Recent Advances in Construction of Polycyclic Natural Product Scaffolds via One-Pot Reactions Involving Alkyne Annulation

Abstract

Polycyclic scaffolds are omnipresent in natural products and drugs, and the synthetic strategies and methods toward construction of these scaffolds are of particular importance. Compared to simple cyclic ring systems, polycyclic scaffolds have higher structure complexity and diversity, making them suitable for charting broader chemical space, yet bringing challenges for the syntheses. In this review, we surveyed progress in the past decade on synthetic methods for polycyclic natural product scaffolds, in which the key steps are one-pot reactions involving intermolecular or intramolecular alkyne annulation. Synthetic strategies of selected polycyclic carbocycles and heterocycles with at least three fused, bridged, or spiro rings are discussed with emphasis on the synthetic efficiency and product diversity. Recent examples containing newly developed synthetic concepts or toolkits such as collective and divergent total synthesis, gold catalysis, C-H functionalization, and dearomative cyclization are highlighted. Finally, several "privileged synthetic strategies" for "privileged polycyclic scaffolds" are summarized, with discussion of remained challenges and future perspectives.

Dual Activation of Unsaturated Amides with Schwartz's Reagent: A Diastereoselective Access to Cyclopentanols and N,O‐Dimethylcyclopentylhydroxylamines.

“…Thus, trans 6 a was obtained from cyclopentylhydroxylamine 3′ da by Zn/HCl‐mediated reduction followed by Pd‐catalyzed hydrogenolysis, [16] and cis 6 a by applying a mesylation/azide displacement/reduction sequence to cyclopentanol 2 a . Synthetic applications of the method were next orientated towards the synthesis of polycycles [17] …”

1,3,4-Oxadiazole Contained Sesquiterpene Derivatives: Synthesis and Microbiocidal Activity for Plant Disease

“…For plant disease, such as Xoo, Xac or TMV, although there are traditional medicines (such as Bismerthiazol, Thiodiazole copper, Ningnanmycin and Ribavirin), their effectiveness is limited various forms of disease and insect resistance ( Buttimer et al, 2017 ; Liu et al, 2021 ). Natural products have special structural characteristics and unique biological activity mechanisms, and they are an important source for discovery of highly effective, safe, and environmentally compatible drugs ( Zhang et al, 2018 ; Zheng and Hua, 2020 ; Li and Wang, 2021 ).…”

Isoquinolone Syntheses by Annulation Protocols

“…Annulation protocols with unsaturated hydrocarbons are important and efficient methods for syntheses of cyclic compounds with high atom-utilization and step-economy, which have been extensively investigated in synthetic chemistry [1][2][3][4][5][6][7][8][9][10]. Isoquinolones are not only interesting and important nitrogen-heterocyclic compounds showing versatile biological and physiological activities but also useful synthetic blocks [11][12][13][14].…”