Spirolactones from Dirhodium(II)-Catalyzed Diazo Decomposition with Regioselective Carbon-Hydrogen Insertion
摘要:
Dirhodium(II) caprolactamate, Rh-2(cap)(4), catalyzes diazo decomposition of cycloalkylmethyl diazoacetates which form spirolactones in moderate to high yield by insertion into a tertiary carbon-hydrogen bond. Similar results are obtained with diazoacetates derived from tetrahydropyran-2-methanol and tetrahydrofurfuryl alcohol but not from cyclopropylmethanol. With tetrahydrofuran-3-ylmethyl diazoacetate, Rh-2(cap)(4) catalysis promotes delta-lactone formation via insertion into the oxygen-activated secondary C-H bond instead of gamma-lactone formation by carbene insertion into the unactivated tertiary C-H bond. However, when both 1,5- and 1,6-positions are activated for insertion by adjacent oxygen atoms, as in (2,2-dimethyl-1,3-dioxolan-4-yl)methyl diazoacetate, five-membered ring formation occurs exclusively in Rh-2(cap)(4)-catalyzed reactions, whereas use of dirhodium(II) acetate leads to both insertion products.
Radical Cation Cyclopropanations via Chromium Photooxidative Catalysis
作者:Francisco J. Sarabia、Eric M. Ferreira
DOI:10.1021/acs.orglett.7b01095
日期:2017.6.2
The chromium photocatalyzed cyclopropanation of diazo reagents with electron-rich alkenes is described. The transformation occurs under mild conditions and features specific distinctions from traditional diazo-based cyclopropanations (e.g., avoiding β-hydride elimination, chemoselectivity considerations, etc.). The reaction appears to work most effectively using chromium catalysis, and a number of
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.
A highly enantioselective 1,3-dipolarcycloaddition of α-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N, N’-dioxide complex as the catalyst. This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes (up to 97% yield, 98% ee with >95:5 dr). Moreover, enantioenriched 2-pyrazoline-based
Two Distinct Ag(I)- and Au(I)-Catalyzed Olefinations between α-Diazo Esters and <i>N</i>-Boc-Derived Imines
作者:Rahul Dadabhau Kardile、Rai-Shung Liu
DOI:10.1021/acs.orglett.9b02343
日期:2019.8.16
Metal-catalyzed reactions between α-diazo esters and imines were well-known to yield aziridine derivatives exclusively. This work reports two newolefinationreactions between N-Boc-derived (Boc = tert-Butyloxycarbonyl) imines and α-diazo esters with Ag(I) and Au(I) catalysts, respectively. Our mechanistic studies reveal that these newolefinations involve an initial attack of diazo esters on metal/imine
[EN] NOVEL MACROCYLES AND METHODS FOR THEIR PRODUCTION<br/>[FR] NOUVEAUX MACROCYLES ET LEURS PROCÉDÉS DE PRODUCTION
申请人:BIOTICA TECH LTD
公开号:WO2011045593A1
公开(公告)日:2011-04-21
There are provided compounds of formula (I) or a pharmaceutically acceptable salt thereof: wherein the variables R1-R3 are as described in the description, said compounds being useful as anti-inflammatory agents with reduced systemic effects.