title: Total Synthesis of the Galbulimima Alkaloids Himandravine and GB17 Using Biomimetic Diels-Alder Reactions of Double Diene Precursors.
abstract: The enantioselective total syntheses of himandravine and GB17 were completed through a common biomimetic strategy involving Diels-Alder reactions of unusual double diene containing linear precursors. The double diene precursors, containing or lacking a C12 substituent as required to produce GB17 or himandravine, respectively, were found to undergo Diels-Alder reactions to afford mixtures of regioisomeric cycloadducts that map onto the alternative carbocyclic frameworks of both himandravine and GB17. Computational investigations revealed that these Diels-Alder reactions proceed via transition state structures of similar energy that have a high degree of bispericyclic character and that the low levels of regioselectivity observed in the reactions are a consequence of competing orbital interaction and distortion energies. The combined experimental and computational results provide valuable insights into the biosynthesis of the Galbulimima alkaloids.
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Reed T
authors: RT
authors: Larson
authors: Department of Chemistry, University of California-Davis , 1 Shields Avenue, Davis, California 95616, United States.
authors: Ryan P
authors: RP
authors: Pemberton
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Jenna M
authors: JM
authors: Franke
authors: Department of Chemistry, University of California-Davis , 1 Shields Avenue, Davis, California 95616, United States.
authors: Dean J
authors: DJ
authors: Tantillo
authors: Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors: Regan J
authors: RJ
authors: Thomson
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D032701:Biomimetics; D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D008958:Models, Molecular; D015394:Molecular Structure; D010880:Piperidines / Q000138:chemical synthesis* / Q000737:chemistry; D054837:Quinolizidines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000466:Alkadienes; D000470:Alkaloids; D010880:Piperidines; D054837:Quinolizidines; C438970:himandravine