Retro-Diels-Alder Strategy in Natural Product Synthesis

Abstract

Retro-Diels-Alder reactions have been widely applied to the synthesis of bioactive natural products, i. e., acetogenins, terpenes, steroids and alkaloids, The strategy is generally utilized to protect a double bond reformed after elimination of the diene or to mask a diene fragment and to construct an aromatic moiety after elimination of the dienophile. More recently, the spontaneous hetero-cycloreversions eliminating carbon dioxide, nitrogen or nitriles are often used in the syntheses of natural products containing aromatic rings, Cheletropic extrusion for the synthetic strategy and cycloreversion of natural product are also referred. 1. Introduction 2. Retro-Diels-Alder Reactions in Carbocycle 2.1. Elimination of Dienes 2.2. Elimination of Dienophiles 3. Retro-Hetero-Diels-Alder Reactions 3.1. Elimination of Carbon Dioxide 3.2. Elimination of Nitrogen 3.3. Elimination of Nitriles 3.4. Elimination of 4-Phenyl-1,2,4-triazoline-3,5-dione 3.5. Elimination of Miscellaneous Dienophiles 3.6. Elimination of Dienes 4. Cheletropic Extrusions 5. Cycloreversion of Natural Products 6. Conclusion