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6
ChiPros Chiral Epoxides
Oxiranes are very valuable building blocks which allow
derivatization:
• by forming C-X bonds (through reactions with alcohols,
ammonia, amines, phenolates etc.)
• or by forming new C–C bonds (through reactions with cyanide,
malonates, allyl silyl reagents, metal-organic reagents, e.g. Mg, Zn,
Li organyls)
There are several alternative r<strong>out</strong>es towards chiral aryl-substituted epoxides,
among them Jacobsen’s asymmetric epoxidation 5 or his hydrolytic
kinetic resolution 6 method, Sharpless’s asymmetric epoxidation 7 using
catalytic titan(IV)- isopropylate/diethyl tartrate complexes and tert-butylhydroperoxide,
complemented by Shi’s reaction 8 using peroxomonosulfate
with a chiral ketone as catalyst, or among the enzymatic methods,
application of epoxide hydrolases, lipases or monooxygenases. The stereoselective
reduction of α-chlorinated acetophenones using dehydrogenases,
however, aff ords a very versatile and more cost-effi cient access
to a wide range of oxiranes, including both enantiomers of styrene oxide
as well as very diff erently substituted phenyl oxiranes (Scheme 3).
Aldrich.com
O O
CH 3
R R
Scheme 3: Stereoselective synthesis of oxiranes.
X
R
OH
X
Base
R
TO ORDER: Contact your local Sigma-Aldrich offi ce (see back cover), or visit Aldrich.com/chemicalsynthesis.
O
O
726508
F
727253
O
Cl
726699
O
O
726834
Aldrich Chemistry is proud to off er ChiPros in small quantities (up to
kilograms). A total of 79 products from the ChiPros portfolio are available
from Aldrich Chemistry, including chiral amines, alcohols, epoxides and
carboxylic acids.
References:
(1) http://www.chipros.com (2) Karl, U.; Simon, A. Chimica Oggi/Chemistry Today 2009,
27, 5. (3) Breuer, M.; Ditrich, K. et al. Angew. Chem. Int. Ed. 2004, 43, 788-824. (4) Blaser, H.
U.; Schmidt, E. Asymmetric Catalysis on Industrial Scale, Wiley-VCH. 2004 (5) Zhang, W.;
Loebach, J. L. et al. J. Am. Chem. Soc. 1990, 112, 2801-2803. (6) White, D. E.; Jacobsen, E. N.
Tetrahedron: Asymmetry 2003, 14, 3633-3638. (7) (a) Katsuki, T.; Sharpless, K. B. J. Am. Chem.
Soc. 1980, 102, 5974-5976. (b) Review: Hüft, E. Top. Curr. Chem. 1993, 164, 63-77.
(8) (a) Wang, Z.-X.; Tu, Y. et al. J. Am. Chem. Soc. 1997, 119, 11224-11235; (b) Ager, D.;
Anderson, K. et al., Org. Proc. Res. Dev. 2007, 11, 44-51; (c) Aldrich Chemfi les 2010, 3, 4-5.
For a complete list of Chiral Building Blocks available from
Aldrich Chemistry, visit Aldrich.com/chiralbb