771476-40-5Relevant academic research and scientific papers
Dual-organocatalyst-promoted asymmetric cascade reaction: Highly efficient construction of enantiopure fully substituted tetrahydro-1,2-oxazines
Lin, Hua,Sun, Xing-Wen,Lin, Guo-Qiang
, p. 752 - 755 (2014)
A four-component asymmetric α-aminoxylation/aza-Michael/Mannich cascade reaction for the construction of fully substituted chiral tetrahydro-1,2-oxazine derivatives was accomplished in high yields with excellent enantio- and diastereoselectivities under m
Highly enantioselective l-thiaproline catalyzed α-aminoxylation of aldehydes in aqueous media
Chua, Pei Juan,Tan, Bin,Zhong, Guofu
supporting information; experimental part, p. 543 - 547 (2010/04/23)
Highly enantioselective L-thiaproline catalyzed α-aminoxylation of aldehydes in the presence of water and tetrabutylammonium bromide followed by in situ reduction to afford the respective α-aminoxy alcohols has been developed in good to high yields (74-88%) and excellent enantioselectivities (93->99%).
Highly enantioselective α-aminoxylation of aldehydes and ketones with a polymer-supported organocatalyst
Font, Daniel,Bastero, Amaia,Sayalero, Sonia,Jimeno, Ciril,Pericas, Miquel A.
, p. 1943 - 1946 (2008/02/02)
The first catalytic enantioselective α-aminoxylation of aldehydes and ketones using an insoluble, polymer-supported organocatalyst (1) derived from trans-4-hydroxyproline is reported (ee: 96-99%). Reaction rates in the aminoxylation of cyclic ketones with 1 are higher than those reported with L-proline. The insoluble nature of 1 simplifies workup conditions and allows catalyst recycling without an apparent decrease in enantioselectivity or yield.
A highly selective, organocatalytic route to chiral dihydro-1,2-oxazines
Kumarn, Sirirat,Shaw, David M.,Longbottom, Deborah A.,Ley, Steven V.
, p. 4189 - 4191 (2007/10/03)
(Chemical Equation Presented) The organocatalyzed asymmetric synthesis of chiral dihydro-1,2-oxazines from achiral starting materials proceeds in moderate to excellent yields and excellent enantioselectivity. This sequential reaction gives the desired pro
The direct catalytic asymmetric α-aminooxylation reaction: Development of stereoselective routes to 1,2-diols and 1,2-amino alcohols and density functional calculations
Cordova, Armando,Sunden, Henrik,Bogevig, Anders,Johansson, Mikael,Himo, Fahmi
, p. 3673 - 3684 (2007/10/03)
Proline-catalyzed direct asymmetric α-aminooxylation of ketones and aldehydes is described. The proline-catalyzed reactions between unmodified ketones or aldehydes and nitrosobenzene proceeded with excellent diastereo- and enantioselectivities. In all cases tested, the corresponding products were isolated with > 95% ees. Methyl alkyl ketones were regiospecifically oxidized at the methylene carbon atom to afford enantiomerically pure α-aminooxylated ketones. In addition, cyclic ketones could be α,α′-dioxidized with remarkably high selectivity, furnishing the corresponding diaminooxylated ketones with > 99% ees. The reaction mechanism of the proline-catalyzed direct asymmetric α-aminooxylation was investigated, and we performed density functional theory (DFT) calculations in order to investigate the nature of the plausible transition states further. We also screened other organocatalysts for the asymmetric α-oxidation reaction and found that several proline derivatives were also able to catalyze the transformation with excellent enantioselectivities. Moreover, stereoselective routes for the synthesis of monoprotected vicinal diols and hydroxyketones were found. In addition, short routes for the direct preparation of enantiomerically pure epoxides and 1,2-amino alcohols are presented. The direct catalytic α-oxidation is also a novel route for the stereoselective preparation of β-adrenoreceptor antagonists.
Efficient asymmetric syntheses of (+)-strictifolione
Enders, Dieter,Lenzen, Achim,Müller, Michael
, p. 1486 - 1496 (2007/10/03)
The asymmetric synthesis and a formal asymmetric synthesis of (+)-strictifolione are described. As key step in both approaches the Julia-Kocienski olefination to create an E-configured alkene was used. The anti-1,3-diol moiety was synthesized by employing
The direct and enantioselective organocatalytic α-oxidation of aldehydes
Brown, Sean P.,Brochu, Michael P.,Sinz, Christopher J.,MacMillan, David W. C.
, p. 10808 - 10809 (2007/10/03)
The first direct enantioselective catalytic α-oxidation of carbonyls has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective oxyamination of aldehydes, to generate α-oxyaldehydes, important chiral synthons for natural product and medicinal agent synthesis. The use of l-proline as the asymmetric catalyst has been found to mediate the oxidation of a large variety of aldehyde substrates with nitrosobenzene serving as the electrophilic oxidant. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. While catalyst quantities of 2 mol % were generally employed in this study, successful oxidations conducted using catalyst loadings as low as 0.5 mol % are described. Copyright
