Generation of Cycloalkylidene Carbenes via Exo-Type Cyclization of Alkynyllithiums Bearing Remote Leaving Group
摘要:
The reaction of 5-hexynyl tosylate (3a) with alkynyllithium (RC=CLi; R Ph, TMS) gives enynes 5 and 6. The reaction proceeds through a mechanism involving a novel exo-type cyclization of 6-lithiod-hexynyl tosylate to form cyclopentylidene carbene. Enyne 6 is produced by the addition of RC=CLi to the carbene, whereas rearrangement of the carbene to cyclohexyne followed by carbolithiation with RC=CLi gives enyne 5. The formation of cyclopentylidene carbene and cyclohexyne as intermediates is clearly demonstrated by trapping experiments with cyclohexene land triethylsilane) and with 1,3-diphenylisobenzofuran, respectively. Alkynyllithiums derived from 3-butynyl and 6-heptynyl p-fluorobenzenesulfonates (19a,b) undergo a similar exo-type cyclization to give cyclopropylidene and cyclohexylidene carbenes, respectively.
Electrophotocatalytic Acetoxyhydroxylation of Aryl Olefins
作者:He Huang、Tristan H. Lambert
DOI:10.1021/jacs.1c01967
日期:2021.5.19
conditions is described. The procedure uses a trisaminocyclopropenium (TAC) ion catalyst with visible light irradiation under a controlled electrochemical potential to convert aryl olefins to the corresponding glycol monoesters with high chemo- and diastereoselectivity. This reaction can be performed in batch or in flow, enabling multigram synthesis of the monoester products.
Waste-Free Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles and Synthesis of Naphthopyrans
作者:J. McCubbin、Costa Nassar、Oleg Krokhin
DOI:10.1055/s-0030-1260146
日期:2011.10
pyrroles, as well as methoxy-substituted benzenes and naphthalenes. Reaction with 2-naphthol affords substituted naphthopyrans as products. Preliminary evidence suggests a Friedel-Crafts-like substitution mechanism, which occurs via an in situ generated carbocation. organocatalysis - boronic acids - propargylic alcohols - Friedel-Craftsreaction
Generation, optimization and characterization of novel anti-prion compounds
作者:Andrea Altieri、Evgeny A. Spiridonov、Semen I. Sivtzev、Daisuke Ishibashi、Silvia Biggi、Noriyuki Nishida、Emiliano Biasini、Alexander V. Kurkin
DOI:10.1016/j.bmc.2020.115717
日期:2020.11
the chemical space exploration around the anti-prion compound BB 0300674 in order to gain an understanding of its Structure Activity Relationships (SARs). A series of 43 novel analogues, based on four different chemical clusters, were synthetized and tested against PrPSc and mutant PrP toxicity assays. From this biological screening, two compounds (59 and 65) emerged with a 10-fold improvement in anti-prion
aziridines with a platinum catalyst in aqueous media are described. Furans having a variety of substituents were conveniently synthesized by the platinum-catalyzed reaction of propargylic oxiranes. The reaction in the presence of N-iodosuccinimide afforded the 3-iodo-substituted furan, which was further functionalized to tetrasubstituted furans with high efficiency. Propargylic aziridines were also reacted