International audienceThe classical Prins cyclization reaction has been one of the most studied reactions during the last two decades and it has found many applications in key steps of natural product syntheses, especially for products containing pyran units and related structures in their core skeletons. The nitrogen-based version of the Prins reaction, aza-Prins cyclization, has found its own relevance in organic synthesis owing to the fact that it gives direct access to piperidines, which are even more widespread in natural products and in drugs. Even though the potential scope of the reaction is vast, and despite it having afforded significant progress in the synthesis of various azaheterocycles, its applications in the field of natural product synthesis is massively underdeveloped in comparison with the classical Prins reaction. A compilation of the applications of azaPrins cyclization in the preparation of natural products and selected analogues, especially compounds of potential biological interest, is presented, with emphasis placed on the key roles of this reaction in the total synthesis of these products
The classical Prins cyclization has been one of the most intensively studied reactions during the last two decades, and it has found many applications in key steps of natural product syntheses, especially for products containing tetrahydropyran motifs and related structures in their core skeletons. The application of this reaction to the synthesis of spirocylic networks has made substantial progress recently. Spiro motifs are found in many natural products with promising biorelevance and are increasingly being incorporated in drug candidates. Further, various spirocyclic chiral ligands have shown promising efficiency in asymmetric synthesis. Here a compilation of recent spiroannulation reactions by Prins cyclization is presented, focusing on the scope and versatility of this method.
A wide array of aldehydes undergo smooth cross‐coupling with 5,6‐bis(2‐hydroxyethyl)‐2‐phenyl‐3a,4,7,7a‐tetrahydro‐1H‐isoindole‐1,3(2H)‐dione in the presence of 1.2 equiv. TMSOTf at –78 °C in dichloromethane to afford the corresponding hexahydro‐8a,4a‐(epoxyethano)pyrano[3,4‐f]isoindole‐1,3(2H,5H)‐dione derivatives in good yields with excellent diastereoselectivity. This is the first report on the stereoselective construction of oxa‐bridged tetracyclic frameworks through a bicyclization strategy.
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