420849-80-5Relevant articles and documents
The cinchona primary amine-catalyzed asymmetric epoxidation and hydroperoxidation of α,β-unsaturated carbonyl compounds with hydrogen peroxide
Lifchits, Olga,Mahlau, Manuel,Reisinger, Corinna M.,Lee, Anna,Fares, Christophe,Polyak, Iakov,Gopakumar, Gopinadhanpillai,Thiel, Walter,List, Benjamin
supporting information, p. 6677 - 6693 (2013/06/05)
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen peroxide as the oxidant, we have developed highly enantioselective Weitz-Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5-15-membered cyclic enones, and α-branched enals as substrates. In addition to an expanded scope, synthetic applications of the products are presented. We also report detailed mechanistic investigations of the catalytic intermediates, structure-activity relationships of the cinchona amine catalyst, and rationalization of the absolute stereoselectivity by NMR spectroscopic studies and DFT calculations.
Catalytic asymmetric hydroperoxidation of α,β-unsaturated ketones: An approach to enantiopure peroxyhemiketals, epoxides, and aldols
Reisinger, Corinna M.,Wang, Xingwang,List, Benjamin
supporting information; experimental part, p. 8112 - 8115 (2009/04/13)
(Chemical Equation Presented) Efficient, selective: The primary amine salt 1 derived from quinine efficiently catalyzes the highly enantioselective hydroperoxidation of α,β-unsaturated ketones furnishing stable and isolable cyclic peroxyhemiketals in enan
Synthesis of α,β-epoxy ketones from alkyl- and arylsubstituted cyclopropanols
Kulinkovich,Astashko,Tyvorskii,Ilyina
, p. 1453 - 1455 (2007/10/03)
A number of aliphatic and arylaliphatic α,β-epoxy ketones were prepared in good yields in a one-pot procedure by a manganese-catalyzed ring cleavage of 1-substituted and 1,2-disubstituted cyclopropanols with oxygen followed by dehydration of the resulting
Catalytic asymmetric epoxidation of aliphatic enones using tartrate-derived magnesium alkoxides
Jacques,Richards,Jackson
, p. 2712 - 2713 (2007/10/03)
Simple aliphatic enones can be converted into the corresponding epoxides in 71-93% ee using tert-butylhydroperoxide in the presence of a catalyst derived from dibutylmagnesium and di-tert-butyl tartrate.
A Halide-Free Method for Olefin Epoxidation with 30% Hydrogen Peroxide
Sato, Kazuhiko,Aoki, Masao,Ogawa, Masami,Hashimoto, Tadashi,Panyella, David,Noyori, Ryoji
, p. 905 - 915 (2007/10/03)
A catalytic system consisting of sodium tungstate dihydrate, (aminomethyl) phosphonic acid, and methyltrioctylammonium Hydrogensulfate, effects the epoxidation of olefins using 30% hydrogen peroxide with a substrate-to-catalyst molar ratio of 50 - 500. The reaction proceeds in high yield without solvents, or, alternatively, with added toluene under entirely halide-free conditions. Lipophilic ammonium hydrogensulfate, which replaces the conventional chloride, and an (α-aminoalkyl)phosphonic acid are crucial for the high reactivity. This method is operationally simple, environmentally benign, and much more economical than the oxidation with m-chloroperbenzoic acid, allowing for a large-scale preparation of epoxides. Various substrates including terminal olefins, 1,1- and 1,2-disubstituted olefins, cyclic olefins, and tri- and tetrasubstituted olefins as well as allylic alcohols, esters, α,β-unsaturated ketones, and ethers can be epoxidized in high yield. The scope and limitations of this new reaction system are discussed.
Organosilicon compounds with functional groups proximate to silicon. XVII. Synthetic and mechanistic aspects of the lithiation of α,β-epoxyalkylsilanes and related α-heterosubstituted epoxides
Eisch, John J.,Galle, James E.
, p. 293 - 314 (2007/10/02)
A series of α-heterosubstituted epoxides, , has been found to undergo lithiation in the temperature range of -75 to -115 deg C at the C-H bond of the epoxide.The substituent Z could be Me3Si, Ph3Si, n-Bu3Sn, Ph3Sn, PhSO2, (OEt)2PO and Ph; the groups R and R' were H, Ph and n-C6H13; and the lithiating reagents were n-butyllithium, t-butyllithium and lithium diisopropylamide in donor media of THF or TMEDA.The lithiation occurs with retention of configuration and the resulting lithio-epoxide is unstable above 0 deg C, decomposing in a carbenoid manner.The lithiation is facile except for compounds where Z and R (an alkyl or aryl) are cis-oriented; where Z = R3Sn, lithiation occurs by tin-lithium, rather than hydrogen-lithium, exchange.The lithio-epoxides thereby generated can be quenched with various reagents to yield epoxides where the epoxide H has been replaced by D, Me3Sn, R, RCO and COOH.The utility of this procedure in organic synthesis is emphasized.Finally, the possible explanations for the acidity of such α-heterosubstituted epoxides and for the relative stability of the derived lithio-epoxides are considered and assessed.
