- Expedient synthesis of a-heteroaryl piperidines using a pd-catalyzed suzuki cross-coupling-reduction sequence
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A method for the modular synthesis of a-heteroaryl piperidines is reported. The two-step procedure consists of an initial Pd-catalyzed Suzuki cross-coupling of the heteroaryl bromide with a boronate ester derived from N-Boc piperidone, followed by subsequ
- Hesp, Kevin D.,Fernando, Dilinie P.,Jiao, Wenhua,Londregan, Allyn T.
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- [Co(TPP)]-Catalyzed Formation of Substituted Piperidines
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Radical cyclization via cobalt(III)-carbene radical intermediates is a powerful method for the synthesis of (hetero)cyclic structures. Building on the recently reported synthesis of five-membered N-heterocyclic pyrrolidines catalyzed by CoII porphyrins, the [Co(TPP)]-catalyzed formation of useful six-membered N-heterocyclic piperidines directly from linear aldehydes is presented herein. The piperidines were obtained in overall high yields, with linear alkenes being formed as side products in small amounts. A DFT study was performed to gain a deeper mechanistic understanding of the cobalt(II)-porphyrin-catalyzed formation of pyrrolidines, piperidines, and linear alkenes. The calculations showed that the alkenes are unlikely to be formed through an expected 1,2-hydrogen-atom transfer to the carbene carbon. Instead, the calculations were consistent with a pathway involving benzyl-radical formation followed by radical-rebound ring closure to form the piperidines. Competitive 1,5-hydrogen-atom transfer from the β-position to the benzyl radical explained the formation of linear alkenes as side products.
- Lankelma, Marianne,Olivares, Astrid M.,de Bruin, Bas
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supporting information
p. 5658 - 5663
(2019/04/08)
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- Palladium-catalyzed direct C-H arylation of N-iminopyridinium ylides: Application to the synthesis of (±)-anabasine
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Palladium-catalyzed direct C-H arylation of N-iminopyridinium ylides provides a powerful and versatile method for the synthesis of functionalized piperidines in good yields. Chemoselective functionalization of the pyridinium ring in the presence of a pyridine substituent is possible as exemplified by the expedient synthesis of anabasine in 61% overall yield over three steps. Copyright
- Larivee, Alexandre,Mousseau, James J.,Charette, Andre B.
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- Synthesis of 2-arylpiperidines by palladium couplings of aryl bromides with organozinc species derived from deprotonation of N-Boc-piperidine
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(Figure Presented) The organolithium species derived from proton abstraction of N-Boc-piperidine with s-BuLi and TMEDA can be transmetalated to the organozinc reagent, and this organometallic species can be coupled directly with aryl bromides in a Negishi-type reaction using palladium catalysis with the ligand tri-tert-butylphosphine (t-Bu3P-HBF4). The chemistry was applied to a very short synthesis of the alkaloid anabasine.
- Coldham, Iain,Leonori, Daniele
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supporting information; experimental part
p. 3923 - 3925
(2009/05/31)
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- Intramolecular cyclizations of α-lithioamine synthetic equivalents: Convenient syntheses of 3-, 5-, and 6-membered-ring heterocyclic nitrogen compounds and elaborations of 3-membered ring systems
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A lithiation-intramolecular cyclization reaction of N-Boc chloroalkyl secondary amines is reported to provide the 2-aryl-substituted pyrrolidine and piperidines 6, 7, 9, and 11 and a series of 2-azabicyclo[3.1.0] derivatives 14-25, including cyclopropane derivatives of proline and of the indolizidine-pyrrolizidine alkaloid ring system. Lithiation-substitutions of N-Boc-N-ethylcyclopropylamine to give 27-29 and lithiation-silylations of N- Boc aziridines to give 31-33 also are reported.
- Beak,Wu,Eul Kyun Yum,Young Moo Jun
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p. 276 - 277
(2007/10/02)
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