Browsing by Author "Andrew R. Macdonald"

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    Synthesis of the Marine Alkaloid Cylindricine C and Serendipitous Synthesis of Its 2,13-Di-epi Stereoisomer
    (American Chemical Society, 2023-09-18) Arnaud Pastor; Rohen Prinsloo; Kristen N. Burford; Andrew R. Macdonald; Masood Parvez; Chris Gendy; Thomas G. Back
    A new approach to the marine alkaloid cylindricine C afforded its previously unreported (±)-2,13-di-epi stereoisomer as the major product along with a minor amount of the racemic parent alkaloid. Key steps included a stereoselective dianion alkylation of a monoester of 1,2-cyclohexanedicarboxylic acid and an annulation based on the tandem conjugate addition of a primary amine to an acetylenic sulfone, followed by intramolecular acylation of the resulting sulfone-stabilized carbanion. The cis-azadecalin moiety thus formed, comprising the cyclohexane A-ring and enaminone B-ring of the products, was further elaborated by the selenenyl chloride-induced cyclofunctionalization of a pendant butenyl substituent with the enaminone moiety, followed by a seleno-Pummerer reaction. Desulfonylation and enaminone reduction afforded the final products. Molecular modeling and X-ray crystallography provided further insight into these processes.