Carey & Sundberg: Part A ; Chapter 11 Carey & Sundberg: Part B ; Chapter 6 Fleming, Chapter 4

1. Pericyclic Reactions Carey & Sundberg: Part A; Chapter 11 Carey & Sundberg: Part B; Chapter 6 Fleming, Chapter 4

2. Pericyclic Reactions – Introduction/Definitions A pericyclic reaction is characterized as a change in bonding relationships that takes place as a continuous, concerted reorganization of electrons. The term "concerted" specifies that there is one single transition state and therefore no intermediates are involved in the process. To maintain continuous electron flow, pericyclic reactions occur through cyclic transition states. More precisely: The cyclic transition state must correspond to an arrangement of the participating orbitals which has to maintain a bonding interaction between the reaction components throughout the course of the reaction.

3. Major Categories of Pericyclic Reactions

4. Major Categories of Pericyclic Reactions

5. Major Categories of Pericyclic Reactions

6. Analysis of Pericyclic Processes

7. Electrocyclic Reactions

8. Electrocyclic Ring Closing/Opening

9. Electrocyclic Reactions: Stereochemical Considerations It was noted that butadienes undergo conrotatory closure under thermal conditions, while hexatrienes undergo disrotatory closure under thermal conditions. The microscopic reverse reactions also occur with the same rotational sense (i.e. cyclobutenes open in a conrotatory sense when heated, and cyclohexadienes open in a disrotatory sense when heated.)

10. Molecular Orbitals in Conjugated Systems

11. FMO Treatment of Electrocyclic Reactions

12. FMO Treatment of Electrocyclic Reactions Photochemical activation: When light is used to initiate an electrocyclic rxn, an electron is excited from 2 to 3. Treating 3 as the HOMO now shows that disrotatory closure is allowed and conrotatory closure is forbidden.

13. Sigmatropic Rearrangements

14. Sigmatropic Rearrangements

15. [1,2] Sigmatropic Rearrangements

16. Sigmatropic Rearrangements

17. Sigmatropic Rearrangements

18. Sigmatropic Rearrangements [1,3]: [1,5]:

19. Examples of Sigmatropic Rearrangements/Shifts

20. Sigmatropic Rearrangements

21. [2,3] Sigmatropic Rearrangements

22. [2,3] Sigmatropic Rearrangements

23. Examples of [2,3] Sigmatropic Rearrangements

24. Coupled [2,3] Sigmatropic Rearrangement/ Reductive Cleavage

25. [2,3] Sigmatropic Rearrangements: Transition State Structures

26. [2,3] Sigmatropic Rearrangements in Synthesis

27. Sigmatropic Rearrangements

28. [3,3] Sigmatropic Rearrangements

29. [3,3] Sigmatropic Rearrangements

30. [3,3] Sigmatropic Rearrangements

31. [3,3] Sigmatropic Rearrangements

32. [3,3] Sigmatropic Rearrangements

33. [3,3] Sigmatropic Rearrangements

34. Complex Total Synthesis; An Introduction

35. Complex Total Synthesis; An Introduction

36. Complex Total Synthesis; An Introduction

37. Complex Total Synthesis; An Introduction

38. Complex Total Synthesis; An Introduction

39. Complex Total Synthesis; An Introduction

40. Complex Total Synthesis; An Introduction

41. The Claisen Rearrangement

42. Traditional Claisen Rearrangements

43. The Claisen Rearrangement in Cyclic Systems

44. Synthesis of Allyl Vinyl Ethers

45. Other Claisen Variants

46. Other Claisen Variants

47. Introduction to Retrosynthesis

48. Introduction to Retrosynthesis

49. Introduction to Retrosynthesis

50. Introduction to Retrosynthesis