Development of the Juliá asymmetric epoxidation reaction. Part 2. Application of the oxidation to alkyl enones, enediones and unsaturated keto esters
摘要:
Polyleucine-based systems have been used to catalyse the asymmetric oxidation of a variety of alkyl enones 1-4,9-14, an enynone 16 and a dienone 17 to afford the corresponding epoxides 5-8, 18-26 in good to excellent yield and optical purity. A range of enediones 30-32, 34 and one unsaturated keto ester 33 have also been epoxidised stereoselectively to afford optically active epoxides 35-39. The epoxidations were carried out with basic peroxide as the oxidant; the polyleucine catalyst was prepared from leucine N-carboxyanhydride using 1,3-diaminopropane, water (employing a humidity cabinet) or a polystyrene immobilised amine as the initiator. Preliminary mass spectral data on material derived from L-leucine and 1,3-diaminopropane (DAP-PLL) suggest that the catalyst consists of material that contains 22 +/- 10 leucine residues.
A Catalytic Cross‐Olefination of Diazo Compounds with Sulfoxonium Ylides
作者:James D. Neuhaus、Adriano Bauer、Alexandre Pinto、Nuno Maulide
DOI:10.1002/anie.201809934
日期:2018.12.3
A ruthenium‐catalysed cross‐olefination of diazo compounds and sulfoxonium ylides is presented. Our reaction design exploits the intrinsic difference in reactivity of diazo compounds and sulfoxonium ylides as both carbene precursors and nucleophiles, which results in a highly selective reaction.
Catalyst-Controlled, Enantioselective, and Diastereodivergent Conjugate Addition of Aldehydes to Electron-Deficient Olefins
作者:S. B. Jennifer Kan、Hiroki Maruyama、Matsujiro Akakura、Taichi Kano、Keiji Maruoka
DOI:10.1002/anie.201705546
日期:2017.8.1
A chiral-amine-catalyzed enantioselective and diastereodivergent method for aldehyde addition to electron-deficient olefins is presented. Hydrogen bonding was used as a control element to achieve unusual anti selectivity, which was further elucidated through mechanistic and computational studies.
Enantioselective Photocatalytic [3 + 2] Cycloadditions of Aryl Cyclopropyl Ketones
作者:Adrian G. Amador、Evan M. Sherbrook、Tehshik P. Yoon
DOI:10.1021/jacs.6b01728
日期:2016.4.13
Control of stereochemistry in photocycloaddition reactions remains a substantial challenge; almost all successful catalytic examples to date have involved [2 + 2] photocycloadditions of enones. We report a method for the asymmetric [3 + 2] photocycloaddition of aryl cyclopropyl ketones that enables the enantiocontrolled construction of densely substituted cyclopentane structures not synthetically accessible
A highly enantioselective Friedel–Craftsreaction of activatedphenols with (E)-4-oxo-4-arylbutenoates has been developed with the N,N′-dioxide-scandium(III) complex as the catalyst. A variety of (E)-4-oxo-4-arylbutenoates were found to be suitable substrates for the reaction. The desired products were obtained in moderate to high yields (up to 98%) and excellent enantioselectivities (up to 97% ee)
Herein, a series of indenone structures containing the SCF3 group and an adjacent chiral quaternary stereocenter were synthesized by an asymmetric Michael addition reaction using an ion pair catalyst derivedfrom amino acids. The desired products were obtained in excellent yields (up to 98%) and good to high stereoselectivities (up to 97% ee and >20:1 dr).