TOTAL SYNTHESES OF (-)-SECU AMAMINE A AND RACEMIC COMMUNESIN F

Open Access
Author:
Liu, Peng
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 24, 2010
Committee Members:
  • Steven M Weinreb, Dissertation Advisor
  • Steven M Weinreb, Committee Chair
  • Raymond Lee Funk, Committee Member
  • Przemyslaw Maslak, Committee Member
  • Ryan John Elias, Committee Member
Keywords:
  • communesin F
  • total synthesis
  • secuamamine A
Abstract:
In part I, a convergent stereoselective total synthesis of the novel Securinega alkaloid (-)- secu’amamine A (9) was described. The synthesis requires 15 steps starting from aldehyde 34 and proceeds in approximately 9% overall yield. Key steps include a stereoselective conjugate addition of amino enedione 86 to afford indolizidine 91 as the major product and a tandem aldol/lactonization of diketoester 92 to produce tetracyclic γ-lactone 93. In part II, a stereoselective total synthesis of the heptacyclic alkaloid communesin F (8) was achieved in racemic form in 30 steps from the known enol triflate 147 and commercially available o-nitrobenzeneboronic acid. Key transformations in the sequence include an intramolecular Heck cyclization of a tetrasubstituted alkene to generate a tetracycle with a quaternary carbon center, a reductive cyclization of an N-Boc aniline onto an oxindole moiety to form the pentacyclic framework containing the lower aminal, a stereoselective lactam C-allylation to introduce the second quaternary carbon center, and an azide reduction/translactamization cascade eventually leading to the upper aminal functionality.