Hydroperoxides boranes

Trialkyl- Hydroperoxide Unstable intermediate Borate ester borane ion... 

The carbanions take up 02 and these take up protons to give hydroperoxides in good yields. But because they are explosive in nature, they are not usually isolated and on reduction with sodium sulphite on trialkyl phosphite give alcohols. Alcohols can also be prepared via hydroperoxy molybdenum complexes and alkyl boranes. These reactions are summarized as follows ... 

Cleavage of hydroperoxides 8-23 Rearrangement of ethers upon treatment with alkyllithiums (Wittig) 8-24 From boranes and CO, or CN, or CHCEOMe... 

Cleavage of hydroperoxides 8-25 Treatment of boranes with CO and H20, followed by NaOH and H202 or with CN followed by trifluo-roacetic anhydride from dialkyl-chloroboranes... 

The synthetic value of the reaction lies in the modification of these organoboranes. The commonest reaction involves the decomposition of the borane by alkaline hydrogen peroxide. The highly nucleophilic hydroperoxide anion attacks the electron-deficient boron with the formation of an ate complex. Rearrangement of this leads to the formation of a borate ester which then undergoes hydrolysis to an alcohol in which an oxygen atom has replaced the boron (Scheme 3.15). The overall outcome of this reaction is the anti-Markownikoff hydration of the double bond. The regiochemistry is the reverse of the acid-catalysed hydration of an alkene. The overall addition of water takes place in a cis manner on the less-hindered face of the double bond. 

The reaction of alkenes with borane, monoalkyl and dialkylboranes leads to a new organoborane (see 15-16). Treatment of organoboranes with alkaline H2O2 oxidizes trialkylboranes to esters of boric acid." This reaction does not affect double or triple bonds, aldehydes, ketones, halides, or nitriles that may be present elsewhere in the molecule. There is no rearrangement of the R group itself, and this reaction is a step in the hydroboration method of converting alkenes to alcohols (15-16). The mechanism has been formulated as involving initial formation of an ate complex when the hydroperoxide anion attacks the electrophilic boron... 

BUTENEDIOL or 2-BUTENE-l,4-DIOL or cis-2-BUTENE-l,4-DIOL (110-64-5) C4H8O2 Combustible liquid (flash point 263°F/128°C oc). Contact with strong oxidizers may cause fire and explosions. Reacts violently with oxidizers, aliphatic amines, alkalis, ammonium persulfate, boranes, bromine dioxide, isocyanates, nitric acid, perchlorates, permanganates, peroxides and hydroperoxides, sodium peroxide, sulfuric acid, uranium fluoride. 

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