2. Synthesis

3. Biosynthesis Reagents = small carbon-based molecules (e.g. amino acids, carbohydrates) Catalysts = enzymes, proteins that bind and then catalyze chemical reaction

4. Chapter 17: Aldehydes and Ketones – Nucleophilic Addition

5. 17.1 – Nomenclature of Aldehydes and Ketones

6. 17.2 – 17.4 – Structure of C=O and Sources

7. 17.5 – Nucleophilic Addition Nucleophiles: H 2 O – hydrates H - from NaBH 4 or LiAlH 4 R - from RMgX, RLi NC-, ROH, RNH 2, R 2 NH

8. a Hydrate Formation (relevant to H 2 CrO 4 oxidation) Table 17.3 17.6 – Hydration of Aldehydes and Ketones

9. Electronic (how stable is the carbonyl – how positive is the carbon?) Steric (how crowded does the hydrate become?) Hydrate becomes more crowded, which effects the equilibrium with the precursor aldehyde or ketone

10. 17.6 – Hydration of Aldehydes and Ketones Hydrate Formation is Base-Catalyzed Reaction faster than just with water (pH 7) Hydroxide is much more nucleophilic than water Hydroxide regenerated in second step

11. 17.6 – Hydration of Aldehydes and Ketones

12. 17.6 – Hydration of Aldehydes and Ketones – Fig 17.5

13. 17.6 – Hydration of Aldehydes and Ketones Hydrate Formation is also Acid-Catalyzed Reaction faster than just H 2 O, H + regenerated in second step

14. 17.7 – Cyanohydrin Formation Both HCN and cyanide anion present in mixture Cyanide anion catalyzes the reaction, adds to the C=O New C-C bond formed (compare with Grignard)

15. 17.8 – Acetal Formation Acid catalyzed, use TsOH for example Use excess ROH to drive equilibrium to the right Water is the byproduct Acetals are stable to bases and nucleophiles Use excess water and H + to go back to carbonyl - mechanism

16. Acetals do not react with bases or nucleophiles - useful 17.8 – Acetal Formation

17. 17.9 – Acetals as Protecting Groups Possible solution:

18. 17.9 – Acetals as Protecting Groups

19. 17.9 – Acetals as Protecting Groups – Hydrolysis

20. 17.10 – Reaction with Primary Amines – Imines

21. opsin

22. 17.10 – Reaction with Primary Amines – Imines

23. 17.11 – Reaction with Secondary Amines – Enamines

24. 17.12 – The Wittig Reaction Phosphonium salt Wittig ylide

25. 17.12 – The Wittig Reaction

26. Retrosynthesis: Synthesis:

27. 17.13 – Planning an Alkene Synthesis by the Wittig Reaction

28. 17.14 – Stereoselective Addition to Carbonyls

29. 17.15 – Oxidation of Aldehydes (via the Hydrate)

30. 17.16 – Baeyer-Villager Oxidation of Ketones