[]Bicycles (n = 3–6) can be synthesized using palladium-catalyzed asymmetric allylic alkylation followed by rutheniumcatalyzed cycloisomerization. New types of triarylphosphino-1,2-diaminooxazoline ligands show the same high levels of enantioselectivity observed with Trost ligand when employed in Pd-catalyzed allylic alkylation reactions. The enyne products of these allylic alkylation reactions were further elaborated using a Ru-catalyzed redox isomerization process, for which a mechanism is proposed. | Turkish Journal of Chemistry Turk J Chem 2020 44 1445-1462 http chem TÜBİTAK Research Article doi kim-2004-81 Effective synthesis of bicyclodienes via palladium-catalyzed asymmetric allylic alkylation and ruthenium-catalyzed cycloisomerization Nizam HAVARE Department of Chemistry School of Humanities amp Sciences Stanford University Stanford California 94305-5580 United States Received Accepted Published Online Final Version Abstract Bicycles n 3 6 can be synthesized using palladium-catalyzed asymmetric allylic alkylation followed by ruthenium- catalyzed cycloisomerization. New types of triarylphosphino-1 2-diaminooxazoline ligands show the same high levels of enantioselectivity observed with Trost ligand when employed in Pd-catalyzed allylic alkylation reactions. The enyne products of these allylic alkylation reactions were further elaborated using a Ru-catalyzed redox isomerization process for which a mechanism is proposed. Key words Synthetic method development asymmetric catalysis Tsuji-Trost-reaction palladium-catalyzed asymmetric allylic alkylation ruthenium-catalyzed cycloisomerization 1. Introduction The development of novel and effective cyclization methods constitutes a continuing challenge in organic synthesis as five- and six-membered cycles are essential structural units in pharmaceuticals agrochemicals and other biologically active molecules 1 . Transition-metal carbenes play a fundamental role as reactive intermediates in the synthesis of these pharmaceuticals and or agrochemicals 2 3 . Since the initial report by Trost et. al. metal-catalyzed enyne cycloisomerization 4 has become an important tool for synthesizing complex molecules 5 8 from simple building blocks while maintaining good selectivity 9 and perfect atom economy 10 . Several inter- and intramolecular reaction types have been developed including alkyne addition to allylic alcohols 11 14 intramolecular addition of .
