- Halogen-Bridged Methylnaphthyl Palladium Dimers as Versatile Catalyst Precursors in Coupling Reactions
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Halogen-bridged methylnaphthyl (MeNAP) palladium dimers are presented as multipurpose Pd-precursors, ideally suited for catalytic method development and preparative organic synthesis. By simply mixing with phosphine or carbene ligands, they are in situ converted into well-defined monoligated complexes. Their catalytic performance was benchmarked against state-of-the-art systems in challenging Buchwald–Hartwig, Heck, Suzuki and Negishi couplings, and ketone arylations. Their use enabled record-setting activities, beyond those achievable by optimization of the ligand alone. The MeNAP catalysts permit syntheses of tetra-ortho-substituted arenes and bulky anilines in near-quantitative yields at room temperature, allow mono-arylations of small ketones, and enable so far elusive cross-couplings of secondary alkyl boronic acids with aryl chlorides.
- Doppiu, Angelino,Goo?en, Lukas J.,Hu, Zhiyong,Pirkl, Nico,Sivendran, Nardana
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supporting information
p. 25151 - 25160
(2021/10/19)
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- Cooperative NHC/Photoredox Catalyzed Ring-Opening of Aryl Cyclopropanes to 1-Aroyloxylated-3-Acylated Alkanes
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Cyclopropanes are an important class of building blocks in organic synthesis. Herein, a ring-opening/arylcarboxylation/acylation cascade reaction for the 1,3-difunctionalization of aryl cyclopropanes enabled by cooperative NHC and organophotoredox catalysis is reported. The cascade works on monosubstituted cyclopropanes that are in contrast to the heavily investigated donor–acceptor cyclopropanes more challenging to be difunctionalized. The key step is a radical/radical cross coupling of a benzylic radical generated in the photoredox catalysis cycle with a ketyl radical from the NHC catalysis cycle. The transformation features metal-free reaction conditions and tolerates a diverse range of functionalities.
- Daniliuc, Constantin G.,Studer, Armido,Zuo, Zhijun
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supporting information
p. 25252 - 25257
(2021/10/29)
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- Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations
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Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
- Svec, Riley L.,Hergenrother, Paul J.
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supporting information
p. 1857 - 1862
(2019/12/27)
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- Redox-Neutral Photocatalytic Cyclopropanation via Radical/Polar Crossover
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A benchtop stable, bifunctional reagent for the redox-neutral cyclopropanation of olefins has been developed. Triethylammonium bis(catecholato)iodomethylsilicate can be readily prepared on multigram scale. Using this reagent in combination with an organic photocatalyst and visible light, cyclopropanation of an array of olefins, including trifluoromethyl- and pinacolatoboryl-substituted alkenes, can be accomplished in a matter of hours. The reaction is highly tolerant of traditionally reactive functional groups (carboxylic acids, basic heterocycles, alkyl halides, etc.) and permits the chemoselective cyclopropanation of polyolefinated compounds. Mechanistic interrogation revealed that the reaction proceeds via a rapid anionic 3-exo-tet ring closure, a pathway consistent with experimental and computational data.
- Phelan, James P.,Lang, Simon B.,Compton, Jordan S.,Kelly, Christopher B.,Dykstra, Ryan,Gutierrez, Osvaldo,Molander, Gary A.
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supporting information
p. 8037 - 8047
(2018/07/03)
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- Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated Cyclopropanes Using a Hypervalent Iodine Reagent
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A facile and effective system has been developed for the regio- and chemoselective ring-opening/electrophilic functionalization of cyclopropanes through C?C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p-toluenesulfonamide. The p-toluenesulfonamide-promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3-diol products in good yields and regioselectivity.
- Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 3782 - 3786
(2018/03/13)
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- A Stereoconvergent Cyclopropanation Reaction of Styrenes
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The first stereoconvergent cyclopropanation reaction by means of photoredox catalysis using diiodomethane as the methylene source is described. This transformation exhibits broad functional group tolerance and it is characterized by an excellent stereocontrol en route to trans-cyclopropanes regardless of whether E- or Z-styrene substrates were utilized.
- del Hoyo, Ana M.,Herraiz, Ana G.,Suero, Marcos G.
