71074-06-1Relevant academic research and scientific papers
Photocatalyzed Diastereoselective Isomerization of Cinnamyl Chlorides to Cyclopropanes
Dykstra, Ryan,Gutierrez, Osvaldo,Martin, Robert T.,Tambar, Uttam K.,Troian-Gautier, Ludovic,Xu, Bin
supporting information, p. 6206 - 6215 (2020/04/27)
Endergonic isomerizations are thermodynamically unfavored processes that are difficult to realize under thermal conditions. We report a photocatalytic and diastereoselective isomerization of acyclic cinnamyl chlorides to strained cyclopropanes. Quantum mechanical calculations (uM06-2X and DLPNO), including TD-DFT calculations, and experimental studies provide evidence for the energy transfer from an iridium photocatalyst to the allylic chloride substrate followed by C-Cl homolytic cleavage. Subsequent Cla￠ radical migration forms a localized triplet 1,3-diradical intermediate that, after intersystem crossing, undergoes ring-closing to form the desired product. The mild reaction conditions are compatible with a broad range of functional groups to generate chlorocyclopropanes in high yields and diastereoselectivities. A more efficient process is developed by addition of a catalytic amount of a nickel complex, and we propose a novel role for this cocatalyst to recycle an allyl chloride byproduct generated in the course of the reaction. The reaction is also shown to be stereoconvergent, as an E/Z mixture of cinnamyl chlorides furnish the anti-chlorocyclopropane product in high diastereoselectivity. We anticipate that the use of a visible light activated photocatalyst to transform substrates in combination with a transition metal catalyst to recycle byproducts back into the catalytic cycle will provide unique opportunities for the discovery of new reactivity.
Ruthenium-Catalyzed Asymmetric Allylic Alkylation of Isatins
Kalnmals, Christopher A.,Parkin, Sean,Ramakrishnan, Divya,Ryan, Michael C.,Smaha, Rebecca W.,Trost, Barry M.
, (2020/04/02)
A new ruthenium-based catalytic system for branched-selective asymmetric allylic alkylation is disclosed and applied to the synthesis of chiral isatin derivatives. The catalyst, which is generated in situ from commercially available CpRu(MeCN)3PF6 and a BINOL-derived phosphoramidite, is both highly active (TON up to 180) and insensitive to air and moisture. Additionally, the N-alkylated isatins accessible using this methodology are versatile building blocks that are readily transformed into chiral analogs of achiral drug molecules.
BENZO[B]FURANS AS BROMODOMAIN INHIBITORS
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, (2017/11/06)
The present invention relates to compounds of formula (I) and salts thereof, pharmaceutical compositions containing such compounds and to their use in therapy.
Palladium-catalyzed oxidative arylacetoxylation of alkenes: Synthesis of indole and indoline derivatives
Karnakanti, Shuklachary,Zang, Zhong-Lin,Zhao, Sheng,Shao, Pan-Lin,Hu, Ping,He, Yun
supporting information, p. 11205 - 11208 (2017/10/17)
A method for the oxidative arylacetoxylation of alkenes has been developed to synthesize indole and indoline derivatives from readily accessible substrates. The cinnamyl tethered anilines with picolinamide as a directing group provided 3-substituted indoles via intramolecular oxidative arylacetoxylation, and the 2-methyl substituted cinnamyl anilines furnished indoline derivatives with 3-position quaternary stereocenters in good to excellent yields via sequential intramolecular oxidative arylacetoxylation, hydrolysis and oxidation steps.
Divergent Gold(I)-Catalyzed Skeletal Rearrangements of 1,7-Enynes
Mei?, Rebecca,Kumar, Kamal,Waldmann, Herbert
, p. 13526 - 13530 (2015/09/22)
The gold(I) complex catalyzed cycloisomerization and skeletal rearrangement of 1,n-enynes (n=5-7) is a powerful methodology for the efficient synthesis of complex molecular architectures. In contrast to 1,6-enynes, readily accessible homologous 1,7-enynes are largely unexplored in such transformations. Here, the divergent skeletal rearrangement of all-carbon 1,7-enynes by catalysis with a cationic gold(I) complex is reported. Depending on electronic and steric factors, differently substituted 1,7-enynes react via different carbocations formed from a common gold carbene intermediate to yield on the one hand novel exocyclic allenes and on the other hand tricyclic hexahydro-anthracenes through a novel dehydrogenative Diels-Alder reaction. Two birds with a gold-stone! Divergent gold(I) catalysis unraveled a novel cycloisomerization and a dehydrogenative Diels-Alder reaction of 1,7-enynes.
