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Shawn K. Collins Universit é de Montr é al Department of Chemistry PowerPoint Presentation
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Shawn K. Collins Universit é de Montr é al Department of Chemistry

Shawn K. Collins Universit é de Montr é al Department of Chemistry

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Shawn K. Collins Universit é de Montr é al Department of Chemistry

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  1. PRIMARY ALCOHOLS FROM TERMINAL OLEFINS: FORMAL ANTI-MARKOVNIKOV HYDRATION VIA TRIPLE RELAY CATALYSIS Guangbin Dong, PeiliTeo, Zachary K. Wickens, Robert H. GrubbsScience2011, 333, 1609. Shawn K. Collins Université de Montréal Department of Chemistry Centre for Green Chemistry and Catalysis shawn.collins@umontreal.ca Web: http://www.mapageweb.umontreal.ca/collinss/ CHARETTE/COLLINS LITERATURE MEETING Université de Montréal (UdeM) March 12th, 2014 Montréal, Québec

  2. STOICHIOMETRIC SYNTHESIS OF PRIMARY ALCOHOLS Brown, H. C.; Gupta, S. K. J. Am. Chem. Soc. 1975, 97, 5249.

  3. CATALYTIC SYNTHESIS OF PRIMARY ALCOHOLS Jensen, C. M.; Trogler, W. C. Science1986,233, 1069. Later proved to “difficult to reproduce” • Marsella and co-workers prepared analytically pure “active” species and proved it to be inactive Ramprasad, D.; Yue, H. J.; Marsella, J. A. Inorg. Chem. 1988, 27, 3151. • Demonstrated each step of a catalytic cycle, but never completed the cycle! Sanford, M. S.; Groves, J. T. Angew. Chem. Int. Ed. 2004, 43, 588 .

  4. CATALYTIC SYNTHESIS OF PRIMARY ALCOHOLS One step reaction, but would require an additional saponification and hydrogenation. Campbell, A. N.; White, P. B.; Guzei, I. A.; Stahl, S. S. J. Am. Chem. Soc.2010, 132, 15116. Other work uses “activated” olefins…in this paper they comment that the hydration equivalent is an unknown transformation for organic synthetic chemists…. Stewart, I. C.; Bergman, R. G.; Toste, F. D. J. Am. Chem. Soc. 2003, 125, 8696. Using Cu catalysis and DNA…Feringa and co-workers finally accomplished this in 2010… Boersma, A. J.; Coquie`re, D.; Geerdink, D.; Rosati, F.; Feringa, B. L.; Roelfes, G. Nature Chem. 2010,2, 991.

  5. PROPOSED CATALYTIC RELAY Challenges include: •How to get aldehyde selectivity in the Wacker Oxidation (particularly for styrene derivatives) • Which metal complex could participate in the reduction, and under aqueous conditions?

  6. WACKER OXIDATION Wright, J. A.; Gaunt, M. J.; Spencer, J. B. Chem.-Eur. J. 2006, 12, 949. Ogura, T.; Kamimura, R.; Shiga, A.; Hosokawa, T. Bull. Chem. Soc. Jpn. 2005, 78, 1555. Strategy: •PdCl2 complexes/styrene starting materials • t-BuOH as solvent

  7. PROPOSED CATALYTIC RELAY Challenges include: •How to get aldehyde selectivity in the Wacker Oxidation (particularly for styrene derivatives) • Which metal complex could participate in the reduction, and under aqueous conditions?

  8. SHVO’S CATALYST Shvo, Y.; Czarkie, D. J. Organomet. Chem. 1986, 315, C25. Casey, C. P.; Singer, S.; Powell, D. R.; Hayashi, R. K.; Kavana, M. J. Am. Chem. Soc. 2001, 123, 1090. Persson, B. A.; Larsson, A. L. E.; Le Ray, M.; Backvall, J.-E. J. Am. Chem. Soc. 1999, 121, 1645. Strategy: •Use Shvo’s catalyst but add alcohol as hydride source?

  9. PROPOSED CATALYTIC RELAY: TRIPLE RELAY Challenges include: •How to get aldehyde selectivity in the Wacker Oxidation (particularly for styrene derivatives) • Which metal complex could participate in the reduction, and under aqueous conditions? • How to transform the enol ether into the aldehyde necessary for the second relay?

  10. PROPOSED CATALYTIC RELAY: TRIPLE RELAY Challenges include: •How to get aldehyde selectivity in the Wacker Oxidation (particularly for styrene derivatives) • Which metal complex could participate in the reduction, and under aqueous conditions? • How to transform the enol ether into the aldehyde necessary for the second relay?

  11. PRELIMINARY RESULTS Controls: •No palladium catalyst 26 % of desired product (34 % conv.) • No Shvo catalyst: only aldehyde product 42 % • No Shvo catalyst or water: 17 % • No CuCl2: 48 % of desired product (32 % ethylbenzene) • No benzoquinone 58% conv, almost no by-products ??? • No iPrOH 57% aldehyde • No tBuOH 58% conv, 18 % desired product. • No tBuOH but 28 eq. H2O 64 % desired product • no H2O, but 4A MS, 57 % ethyl benzene

  12. SCOPE

  13. SUMMARY. Compared to the classic hydroboration/oxidation sequence, our approach is still far from perfect, with its relatively high catalyst loadings and use of stoichiometric BQ. However, we are strongly encouraged by the excellent selectivity with arylsubstituted olefins, initial promising results with aliphatic alkenes, and the facile recovery of BQ to reduce the overall expense. Despite being in its infancy, this methodology has demonstrated great potential and will stimulate ongoing research in the field of olefin hydration

  14. EXTENSION TO HYDROAMINATION Bronner, S. M.; Grubbs, R. H. Chem. Sci. 2014, 5, 101.