A Diels–Alder-Based Total Synthesis of (−)-Kainic Acid

Proline Analogues

Within the canonical repertoire of the amino acid involved in protein biogenesis, proline plays a unique role as an amino acid presenting a modified backbone rather than a side-chain. Chemical structures that mimic proline but introduce changes into its specific molecular features are defined as proline analogues. This review article summarizes the existing chemical, physicochemical, and biochemical knowledge about this peculiar family of structures. We group proline analogues from the following compounds: substituted prolines, unsaturated and fused structures, ring size homologues, heterocyclic, e.g., pseudoproline, and bridged proline-resembling structures. We overview (1) the occurrence of proline analogues in nature and their chemical synthesis, (2) physicochemical properties including ring conformation and cis/trans amide isomerization, (3) use in commercial drugs such as nirmatrelvir recently approved against COVID-19, (4) peptide and protein synthesis involving proline analogues, (5) specific opportunities created in peptide engineering, and (6) cases of protein engineering with the analogues. The review aims to provide a summary to anyone interested in using proline analogues in systems ranging from specific biochemical setups to complex biological systems.

Hyperbaric reactions in organic synthesis. Progress from 2006 to 2020

This comprehensive review summarizes the published literature data concerning above 1 kbar reactions for the purposes of preparative organic synthesis (more then 50 mg of the initial substance) from 2006...

Marine Excitatory Amino Acids: Structure, Properties, Biosynthesis and Recent Approaches to Their Syntheses

This review considers the results of recent studies on marine excitatory amino acids, including kainic acid, domoic acid, dysiherbaine, and neodysiherbaine A, known as potent agonists of one of subtypes of glutamate receptors, the so-called kainate receptors. Novel information, particularly concerning biosynthesis, environmental roles, biological action, and syntheses of these marine metabolites, obtained mainly in last 10–15 years, is summarized. The goal of the review was not only to discuss recently obtained data, but also to provide a brief introduction to the field of marine excitatory amino acid research.

Enantioselective total synthesis of (-)-kainic acid and (+)-acromelic acid C via Rh(i)-catalyzed asymmetric enyne cycloisomerization

A diversity-oriented synthetic strategy was developed for the total synthesis of kainoid amino acids, which led to the enantioselective synthesis of (-)-kainic acid and the first total synthesis of (+)-acromelic acid C. Rh(i)-catalyzed asymmetric enyne cycloisomerization served as the key reaction in this strategy for the rapid construction of highly functionalized lactam, and the resulting vinyl acetate moiety was further utilized as a versatile building block for the installation of both isopropylidene and 2-pyridone units existing in natural kainoids.

Total synthesis of (-)-kainic acid and (+)-allo-kainic acid through SmI2-mediated intramolecular coupling between allyl chloride and an α,β-unsaturated ester

A 3,4-disubstituted pyrrolidine ring was effectively cyclized through SmI₂-mediated reductive coupling between allyl chloride and an α,β-unsaturated ester, although little has been reported about SmI₂-promoted C-C bond formation of an allyl chloride with an α,β-unsaturated ester. Selection of either the 3,4-cis- or 3,4-trans-selective cyclization can be accomplished simply by changing the additives from NiI₂ to HMPA during reductive cyclization conducted in H₂O-THF. Total synthesis of (-)-kainic acid and (+)-allo-kainic acid, which are pyrrolidine alkaloids used in neuroscience and neuropharmacology as useful molecular probes, was successfully achieved by using the stereo-complementary ring closure reactions promoted by SmI₂ for the construction of the 2,3,4-trisubsituted pyrrolidine scaffold of kainoids.

Bioactive marine drugs and marine biomaterials for brain diseases

Marine invertebrates produce a plethora of bioactive compounds, which serve as inspiration for marine biotechnology, particularly in drug discovery programs and biomaterials development. This review aims to summarize the potential of drugs derived from marine invertebrates in the field of neuroscience. Therefore, some examples of neuroprotective drugs and neurotoxins will be discussed. Their role in neuroscience research and development of new therapies targeting the central nervous system will be addressed, with particular focus on neuroinflammation and neurodegeneration. In addition, the neuronal growth promoted by marine drugs, as well as the recent advances in neural tissue engineering, will be highlighted.

Short total synthesis of (-)-kainic acid

A short total synthesis of (-)-kainic acid has been developed involving a novel diastereofacial differentiating Cu-catalyzed Michael addition-cyclization reaction, which provided access to a chiral pyrroline in a highly stereoselective manner. The chiral pyrroline was converted to (-)-kainic acid via the stereoselective 1,4-reduction of the pyrroline double bond in three steps.

Total synthesis of (-)-α-kainic acid via chirality transfer through Ireland-Claisen rearrangement

The total synthesis of (-)-α-Kainic acid is accomplished using a linear strategy involving Noyori asymmetric reduction and chirality transfer through Ireland-Claisen rearrangement as key steps.