4 158 1 157 5 155 6 138 2 137 9 130 0 129 8 129 3 129 2 128 7 128 57 128 52 128 3 128 29 128 28 121 8 118 1 113 1 108 9 105 9 102 9 90 1 70 9 70 4 68 9 25 9 u2212 4 3 u2212 11 4 anal calcd for c 17 h 18 o 7 c 76 30 h 6 95 found c 76 02 h 7 09 4 u2032 t butyldimethylsilyloxy 2 u2032 7 dibenzyloxy isoflavan 3 4 diol g8 to a solution of chiral ligand dhqd 2 phal 15 6 g 20 0 mmol in ch 2 cl 2 80 ml oso4 5 g 20 0 mmol was added after stirring at u2212 20 u00b0 c for 1 h a solution of g7 10 g 18 1 mmol in ch cl 2 80 ml was slowly added over 10 15 min and the mixture was stirred at u2212 20 u00b0 c for 18 20 h reaction progress was monitored by tlc after completion the reaction was allowed to warm to rt and 10 sodium sulfite 100 ml ph u02dc 9 0 and 10 sodium bisulfite 100.