A mixture of 6-methylsulfonyloxy-2,2,3,3,10,10,11,11-octamethyl-4,9-dioxa-3,10-disiladodecane (i.e. the product of Step B) (59.29 g, 0.144 mol) and sodium cyanide (15.55 g, 0.317 mol) in DMSO was heated at 90° C. (using an oil bath) for 2 h. The reaction mixture was cooled to room temperature, water (500 mL) was added and the mixture was extracted with diethyl ether (4×250 mL). The combined organic layers were washed with saturated aqueous sodium chloride solution (300 mL), dried over magnesium sulfate, filtered and concentrated under reduced pressure to a dark-yellow oil (48.86 g). The oil was purified by silica gel chromatography (eluting with petroleum ether, followed 1-4% gradient of ethyl acetate in petroleum ether) to provide the title compound (150 mg), a compound of the present invention, as a dark foam. Mixed fractions were combined with mixtures from a previous experiment (total weight 19 g) and purified by silica gel chromatography to provide the title compound (about 11 g).
