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Bacterial infections caused by 'superbugs' are increasing globally, and conventional antibiotics are becoming less effective against these bacteria, such that we risk entering a post-antibiotic era. In recent years, antimicrobial peptides (AMPs) have gained significant attention for their clinical potential as a new class of antibiotics to combat antimicrobial resistance. In this review, we discuss several facets of AMPs including their diversity, physicochemical properties, mechanisms of action, and effects of environmental factors on these features. This review outlines various chemical synthetic strategies that have been applied to develop novel AMPs, including chemical modifications of existing peptides, semi-synthesis, and computer-aided design. We will also highlight novel AMP structures, including hybrids, antimicrobial dendrimers and polypeptides, peptidomimetics, and AMP–drug conjugates and consider recent developments in their chemical synthesis. [ABSTRACT FROM AUTHOR]

The growing antimicrobial resistance crisis necessitates the discovery and development of novel classes of antibiotics if a 'postantibiotic era' is to be avoided. Ribosomally synthesised and post-translationally modified peptides, or RiPPs, are becoming increasingly recognised as a potential source of antimicrobial drugs. This is due to a combination of their potent antimicrobial activity and their high stability relative to unmodified linear peptides. However, as peptide drugs, their clinical development is often perturbed by issues such as low solubility and poor bioavailability. Chemical synthesis has the potential to overcome some of these challenges. Furthermore, the structural complexity of RiPPs makes them interesting synthetic targets in their own right, with the total synthesis of some structural classes having only been recently realised. This review focusses on the use of RiPPs as antimicrobial agents and will highlight various strategies that have been employed to chemically synthesise three major classes of RiPPs: lasso peptides, cyclotides, and lanthipeptides. [ABSTRACT FROM AUTHOR]

In the presence of a CuBr·SMe2 catalytic system, a very simple and efficient approach for the synthesis of the key precursor of the core of endiandric acids starting from the readily and abundantly available 3-butyn-1-ol in five linear steps with an overall yield of 40% was developed. [ABSTRACT FROM AUTHOR]

Small-molecule modulators of biological targets play a crucial role in biology and medicine. In this context, diversity-oriented synthesis (DOS) provides strategies toward generating small molecules with a broad range of unique scaffolds, and hence three-dimensionality, to target a broad area of biological space. In this study, an organocatalysis-derived DOS library of macrocycles was synthesized by exploiting the pluripotency of aldehydes. The orthogonal combination of multiple diversity-generating organocatalytic steps with alkene metathesis enabled the synthesis of 51 distinct macrocyclic structures bearing 48 unique scaffolds in only two to four steps without the need for protecting groups. Furthermore, merging organocatalysis and alkene metathesis in a one-pot protocol facilitated the synthesis of drug-like macrocycles with natural-product-like levels of shape diversity in a single step. [ABSTRACT FROM AUTHOR]

The 4 H-quinolizin-4-one scaffold is of significant pharmaceutical interest. This heterocyclic structure is predicted to have attractive physico-chemical properties and is present in a variety of biologically active molecules. Despite these interesting characteristics, 4 H-quinolizin-4-ones are largely under-represented in current small molecule screening libraries, and, therefore, this scaffold has been poorly investigated. Herein, a new strategy is reported for the syntheses of these rare and biologically interesting 4 H-quinolizin-4-ones. This modular route involves the regioselective N-alkylation of 6-halo-2-pyridones followed by a Stille cross-coupling, ring-closing metathesis, and palladium-catalyzed dehydrogenation reaction sequence. This method furnishes the target compounds in good yields and allows for access to unusual substitution patterns that are difficult to achieve by using other synthetic strategies. [ABSTRACT FROM AUTHOR]

Synthetic peptides incorporating analogues of phosphoserine are valuable tools for the study of protein kinases and phosphatases. In addition, derivatives of naturally occurring peptides incorporating phosphate groups may have interesting biological properties. Herein we describe a new Fmoc/t-Bu solid-phase peptide synthesis (SPPS) strategy for the convenient generation of phosphoserine-based peptides. A proof-of-concept synthesis that demonstrates the feasibility of this approach is presented. [ABSTRACT FROM AUTHOR]

The concise and step-economical total syntheses of three hydroxyaurones and one polymethoxyflavone from readily available starting materials is described. A divergent synthetic strategy is employed, which centres on a common chalcone scaffold from which both the aurone and flavone frameworks can be accessed through the use of different oxidative cyclisation methods. These are the first reported total syntheses of these biologically interesting compounds. [ABSTRACT FROM AUTHOR]

Oxidation of alkenyl organocuprates formed from alkenyl halides allows the formation of highly substituted symmetrical 1,3-dienes. Cuprates formed from organolithiums and Grignard reagents can be tolerated and the reaction proceeds with retention of alkenyl geometry. [ABSTRACT FROM AUTHOR]

The first total synthesis of bussealin E, a natural product with a unique cycloheptadibenzofuran scaffold, is reported. A strategy inspired by a proposed biosynthesis was employed whereby a diphenylpropane derivative underwent an oxidative phenolic coupling to forge the tetracyclic ring system. The synthesis of the diphenylpropane featured a key sp²-sp³ Hiyama coupling between a vinyldisiloxane and a benzylic bromide. [ABSTRACT FROM AUTHOR]

Herein, we report on work towards the development of a new strategy for the synthesis of rare and biologically interesting indolizin-5(3 H )-ones, which is based around the use of ring-closing metathesis to construct the carbocyclic ring system. This study has provided insights into the general stability of indolizin-5(3 H )-ones and their tendency to exist as the tautomeric indolizin-5-ols. Furthermore, this approach has allowed access to other novel structurally related compounds based around unusual 6,5-azabicyclic scaffolds, which are also difficult to generate using typical methods. The azabicyclic compounds synthesized in this study reside in attractive regions of heterocyclic chemical space that are underexploited in current drug and agrochemical discovery efforts. [ABSTRACT FROM AUTHOR]

The enantioselective intramolecular Rauhut-Currier reaction has been developed using a bifunctional dipeptidic phosphane catalyst, providing a direct access to biologically active a-methylene-d-valerolactones in high yields and enantiomeric excesses. The novel catalyst is accessible in only four steps from commercial sources and exhibits unusual binding selectivities for a small molecule, suggesting the possibility for long-range interactions between the catalyst and the substrate. [ABSTRACT FROM AUTHOR]

Starting from 6-bromo-2-pyridone a novel strategy for the synthesis of 4H-quinolizin-4-ones is developed. [ABSTRACT FROM AUTHOR]