1: dimethyl (S) 2-hydroxybutane-1,4-dioate With sodium tetrahydroborate; dimethylsulfide borane complex in tetrahydrofuran
T=20°C; 3 h;
2: With methanol in tetrahydrofuran
T=20°C;
3: 2,2-dimethoxy-propane; acetone With toluene-4-sulfonic acid
T=20°C;