Total Synthesis of Chloptosin, a Potent Apoptosis-Inducing Cyclopeptide

Asymmetric Synthesis with Organoselenium Compounds - The Past Twelve Years

The discovery and synthetic applications of novel organoselenium compounds and their reactions proceeded rapidly during the past fifty years and such processes are now carried out routinely in many laboratories. At the same time, the growing demand for new enantioselective processes provided new challenges. The convergence of selenium chemistry and asymmetric synthesis led to key developments in the 1970s, although the majority of early work was based on stoichiometric processes. More recently, greater emphasis has been placed on greener catalytic variations, along with the discovery of novel reactions and a deeper understanding of their mechanisms. The present review covers the literature in this field from 2010 to early 2023 and encompasses asymmetric reactions mediated by chiral selenium-based reagents, auxiliaries, and especially, catalysts. Protocols based on achiral selenium compounds in conjunction with other species of chiral catalysts, as well as reactions that are controlled by chiral substrates, are also included.

Total Synthesis of Incarnatapeptins A and B

The first total synthesis of incarnatapeptins A and B, two novel marine natural products, was accomplished from readily available (S)-1-benzyloxycarbonylhexahydropyridazine-3-carboxylic acid. This route, whose longest linear sequence was 12 steps, provided the incarnatapeptins A and B in yields of 26.5 % and 19.7 %, respectively, and enabled the structure and stereochemistry of both natural products to be unambiguously confirmed. Highlights of our synthesis include the photoredox-mediated decarboxylative 1,4-addition reaction and a novel and practical N-acylation paradigm promoted by silver carbonate. The unusual facile atropisomerism of some linear peptidic intermediates was also observed by TLC analysis in the course of this work.

Naturally Occurring Organohalogen Compounds-A Comprehensive Review

The present volume is the third in a trilogy that documents naturally occurring organohalogen compounds, bringing the total number-from fewer than 25 in 1968-to approximately 8000 compounds to date. Nearly all of these natural products contain chlorine or bromine, with a few containing iodine and, fewer still, fluorine. Produced by ubiquitous marine (algae, sponges, corals, bryozoa, nudibranchs, fungi, bacteria) and terrestrial organisms (plants, fungi, bacteria, insects, higher animals) and universal abiotic processes (volcanos, forest fires, geothermal events), organohalogens pervade the global ecosystem. Newly identified extraterrestrial sources are also documented. In addition to chemical structures, biological activity, biohalogenation, biodegradation, natural function, and future outlook are presented.

Total Synthesis of Melicoptelines C-E: Antiviral Cyclopeptides Containing a Hexahydropyrrolo[2,3-b]indole Moiety

Melicoptelines, natural cyclopeptides containing a 3a-hydroxy hexahydropyrrolo[2,3-b]indole (HPI) moiety, exhibit anti-influenza activity. Herein, we report the first total synthesis of melicoptelines C-E (1-3, respectively). The core 3a-hydroxy HPIs were synthesized in a diastereoselective manner from l-tryptophan using dimethyldioxirane-mediated oxidation. Subsequently, sequential peptide couplings and cyclization completed the synthesis of melicoptelines C-E and unnatural melicopteline 4. The synthesized melicoptelines were evaluated for their anti-influenza activity, and melicopteline E showed the most potent inhibition of cytopathic effects.

Synthetic and biosynthetic routes to nitrogen-nitrogen bonds

The nitrogen-nitrogen bond is a core feature of diverse functional groups like hydrazines, nitrosamines, diazos, and pyrazoles. Such functional groups are found in >300 known natural products. Such N-N bond-containing functional groups are also found in significant percentage of clinical drugs. Therefore, there is wide interest in synthetic and enzymatic methods to form nitrogen-nitrogen bonds. In this review, we summarize synthetic and biosynthetic approaches to diverse nitrogen-nitrogen-bond-containing functional groups, with a focus on biosynthetic pathways and enzymes.

Dimerization decrypts antibiotic activity

Direct dimerization simplifies the synthesis of himastatin and elucidates its mode of action.

Total synthesis of himastatin

The natural product himastatin has an unusual homodimeric structure that presents a substantial synthetic challenge. We report the concise total synthesis of himastatin from readily accessible precursors, incorporating a final-stage dimerization strategy that was inspired by a detailed consideration of the compound's biogenesis. Combining this approach with a modular synthesis enabled expedient access to more than a dozen designed derivatives of himastatin, including synthetic probes that provide insight into its antibiotic activity.

Selenocyclization by formation of carbon-nitrogen bonds

Selenium promoted cyclization of unsaturated substrates containing internal nitrogen nucleophiles, such as different amines and amides, including the examples of its application in the synthesis of more complex polycyclic compounds is reviewed. Selenocyclization reactions of some more specific polyfunctional substrates, like Biginelli hybrids and hydantoins, are also covered.

The synthesis of head-to-tail cyclic sulfono-γ-AApeptides

Head-to-tail cyclic sulfono-γ-AApeptides.

Constructing molecular complexity and diversity: total synthesis of natural products of biological and medicinal importance

The advent of organic synthesis and the understanding of the molecule as they occurred in the nineteenth century and were refined in the twentieth century constitute two of the most profound scientific developments of all time. These discoveries set in motion a revolution that shaped the landscape of the molecular sciences and changed the world. Organic synthesis played a major role in this revolution through its ability to construct the molecules of the living world and others like them whose primary element is carbon. Although the early beginnings of organic synthesis came about serendipitously, organic chemists quickly recognized its potential and moved decisively to advance and exploit it in myriad ways for the benefit of mankind. Indeed, from the early days of the synthesis of urea and the construction of the first carbon-carbon bond, the art of organic synthesis improved to impressively high levels of sophistication. Through its practice, today chemists can synthesize organic molecules--natural and designed--of all types of structural motifs and for all intents and purposes. The endeavor of constructing natural products--the organic molecules of nature--is justly called both a creative art and an exact science. Often called simply total synthesis, the replication of nature's molecules in the laboratory reflects and symbolizes the state of the art of synthesis in general. In the last few decades a surge in total synthesis endeavors around the world led to a remarkable collection of achievements that covers a wide ranging landscape of molecular complexity and diversity. In this article, we present highlights of some of our contributions in the field of total synthesis of natural products of biological and medicinal importance. For perspective, we also provide a listing of selected examples of additional natural products synthesized in other laboratories around the world over the last few years.