Transition-Metal-Free Stereocomplementary Cross-Coupling of Diols with Boronic Acids as Nucleophiles

Synergizing structure and function: Cinnamoyl hydroxamic acids as potent urease inhibitors

The current investigation encompasses the structural planning, synthesis, and evaluation of the urease inhibitory activity of a series of molecular hybrids of hydroxamic acids and Michael acceptors, delineated from the structure of cinnamic acids. The synthesized compounds exhibited potent urease inhibitory effects, with IC50 values ranging from 3.8 to 12.8 µM. Kinetic experiments unveiled that the majority of the synthesized hybrids display characteristics of mixed inhibitors. Generally, derivatives containing electron-withdrawing groups on the aromatic ring demonstrate heightened activity, indicating that the increased electrophilicity of the beta carbon in the Michael Acceptor moiety positively influences the antiureolytic properties of this compounds class. Biophysical and theoretical investigations further corroborated the findings obtained from kinetic assays. These studies suggest that the hydroxamic acid core interacts with the urease active site, while the Michael acceptor moiety binds to one or more allosteric sites adjacent to the active site.

Broadly Applicable Ion Pair-Assisted Nucleophilic Substitution of sp3-Carbon Electrophiles with Alkynyltrifluoroborates

Alkynyltrifluoroborate nucleophiles react smoothly with a wide range of sp³-carbon electrophiles, including propargyl methanesulfonates and unactivated alkyl triflates, to give Sonogashira-type products, via a novel ion pair-assisted nucleophilic substitution mechanism. An ion pair-organic complex, investigated using computational chemistry and in situ NMR experiments, may play a crucial role in this reaction.

DDQ-Catalyzed Oxidative C(sp3)-H Functionalization of Aryltetralins and Subsequent Chemoselective Oxidative Demethylation to Access Dihydronaphthalenes and Dihydronaphthoquinones

A highly controlled DDQ-catalyzed oxidative C(sp³)-H functionalization of three contiguous carbon atoms in aryltetralins is reported for efficient access to diverse oxygenated dihydronaphthalene scaffolds. The first total synthesis of pachypostaudin B is realized. Further, a CAN-mediated chemoselective oxidative demethylation on the dihydronaphthalene scaffolds is demonstrated to arrive at the rarely observed dihydronaphthoquinone core in moderate to good yields. The present methodology enables quick access to a library of magnoshinin and merrilliaquinone analogs.

Indolylboronic Acids: Preparation and Applications

Indole derivatives are associated with a variety of both biological activities and applications in the field of material chemistry. A number of different strategies for synthesizing substituted indoles by means of the reactions of indolylboronic acids with electrophilic compounds are considered the methods of choice for modifying indoles because indolylboronic acids are easily available, stable, non-toxic and new reactions using indolylboronic acids have been described in the literature. Thus, the aim of this review is to summarize the methods available for the preparation of indolylboronic acids as well as their chemical transformations. The review covers the period 2010-2019.

Lewis Acid-Promoted Regio- and Diastereoselective Cross-Coupling of Aryl-Substituted 1,2-Diols and Boronic Acids

A Lewis acid-promoted highly regio- and diastereoselective C(sp³)-C(sp²) cross-coupling reaction between unprotected aryl-substituted 1,2-diols and styryl-, aryl-, heteroaryl-, and polyarylboronic acids has been developed in a one-pot procedure. The regioselective opening of aryl-substituted cyclic boronic esters promoted by a Lewis acid followed by subsequent intramolecular 1,4-transfer of the carbon ligand from boron to a resonance-stabilized benzylic carbenium ion minimizing the allylic 1,3-strain in a stereoselective fashion led to the corresponding α-substituted syn-phenylethyl alcohols. The synthetic utility of the method was illustrated by a short and efficient enantioselective synthesis of cherylline diethyl ether (-)-16.

Tryptophol and derivatives: natural occurrence and applications to the synthesis of bioactive compounds

This report presents some fundamental aspects related to the natural occurrence and bioactivity of tryptophol as well as the synthesis of tryptophols and their utilization for the preparation of naturally occurring alkaloid metabolites embedding the indole system.