ORGN 595 |
1-Bromo-1-lithioethene: Reactions with aliphatic aldehydes, protected α-hydroxy carbonyl compounds and acylsilanes
| Yehor Novikov and Paul Sampson. Department of Chemistry, Kent State University, Kent, OH 44242 |
| Building on our previously reported development of 1-bromo-1-lithioethene (1) as a synthetically useful reagent, we have observed that the presence of 1 eq Me3SiCl during the addition of 1 to aliphatic aldehydes significantly increases the yield of the resulting bromoallylic alcohols. Highly diastereoselective Felkin-Ahn addition to α-siloxy aldehydes is achieved in moderate to good yield under the same conditions (e.g., eq 1). Completely diastereoselective addition of 1 to various acetal-protected carbohydrate-derived ketones is achieved in high yield in the presence of catalytic NdBr3. Acylsilanes react with 1 to afford α-silyl allylic alcohols 2 which undergo clean rearrangement to α-bromo-α-silyl ketones 3 (eq 2). Some mechanistic insight into the above chemistry has been gained using ab initio computations, employing the SM5.42 solvation model. 
|
| |
|
New Reactions, Methodology, Heterocycles, Aromatics
8:00 PM-10:00 PM, Wednesday, August 25, 2004 Pennsylvania Convention Center -- Hall D, Poster
Division of Organic Chemistry
The 228th ACS National Meeting, in Philadelphia, PA, August 22-26, 2004
|