279:
264:
258:. There are three major pathways. The concerted pathway, the metalla oxetane pathway and the radical pathway. The most accepted mechanism is the concerted pathway mechanism. After the formation of the Mn(V) complex, the catalyst is activated and therefore can form epoxides with alkenes. The alkene comes in from the "top-on" approach (above the plane of the catalyst) and the oxygen atom now is bonded to the two carbon atoms (previously C=C bond) and is still bonded to the manganese metal. Then, the Mn–O bond breaks and the epoxide is formed. The Mn(III)-salen complex is regenerated, which can then be oxidized again to form the Mn(V) complex.
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In the early 1990s, Jacobsen and
Katsuki independently released their initial findings about their catalysts for the enantioselective epoxidation of isolated alkenes. In 1991, Jacobsen published work where he attempted to perfect the catalyst. He was able to obtain ee values above 90% for a variety
235:-1,2-disubstituted alkenes are poor substrates for Jacobsen's catalysts but yet give higher enantioselectivities when Katsuki's catalysts are used. Furthermore, the enantioselective epoxidation of conjugated dienes is much higher than that of the nonconjugated dienes.
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302:
400:
Irie, R.; Noda, K.; Ito, Y.; Matsumoto, N.; Katsuki, T. (1991). "Catalytic asymmetric epoxidation of unfunctionalized olefins using chiral (salen)manganese(III) complexes".
288:
Dimethyldioxirane]] can be used as a source of O atomes.DMD of a chiral metal catalyst followed by epoxidation, or (2) epoxidation by chiral dioxiranes, which are generated
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sometimes being included. Chiral-directing catalysts are useful to organic chemists trying to control the stereochemistry of biologically active compounds and develop
402:
366:; Zhang, Wei; Muci, Alexander R.; Ecker, James R.; Deng, Li (1991). "Highly enantioselective epoxidation catalysts derived from 1,2-diaminocyclohexane".
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The degree of enantioselectivity depends on numerous factors, namely the structure of the alkene, the nature of the axial donor ligand on the active
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The mechanism of the
Jacobsen–Katsuki epoxidation is not fully understood, but most likely a manganese(V)-species (similar to the
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The enantioselectivity is explained by either a "top-on" approach (Jacobsen) or by a "side-on" approach (Katsuki) of the alkene.
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The radical intermediate accounts for the formation of mixed epoxides when conjugated dienes are used as substrates.
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Brandes, B. D.; Jacobsen, E. N. (1994). "Highly
Enantioselective, Catalytic Epoxidation of Trisubstituted Olefins".
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329:(March 1990). "Enantioselective epoxidation of unfunctionalized olefins catalyzed by salen manganese complexes".
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of ligands. Also, the amount of catalyst used was no more than 15% of the amount of alkene used in the reaction.
432:; Deng, L.; Furukawa, Y.; MartĂnez, L. E. (1994). "Enantioselective Catalytic Epoxidation of Cinnamate Esters".
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epoxidation of unfunctionalized alkyl- and aryl- substituted alkenes. It is complementary to the
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Mechanisms of the free-radical and metallo-oxetane pathways of the
Jacobsen-Katsuki reaction
465:(1994). "Effect of Chiral Quaternary Ammonium Salts on (salen)Mn-Catalyzed Epoxidation of
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from a catalytic amount of ketone and a stoichiometric amount of a terminal oxidant). Mn-
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231:-1,2-disubstituted alkenes are epoxidized with almost 100% enantioselectivity whereas
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Linker, T. (1997). "Jacobsen-Katsuki epoxidation and its controversial mechanism".
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LĂ©vai, A.; Adam, W.; Fell, R. T.; Gessner, R.; Patonay, T.; Simon, A.; TĂłth, G.
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or similar oxidant. The reaction takes its name from its inventor,
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Mechanism of the
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have been used with success to accomplish the first strategy.
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amounts. The manganese atom transfers an oxygen atom from
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species and the reaction temperature. Cyclic and acyclic
469:-Olefins. A Highly Enantioselective, Catalytic Route to
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124:Jacobsen-Katsuki epoxidation
54:jacobsen-katsuki-epoxidation
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638:Organic oxidation reactions
556:Angew. Chem. Int. Ed. Engl.
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532:. Organic Chemistry Portal
461:Chang, S.; Galvin, J. M.;
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109:R = Aryl, substituted aryl
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49:Organic Chemistry Portal
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142:from the double bond in
628:Ring forming reactions
568:10.1002/anie.199720601
530:"Jacobsen Epoxidation"
403:Tetrahedron: Asymmetry
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633:Epoxidation reactions
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136:Sharpless epoxidation
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38:Ring forming reaction
19:Jacobsen epoxidation
86:Jacobsen's catalysts
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488:10.1021/ja00094a059
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171:, which is used in
107:Katsuki's catalysts
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582:J. Am. Chem. Soc.
562:(19): 2060–2062.
510:(16): 4378–4380.
482:(15): 6937–6938.
476:J. Am. Chem. Soc.
442:(15): 4323–4334.
364:Jacobsen, Eric N.
189:enantiopure drugs
169:salen-like ligand
151:stereoselectivity
128:chemical reaction
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252:Cytochrome P450
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185:Tsutomu Katsuki
177:chlorine bleach
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111:R = Aryl, Alkyl
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534:. Retrieved
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473:-Epoxides".
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376:(18): 7063.
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225:oxomanganese
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69:RXNO:0000686
64:ontology ID
44:Identifiers
24:Named after
602:Tetrahedron
435:Tetrahedron
119:epoxidation
89:R = Alkyl,
622:Categories
536:2009-09-22
309:References
242:Mechanism
173:catalytic
163:symmetric
117:Jacobsen
97:-trialkyl
611:, 13105.
591:, 11224.
147:alcohols
140:epoxides
93:-alkyl,
290:in situ
210:History
183:, with
153:from a
144:allylic
248:ferryl
471:Trans
233:trans
126:is a
605:1998
585:1997
115:The
589:119
564:doi
512:doi
484:doi
480:116
467:Cis
444:doi
412:doi
378:doi
374:113
341:doi
337:112
229:cis
62:RSC
624::
609:54
607:,
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158:2
156:C
95:O
91:O
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