62 t 35 47 d 28 76 t 27 37 t 25 93 q sic me 3 25 84 q sic me 3 25 78 q sic me 3 23 87 q c 27 23 43 t 22 42 t 22 11 t 18 56 q c 21 18 25 s si c me 3 18 17 s 2 u00d7 si c me 3 12 30 q c 18 u2212 4 38 q si me u2212 4 67 q si me u2212 4 87 q 3 u00d7 si me u2212 5 09 q si me exact mass calculated for c 44 h 84 o 3 si 3 na mna 767 5626 found 767 5612 the protected vitamin 16 33 mg 44 u03bcmol was dissolved in thf 2 ml and acetonitrile 2 ml a solution of aq 48 hf in acetonitrile 1 9 ratio 2 ml was added at 0 u00b0 c and the resulting mixture was stirred at room temperature for 6 h saturated aq nahco 3 solution was added and the reaction mixture was extracted with ethyl acetate the combined organic phases were washed with brine dried na 2 so 4 and concentrated under reduced pressure the residue was diluted with 2 ml of hexane.