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

Marine natural products.

Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.

Multicomponent Reactions with Isocyanides.

The direct functionalization of C-H bonds in organic compounds has recently emerged as a powerful and ideal method for the formation of carbon-carbon and carbon-heteroatom bonds. This Review provides an overview of C-H bond functionalization strategies for the rapid synthesis of biologically active compounds such as natural products and pharmaceutical targets.

C-H bond functionalization: emerging synthetic tools for natural products and pharmaceuticals

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.

III. Foldamer Research 3910 A. Overview 3910 B. Motivation 3910 C. Methods 3910 D. General Scope 3912 IV. Peptidomimetic Foldamers 3912 A. The R-Peptide Family 3913 1. Peptoids 3913 2. N,N-Linked Oligoureas 3914 3. Oligopyrrolinones 3915 4. Oxazolidin-2-ones 3916 5. Azatides and Azapeptides 3916 B. The â-Peptide Family 3917 1. â-Peptide Foldamers 3917 2. R-Aminoxy Acids 3937 3. Sulfur-Containing â-Peptide Analogues 3937 4. Hydrazino Peptides 3938 C. The γ-Peptide Family 3938 1. γ-Peptide Foldamers 3938 2. Other Members of the γ-Peptide Family 3941 D. The δ-Peptide Family 3941 1. Alkene-Based δ-Amino Acids 3941 2. Carbopeptoids 3941 V. Single-Stranded Abiotic Foldamers 3944 A. Overview 3944 B. Backbones Utilizing Bipyridine Segments 3944 1. Pyridine−Pyrimidines 3944 2. Pyridine−Pyrimidines with Hydrazal Linkers 3945

A field guide to foldamers.

Solvolysis of the neopentyl triflates 14, 25 and 32 resulted in ring expansion of a seven-membered ring into the eight-membered ring required for the synthesis of the taxanes diterpenoids.

New Strategy for the Synthesis of the Taxane Diterpenes: Formation of the Eight-Membered B-Ring of Taxol by Semi-Pinacol Rearrangement.

The nine-membered ring sec-amine4 reacts with methyl propiolate/sodium hydride in toluene at reflux to give the strychnos core structure12 in a single step.

A New Approach to the Synthesis of the Strychnos Alkaloids Core Structure.

Diphenylseleninic anhydride (1) reacts with phenols under neutral conditions to give o- and p-hydroxylation, whereas with phenolate anions only o-hydroxylation is observed.

Oxidation of phenols to hydroxycyclohexadienones using diphenylseleninic anhydride

Deprotection of the readily available bicyclo[7.3.1]enediyne alcohol 14 resulted in dimerization to give 18. Replacement of the 12α-hydroxyl group with a p-methoxyanilino group proceeded with overall retention to give 23 which also produced a dimer on attempted deprotection.

Dimerization of o-Hydroxycyclohexadienones Related to Calicheamicinone: SN2 Displacement of the 12α-Hydroxyl Group.

Treatment of 1 with DEAD in the presence of BF3·OEt2 gave 2 (R = H), which was N-alkylated to give 2 (R = CH2CO2Et), and insitu eliminated (E1cb) to give α-carbamoyl ketals.

Philip Magnus

Papers

New Strategy for the Synthesis of the Taxane Diterpenes: Formation of the Eight-Membered B-Ring of Taxol by Semi-Pinacol Rearrangement.

A New Approach to the Synthesis of the Strychnos Alkaloids Core Structure.

Oxidation of phenols to hydroxycyclohexadienones using diphenylseleninic anhydride

Dimerization of o-Hydroxycyclohexadienones Related to Calicheamicinone: SN2 Displacement of the 12α-Hydroxyl Group.

Lewis Acid Catalyzed α‐Functionalization of Ketals for the Regioselective Synthesis of α‐Carbamoyl Ketals.