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supporting information
p. 1610 - 1613
(2017/02/05)
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- Light-Mediated Reductive Debromination of Unactivated Alkyl and Aryl Bromides
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Cleavage of carbon-halogen bonds via either single-electron reduction or atom transfer is a powerful transformation in the construction of complex molecules. In particular, mild, selective hydrodehalogenations provide an excellent follow-up to the application of halogen atoms as directing groups or the utilization of atom transfer radical addition (ATRA) chemistry for the production of hydrocarbons. Here we combine the mechanistic properties of photoredox catalysis and silane-mediated atom transfer chemistry to accomplish the hydrodebromination of carbon-bromide bonds. The resulting method is performed under visible light irradiation in an open vessel and is capable of the efficient reduction of a variety of unactivated alkyl and aryl substrates.
- Devery, James J.,Nguyen, John D.,Dai, Chunhui,Stephenson, Corey R. J.
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p. 5962 - 5967
(2016/09/09)
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- Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes
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Dinuclear Ni complexes supported by naphthyridine-diimine (NDI) ligands catalyze the reductive cyclopropanation of alkenes with CH2Cl2 as the methylene source. The use of mild terminal reductants (Zn or Et2Zn) confers significant functional-group tolerance, and the catalyst accommodates structurally and electronically diverse alkenes. Mononickel catalysts bearing related N chelates afford comparatively low cyclopropane yields (≤20 %). These results constitute an entry into catalytic carbene transformations from oxidized methylene precursors.
- Zhou, You-Yun,Uyeda, Christopher
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supporting information
p. 3171 - 3175
(2016/03/12)
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- Cyclopropanation of styrenes and stilbenes using lithiomethyl trimethylammonium triflate as methylene donor
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Lithiomethyl trimethylammonium triflate, prepared from tetramethylammonium triflate, cyclopropanates several styrenes and stilbenes with electron-donating and selected electron-withdrawing substituents efficiently. Kinetic data support a stepwise nucleophilic addition-ring closure mechanism for this methylenation. This journal is the Partner Organisations 2014.
- Sarria Toro, Juan M.,Den Hartog, Tim,Chen, Peter
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supporting information
p. 10608 - 10610
(2014/10/15)
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- Synergistic effect of additives on cyclopropanation of olefins
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An efficient cyclopropanation of olefins with Zn(CH2I) 2, a catalytic amount of CCl3CO2H, and 1,2-dimethoxyethane at room temperature is described. A wide variety of olefins, including acid-sensitive substrates,
- Cheng, Donghao,Huang, Deshun,Shi, Yian
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supporting information
p. 5588 - 5591
(2013/09/12)
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- Synthesis and reactivity of solid-supported organotrifluoroborates in suzuki cross-coupling
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Solid-supported organotrifluoroborates were prepared in high yields by ion exchange with Amberlyst resins. The reactivity of solid supported aryltrifluoroborates was evaluated in Suzuki-Miyaura couplings with numerous aryl bromide partners. Electron-rich
- Colombel, Virginie,Presset, Marc,Oehlrich, Daniel,Rombouts, Frederik,Molander, Gary A.
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supporting information; experimental part
p. 1680 - 1683
(2012/06/30)
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- Diels-Alder reactions for the construction of cyclopropylarenes
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The straightforward synthesis of new bicyclopropyl-substituted alkynes and 1,3-dienes and their application in cobalt-catalyzed Diels-Alder reactions are described. The cycloaddition processes generated the desired bicyclopropyl-substituted arene derivatives in moderate to good yields, depending on the steric congestion of the reaction partners. The regioselectivity of the cycloaddition was controlled by the ligand coordinated to the cobalt center. The cyclopropyl moiety remained unchanged over the course of the Diels-Alder reaction, indicating that no radical type intermediates were formed. Only in a single case did the DDQ oxidation of the primarily formed dihydroaromatic product lead to ring opening of a cyclopropyl subunit. In all of the other cases, cyclopropyl-modified arenes with various functionalities were obtained. Copyright
- Arndt, Marion,Hilt, Gerhard,Khlebnikov, Alexander F.,Kozhushkov, Sergei I.,De Meijere, Armin
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experimental part
p. 3112 - 3121
(2012/07/14)
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- Iron-catalyzed cyclopropanation in 6 M KOH with in situ generation of diazomethane
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Diazomethane is a common and versatile reagent in organic synthesis whose broader use is generally impeded by its explosiveness and toxicity. Here we report that a simple iron porphyrin complex catalyzes the cyclopropanation of styrenes, enynes, and dienes under the demanding conditions [aqueous 6 molar potassium hydroxide (KOH) solution, open to air] necessary for the in situ generation of diazomethane from a water-soluble diazald derivative. A biphasic reaction medium arising from the immiscibility of the olefin substrates with water appears essential to the overall efficiency of the process. The work we describe highlights an approach to catalysis with untoward reactive intermediates, in which the conditions for their generation under operationally safe regimes dictate catalyst selection.
