In contrast to well‐established asymmetric hydrogenation reactions, enantioselective protonation is an orthogonal approach for creating highly valuable methine chiral centers under redox‐neutral conditions. Reported here is the highly enantio‐ and diastereoselective hydrofluorination of enals by an asymmetric β‐protonation/α‐fluorination cascade catalyzed by N‐heterocyclic carbenes (NHCs). The two
[EN] DIHYDROOXAZINE OR OXAZEPINE DERIVATIVES HAVING BACE1 INHIBITORY ACTIVITY<br/>[FR] DÉRIVÉS DE DIHYDROOXAZINE OU D'OXAZÉPINE AYANT UNE ACTIVITÉ INHIBITRICE DE BACE1
申请人:SHIONOGI & CO
公开号:WO2014065434A1
公开(公告)日:2014-05-01
The present invention provides a compound which has an effect of inhibiting amyloid beta production, especially an effect of inhibiting BACE1, and which is useful as a therapeutic or prophylactic agent for diseases induced by production, secretion and/or deposition of amyloid beta proteins. A compound of the formula (I):wherein X is -C(R3a)(R3b)-, -C(R3a)(R3b)-C(R3c)(R3d)- or -C(R3a)=C(R3c)-, R1 is substituted or unsubstituted alkyl or the like,R2a, R2b, R3a, R3b, R3c and R3d are each independently hydrogen, halogen or the like, R4 is hydrogen or halogen,Ring B is substituted or unsubstituted carbocycle or a substituted or unsubstituted heterocycle, or a pharmaceutically acceptable salt thereof.
Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy
作者:Michael H. Wang、David Barsoum、C. Benjamin Schwamb、Daniel T. Cohen、Brian C. Goess、Matthias Riedrich、Audrey Chan、Brooks E. Maki、Rama K. Mishra、Karl A. Scheidt
DOI:10.1021/acs.joc.7b00334
日期:2017.5.5
only feasible, but also adaptable to a kinetic resolution of secondaryalcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach
Chiral phosphorate anions are shown to be highly enantioselective templates for proton-transfer catalysis. A salt generated in situ from a bridgehead amine and a BINOL-derived chiral phosphoric acid serves as an effective proton-shuttle that exhibits remarkable enantioselectivity in a bioinspired, triple co-operative catalysis involving an achiral NHC. Thioesters with a β-chiral center can be prepared
Enantioselective β-Protonation of Enals via a Shuttling Strategy
作者:Jiean Chen、Pengfei Yuan、Leming Wang、Yong Huang
DOI:10.1021/jacs.7b02889
日期:2017.5.24
Remote asymmetric protonation is a longstanding challenge due to the small size of protons. Reactions involving electron-deficient olefins pose a further difficulty due to the electrophilic nature of these substrates. We report a shuttling system that delivers a proton in a highly enantioselective manner to the β-carbon of enals using a chiral N-heterocyclic carbene (NHC) catalyst. Choices of a Brønsted