Oceans have shown to be a remarkable source of natural products. The biological properties of many of these compounds have helped to produce great advances in medicinal chemistry. Within them, marine natural products containing an oxepanyl ring are present in a great variety of algae, sponges, fungus and corals and show very important biological activities, many of them possessing remarkable cytotoxic properties against a wide range of cancer cell lines. Their rich chemical structures have attracted the attention of many researchers who have reported interesting synthetic approaches to these targets. This review covers the most prominent examples of these types of compounds, focusing the discussion on the isolation, structure determination, medicinal properties and total synthesis of these products.

The silyl-Prins cyclization of geminal vinylsilyl alcohols and aldehydes, promoted by TMSOTf, provides access to polysubstituted tetrahydropyrans in which the silyl group remains in the molecule and an aryl group has migrated from silicon to carbon. This domino silyl-Prins/aryl migration process is general and high-yielding for aryl, vinyl, or alkyl aldehydes. Moreover, cyclization proceeds with very high stereocontrol in a one-pot reaction in which both quaternary and tertiary stereogenic centers have been created.

Prins cyclization has emerged as one of the most valuable methods for the construction of heterocycles. It proceeds through intramolecular addition of a π‐nucleophile to an oxocarbenium or related ion. The use of electron‐rich alkenes, such as allylsilanes (so‐called silyl‐Prins cyclization) offers the benefit of allowing more selective reactions. The regio‐ and stereochemical outcomes of these transformations are explained by well‐stablished transition states. This review presents the most important contributions involving silyl‐Prins cyclization to the stereoselective preparation of oxygen and nitrogen heterocycles. The influence of different structural variants in the selectivity of the cyclization is discussed. These reactions have frequently been used as key steps in the synthesis of a wide variety of natural products.

Oxygen heterocycles are units that are abundant in a great number of marine natural products. Among them, marine polyketides containing tetrahydrofuran rings have attracted great attention within the scientific community due to their challenging structures and promising biological activities. An overview of the most important marine tetrahydrofuran polyketides, with a focused discussion on their isolation, structure determination, approaches to their total synthesis, and biological studies is provided.

Heterocycles are particularly common moieties within marine natural products. Specifically, tetrahydrofuranyl rings are present in a variety of compounds which present complex structures and interesting biological activities. Focusing on terpenoids, a high number of tetrahydrofuran-containing metabolites have been isolated during the last decades. They show promising biological activities, making them potential leads for novel antibiotics, antikinetoplastid drugs, amoebicidal substances, or anticancer drugs. Thus, they have attracted the attention of the synthetics community and numerous approaches to their total syntheses have appeared. Here, we offer the reader an overview of marine-derived terpenoids and related compounds, their isolation, structure determination, and a special focus on their total syntheses and biological profiles.

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A modular synthesis of unsymmetrical BODIPY dyes based on a [6π] electrocyclization to construct both pyrrole rings is presented. The products carry four aryl moieties in positions 1, 3, 5, and 7, which can be freely selected, as well as optional substitution in positions 2 and 8. The method employs acetophenones, benzaldehydes as well as glycine nitrile or glycine ethyl ester as the key building blocks.

Tetrahydropyrans are abundantly found in marine natural products. The interesting biological properties of these compounds and their analogues make necessary the development of convenient procedures for their synthesis. In this paper, an atom economy access to tetrahydropyrans by intramolecular acid-mediated cyclization of silylated alkenols is described. p-TsOH has shown to be an efficient reagent to yield highly substituted tetrahydropyrans. Moreover, excellent diastereoselectivities are obtained both for unsubstituted and alkylsubstituted vinylsilyl alcohols. The methodology herein developed may potentially be applied to the synthesis of marine drugs derivatives.