Biostrategies in total synthesis

In this book main approaches toward construction of complex polycyclic core structures of biomolecules are discussed. Successful implementation of the chosen strategies for the synthesis of symbioimines and platencine is shown. A Lewis acid induced intramolecular Diels-Alder (IMDA) reactions are used as the key steps in the formation of symbioimine and (+)-neosymbioimine iminium alkaloids. The enantioselective total synthesis of (+)-neosymbioimine was accomplished in 18 steps from (-)-(S)-citronellol utilizing an organocatalytic α-oxidation. All double bonds of Diels-Alder substrate were made in a stereoselective manner by Wittig-type reactions. A concise formal synthesis of platencin was based on an efficient oxygen-mediated palladium-catalyzed cycloalkenylation to form a bicyclo 3.2.1]octane, and a deoxygenative rearrangement of tosylhydrazone to construct the bicyclo 2.2.2]octane in 17.5 % total yield for 13 steps from commercially available compounds.