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Nucleophilic Neighboring Group Participation

Nucleophilic Neighboring Group Participation. Nucleophilic Neighboring Group Participation. Case I: Rationale. Nucleophilic NGP. Case II. Nucleophilic NGP. Case III. “Non-nucleophilic” NGP. Acetolysis of Phenyl tosylates. Possible explanations for the results of the acetolysis reactions.

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Nucleophilic Neighboring Group Participation

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  1. Nucleophilic Neighboring Group Participation

  2. Nucleophilic Neighboring Group Participation Case I: Rationale

  3. Nucleophilic NGP Case II

  4. Nucleophilic NGP Case III

  5. “Non-nucleophilic” NGP Acetolysis of Phenyl tosylates

  6. Possible explanations for the results of the acetolysis reactions • Direct bimolecular nucleophilic attack at C-2 • Inconsistent with the experimental data. Why? • Formation of a secondary carbocation at C-2 • Inconsistent with the experimental data. Why?

  7. Rapidly equilibrating secondary carbocations to account for the acetolysis results? The “Windshield-Wiper” Effect

  8. Additional data concerning acetolysis of phenyl tosylates Fact One - Scrambling of a label

  9. Additional data concerning acetolysis of phenyl tosylates Fact Two - Substituent effects

  10. Additional data concerning acetolysis of phenyl tosylates Fact Three - Formation of Spirane products

  11. Additional data concerning acetolysis of phenyl tosylates Fact Four - Unusual Kinetics

  12. Explanation to account for the acetolysis results Phenonium ion participation

  13. Alkyl Participation  - bridged complexes

  14. Corroborating evidence for alkyl participation

  15. Open carbocation possibility

  16. Methyl bridged intermediate

  17. Data for the solvolysis of cyclohexyl tosylates

  18. Rationale for cyclohexyl tosylate solvolysis

  19. Rationale for cyclohexyl tosylate solvolysiscont’d. -Hydrogen participation

  20. Solvolysis of unsaturated tosylates

  21. Possible explanations for solvolysis of unsaturated tosylates

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