- Morandi, Bill,Carreira, Erick M.
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scheme or table
p. 1471 - 1474
(2012/07/13)
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- Cross-coupling of mesylated phenol derivatives with potassium cyclopropyltrifluoroborate
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C-O activation of mesylates by a palladium catalyst and subsequent cross-coupling with potassium cyclopropyltrifluoroborate have been achieved with high yield. Both electron-enriched and electron-deficient aryl mesylates are suitable electrophilic partners for the Suzuki-Miyaura reaction. The scope was successfully extended to heteroaryl mesylates with yields up to 94%. (Figure presented)
- Molander, Gary A.,Beaumard, Floriane,Niethamer, Terren K.
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experimental part
p. 8126 - 8130
(2011/11/12)
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- Palladium-catalyzed cross-coupling of cyclopropylmagnesium bromide with aryl bromides mediated by zinc halide additives
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The key Pd-catalyzed cross-coupling of aryl bromides or triflates and cyclopropylmagnesium bromide in the presence of substoichiometric amounts of zinc bromide produces cyclopropyl arenes in good to excellent yields. The cross-coupling of other alkyl, cyc
- Shu, Chutian,Sidhu, Kanwar,Zhang, Li,Wang, Xiao-Jun,Krishnamurthy, Dhileepkumar,Senanayake, Chris H.
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experimental part
p. 6677 - 6680
(2010/12/19)
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- Dual role of silanol groups in cyclopropanation and Hiyama-Denmark cross-coupling reactions
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"Chemical Equation Presented" Di-tert-butoxy(alkenyl)silanols serve as substrates in the Simmons-Smith cyclopropanation reaction furnishing the corresponding di-tertbutoxy(cyclopropyl)silanols, which may be Included In a Hiyama-Denmark cross-coupling reaction. The silanol group bears two distinct roles as it provides a directing group during the cyclopropanation and mediates the transmetalation event in the cross-coupling. The nature of the ligands on the silicon atom had a profound effect on reactivity in the cross-coupling, whereby substituting the alkoxide groups for fluorides allowed for efficient cross-coupling.
- Beaulieu, Louis-Philippe B.,Delvos, Lukas B.,Charette, Andre B.
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supporting information; experimental part
p. 1348 - 1351
(2010/06/17)
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- Air-stable secondary phosphine oxide or chloride (Pre)ligands for cross-couplings of unactivated alkyl chlorides
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In situ generated and crystallographically well-defined, isolated palladium complexes derived from seven novel air-stable secondary phosphine oxides or chlorides enabled challenging Kumada-Corriu cross-couplings of unactivated alkyl chlorides bearing β-hy
- Ackermann, Lutz,Kapdi, Anant R.,Schulzke, Carola
-
supporting information; experimental part
p. 2298 - 2301
(2010/08/05)
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- General and user-friendly protocol for the synthesis of functionalized aryl- and heteroaryl-cyclopropanes by Negishi cross-coupling reactions
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The introduction of an unsubstituted cyclopropyl moiety was efficiently accomplished via Negishi cross-coupling of cyclopropylzinc bromide with functionalized aryl halides in high yields and fast reaction rates. The stability and the efficient one-step sy
- Coleridge, Brian M.,Bello, Charles S.,Leitner, Andreas
-
experimental part
p. 4475 - 4477
(2009/12/03)
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- Cross-coupling of cyclopropyl- and cyclobutyltrifluoroborates with aryl and heteroaryl chlorides
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(Chemical Equation Presented) Suitable conditions were found for the Suzuki-Miyaura cross-coupling reaction of potassium cyclopropyl-and cyclobutyltrifluoroborates with aryl chlorides. Both of these secondary alkyl trifluoroborates coupled in moderate to excellent yield with electron-rich, electron-poor, and hindered aryl chlorides to give a variety of substituted aryl cyclopropanes and cyclobutanes.
- Molander, Gary A.,Gormisky, Paul E.
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p. 7481 - 7485
(2008/12/23)
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- Suzuki coupling of cyclopropylboronic acid with aryl halides catalyzed by a palladium-tetraphosphine complex
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The tetraphosphine all-cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)- cyclopentane (Tedicyp) in combination with [Pd(C3H 5)Cl]2 affords a very efficient catalyst for the coupling of cyclopropylboronic acid with aryl bromides and aryl chlorides. Higher reactions rates were observed with aryl bromides than with aryl chlorides; however, even in the presence of 1-0.4% of catalyst, a few aryl chlorides gave the coupling products in good yields. A wide variety of substituents such as alkyl, methoxy, trifluoromethyl, acetyl, benzoyl, formyl, carboxylate, nitro, and nitrile on the aryl halides are tolerated. The coupling reaction of sterically very congested aryl bromides such as bromomesitylene or 2,4,6-triisopropylbromobenzene also proceeds in good yields. Copyright Taylor & Francis LLC.
