Hydrogen fluoride abstraction from vicinal difluoroalkanes: reaction conditions and syn/anti-stereoselectivity
vic-Difluoroalkanes are as inert as monofluoroalkanes toward NaOMe in MeOH. Stronger bases, however, can perform dehydrofluorinations relatively smoothly. KOCMe3 in THF at 75 Deg acts exclusively by an antiperiplanar process: meso- and dl-6,7-difluorododecane are converted to (E)- and (Z)-6-fluoro-6-dodecene, resp. Lithium diisopropylamide was an extremely powerful eliminating reagent when employed in hexane, while its reactivity is considerably diminished in di-Et ether and has almost completely vanished in THF. This solvent effect together with the loss of stereoselectivity points at an electrophilic assistance as the key event in lithium amide-induced dehydrofluorinations. [on SciFinder (R)]
Keywords: Stereochemistry (of dehydrofluorination of difluoroalkanes); Kinetics of dehydrofluorination (of difluoroalkanes); Dehydrofluorination (of difluoroalkanes ; mechanism of); Alkanes Role: RCT (Reactant) ; RACT (Reactant or reagent) (fluoro ; dehydrofluorinat ; dehydrofluorination difluoroalkane kinetics stereochemistry; difluoroalkane dehydrofluorination kinetics stereochemistry
Physical Organic Chemistry
Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz.
written in English.
119105-48-5 (5-Nonyl fluoride) Role: RCT (Reactant), RACT (Reactant or reagent) (attempted dehydrofluorination of); 119105-44-1; 119105-45-2 Role: RCT (Reactant), RACT (Reactant or reagent) (dehydrofluorination of, stereochem. in mechanism of); 7664-39-3 Role: PRP (Properties) (dehydrofluorination, of difluoroalkanes, mechanism of); 6975-99-1P (6-Dodecyne); 119105-46-3P; 119105-47-4P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of)
Record created on 2006-03-03, modified on 2016-08-08