Dibromomethyl trimethylsilane

In an alternative procedure, the lithium reagent was obtained by reaction with lithium metal. Subsequent reaction with a tri-aUcylborane (eq 3) followed by oxidation provided access to a-hydroxysilanes. The yields are good for simple trialkylboranes but are diminished as the alkyl groups become more hindered.  

Physical Data bp 49.5-51.5 °C/12 mmHg d 1.519 gcm . Solubility sol most organic solvents. 

Deprotonation. (Dibromomethyl)trimethylsilane can be de-protonated with lithium diisopropylamide at —78 °C. Reaction of the intermediate anion with n-butyl iodide (eq 4) furnished the alkylated product in 93% yield. If the anion was allowed to warm to 20 °C in the absence of an electrophile, the bis(trimethyl-silyl)ethylene (eq 5) was produced.  

Lithium-Halogen Exchange. Reaction of (dibromomethyl)-trimethylsilane with n-butyllithium at — 110°C results in the formation of trimethylsilylbromomethyllithium. The silane and the -BuLi are added simultaneously in order to suppress side reactions. Treatment of the intermediate lithium reagent with chlorotrimethylsilane (eq 1) or mercury(II) bromide (eq 2) affords bis(trimethylsilyl)bromomethane or bis(trimethylsilyl-bromDmethyl)mercury, respectively. If the lithium reagent is 

The em-dichromium reagent was prepared by reduction of the dibromide with chromium(II) chloride. This reagent will stere-oselectively produce ( )-aIkenylsilanes in excellent yield. The reagent can chemoselectively react with an aldehyde (eq 7) in the presence of a ketone.  

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