1. Chapter 20
Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

2. 1. Introduction [1] Hydrogen atoms bonded to the carbonyl
[2] Electronegative atom bonded to the carbonyl

3. Carbonyl carbons: sp2 hybridized, trigonal planar,
and ~1200.
Two resonance structures.

4. 2. General Reaction of Carbonyl Compounds

5. Aldehydes and ketones react with nucleophiles

6. Aldehydes are more reactive than ketones

7. Carbonyl compounds with leaving groups react with nucleophiles to form substitution products by a two-step process

9. 3. Preview of Oxidation and Reduction

10. Three most useful oxidation and reduction reactions of carbonyl starting materials.

11. 4. Reduction of Aldehydes and Ketones
most useful reagents for reducing aldehydes and ketones.

13. Catalytic hydrogenation: aldehydes and ketones to 1° and 2° alcohols
A C=C is reduced faster than a C=O with H2 (Pd-C).
A C=O is readily reduced with NaBH4 and LiAlH4, but a C=C is inert.

15. 5. Stereochemistry of Carbonyl Reduction

16. 6. Enantioselective Carbonyl Reductions

19. In cells, the reducing agent is NADH.

21. LiAlH4: a strong reducing agent.
Diisobutylaluminum hydride
([(CH3)2CHCH2]2AlH, DIBAL-H: less reactive than LiAlH4)
Lithium tri-tert-butoxyaluminum hydride,
(LiAlH[OC(CH3)3]3:less nucleophilic than LiAlH4)

25. 7. Reduction of Carboxylic Acids and Their Derivatives

29. 8. Oxidation of Aldehydes
oxidizing agents: CrO3, Na2Cr2O7, K2Cr2O7, and KMnO4.

30. 9. Organometallic Reagents

33. Organometallic reagents are strong bases.

34. alkyl halide into alkane.

35. Organometallic Reagents
[1] Reaction of R—M with aldehydes and ketones to afford alcohols
[2] Reaction of R—M with carboxylic acid derivatives

36. [3] Reaction of R—M with other electrophilic functional groups

37. 10. Reaction of Organometallic Reagents with Aldehydes and Ketones.

40. 11. Retrosynthetic Analysis of Grignard Products

42. 12. Protecting Groups

45. 13. Reaction of Organometallic Reagents with Carboxylic Acid Derivatives.

50. 14. ,-Unsaturated Carbonyl Compounds

54. 15. ,-Unsaturated Carbonyl Compounds

55. Summary of the Reactions of Organometallic Reagents
[1] Organometallic reagents (R—M) attack electrophilic atoms.

56. [2] an organometallic reagent adds to the carbonyl group.
[3] The reactivity of the reagents:
—RLi and RMgX are very reactive reagents.
—R2CuLi is much less reactive.