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First Total Synthesis of (±)-Strychnine via a [4+2]- Cycloaddition /Rearrangement Cascade

First Total Synthesis of (±)-Strychnine via a [4+2]- Cycloaddition /Rearrangement Cascade. Hongjun Zhang, Jutatip Boonsombat , and Albert Padwa * Org . Lett . 2007, 9, 279-282 . Jixin Liu 2/21/2012 Chem 635. Outline. Brief introduction of Dr. Albert Padwa . Strychnine

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First Total Synthesis of (±)-Strychnine via a [4+2]- Cycloaddition /Rearrangement Cascade

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  1. First Total Synthesis of (±)-Strychnine via a [4+2]-Cycloaddition/Rearrangement Cascade Hongjun Zhang, JutatipBoonsombat, and Albert Padwa* Org. Lett. 2007, 9, 279-282. Jixin Liu 2/21/2012 Chem 635

  2. Outline • Brief introduction of Dr. Albert Padwa. • Strychnine • Retrosynthesis • Forwardsynthesis • Summary

  3. Dr. Albert Padwa Education: B.A., Columbia University; Ph.D., Columbia University; Postdoctoral Research Fellow, University of Wisconsin. Academic : -William P. Timmie Professor of Chemistry, Emory University -Mentored around 200 Graduate Students and Postdocs -Approximately 820 publications including many reviews and book chapters -Editorial Boards of JACS, JOC, Org. Lett. among others -Served as an Alternate Councilor, Chairman of the Organic Division of the ACS, and has been the President of the International Society of Heterocyclic Chemistry. -Avid Mountain Climber and Runner Biography: http://www.arkat-usa.org/get-file/18783/

  4. Strychnine highly toxic colorless crystalline alkaloid, isolated In 1818. Structure determined by Robert Robinson in 1947. Fruit of Strychnine 6 stereo centers, 5 of which are included within one saturated 6-membered ring Completed Total Synthesis first by Woodward (1954), then by many others.

  5. Strychnine

  6. Padwa Synthesis Hongjun Zhang; JutatipBoonsombat; Albert Padwa; Org. Lett. 2007, 9, 279-282 Hongjun Zhang; JutatipBoonsombat; Albert Padwa; Org. Lett. 2007, 9, 279-282

  7. Hongjun Zhang; JutatipBoonsombat; Albert Padwa; Org. Lett. 2007, 9, 279-282

  8. Retrosynthesis

  9. Forward synthesis Key step

  10. Upon MMFF94 Minimization, Iteration 500; Final Energy: 97.153

  11. Forward synthesis

  12. Summary • a concise synthesis of the Strychnosalkaloid (+)-strychnine • The central step in the synthesis consists of an intramolecular [4+2] cycloaddition/rearrangement. • Closure of the remaining D-ring was carried out from the aza-tetracyclic intermediate by an intramolecularpalladium-catalyzed enolate-driven cross-coupling between the N-tethered vinyl iodide and the ketogroup. Thank you!

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