Highly enantioselective Darzens-type epoxidation of diazoesters with glyoxal derivatives was accomplished using a chiral boron–Lewis acid catalyst, which facilitated asymmetric synthesis of trisubstituted α,β-epoxy esters. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction proceeded in high yield (up to 99 %) with excellent enantio- and diastereoselectivity (up to >99 % ee and
Rhodium-catalyzed enantioselective cyclopropanation of electron-deficient alkenes
作者:Hengbin Wang、David M. Guptill、Adrian Varela-Alvarez、Djamaladdin G. Musaev、Huw M. L. Davies
DOI:10.1039/c3sc50425e
日期:——
The rhodium-catalyzed reaction of electron-deficient alkenes with substituted aryldiazoacetates and vinyldiazoacetates results in highly stereoselective cyclopropanations. With adamantylglycine derived catalyst Rh2(S-TCPTAD)4, high asymmetric induction (up to 98% ee) can be obtained with a range of substrates. Computational studies suggest that the reaction is facilitated by weak interaction between
Cu(I)/Chiral Bisoxazoline-Catalyzed Enantioselective Sommelet–Hauser Rearrangement of Sulfonium Ylides
作者:Shu-Sen Li、Jianbo Wang
DOI:10.1021/acs.joc.0c01590
日期:2020.10.2
asymmetric thia-Sommelet–Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality
Catalytic Enantioselective Cyclopropanation of α-Fluoroacrylates: An Experimental and Theoretical Study
作者:Amandine Pons、Vincent Tognetti、Laurent Joubert、Thomas Poisson、Xavier Pannecoucke、André B. Charette、Philippe Jubault
DOI:10.1021/acscatal.9b00354
日期:2019.3.1
Herein, we report the catalytic asymmetric synthesis of functionalized fluorocyclopropanes from α-fluoroacrylates. The method using Rh2((S)-TCPTTL)4 allowed the difficult reaction of an in situ-generated electrophilic Rh-carbene with an electron-poor α-fluoroacrylate. The desired fluorocyclopropanes were obtained in good yields, excellent dr and ee. Finally, the mechanism of this transformation was
PIPERIDINE DERIVATIVES FOR TREATMENT OF ALZHEIMER'S DISEASE
申请人:Madin Andrew
公开号:US20090186919A1
公开(公告)日:2009-07-23
Compounds of formula (I) modulate the activity of gamma secretase and hence find use in treatment or prevention of Alzheimer's disease and related conditions.