Tetrakis trimethylsilane

Cyclododecanone is reduced to a mixture of cis- and /ra .s -cyclododecenc in high yield with trimethylsilane and tetrakis-3,5-bis(trifluoromethylphenyl)borate (TFPB, 77) (Eq. 254).424... 

DIENES Bis-3-methyl-2-butyl-borane. Chlorobis(cyclopentadienyl)-hydridozirconium. Formylmethylene-triphenylphosphorane. LithioaUyl-trimethylsilane. Methylcopper. Pal-ladium(II) acetate. Palladium(ll) chloride. Tetrakis(triphenylphosphine)-palladium(O). 

To a stirred solution of 1.01 g (2-bromophenylethynyl)trimethylsilane (4 mmol) in 20 mL dry THF was added 3.25 mL 1.6 M n-BuLi in hexane (5.2 mmol) at -95°C. After the mixture was stirred for 10 min, 0.54 g trimethylborate (5.2 mmol) was added. The solution was allowed to warm to —5°C, and 3.71 g Ag20 in 16 mL water, 0.23 g tetrakis(triphenylphosphine)-palladium (0.2 mmol), 0.49 g triphenylarsine (1.6 mmol), and 0.99 g bromoallene (4 mmol) were added successively. The reaction was stirred at 25°C for 24 h. AgaO was removed by filtration, and the crude product was diluted in 40 mL Et20. The organic layer was washed with 50 mL distilled water, 50 mL saturated NaHCOs, and 50 mL brine and dried over MgS04. After filtration, the solvent was removed under reduced pressure, and the residue was purified by column chromatography with hexane/Et20 (10 1) to afford 0.39 g naphthalene (29%) and 0.44 g yne-allene (41%) as pale yellow oils. 

Bromodifluoromethyl phenyl sulfone can be transformed to [difluoro(phenylsulfonyl)methyl]trimethylsilane which was employed for fluoride-induced (phenylsulfonyl)difluoromethylation (eq 4). Alternatively, the reaction of bromodifluoromethyl phenyl sulfone with aldehydes mediated by electron-transfer reagent, tetrakis(dimethylamino)ethylene (TDAE), yields (phenyl-sulfonyl)-difluoromethylated alcohols in good yields which can be further transformed to difluoromethyl alcohols and e/B-difluoroalkenes via reductive desulfonylation and Julia olefination, respectively (eq 5). ... 

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