Covering: January 2013 to September 2018Sulfur-containing natural products are a large class of significant functional molecules. Many of these compounds exhibit potent biological activities and ...pharmacological properties; in fact, some of them have been developed into important drugs. The total synthesis of sulfur-containing natural products is a subject that has long attracted significant attention from synthetic organic chemists; to achieve this goal, various methods have been developed over the past years. This review surveys total syntheses of sulfur-containing natural products that introduce sulfur atoms using different sulfurization agents to construct related sulfur-containing moieties.
The isoxazolidine ring represents one of the privileged structures in medicinal chemistry, and there have been an increasing number of studies on isoxazolidine and isoxazolidine-containing compounds. ...Optimization of the 1,3-dipolar cycloaddition (1,3-DC), original methods including electrophilic or palladium-mediated cyclization of unsaturated hydroxylamine, has been developed to obtain isoxazolidines. Novel reactions involving the isoxazolidine ring have been highlighted to accomplish total synthesis or to obtain bioactive compounds, one of the most significant examples being probably the thermic ring contraction applied to the total synthesis of (±)-Gelsemoxonine. The unique isoxazolidine scaffold also exhibits an impressive potential as a mimic of nucleosides, carbohydrates, PNA, amino acids, and steroid analogs. This review aims to be a comprehensive and general summary of the different isoxazolidine syntheses, their use as starting building blocks for the preparation of natural compounds, and their main biological activities.
The development and application of continuous flow chemistry methods for synthesis is a rapidly growing area of research. In particular, natural products provide demanding challenges to this ...developing technology. This review highlights successes in the area with an emphasis on new opportunities and technological advances.
The development and application of continuous flow chemistry methods for synthesis have been ongoing in research laboratories for more than a decade, during which time a number of natural product syntheses have been investigated and reported using such tools.
Expression of concern for ‘Total synthesis of tubulysin U and N14-desacetoxytubulysin H’ by Bohua Long et al., Org. Biomol. Chem., 2020, 18, 5349–5353, https://doi.org/10.1039/D0OB01109F.
A direct and regioselective lithiation was realized on N‐Boc‐pyrrolo2,1‐f1,2,4triazine, simply utilizing the distinct sigma‐acidity on C‐9. Starting from this enabling discovery, C‐glycoside ...formation, cyanation, and global deprotection steps constitute one of the most efficient syntheses of GS‐441524. Furthermore, transient protection was applied on GS‐441524 with phenyl boronic acid, which facilitated a powerful one‐pot synthesis of remdesivir.
The ease of synthesis and the exceptional reactivity of alkoxyallenes has led to their use in a large number of highly diverse applications. This Report describes their use in various versions of the ...allene ether Nazarov cyclization. Following a brief introduction to the Nazarov cyclization (Section 1), the oxidative cyclization of vinyl alkoxyallenes is discussed first (Section 2). Nazarov cyclizations of α-alkoxyallenyl vinyl ketones and of α-alkoxyallenyl vinyl tertiary carbinols are covered (Section 3). The discovery and the subsequent rational design of acetals that serve as chiral auxiliaries on the allene in highly enantioselective Nazarov cyclizations is explained (Section 4). Interrupted Nazarov cyclizations of alkoxyallenes that are generated
in situ
from the isomerization of propargyl ethers on solid supports are discussed, including the evolution of a highly diastereoselective, chiral auxiliary controlled version of the reaction. Some applications of the methodology to natural products total synthesis have been included so as to provide the reader with benchmarks with which to judge the utility of the methodology.
The ease of synthesis and the exceptional reactivity of alkoxyallenes has led to their use in a large number of highly diverse applications.
A study investigated the occurrence, biogenesis and synthesis of biologically active carbazole alkaloids, which can be constructed by cycling biphenyls with an orthonitrogen substitute or ...diarylamines. Fischer-Borche synthesis is one avenue by which carbazoles can be prepared.
A visible‐light‐induced radical cascade cyclization of ortho‐diisocyanoarenes for the synthesis of diethyl benzoaphenazine‐6,6(5H)‐dicarboxylates has been developed. This process provides an ...efficient and convenient protocol for the construction of benzoaphenazine skeleton that widely present in biologically active molecules and pharmaceuticals. The reaction takes place under mild conditions and the products are obtained in moderate to excellent yields.
A transition‐metal‐free one‐pot synthesis of 3‐halo‐2‐organochalcogenylbenzobchalcogenophenes has been developed using 1‐(2‐organochalcogenylethynyl)‐2‐butylchalcogenylbenzenes generated in situ from ...1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and diorganoyl dichalcogenides. By this method, several 2,3‐disubstituted benzobchalcogenophenes were prepared in yields of 48–93%. The mechanistic investigation suggests that the formation of chalcogenoacetylenes containing an adjacent chalcogen atom in the first step of this one‐pot procedure involves acetylide anions formed from 1‐(2,2‐dibromovinyl)‐2‐organochalcogenylbenzenes and mild bases.
