C O M M U N I C A T I O N S
Table 2. Hydroacylation with Various Salicylaldehydesa
existing ways to make quaternary carbon-substituted cyclopropanes5
and represents a rare asymmetric cyclopropene reaction.5f,9 These
findings highlight the use of strain energy for enantioselective
catalytic transformations of C-H bonds.
Acknowledgment. University of Toronto, CFI, ORF, NSERC,
and Boehringer Ingelheim (Canada) Ltd. for funding. VMD is a Sloan
Fellow, and KGMK a Walter and Warren OGSST scholar. We thank
Matthew Coulter for helpful suggestions, Dr. Alan Lough (U of
Toronto) and Dr. Thierry Maris (U de Montréal) for X-ray structure
analyses, and Solvias for the donation of diphosphine ligands.
Supporting Information Available: Experimental procedures, X-ray
crystallographic data, characterization data for new compounds, and
chiral chromatographic analyses (PDF). This material is available free
a Conditions: 0.2 mmol of 1, 0.3 mmol of 2a. b Based on 1H NMR
integration of the crude reaction mixture. c Isolated yields, ee’s were
determined by chiral HPLC analysis.
References
Table 3. Hydroacylation of Various Cyclopropenesa
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(4) For reviews on olefin hydroacylation, see: (a) Fu, G. C. In Modern Rhodium-
Catalyzed Reactions; Evan, P. A., Ed.; Wiley-VCH: New York, 2005; pp
79-91. (b) Willis, M. Chem. ReV. 2010, 110, 725. For a recent contribution
from our lab, see: (c) Coulter, M. M.; Dornan, P. K.; Dong, V. M. J. Am.
Chem. Soc. 2009, 131, 6932.
(5) For selected enantioselective synthesis of cyclopropanes with quaternary
stereocenters, see: (a) Shibata, Y.; Noguchi, K.; Tanaka, K. J. Am. Chem.
Soc. 2010, 132, 7896. (b) Marcoux, D.; Charette, A. B. Angew. Chem., Int.
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A.; Rios, R. Eur. J. Org. Chem. 2009, 3075. (d) Marini, F.; Sternativo, S.;
Del Verme, F.; Testaferri, L.; Tiecco, M. AdV. Synth. Catal. 2009, 351, 1801.
(e) Denton, J. R.; Davies, H. M. L. Org. Lett. 2009, 11, 787. (f) Sherill,
W. M.; Rubin, M. J. Am. Chem. Soc. 2008, 130, 13804.
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Gevorgyan, V. Chem. ReV. 2007, 107, 3117, and references therein.
(7) (a) Osborne, J. D.; Randell-Sly, H. E.; Currie, G. S.; Cowley, A. R.; Willis,
M. C. J. Am. Chem. Soc. 2008, 130, 17232. (b) Shibata, Y.; Tanaka, K.
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(8) See Supporting Information for details on optimization of the catalyst and other
parameters. The absolute configurations of trans-3b, cis-3c, trans-3l, trans-4g
and trans-4h were assigned from single crystal X-ray crystallography results.
Absolute configurations of other products are assigned by analogy.
(9) (a) Nakamura, M.; Hirai, A.; Nakamura, E. J. Am. Chem. Soc. 2000, 122,
978. (b) Liu, X.; Fox, J. M. J. Am. Chem. Soc. 2006, 128, 5600. (c) Rubina,
M.; Rubin, M.; Gevorgyan, V. J. Am. Chem. Soc. 2002, 124, 11566. (d)
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a Conditions: 5 mol % catalyst, 10 mol % K3PO4, 70 °C, 12 h, 0.2
mmol of 1a, 0.3 mmol of 2. b 30 mol % K3PO4, 24 h. c Based on 1H
NMR integration of crude reaction mixture. d Isolated yields, ee’s were
determined by chiral HPLC analysis.
performed hydroacylation on cyclopropene 2h to afford 4h featuring
a spiro-quaternary carbon center in >99% ee and 3.5:1 dr (eq 4).
Through X-ray crystallography with copper irradiation, the absolute
configuration of the trans-4h product was found to be the (1S,2S)-
isomer.8
To conclude, intermolecular Rh-catalyzed hydroacylation yields
enantioenriched cyclopropylketones with vicinal tertiary and qua-
ternary chiral centers. Our catalytic method complements the few
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