1. Aromatic Amines Recall: The amino group is a powerful activating group that directs ortho and para 1

2. Reduction of Nitro Compounds Catalytic hydrogenation: Reduction with finely divided metal powders: 2 23.11 Synthesis of Amines

3. Reduction of Nitro Compounds LiAlH 4 and NaBH 4 fail to provide the amine 3 23.11 Synthesis of Amines

4. Problems Draw the products for the following reactions: 4

5. Reductive Amination 5

6. 6

7. 7

8. Sodium cyanoborohydride, NaBH 3 CN and sodium triacetoxyborohydride, NaBH(OAc) 3, are common choices in the lab for the reduction step

9. Formaldehyde can be used to introduce methyl groups 9

10. 10 23.7 Alkylation and Acylation Reactions of Amines

11. Problem Draw the complete mechanism for the following problem: 11

12. Hofmann and Curtius Rearrangements 12

13. The Hofmann Rearrangement Sometimes called the Hofmann hypobromite reaction Cl 2 is sometimes used in place of Br 2 A primary amide is the required starting compound 13 23.11 Synthesis of Amines

14. 14

15. 15

16. The Curtius Rearrangement Acyl azides provide access to primary amines via an isocyanate Concerted reaction 16

17. The Curtius Rearrangement The resulting isocyanate can be hydrated in acid or base Carbamic acids spontaneously decarboxylate 17 23.11 Synthesis of Amines

18. Hofmann vs. Curtius In the Hofmann rearrangement, the isocyanate cannot be isolated as the reaction is carried out in aqueous base 18 23.11 Synthesis of Amines

19. Curtius and Hofmann Rearrangements In both of these reactions, the alkyl group migrates with complete retention of configuration 19 23.11 Synthesis of Amines

20. 20 Problems Draw the mechanisms for the following rxns

21. 21

22. Acylation of Amines Amines can be converted into amides by reaction with acid chlorides, anhydrides, or esters. 22

23. 23

24. See section 21.8 for review of these rxns 24