161040-21-7Relevant 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.
Thiourea/proline derivative-catalyzed synthesis of tetrahydrofuran derivatives: A mechanistic view
Opalka, Suzanne M.,Steinbacher, Jeremy L.,Lambiris, Brandon A.,McQuade, D. Tyler
experimental part, p. 6503 - 6517 (2011/10/02)
A thiourea/proline derivative-catalyzed synthesis of linear α-substituted tetrahydrofuran/pyran derivatives starting with lactol substrates is presented. This study demonstrates the utility and potential complications of using (thio)urea/proline cocatalysis as each of these catalysts is necessary to provide the observed reactivity, but a time-dependent decrease in enantioselectivity is observed. New mechanistic insights into (thio)urea/proline cocatalysis are presented.
Gold-catalyzed synthesis of oxygen- and nitrogen-containing heterocycles from alkynyl ethers: Application to the total synthesis of andrachcinidine
Hyung, Hoon Jung,Floreancig, Paul E.
, p. 7359 - 7366 (2008/02/11)
(Chemical Equation Presented) In this paper we report that homopropargylic ethers containing pendent oxygen or nitrogen nucleophiles react with electrophilic gold catalysts in the presence of water to form saturated heterocyclic ketones. Mechanistic studies demonstrated that the reactions proceed through a sequence of alkyne hydration, alkoxy group elimination, and intramolecular conjugate addition. Diastereoselectivities for tetrahydropyran and piperidine formation are very good to excellent. This method has been applied to an efficient total synthesis of the natural product andrachcinidine. Utilizing propargylic ether substrates rather than homopropargylic ethers promotes regioselective hydration of internal alkynes, thereby expanding the scope of products that can be accessed through this protocol.
Gold-catalyzed heterocycle synthesis using homopropargylic ethers as latent electrophiles
Jung, Hyung Hoon,Floreancig, Paul E.
, p. 1949 - 1951 (2007/10/03)
Homopropargylic ethers with pendent nucleophiles, when subjected to Au catalysts in aqueous solvent, provide heterocyclic ketones. The reactions are efficient, tolerant of functionality and ambient atmosphere, and operationally simple. Diastereoselectivity can be predicted on the basis of product thermodynamics. This process demonstrates the viability of homopropargylic ethers to serve as latent electrophiles that can be unraveled under highly selective conditions to promote heterocycle formation through nucleophilic additions to α,β-unsaturated ketones.
Radical addition of ethers to alkenes under dioxygen catalyzed by N-hydroxyphthalimide (NHPI)/Co(OAc)2
Hirano, Kazutaka,Sakaguchi, Satoshi,Ishii, Yasutaka
, p. 3617 - 3620 (2007/10/03)
The reaction of various ethers with alkenes bearing an electron-withdrawing substituent in the presence of N-hydroxyphthalimide combined with Co(OAc)2 under dioxygen produced the corresponding adducts in which oxygen is incorporated to alkenes
Remote allylic silyloxy groups as stereocontrol elements in intramolecular oxymercurations of γ-hydroxyalkenes
Bratt, Katharina,Garavelas, Agatha,Perlmutter, Patrick,Westman, Gunnar
, p. 2109 - 2117 (2007/10/03)
The diastereoselectivity in intramolecular oxymercurations of γ-hydroxyalkenes bearing a remote allylic oxy substituent has been investigated. It was found that the best selectivity was obtained by employing a combination of (Z)-alkene geometry and a tert-butyldiphenylsilyl protecting group attached to the remote allylic oxygen as in 4a-g. Cyclization, using mercuric acetate in dichloromethane, of all the (Z)-alkenols gave the syn diastereomer, 5a-g, as the major product. For example, cyclization of 4b gave syn diastereomer 5b and anti diastereomer 6b in a ratio of 7:1. It was found that this ratio could be improved by replacing dichloromethane with acetonitrile. Under these conditions the ratio of 5b to 6b increased to 19:1. Cyclization of (E)-alkene 9 gave very poor diastereoselection. These syn-selective intramolecular oxymercurations were exploited in enantioselective syntheses of two diastereomers of methyl nonactate.
Stereoselective synthesis of tetrahydrofurans using intramolecular oxymercurations
Garavelas, Agatha,Mavropoulos, Irene,Perlmutter, Patrick,Westman, Gunnar
, p. 463 - 466 (2007/10/02)
The influence of alkene geometry and remote substitution on the stereochemical outcome of intramalecular oxymercurations leading to five-membered rings is described.
Anodic α-Methoxylation of Aliphatic Saturated Ethers
Shono, Tatsuya,Matsumura, Yoshihiro,Onomura, Osamu,Yamada, Yasufu
, p. 1099 - 1100 (2007/10/02)
The anodic oxidation of aliphatic saturated ethers carried out in a mixed solvent of methanol and acetic acid gave α-methoxylated ethers in much better yields than those obtained by using only methanol as a solvent.
DECOMPOSITION DU PERCARBONATE DE O,O-t-BUTYLE ET O-ISOPROPENYLE EN SOLUTION-2. ACETONYLATION DE CYCLANONES ET OXACYCLANES.
Jaouhari, R.,Maillard, B.,Filliatre, C.,Villenave, J. J.
, p. 1559 - 1566 (2007/10/02)
The decomposition of O,O-tert-butyl and O-isopropenyl peroxycarbonate in cyclanones and oxycyclanes leads to acetonylated derivatives of these solvents.Although the reaction mechanism involves in both cases the addition of free radicals derived from solvent to the double bond of the peroxycarbonate, the orientation of the whole process depends on the solvent.In the case of oxacyclanes the relative ratios of α-,β-and γ-(with regard to the heteroatom) acetonylated products are likely to express the reactivity of t-butoxy radicals towards the differenet carbon atoms of the solvent.On the contrary, in the case of cyclanones transfer reactions occur from β- or γ-radicals (with regard to the carbonyl group) to α-carbon atoms of other solvent molecules and the relative ratios of α-, β- and γ-acetonylated products depend on on the peroxycarbonate concentration: when it is high, about 25percent β and γ isomers are formed; when it is low, only the α isomer is obtained.
Reactions radicalaires du percarbonate de O,O-tert-butyle et O-isopropenyle: acetonylations assistees par un co-amorceur
Jaouhari, Rabih,Filliatre, Claude,Villenave, Jean-Jacques
, p. 2295 - 2298 (2007/10/02)
By decomposition in alkanes, ethers, ketones, acids, esters and nitriles of equimolecular mixtures of O,O-tert-butyl and O-isopropenyl peroxicarbonate and tert-butyl peroxyacetate, the "assisted" acetonylation of the solvents has been accomplished.The presence of the co-initiator allows the yield of the free radical acetonylation to be markedly improved: the formation of the by-product acetonylacetone is avoided and the yield of acetonylated derivatives is strongly enhanced while the regioselectivity of the processes is preserved and even increased in some cases.
