1: 3-[(4R,5R)-4,5-Bis(1-methoxycyclopentyl)-1,3,2-dioxoborolan-2-yl]propiophenone O-methyloxime With dimethylsulfide borane complex in tetrahydrofuran T=-15 - 20°C; Reduction; 16 h; 2: With sodium hydroxide; dihydrogen peroxide in water oxidative cleavage; 3: acetylation agent Acetylation;

1: (S)-4-isopropyl-5,5-diphenyl[1,3,2]oxazaborolidine; BH3*THF / tetrahydrofuran / 14 h / 20 °C 2: tetrahydrofuran / 1 h / 20 °C 3: aq. NaOH; H2O2 / tetrahydrofuran / 2 h / 20 °C View Scheme

1: (S)-4-isopropyl-5,5-diphenyl[1,3,2]oxazaborolidine; BH3*THF / tetrahydrofuran / 14 h / 20 °C 2: tetrahydrofuran / 1 h / 20 °C 3: aq. NaOH; H2O2 / tetrahydrofuran / 2 h / 20 °C View Scheme