A Representative Synthetic Route for C5 Angucycline Glycosides: Studies Directed toward the Total Synthesis of Mayamycin

A Formal (4 + 2) Cycloaddition of Phosphorus Ylides: Synthesis of Aromatic and Heteroaromatic 1,2-Diesters and Diones

Heteroarylmethylenephosphorus ylides underwent Michael addition with alkynediones and alkynediesters, followed by intramolecular cyclization and elimination of triphenylphosphine oxide to afford 1,2-diaroylbenzenes and 1,2-alkoxycarbonylcarbo- and heterocycles. The analogous (4 + 2) cycloaddition led to the formation of 2,3-diaroylquinolines.

Anticancer Activities of Marine-Derived Phenolic Compounds and Their Derivatives

Since the middle of the last century, marine organisms have been identified as producers of chemically and biologically diverse secondary metabolites which have exerted various biological activities including anticancer, anti-inflammatory, antioxidant, antimicrobial, antifouling and others. This review primarily focuses on the marine phenolic compounds and their derivatives with potent anticancer activity, isolated and/or modified in the last decade. Reports on the elucidation of their structures as well as biosynthetic studies and total synthesis are also covered. Presented phenolic compounds inhibited cancer cells proliferation or migration, at sub-micromolar or nanomolar concentrations (lamellarins D (37), M (38), K (39), aspergiolide B (41), fradimycin B (62), makulavamine J (66), mayamycin (69), N-acetyl-N-demethylmayamycin (70) or norhierridin B (75)). In addition, they exhibited anticancer properties by a diverse biological mechanism including induction of apoptosis or inhibition of cell migration and invasive potential. Finally, phlorotannins 1–7 and bromophenols 12–29 represent the most researched phenolic compounds, of which the former are recognized as protective agents against UVB or gamma radiation-induced skin damages. Finally, phenolic metabolites were assorted into six main classes: phlorotannins, bromophenols, flavonoids, coumarins, terpenophenolics, quinones and hydroquinones. The derivatives that could not be attributed to any of the above-mentioned classes were grouped in a separate class named miscellaneous compounds.

Recent advances in Wacker oxidation: from conventional to modern variants and applications

Recent developments in the well-known Wacker oxidation process from conventional to modern variants and applications to natural products' synthesis are compiled in this review.

Cobalt(iii)-catalyzed ketone-directed C–H vinylation using vinyl acetate

Weakly coordinating, ketone-directed C–H vinylation using vinyl acetate is reported here for a wide range of aromatic ketones such as acetophenones, diaryl ketones, chromones and chalcones under cost-effective and air-stable cobalt(iii)-catalysis.

Synthesis of indenofurans, benzofurans and spiro-lactones via Hauser–Kraus annulation involving 1,6-addition of phthalide to quinone methides

Base mediated 1,6-addition–Dieckmann cyclization of phthalide with quinone methide leads to oxygen heterocycles such as indenofurans, spiro-lactones and benzofurans through a cascade of rearrangements involving multiple ring opening and ring closure.

Synthesis of Spiro- and Fused Heterocycles via (4+4) Annulation of Sulfonylphthalide with o-Hydroxystyrenyl Derivatives

An expedient one-pot protocol for the synthesis of functionalized benzofuran containing fused and spiro-heterocycles has been accomplished by the modified Hauser-Kraus (HK) annulation of sulfonylphthalide with o-hydroxychalcones and o-hydroxynitrostyrylisoxazoles. The multicascade process involves Michael addition, Dieckmann cyclization, and a series of cyclizations, eliminations, and rearrangements to deliver the fused and spiro-heterocyclic products. An unusual transformation of fused indenofuran to naphthoquinone, the classical HK adduct, unraveled a novel pathway for the synthesis unsymmetrical naphthoquinones.