https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

In studying the evolution of organic chemistry and grasping its essence, one comes quickly to the conclusion that no other type of reaction plays as large a role in shaping this domain of science than carbon-carbon bond-forming reactions. The Grignard, Diels-Alder, and Wittig reactions are but three prominent examples of such processes, and are among those which have undeniably exercised decisive roles in the last century in the emergence of chemical synthesis as we know it today. In the last quarter of the 20th century, a new family of carbon-carbon bond-forming reactions based on transition-metal catalysts evolved as powerful tools in synthesis. Among them, the palladium-catalyzed cross-coupling reactions are the most prominent. In this Review, highlights of a number of selected syntheses are discussed. The examples chosen demonstrate the enormous power of these processes in the art of total synthesis and underscore their future potential in chemical synthesis.

Palladium-catalyzed cross-coupling reactions in total synthesis.

Medicinal plants: Traditions of yesterday and drugs of tomorrow

Multicomponent reactions (MCRs) are one-pot reactions employing more than two starting materials, e.g. 3, 4, … 7, where most of the atoms of the starting materials are incorporated in the final product.1 Several descriptive tags are regularly attached to MCRs (Fig. 1): they are atom economic, e.g. the majority if not all of the atoms of the starting materials are incorporated in the product; they are efficient, e.g. they efficiently yield the product since the product is formed in one-step instead of multiple sequential steps; they are convergent, e.g. several starting materials combine in one reaction to form the product; they exhibit a very high bond-forming-index (BFI), e.g. several non-hydrogen atom bonds are formed in one synthetic transformation.2 Therefore MCRs are often a useful alternative to sequential multistep synthesis.






Open in a separate window


Figure 1


Above: multistep syntheses can be divergent (sequential) or convergent; below: in analogy MCR reactions are convergent and one or two component reactions are divergent or less convergent.

Chemistry and Biology Of Multicomponent Reactions

Hydrogen bonding is responsible for the structure of much of the world around us. The unusual and complex properties of bulk water, the ability of proteins to fold into stable three-dimensional structures, the fidelity of DNA base pairing, and the binding of ligands to receptors are among the manifestations of this ubiquitous noncovalent interaction. In addition to its primacy as a structural determinant, hydrogen bonding plays a crucial functional role in catalysis. Hydrogen bonding to an electrophile serves to decrease the electron density of this species, activating it toward nucleophilic attack. This principle is employed frequently by Nature's catalysts, enzymes, for the acceleration of a wide range of chemical processes. Recently, organic chemists have begun to appreciate the tremendous potential offered by hydrogen bonding as a mechanism for electrophile activation in small-molecule, synthetic catalyst systems. In particular, chiral hydrogen-bond donors have emerged as a broadly applicable class of catalysts for enantioselective synthesis. This review documents these advances, emphasizing the structural and mechanistic features that contribute to high enantioselectivity in hydrogen-bond-mediated catalytic processes.

/pdf/asymmetric-catalysis-by-chiral-hydrogen-bond-donors-c4px56xxy0.pdf

Asymmetric catalysis by chiral hydrogen-bond donors.

Atomic-structure of the buried catalytic pocket of escherichia-coli chorismate mutase.

Korupensamines A-D, Novel Antimalarial Alkaloids from Ancistrocladus korupensis

The single-crystal X-ray diffraction of a novel alkaloid, stellettamine (15), together with long-range 1 H- 13 C coupling constants obtained by inverse detection methods, and metal chelation studies have shown that the previously reported regiochemistry of the thiazole moiety of dercitin (1) and four other related alkaloids 2-5 has to be revised. The corrected structures 10-14 are related to, and in one case identical to, those of the kuanoniamines 6-9

Pyridoacridine alkaloids from deep-water marine sponges of the family Pachastrellidae: structure revision of dercitin and related compounds and correlation with the kuanoniamines

Angela Y. Lee

Papers

Atomic-structure of the buried catalytic pocket of escherichia-coli chorismate mutase.

Korupensamines A-D, Novel Antimalarial Alkaloids from Ancistrocladus korupensis

Pyridoacridine alkaloids from deep-water marine sponges of the family Pachastrellidae: structure revision of dercitin and related compounds and correlation with the kuanoniamines

New insight into the catalytic mechanism of chorismate mutases from structural studies

Application of the allylic diazene rearrangement: synthesis of the enediyne-bridged tricyclic core of dynemicin A