di-isopropyl azodicarboxylate; triphenylphosphine in tetrahydrofuran T=0 - 20°C; Mitsunobu Displacement; regioselective reaction;

1: With maleic anhydride; palladium (II) trifluoroacetate; oxygen in N,N-dimethyl acetamide T=60°C; P=4560.31 Torr; Molecular sieve; 2: With Pd/C; hydrogen in methanol P=760.051 Torr;