How is 4-Nitrophenyl N-{[(2-methyl-2-propanyl)oxy]carbonyl}-L-isoleucinate (CAS: 16948-38-2) typically synthesized?

4-Nitrophenyl N-{[(2-methyl-2-propanyl)oxy]carbonyl}-L-isoleucinate is typically synthesized via a multistep process involving the protection of L-isoleucine with a 2-methyl-2-propanol group, followed by the introduction of a nitrophenyl group. The synthesis involves the use of reagents like di-tert-butyl dicarbonate and can yield up to 90% purity under optimized conditions. The reaction is typically performed in dichloromethane with a base such as triethylamine.