ORGN 576 |
Intermolecular hydroboration using activated amine boranes
| Julia Clay and Edwin Vedejs. Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, MI 48109 |
| Amine boranes have seen limited use in hydroboration reactions, presumably because these complexes often require high reaction temperatures to facilitate the dissociation to the amine and free borane. We found that stable amine boranes could be activated by replacing one of the hydrides with an iodide, thus forming a reactive hydroborating reagent. This reaction pathway may proceed via displacement of iodide (path A or B) and formation of a cationic borane-olefin π-complex, followed by addition of B-H across the π-system. Hydroboration via iodine activated amine boranes afforded mono-hydroborated adducts that were isolated as the corresponding potassium mono-alkyl trifluoroborate salts upon treatment with KHF2 (aq). Terminal alkenes containing a variety of functional groups were hydroborated cleanly using this amine•BH2I reagent to give, after work-up, the desired alcohol (>20 : 1 regioselectivity). Alkynes were also hydroborated efficiently with good yield and selectivity. 
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New Reactions, Methodology, Heterocycles, Aromatics
8:00 PM-10:00 PM, Wednesday, August 25, 2004 Pennsylvania Convention Center -- Hall D, Poster
Sci-Mix
8:00 PM-10:00 PM, Monday, August 23, 2004 Pennsylvania Convention Center -- Hall D, Sci-Mix
Division of Organic Chemistry
The 228th ACS National Meeting, in Philadelphia, PA, August 22-26, 2004
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