2/ Amino Acid Esters and Ethers

3/ Amino Acid Amides via Amidation: -COOH -------- -CONH2

4/ T-Butylation for Amino Acid
-COOH ----------- -COOC(CH3)3
-OH ------------ -OC(CH3)3

5/ Chloromethylation

6/ Chlorination via POCl3 & PCl3

7/ Reduction by: Sodium Borohydride, Potassium Borohydride
Hydrogen gas

8/ Combination through Sodium Amide

9/ T-Butylation