Jacobsen's catalysts R = Alkyl, O -alkyl, O -trialkyl Best Jacobsen catalyst: R = t Bu
Katsuki's catalysts R1 = Aryl, substituted aryl R2 = Aryl, Alkyl
The Jacobsen epoxidation , sometimes also referred to as Jacobsen-Katsuki epoxidation is a chemical reaction which allows enantioselective epoxidation of unfunctionalized alkyl- and aryl- substituted alkenes.[ 1] [ 2] [ 3] It is complementary to the Sharpless epoxidation (used to form epoxides from the double bond in allylic alcohols ). The Jacobsen epoxidation gains its stereoselectivity from a C2 symmetric manganese(III) salen-like ligand , which is used in catalytic amounts. The manganese atom transfers an oxygen atom from chlorine bleach or similar oxidant. The reaction takes its name from its inventor, Eric Jacobsen , with Tsutomu Katsuki sometimes being included. Chiral-directing catalysts are useful to organic chemists trying to control the stereochemistry of biologically active compounds and develop enantiopure drugs .
Several improved procedures have been developed.[ 4] [ 5] [ 6]
A general reaction scheme follows:[ 7]
^ Zhang, W.; Loebach, J. L.; Wilson, S. R.; Jacobsen, E. N. (March 1990). "Enantioselective epoxidation of unfunctionalized olefins catalyzed by salen manganese complexes". Journal of the American Chemical Society . 112 (7): 2801–2803. doi :10.1021/ja00163a052 .
^ Jacobsen, Eric N. ; Zhang, Wei; Muci, Alexander R.; Ecker, James R.; Deng, Li (1991). "Highly enantioselective epoxidation catalysts derived from 1,2-diaminocyclohexane". Journal of the American Chemical Society . 113 (18): 7063. doi :10.1021/ja00018a068 .
^ Irie, R.; Noda, K.; Ito, Y.; Matsumoto, N.; Katsuki, T. (1991). "Catalytic asymmetric epoxidation of unfunctionalized olefins using chiral (salen)manganese(III) complexes". Tetrahedron: Asymmetry . 2 (7): 481–494. doi :10.1016/S0957-4166(00)86102-9 .
^ E. N. Jacobsen ; Deng, L.; Furukawa, Y.; Martínez, L. E. (1994). "Enantioselective Catalytic Epoxidation of Cinnamate Esters". Tetrahedron . 50 (15): 4323–4334. doi :10.1016/S0040-4020(01)89369-8 .
^ Chang, S.; Galvin, J. M.; E. N. Jacobsen (1994). "Effect of Chiral Quaternary Ammonium Salts on (salen)Mn-Catalyzed Epoxidation of Cis -Olefins. A Highly Enantioselective, Catalytic Route to Trans -Epoxides". J. Am. Chem. Soc. 116 (15): 6937–6938. doi :10.1021/ja00094a059 .
^ Brandes, B. D.; Jacobsen, E. N. (1994). "Highly Enantioselective, Catalytic Epoxidation of Trisubstituted Olefins". J. Org. Chem. 59 (16): 4378–4380. doi :10.1021/jo00095a009 .
^ "Jacobsen Epoxidation" . Organic Chemistry Portal. Retrieved 2009-09-22 .