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ChemInform Abstract: Generation and Carbonyl Addition Reactions of Dibromofluoromethyllithium Derived from Tribromofluoromethane as Applied to the Stereoselective Synthesis of Fluoro Olefins and 2-Bromo-2-fluoro-1,3-alkanediols
- Source :
- ChemInform. 30
- Publication Year :
- 2010
- Publisher :
- Wiley, 2010.
-
Abstract
- The treatment of tribromofluoromethane with BuLi in THF–Et2O (2 : 1) at −130 °C generated dibromofluoromethyllithium, which was allowed to react smoothly with a coexisting aldehyde or ketone (RR′C=O) to give fluorinated alcohol RR′C(OH)CFBr2 (3) in good yield. Alcohol 3 was converted stereoselectively to (E)-1-bromo-1,2-difluoro olefin 5 via fluorination with Et2NSF3, followed by dehydrobromination with lithium 2,2,6,6-tetramethylpiperidide, while (E)-1-bromo-1-fluoro olefin was obtained with high selectivity by acetylation of 3, followed by reductive elimination using EtMgBr/(i-Pr)2NH. Difluoro olefin 5 underwent a cross-coupling reaction with an aryl, alkenyl, or alkynylmetal reagent to afford the corresponding fluoro olefin with retention of configuration. On the other hand, the treatment of RCH[OCH2O(CH2)2OCH3]CFBr2 with BuLi at −130 °C in the presence of 4-heptanone gave the corresponding adduct diastereoselectively. The stereochemical outcome is explained in terms of chelation between lithium and ox...
Details
- ISSN :
- 15222667 and 09317597
- Volume :
- 30
- Database :
- OpenAIRE
- Journal :
- ChemInform
- Accession number :
- edsair.doi...........cf9b8aecedf9f413a8d7a822a880f071
- Full Text :
- https://doi.org/10.1002/chin.199913071