|Chapter 15: Alcohols, Diols and Thiols|
Hydroboration / Oxidation
(review of Chapter 6)
MECHANISM FOR REACTION OF ALKENES WITH BH3
A concerted reaction. The p electrons act as the nucleophile with the electrophilic B and the H is transferred to the C with syn stereochemistry.
First step repeats twice more so that all of the B-H bonds react with C=C
Peroxide ion reacts as the nucleophile with the electrophilic B atom.
Migration of C-B bond to form a C-O bond and displace hydroxide. Stereochemistry at the C center is unchanged i.e. it is retained.
Attack of hydroxide as a nucleophile with the electrophilic B displacing the alkoxide.
An acid / base reaction to form the alcohol.
|© Dr. Ian Hunt, Department of Chemistry, University of Calgary|