1: With sulfur dioxide in dichloromethane T=-40°C; 1 h; Photolysis; 2: With sodium tetrahydroborate; nickel dichloride in tetrahydrofuran; methanol T=0°C; 0.25 h;

1: With sulfur dioxide in dichloromethane T=-40°C; 1 h; Photolysis; 2: With sodium tetrahydroborate; nickel dichloride in tetrahydrofuran; methanol T=0°C; 0.25 h;