- Electrochemical-induced radical allylation via the fragmentation of alkyl 1,4-dihydropyridines
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Aldehydes are abundant chemical motifs presented in natural products and pharmaceuticals. As a radical precursor, its application is limited. Dihydropyridines (DHPs) can act as masked aldehydes, providing alkyl radicals under the activation of Lewis acid, heat, SET oxidant and light irradiation. Herein, we report the direct activation of 4-alkyl DHPs via single electron transfer at the anode. C–C bond homolysis at the C4-position of DHP generated the corresponding alkyl radical, which was captured subsequently by 2-phenyl and 2-ethoxy carbonyl allyl bromide. The following intramolecular elimination reaction afforded 20 different radical allylation products bearing various alkyl substituents with yields up to 92%.
- Chen, Xiaoping,Luo, Xiaosheng,Wang, Ping
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- Visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones
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Herein we report a mild, general protocol for visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones. The protocol permits efficient functionalization of sulfones with a broad range of cyclic and acyclic secondary and tert
- Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin,Yue, Fuyang
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supporting information
p. 8924 - 8928
(2021/11/04)
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- Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Solvent-Assisted Organophotoredox Activation
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Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light-assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the prominent
- Ranjan, Prabhat,Pillitteri, Serena,Coppola, Guglielmo,Oliva, Monica,Van der Eycken, Erik V.,Sharma, Upendra K.
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p. 10862 - 10870
(2021/09/08)
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- Synthesis of Tertiary Benzylic Nitriles via Nickel-Catalyzed Markovnikov Hydrocyanation of α-Substituted Styrenes
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The Markovnikov hydrocyanation of α-substituted styrenes enables the synthesis of tertiary benzylic nitriles under nickel catalysis. The Lewis-acid-free transformation features an unprecedented functional groups tolerance, including the-OH and-NH2 groups. A broad range of tertiary benzylic nitriles were obtained in good to excellent yields. In addition, an asymmetric version of this reaction was preliminarily investigated.
- Xing, Yidan,Yu, Rongrong,Fang, Xianjie
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supporting information
p. 1008 - 1012
(2020/02/04)
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- Electron-deficient olefin ligands enable generation of quaternary carbons by Ni-catalyzed cross-coupling
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A Ni-catalyzed Negishi cross-coupling with 1,1-disubstituted styrenyl aziridines has been developed. This method delivers valuable β-substituted phenethylamines via a challenging reductive elimination that affords a quaternary carbon. A novel electron-deficient olefin ligand, Fro-DO, proved crucial for achieving high rates and chemoselectivity for C-C bond formation over β-H elimination. This ligand is easy to access, is stable, and presents a modular framework for reaction discovery and optimization. We expect that these attributes, combined with the fact that the ligands impart distinct electronic properties to a metal, will support the invention of new transformations not previously possible using established ligands.
- Huang, Chung-Yang,Doyle, Abigail G.
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supporting information
p. 5638 - 5641
(2015/05/20)
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- Nickel-catalyzed Mizoroki-Heck reaction of aryl sulfonates and chlorides with electronically unbiased terminal olefins: High selectivity for branched products
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Achieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (≥19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and steric profile was key to obtaining high branched/linear selectivity, whereas the appropriate base suppressed alkene isomerization of the product. Although aryl triflates are traditionally used to access the cationic Heck pathway, we have shown that, by using triethylsilyl trifluoromethanesulfonate, we can effect a counterion exchange of the catalytic nickel complex, such that cheaper and more stable aryl chlorides, mesylates, tosylates, and sulfamates can be used to yield the same branched products with high selectivity. Branching out: A Ni-catalyzed Heck reaction for the preparation of 1,1-disubstituted alkenes is presented. High selectivity for the branched products is achieved with electronically unbiased aliphatic terminal olefins. Regioselectivities remain consistently high (≥19:1) throughout. TESOTf=triethylsilyl trifluoromethanesulfonate. Copyright
- Tasker, Sarah Z.,Gutierrez, Alicia C.,Jamison, Timothy F.
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supporting information
p. 1858 - 1861
(2014/03/21)
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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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- Highly Regioselective Palladium-Catalyzed Internal Arylation of Allyltrimethylsilane with Aryl Triflates
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Highly regioselective ligand-controlled Heck-arylation reactions of allyltrimethylsilane, delivering branched β-products, were performed in moderate to good yields. The high preference for internal over terminal double-bond arylation suggests a contributi
- Olofsson, Kristofer,Larhed, Mats,Hallberg, Anders
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p. 5076 - 5079
(2007/10/03)
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- PYRIDINE ANCHORS FOR HMG-COA REDUCTASE INHIBITORS
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Compounds which are useful as inhibitors of cholesterol biosynthesis and thus as hypocholesterolemic agents are provided which have a quinoline or a pyridine anchor attached by means of a linker to a binding domain sidechain, which compounds inhibit the e
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- A Convergent Method for the Stereoselective Synthesis of Trisubstituted Alkenes
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A method for the stereoselective, convergent synthesis of trisubstituted alkenes has been developed.The procedure features the synthesis of allylic alcohols 9 by coupling an aldehyde with a vinyl organometallic reagent.Treatment of 9 with carbon disulfide
- Martin, Stephen F.,Daniel, Dilon,Cherney, Robert J.,Liras, Spiros
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p. 2523 - 2525
(2007/10/02)
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- Dienes, enynes and styrenes from Markovnikov vinylboranes via the Suzuki reaction
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The clean, efficient Pd-catalyzed cross coupling of vinyl, alkynyl and aryl bromides with Markovnikov vinylboranes gives 56-96% yields of the corresponding 1,3-dienes, 1-en-3-ynes and styrenes, with complete retention of configuration observed for the 1,3-dienes.
- Rivera, Isaac,Soderquist, John A.
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p. 2311 - 2314
(2007/10/02)
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- The reaction of iodine with vinyltrialkylborates derived from trialkylboranes and trisylhydrazones of methyl ketones. A new method for synthesis of 1,1-dialkylethenes
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1,1-Dialkylethenes are readily prepared in good yields from vinyltrialkylborates derived from trialkylboranes and trisylhydrazones of methyl ketones by treatment with iodine.
- Avasthi, Kamlakar,Baba, Tsutomu,Suzuki, Akira
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p. 945 - 946
(2007/10/02)
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