2893-05-2Relevant articles and documents
Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Zhang, Dong,Zhang, Fengcai
supporting information, p. 6961 - 6966 (2021/09/11)
An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
Ketone Synthesis from Benzyldiboronates and Esters: Leveraging α-Boryl Carbanions for Carbon-Carbon Bond Formation
Lee, Boran,Chirik, Paul J.
supporting information, p. 2429 - 2437 (2020/03/03)
An alkoxide-promoted method for the synthesis of ketones from readily available esters and benzyldiboronates is described. The synthetic method is compatible with a host of sterically differentiated alkyl groups, alkenes, acidic protons α to carbonyl groups, tertiary amides, and aryl rings having common organic functional groups. With esters bearing α-stereocenters, high enantiomeric excess was maintained during ketone formation, establishing minimal competing racemization by deprotonation. Monitoring the reaction between benzyldiboronate and LiOtBu in THF at 23 °C allowed for the identification of products arising from deborylation to form an α-boryl carbanion, deprotonation, and alkoxide addition to form an "-ate" complex. Addition of 4-trifluoromethylbenzoate to this mixture established the α-boryl carbanion as the intermediate responsible for C-C bond formation and ultimately ketone synthesis. Elucidation of the role of this intermediate leveraged additional bond-forming chemistry and enabled the one-pot synthesis of ketones with α-halogen atoms and quaternary centers with four-different carbon substituents.
Synthesis of α-Borylated Ketones by Regioselective Wacker Oxidation of Alkenylboronates
Corless, Victoria B.,Holownia, Aleksandra,Foy, Hayden,Mendoza-Sanchez, Rodrigo,Adachi, Shinya,Dudding, Travis,Yudin, Andrei K.
supporting information, p. 5300 - 5303 (2018/09/12)
As part of a program aimed at metal-catalyzed oxidative transformations of molecules with carbon-metalloid bonds, the synthesis of α-borylated ketones is reported via regioselective TBHP-mediated Wacker-type oxidation of N-methyliminodiacetic acid (MIDA)-protected alkenylboronates. The observed regioselectivity correlates with the hemilabile nature of the B-N dative bond in the MIDA boronate functional group, which allows boron to guide selectivity through a neighboring group effect.
AuCl3/AgSbF6-catalyzed rapid epoxide to carbonyl rearrangement
Gudla, Vanajakshi,Balamurugan, Rengarajan
, p. 5243 - 5247 (2012/11/07)
An efficient epoxide to carbonyl rearrangement using catalytic AuCl 3/AgSbF6 has been presented. The reactions are fast and high yielding. β-Hydrogen migration takes place exclusively when hydrogen and methyl or substituted methyl groups are present at β-carbon of epoxide. When phenyl/acetyl/benzoyl and hydrogen are available at same carbon atom, migration of the former is preferred over the latter.
β-Keto esters derived from 2-(trimethylsilyl)ethanol: An orthogonal protective group for β-keto esters
Knobloch, Eva,Brueckner, Reinhard
scheme or table, p. 2229 - 2246 (2009/04/08)
β-Keto esters derived from 2-(trimethylsilyl)ethanol undergo cleavage and decarboxylation when treated with 0.75 equivalents of tetrabutylammonium fluoride trihydrate in tetrahydrofuran at 50°C, while β-keto esters derived from methanol, tert-butyl alcohol, allyl alcohol, or benzyl alcohol stay intact. Conversely, methyl-, tert-butyl-, allyl-, or benzyl β-keto esters can be cleaved and decarboxylated without the 2-(trimethylsilyl)ethyl β-keto esters being affected. Similarly, mixed bis(β-keto esters) derived from 2-(trimethylsilyl)ethanol and methanol, tert-butyl alcohol, allyl alcohol, or benzyl alcohol can be defunctionalized chemoselectively under the same reaction conditions. Georg Thieme Verlag Stuttgart.
TiCl4-catalyzed indirect anti-Markovnikov hydration of alkynes: Application to the synthesis of benzo[b]furans
Ackermann, Lutz,Kaspar, Ludwig T.
, p. 6149 - 6153 (2008/02/09)
(Chemical Equation Presented) An efficient methodology for the indirect anti-Markovnikov hydration of unsymmetrically substituted terminal and internal alkynes is based on TiCl4-catalyzed hydroamination reactions. Its application to ortho-alkynylhaloarenes, followed by a copper-catalyzed O-arylation, provides flexible access to substituted benzo[b]furans.
Highly efficient Pd-catalyzed carbonylative cross-coupling reactions with tetraorganoindates
Lee, Sung Wook,Lee, Kooyeon,Seomoon, Dong,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Lee, Phil Ho
, p. 4852 - 4855 (2007/10/03)
Tetraorganoindates, which were prepared easily from the reaction of 1 equiv of InCl3 with 4 equiv of organometallics, could be employed as effective nucleophilic cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method gave unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under a carbon monoxide atmosphere in THF at 60 °C.
Samarium(II)-mediated reactions of γ,δ-unsaturated ketones. Cyclization and fragmentation processes
Hutton, Thomas K.,Muir, Kenneth,Procter, David J.
, p. 2345 - 2347 (2007/10/03)
(Matrix Presented) On treatment with samarium(II) iodide, γ,δ-unsaturated ketones undergo very different processes depending upon the nature of the reaction conditions. Employing samarium(II) iodide and MeOH, functionalized syn-cyclopentanol products are obtained stereoselectively. Mechanistic studies suggest that this cyclization occurs via a sequential reduction/intramolecular aldol reaction. With samarium(II) iodide and HMPA, products of a 4-exo-trig cyclization and of an interesting fragmentation reaction are observed.
A facile and highly efficient route to a traceless pi-arene chromium linker. Applications to synthetic and combinatorial chemistry.
Rigby,Kondratenko
, p. 3683 - 3686 (2007/10/03)
[reaction--see text] A simple and efficient method for the attachment of functionalized arene chromium carbonyls to a polymeric support has been developed. A highly efficient solid-phase synthesis of tertiary alcohols and esters was performed in a traceless manner using this strategy. The linker-fabrication protocol permits simultaneous immobilization of various substrates on the solid support.
A simple method for the synthesis of substituted benzylic ketones: Homologation of aldehydes via the in situ generation of aryldiazomethanes from aromatic aldehydes
Angle, Steven R.,Neitzel, Martin L.
, p. 6458 - 6461 (2007/10/03)
A general method for the homologation of aldehydes to benzylic ketones has been developed. Aryldiazomethanes were generated in situ in the presence of an aldehyde by simply heating the tosylhydrazones of aromatic aldehydes in the presence of a stoichiometric amount of base in polar protic solvents. The resulting polar protic solvent promoted homologation afforded benzylic ketones in moderate to excellent yields with a variety of aldehydes. Isolation of the tosylhydrazones was not necessary; they could be prepared in ethanol and carried through the sequence without isolation. This methodology allows easy access to a wide variety of substituted aryldiazomethanes that would be difficult, or even impossible, to prepare via conventional methods and circumvents the toxicity and stability problems associated with the isolation and/or handling solutions of aryldiazomethanes.