- Lemhadri, Mhamed,Doucet, Henri,Santelli, Maurice
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p. 121 - 128
(2007/10/03)
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- PPAR MODULATORS
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The present invention is directed to a compound of formula I, or a pharmaceutically acceptable salt, solvate, hydrate or stereoisomer thereof, which is useful in treating or preventing disorders mediated by a peroxisome proliferator activated receptor (PPAR) such as syndrome X, type II diabetes, hyperglycemia, hyperlipidemia, obesity, coagaulopathy, hypertension, arteriosclerosis, and other disorders related to syndrome X and cardiovascular diseases.
- -
-
Page/Page column 131
(2010/02/11)
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- Kumada coupling of aryl and vinyl tosylates under mild conditions
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Aryl and alkenyl tosylates are easily prepared, inexpensive and, thus, attractive for transition-metal-catalyzed couplings, but their reactivity is low. We report examples of mild, palladium-catalyzed coupling of aryl, alkenyl, and alkyl Grignard reagents with aryl and alkenyl tosylates. The resulting biaryls, vinylarenes, and alkylarenes were isolated in good to excellent yield. These couplings were conducted with a nearly equimolar ratio of the two reactants, and many examples were conducted at room temperature.
- Limmert, Michael E.,Roy, Amy H.,Hartwig, John F.
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p. 9364 - 9370
(2007/10/03)
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- Indium-mediated, highly efficient cyclopropanation of olefins using CH 2I2 as methylene transfer reagent
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The indium-mediated, one-pot cyclopropanation of a variety of olefins with methylene iodide proceeds smoothly with excellent yields of products.
- Virender,Jain, Suman L.,Sain, Bir
-
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- Nickel catalyzed cross-coupling of modified alkyl and alkenyl Grignard reagents with aryl- and heteroaryl nitriles: Activation of the C-CN bond
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The nickel catalyzed cross-coupling of alkyl and alkenyl Grignard reagents with aryl nitrile derivatives affords good yields of the corresponding aryl alkanes or aryl alkenes via activation of the C-CN bond. To prevent direct addition of the nucleophile to the nitrile group, the reactivity of the Grignard reagent was modulated by reaction with either LiOt-Bu or PhSLi prior to cross-coupling. The optimum catalyst was determined to be NiCl2(PMe3)2, which is a convenient air stable commercially available complex.
- Miller, Joseph A.,Dankwardt, John W.
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p. 1907 - 1910
(2007/10/03)
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- Nickel catalyzed cross-coupling and amination reactions of aryl nitriles
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Aryl nitriles have been found to participate in cross-coupling and amination reactions via nickel-catalyzed activation of the C-CN bond. With the development of these synthetically useful transformations, aryl nitriles can now be considered along with ary
- Miller, Joseph A.,Dankwardt, John W.,Penney, Jonathan M.
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p. 1643 - 1648
(2007/10/03)
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- A straightforward synthesis of cyclopropanes from aldehydes and ketones
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A new synthetic methodology for preparing cyclopropanes is presented. The reaction involves a cooperative zirconium- and Lewis acid-mediated deoxygenative coupling of carbonyl compounds with a Grignard reagent. In this way, various cyclopropanes are obtained in moderate to excellent yields, directly from saturated, unsaturated, and aromatic aldehydes and ketones. This reaction tolerates the presence of several different functional groups.
- Gandon, Vincent,Bertus, Philippe,Szymoniak, Jan
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p. 3713 - 3719
(2007/10/03)
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- Aryl and vinyl cyclopropanes through the in situ generation of B- cyclopropyl-9-BBN and its Suzuki-Miyaura coupling
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Dihydroboration of propargyl bromide with 9-BBN-H followed by treatment of the adduct with aqueous sodium hydroxide affords the hydroxy(cycloropropyl)borate complex (1), which undergoes efficient palladium-catalyzed cross-coupling to produce a variety of aryl and vinyl cyclopropanes (2) in good to excellent yields. (C) Elsevier Science Ltd.