Enantioselective copper-catalysed allylic alkylation of cinnamyl chlorides by Grignard reagents using chiral phosphine-phosphite ligands
Loelsberg, Wibke,Ye, Shute,Schmalz, Hans-Guenther
supporting information; experimental part, p. 2023 - 2031 (2010/10/21)
The copper(I)-catalysed SN2'-type allylic substitution of E-3-aryl-allyl chlorides (cinnamyl chlorides) using Grignard reagents represents a powerful method for the synthesis of compounds carrying a benzylic stereocentre. By screening a small library of modular chiral phosphine-phosphite ligands a new copper(I)-based catalyst system was identified which allows the performance of such reactions with exceptional high degrees of regio- and enantioselectivity. Best results were obtained using TADDOLderived ligands (3 mol%), copper(I) bromide?dimethyl sulfide (CuBr?SMe2) (2.5 mol%) and methyl tert-butyl ether (MTBE) as a solvent. Various (1- alkyl-allyl)benzene derivatives were prepared with up to 99% ee (GC) in isolated yields of up to 99%. In most cases the product contained less than 3% of the linear regioisomer (except for ortho-substituted substrates). Both electron-rich and electron-deficient cinnamyl chlorides were successfully employed. The absolute configuration of the products was assigned by comparison of experimental and calculated CD spectra. The substrates were prepared from the corresponding alcohols by reaction with thionyl chloride. Initially formed mixtures of regioisomeric allylic chlorides were homogenised by treatment with CuBr?SMe2 (2.5 mol%) in the presence of triphenyl phosphine (PPh3) (3 mol%) in MTBE at low temperature to give the pure linear isomers. In reactions with methylmagnesium bromide (MeMgBr) an ortho-diphenylphosphanyl-arylphosphite ligand with an additional phenyl substituent in ortho'-position at the aryl backbone proved to be superior. In contrast, best results were obtained in the case of higher alkyl Grignard reagents (such as ethyl-, n-butyl-, isopropyl-, and 3-butenylmagnesium bromides) with a related ligand carrying an isopropyl substituent in ortho'-position. The method was tested on a multimmol scale and is suited for application in natural product synthesis.
Expedient access to branched allylic silanes by copper-catalysed allylic substitution of linear allylic halides
Vyas, Devendra J.,Oestreich, Martin
supporting information; experimental part, p. 568 - 570 (2010/05/01)
An unprecedented copper-catalysed allylic transposition enables the regioselective synthesis of branched allylic silanes from linear allylic halides through direct C-Si bond formation.
Allylic and allenic halide synthesis via NbCl5- and NbBr 5-mediated alkoxide rearrangements
Ravikumar,Yao, Lihua,Fleming, Fraser F.
supporting information; experimental part, p. 7294 - 7299 (2010/01/16)
(Chemical Equation Presented) Addition of NbCl5 or NbBr 5 to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metallahalo-[3,3] rearrangement, although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure (E)-allylic or -allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. 2009 American Chemical Society.
One-pot formation of allylic chlorides from carbonyl derivatives
Fuchter, Matthew J.,Levy, Jean-Noel
supporting information; experimental part, p. 4919 - 4922 (2009/05/31)
(Chemical Equation Presented) An efficient, one-pot method for the conversion of carbonyl electrophiles to allylic chlorides has been developed, by activating magnesium alkoxides in situ using TiCl4.
Tandem oxidation/halogenation of aryl allylic alcohols under Moffatt-Swern conditions
Yin, Jiandong,Gallis, Christina E.,Chisholm, John D.
, p. 7054 - 7057 (2008/02/11)
(Chemical Equation Presented) Aryl allylic alcohols are converted to halogenated unsaturated ketones or allylic halides using excess Moffatt-Swern reagent. Electron-poor aromatic rings favor formation of the halogenated ketone, while electron-donating substituents in the ortho or para positions favor formation of the allylic halide. The oxidation/halogenation reaction performs well with both oxalyl chloride and oxalyl bromide, providing access to the corresponding chlorides or bromides, respectively.
