- Nucleophile-dependent regio- and stereoselective ring opening of 1-azoniabicyclo[3.1.0]hexane tosylate
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1-[(1R)-(1-Phenylethyl)]-1-azoniabicyclo[3.1.0]hexane tosylate was generated as a stable bicyclic aziridinium salt from the corresponding 2-(3-hydroxypropyl)aziridine upon reaction with p-toluenesulfonyl anhydride. This bicyclic aziridinium ion was then treated with various nucleophiles including halides, azide, acetate, and cyanide in CH3CN to afford either piperidines or pyrrolidines through regio- and stereoselective ring opening, mediated by the characteristics of the applied nucleophile. On the basis of DFT calculations, ring-opening reactions under thermodynamic control yield piperidines, whereas reactions under kinetic control can yield both piperidines and pyrrolidines depending on the activation energies for both pathways. A ring thing: 1-[(1R)-(1-Phenylethyl)]-1-azoniabicyclo[3.1.0]hexane tosylate generated from 2-(3-hydroxypropyl)aziridine with p-toluenesulfonyl anhydride was treated with various nucleophiles including halide, azide, acetate, and cyanide in CH3CN to afford either piperidines or pyrrolidines through regio- and stereoselective ring opening (see scheme).
- Ji, Mi-Kyung,Hertsen, Dietmar,Yoon, Doo-Ha,Eum, Heesung,Goossens, Hannelore,Waroquier, Michel,Vanspeybroeck, Veronique,D'Hooghe, Matthias,Dekimpe, Norbert,Ha, Hyun-Joon
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p. 1060 - 1067
(2014/04/17)
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- Asymmetric synthesis of cyclic β-amino acids and cyclic amines via sequential diastereoselective conjugate addition and ring closing metathesis
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Diastereoselective conjugate addition of lithium (S)-N-allyl-N-α-methylbenzylamide to a range of α,β-unsaturated esters followed by ring closing metathesis is used to afford efficiently a range of substituted cyclic β-amino esters in high d.e. Alternatively, conjugate addition to α,β-unsaturated Weinreb amides, functional group conversion and ring closing metathesis affords cyclic amines in high d.e. The further application of this methodology to the synthesis of a range of carbocyclic β-amino esters via conjugate addition, enolate alkylation and ring closing metathesis is also described. Application of this methodology affords, after deprotection, (S)-homoproline, (S)-homopipecolic acid, (S)-coniine and (1S,2S)-trans-pentacin.
- Chippindale, Ann M.,Davies, Stephen G.,Iwamoto, Keiji,Parkin, Richard M.,Smethurst, Christian A. P.,Smith, Andrew D.,Rodriguez-Solla, Humberto
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p. 3253 - 3265
(2007/10/03)
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- Ring closing metathesis for the asymmetric synthesis of (S)-homopipecolic acid, (S)-homoproline and (S)-coniine
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Diastereoselective conjugate addition of lithium (S)-N-allyl-N-α-methylbenzylamide to α,β-unsaturated esters or Weinreb amides, followed by ring closing metathesis is used to afford the cyclic β-amino acids (S)-homopipecolic acid and (S)-homoproline and the amine (S)-coniine in high ee.
- Davies, Stephen G.,Iwamoto, Keiji,Smethurst, Christian A. P.,Smith, Andrew D.,Rodriguez-Solla, Humberto
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p. 1146 - 1148
(2007/10/03)
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- Synthesis of tetradentate bisamino-bisthiol complexes of oxorhenium(V) as structural mimics of steroids
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Two tetradentate chelate systems have been synthesized in order to prepare metal complexes with oxorhenium(V) whose structures will mimic that of steroids. The chelate system with amide/amine/thioether/thiol donor sites failed to give a stable complex, bu
- Sugano, Yuichi,Katzenellenbogen, John A.
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p. 361 - 366
(2007/10/03)
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- Asymetric Electrophilic α-Amidoalkylation 4: Generation and Trapping Reactions of Chiral N-Acylpyrrolidiniumions
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The pyrrole derivatives 1, 6, and 10 react in the presence of TiCl4 with the silyl enol ether 3 to form α-substituted pyrrolidine amides stereoselectively. 6 and 10 (after HCl-addition =>11) react even at -78 deg C, the reaction of 10 exceeds that of 6 in yield and stereoselctivity.
- Wanner, Klaus Th.,Hoefner, Georg
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