Transcript Diapositive 1 - Université de Montréal

PRIMARY ALCOHOLS FROM TERMINAL
OLEFINS: FORMAL ANTI-MARKOVNIKOV
HYDRATION VIA TRIPLE RELAY CATALYSIS
Guangbin Dong, Peili Teo, Zachary K. Wickens, Robert H.
Grubbs Science 2011, 333, 1609.
Shawn K. Collins
Université de Montréal
Department of Chemistry
Centre for Green Chemistry and Catalysis
[email protected]
Web: http://www.mapageweb.umontreal.ca/collinss/
CHARETTE/COLLINS LITERATURE MEETING
Université de Montréal (UdeM)
March 12th, 2014
Montréal, Québec
STOICHIOMETRIC SYNTHESIS OF PRIMARY ALCOHOLS
Brown, H. C.; Gupta, S. K. J. Am. Chem. Soc. 1975, 97, 5249.
CATALYTIC SYNTHESIS OF PRIMARY ALCOHOLS
Jensen, C. M.; Trogler, W. C. Science 1986, 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 .
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.
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?
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
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?
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?
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?
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?
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
SCOPE
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
EXTENSION TO HYDROAMINATION
Bronner, S. M.; Grubbs, R. H. Chem. Sci. 2014, 5, 101.