Lewis Acid Catalyzed Formal [3+2] Cycloaddition of Donor-Acceptor Cyclopropanes and 1-Azadienes: Synthesis of Imine Functionalized Cyclopentanes and Pyrrolidine Derivatives
作者:Kamal Verma、Prabal Banerjee
DOI:10.1002/adsc.201700744
日期:2017.11.10
Lewisacidcatalyzed formal [3+2] cycloadditions of 1-azadienes with donor acceptor cyclopropanes to synthesize varieties of imine functionalized cyclopentanes and pyrrolidine derivatives in moderate to high yield have been developed. Moreover, pharmaceutically relevant azabicyclo[3.2.1]octane, bearing two all-carbon quaternary stereogenic centers at the bridgehead positions, has been synthesized by
Enantioselective Synthesis of 3,5,6‐Substituted Dihydropyranones and Dihydropyridinones using Isothiourea‐Mediated Catalysis
作者:Daniel G. Stark、Louis C. Morrill、David B. Cordes、Alexandra M. Z. Slawin、Timothy J. C. O'Riordan、Andrew D. Smith
DOI:10.1002/asia.201500907
日期:2016.2
isothiourea-catalyzed processes has been expanded and explored through the use of 2-N-tosyliminoacrylates and 2-aroylacrylates in a Michael addition-lactonization/lactamization cascade reaction. Notably, to ensure reproducibility it is essential to use homoanhydrides as ammonium enolate precursors with 2-aroyl acrylates, while carboxylic acids can be used with 2-N-tosyliminoacrylates, delivering a range of 3,5,6-substituted
PPh<sub>3</sub>-Catalyzed Reactions of Alkyl Propiolates with<i>N</i>-Tosylimines: A Facile Synthesis of Alkyl 2-[aryl(tosylimino)methyl]acrylate and an Insight into the Reaction Mechanism
A new PPh3‐catalyzed synthesis of alkyl2‐[aryl(tosylimino)methyl]acrylates from propiolate and N‐tosylimine has been developed. Deuterium‐labelling experiments show that the reaction mechanism involves several hydrogen‐transfer processes, which are not the turnover‐limiting step and strongly rely on the nature of the reaction media. The stable phosphonium–enamine zwitterion, which was proven to play
Catalytic Asymmetric β,γ Activation of α,β-Unsaturated γ-Butyrolactams: Direct Approach to β,γ-Functionalized Dihydropyranopyrrolidin-2-ones
作者:Xianxing Jiang、Luping Liu、Panpan Zhang、Yuan Zhong、Rui Wang
DOI:10.1002/anie.201302622
日期:2013.10.18
Skeleton in the closet: The title reaction enables the development of the first catalyticβ,γ‐selective Diels–Alder [4+2] annulation of α,β‐unsaturated γ‐butyrolactams (see scheme; Boc=tert‐butoxycarbonyl, Ts=4‐toluenesulfonyl). This process provides a direct method for the enantioselective construction of bi‐ or tricyclic dihydropyranopyrrolidin‐2‐one skeletons in only one step.
Bifunctional Organocatalytic Strategy for Inverse-Electron-Demand Diels-Alder Reactions: Highly Efficient In Situ Substrate Generation and Activation to Construct Azaspirocyclic Skeletons
作者:Xianxing Jiang、Xiaomei Shi、Shoulei Wang、Tao Sun、Yiming Cao、Rui Wang
DOI:10.1002/anie.201107716
日期:2012.2.27
highly enantioselective organocatalytic version of the title reactionusing an in situ substrate generation/activation catalytic mode is described (see scheme). The reaction provides an efficient enantioselective construction of functionalized azaspirocyclic skeletons. The in situgeneration of the enolate provides a new way in which to use this important nucleophile in organic synthesis.