Tert-butyl acetate (0.865 mL) is added to a solution of lithium diisopropylamide (7.52 mmol) in 30 mL of ether at −78° C., and the mixture is stirred for 1 hour. A solution of bis(1,2:5,6-di-O-isopropylidene-α-L-glucofuranos-3-O-yl)cyclopentadienyltitanium chloride (8.34 mmol) in 90 mL of ether is added dropwise over 40 minutes, and the reaction is stirred for an additional 30 minutes at −78° C., warmed to −30° C. and kept for 45 minutes, then recooled to −78° C. A solution of (4R,5S,6S)-3-oxo-5-(2,2,2-trichloroethoxycarbonyloxy)-2,2,4,6-tetramethyl-8-nonenal (2.57 g) in 15 mL of ether is added over 10 minutes and the reaction is continued for 2 hours before addition of 14 mL of 5 M water in THF. The mix is stirred for 1 hour, then filtered through Celite. The filtrate is washed with sat. aq. NaCl, and the brine layer is back extracted with ether. The organic phases are combined, dried with Na2SO4, filtered, and evaporated. The product is purified by chromatography on SiO2 (7% ethyl acetate/hexanes).
