Efficient Continuous Flow Synthesis of Hydroxamic Acids and Suberoylanilide Hydroxamic Acid Preparation

Synthesis of potent and selective HDAC6 inhibitors led to unexpected opening of a quinazoline ring

Histone deacetylase (HDAC) inhibitors are highly involved in the regulation of many pharmacological responses, which results in anti-inflammatory and anti-cancer effects. In the present work, chemoinformatic analyses were performed to obtain two potent and selective aminotriazoloquinazoline-based HDAC6 inhibitors. We unexpectedly obtained an aminotriazole from a water-driven ring opening of the triazoloquinazoline scaffold. Both compounds were evaluated as HDAC6 inhibitors, resulting in subnanomolar inhibitory activity and high selectivity with respect to class I HDAC1 and HDAC8. Importantly, the compounds were about 3- and 15-fold more potent compared to the reference compound trichostatin A. Additionally, the predicted binding modes were investigated with docking. Considering that the aminotriazole scaffold has never been embedded into the chemical structure of HDAC6 inhibitors, the present study suggests that both the aminotriazoloquinazoline and aminotriazole classes of compounds could be excellent starting points for further optimization of potential anticancer compounds, introducing such novel groups into a relevant and new area of investigation.

Potent and selective inhibitors of HDAC6 have been designed, synthesized and tested. An unexpected opening of the quinazoline ring led to both aminotriazoloquinazoline and aminotriazole compounds with potent activity and isoform selectivity.

Catalytic hydrogenation of nitrocyclohexane as an alternative pathway for the synthesis of value-added products

Catalytic hydrogenation of nitrocyclohexane could be an alternative source of various useful chemicals: cyclohexanone oxime, cyclohexanone, cyclohexanol, cyclohexylamine and dicyclohexylamine. Each one of these compounds found application in the modern...

Synthesis of Hydroxamic Acid Derivatives Using Blocked (Masked) O-Isocyanate Precursors

Hydroxamic acids are present in a several pharmaceuticals and agrochemicals. Synthetic strategies providing access to hydroxamic acid derivatives remain limited, typically requiring the use of nucleophilic hydroxylamine reagents. Herein, a synthesis of hydroxamates from unactivated carboxylic acids is reported making use of rare blocked (masked) O-substituted isocyanates. The applicability of this transformation was highlighted by targeting the synthesis of vorinostat and belinostat derivatives.

Hydroxamic Acid: An Underrated Moiety? Marrying Bioinorganic Chemistry and Polymer Science

Even 150 years after their discovery, hydroxamic acids are mainly known as the starting material for the Lossen rearrangement in textbooks. However, hydroxamic acids feature a plethora of existing and potential applications ranging from medical purposes to materials science, based on their excellent complexation properties. This underrated functional moiety can undergo a broad variety of organic transformations and possesses unique coordination properties for a large variety of metal ions, for example, Fe(III), Zn(II), Mn(II), and Cr(III). This renders it ideal for biomedical applications in the field of metal-associated diseases or the inhibition of metalloenzymes, as well as for the separation of metals. Considering their chemical stability and reactivity, their biological origin and both medical and industrial applications, this Perspective aims at highlighting hydroxamic acids as highly promising chelators in the fields of both medical and materials science. Furthermore, the state of the art in combining hydroxamic acids with a variety of polymer structures is discussed and a perspective regarding their vast potential at the interface of bioinorganic and polymer chemistry is given.

A highly efficient uranium grabber derived from acrylic fiber for extracting uranium from seawater

An amidoxime and carboxylate containing chelating adsorbent derived from acrylic fiber shows a fast adsorption rate and high uranium and low vanadium adsorption capacities in real seawater tests.

Methods for Hydroxamic Acid Synthesis

Substituted hydroxamic acid is one of the most extensively studied pharmacophores because of their ability to chelate biologically important metal ions to modulate various enzymes, such as HDACs, urease, metallopeptidase, and carbonic anhydrase. Syntheses and biological studies of various classes of hydroxamic acid derivatives have been reported in numerous research articles in recent years but this is the first review article dedicated to their synthetic methods and their application for the synthesis of these novel molecules. In this review article, commercially available reagents and preparation of hydroxylamine donating reagents have also been described.

Temperature-induced single-crystal-to-single-crystal transformation of a binuclear Mn(ii) complex into a 1D chain polymer

The new binuclear Mn(ii) complex can transform into a new 1D chain structure in a SCSC transformation via dehydration.

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

The implementation of continuous flow processing as a key enabling technology has transformed the way we conduct chemistry and has expanded our synthetic capabilities. As a result many new preparative routes have been designed towards commercially relevant drug compounds achieving more efficient and reproducible manufacture. This review article aims to illustrate the holistic systems approach and diverse applications of flow chemistry to the preparation of pharmaceutically active molecules, demonstrating the value of this strategy towards every aspect ranging from synthesis, in-line analysis and purification to final formulation and tableting. Although this review will primarily concentrate on large scale continuous processing, additional selected syntheses using micro or meso-scaled flow reactors will be exemplified for key transformations and process control. It is hoped that the reader will gain an appreciation of the innovative technology and transformational nature that flow chemistry can leverage to an overall process.

Deciding whether to go with the flow: evaluating the merits of flow reactors for synthesis

The fine chemicals and pharmaceutical industries are transforming how their products are manufactured, where economically favorable, from traditional batchwise processes to continuous flow. This evolution is impacting synthetic chemistry on all scales-from the laboratory to full production. This Review discusses the relative merits of batch and micro flow reactors for performing synthetic chemistry in the laboratory.

Synthesis of (+)-dumetorine and congeners by using flow chemistry technologies

An efficient total synthesis of the natural alkaloid (+)-dumetorine by using flow technology is described. The process entailed five separate steps starting from the enantiopure (S)-2-(piperidin-2-yl)ethanol 4 with 29% overall yield. Most of the reactions were carried out by exploiting solvent superheating and by using packed columns of immobilized reagents or scavengers to minimize handling. New protocols for performing classical reactions under continuous flow are disclosed: the ring-closing metathesis reaction with a novel polyethylene glycol-supported Hoveyda catalyst and the unprecedented flow deprotection/Eschweiler-Clarke methylation sequence. The new protocols developed for the synthesis of (+)-dumetorine were applied to the synthesis of its simplified natural congeners (-)-sedamine and (+)-sedridine.

Continuous-flow organic synthesis: a tool for the modern medicinal chemist

Medicinal chemists are under increasing pressure, not only to identify lead compounds and optimize them into clinical candidates, but also to produce materials in sufficient quantities for subsequent investigation. With this in mind, continuous-flow methodology presents an opportunity to reduce the time taken to, first, identify the compound and, second, scale the process for evaluation and, where necessary, production. It is therefore the aim of this review to provide the reader with an insight into the advantages associated with the use of continuous-flow chemistry through the use of strategically selected literature examples.

Histone deacetylase and microtubules as targets for the synthesis of releasable conjugate compounds

Design and synthesis of an HDAC inhibitor and its merger with three tubulin binders to create releasable conjugate compounds is described. The biological evaluation includes: (a) in vitro reactivity with glutathione, (b) antiproliferative activity, (c) cell cycle analysis and (d) quantification of protein acetylation. The cellular pharmacology study indicated that the HDAC-inhibitor-drug conjugates retained antimitotic and proapoptotic activity with a reduced potency.