- Soderquist, John A.,Huertas, Ramon,Leon-Colon, Gisela
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p. 4251 - 4255
(2007/10/03)
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- Oxidation of aryl- and diarylcyclopropanes in a pentasil zeolite: Ring opening with deprotonation or net hydrogen migration
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Incorporation of trans-1,2-diphenylcyclopropane (1) and its 3,3-D2- isotopomer into the channels of a redox-active pentasil zeolite (Na-ZSM-5) resulted in the formation of exo,exo-1,3-diphenylallyl radical (2.) and its 2-D1 isotopomer, respectively. This conversion requires oxidation, ring opening, and deprotonation, in an unspecified sequence. The allyl radical 2. is also formed upon incorporation of trans-1,3-diphenylpropene (3). A comparison with the solution photochemistry, in the presence or absence of added base, shows the conversion of 1 into 2. to be a zeolite-specific reaction. Incorporation of arylcyclopropanes 9 (R = H, OCH3) into ZSM-5 generated trans-propenylbenzene radical cations 10.+ (R = H, OCH3); the 2,2-D2 isotopomer of 9 (R = OCH3) gave rise to three different isotopomers of 10.+) (R = OCH3).
- Herbertz, Torsten,Lakkaraju, Prasad Sreeramachandra,Blume, Florian,Blume, Matthias,Roth, Heinz Dieter
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p. 467 - 472
(2007/10/03)
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- Pharmacokinetics of hypolipidemic agents, X: Second contribution to the problem of the dehalogenation of the lipid lowering agent ciprofibrate
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rac-2 described as a metabolite of rac-1 was synthesized in four steps starting with rac-3. Partial dehalogenation occurs with LiAlH4. A new structure assignment of the resulting stereoisomers resulted from NMR spectroscopy. After oral administration of rac-1 in multiple dose studies to volunteers, rac-2 could not be detected within the limitations of sensitivity of HPLC (UV-detector) in plasma or in urine.
- Oelschlager,Hellwich,Rothley
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p. 261 - 265
(2007/10/02)
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- The Stereochemistry of Rearrangements of Aryl and Hetaryl Groups to Primary Carbenic Centers
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The products and stereochemistries of carbenic decompositions of varied 2-aryl-1-diazoalkanes and 1-diazo-2-(2-hetaryl)propanes have been determined.
- Slack, W. E.,Taylor, W.,Moseley, C. G.,Chang, K. T.,Kraska, A.,et al.
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p. 2647 - 2650
(2007/10/02)
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- FREE RADICAL CHLORINATION AND ONE-ELECTRON OXIDATION OF ARYLCYCLOPROPANES. DESIGNER PROBES FOR CYTOCHROME P-450 HYDROXYLATION MECHANISMS
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Arylcyclopropyl radicals can be formed under mild conditions (phase-transfer-catalyzed chlorination) and give rise to cyclopropyl products; in contrast one-electron oxidation of arylcyclopropanes by Mn(OAc)3 leads to fragmentation of the cyclopropane ring and the formation of acyclic products.
- Riley, Pamela,Hanzlik, Robert P.
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p. 3015 - 3018
(2007/10/02)
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- Relative Conjugative Abilities of Three-Membered Ring Heterocycles with Benzene Based on 13C and 15N NMR
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The conjugative ability of various three-membered rings with benzene was investigated by observing the sensitivity of β-carbon 13C chemical shifts to para substituents.These Hammett ρ values were 2.0, 1.5, 1.0, and 0.9 ppm for arylcyclopropanes, N-methyl-2-arylaziridines, phenyloxiranes, and N,N-dimethyl-2-arylaziridinium fluorosulfonates, respectively.These values were intermediate to ones for para-substituted styrenes (6.5 ppm) and ethylbenzenes (-0.9 ppm), model compounds which were taken to represent extremes of conjugative ability.Similar results were found for 15N chemical shifts of trans-3-aryl-oxaziridines, which had a slope of 2.1 ppm, intermediate to those for benzylimines (20.2 ppm) and benzylamines (-1.3 ppm).The order of conjugative ability, which decreases with increasing electronegativity of the hetero group, could not be explained by hybridization changes based on comparing open chain analoques with the above compounds or by conformational factors.The trend can, however, be interpreted qualitatively by perturbation theory which shows that more electronegative hetero groups decrease the extent of interaction between aryl-? and cyclopropane orbitals as well as cross ring conjugation.
- Crist, DeLanson R.,Jordan, Guy J.,Moore, Donald W.,Hashmall, Joseph A.,Borsetti, Arnold P.,Turujman, Saleh A.
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p. 4136 - 4142
(2007/10/02)
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