chromium(VI) oxide in dichloromethane; acetic acid T=25°C; 12 h;

in tetrahydrofuran under N2, dropwise addn. of BF3*Et2O to a suspension of NaBH4 in THF at 25°C with stirring, addn. of morpholino derivate after 1h, stirred for additional 3h at 25°C; slowly quenched with MeOH, addn. of NaOH, solvent evapn. (25°C, 12 Torr), alkaline aq. layer cooled to 0°C and acidified (concd. HCl), boronic acid extd.(ether), washed (H2O), dried (MgSO4), evapn.;

oxygen

chromium(VI) oxide in dichloromethane; acetic acid T=25°C; 12 h;