Electroreductive coupling of halofluoro compounds with aldehydes
摘要:
Electroreductive intermolecular coupling of halofluoro compounds such as 1,1,1-trichloro-2,2,2-trifluoroethane, methyl chlorodifluoroacetate, and perfluoroalkyl halides with aldehydes took place effectively in the presence of chlorotrimethylsilane and one of the coupling products, 2,2-dichloro-3,3,3-trifluoro-1-phenyl-1-propanol, was selectively convertible to a variety of compounds with using the electroreduction as a key reaction.
Facile Conversion of Aldehydes into 1-Substituted 2-Chloro-3,3-difluoro-2-propen-1-ols with 1,1-Dibromo-1-chloro-2,2,2-trifluoroethane/Magnesium Reagent
作者:Makoto Fujita、Tamejiro Hiyama
DOI:10.1246/bcsj.61.3321
日期:1988.9
Aldehydes RCHO are converted in excellent yields into chlorodifluoroallyl alcohols RCH(OH)CCl=CF2 upon treatment with CClBr2CF3 and magnesium in tetrahydrofuran at 0 °C.
the presence of a base did not give the expected esters but 2-chloro-1,1-difluoroprop-2-enyl methanesulfonates (4) through a novel [3,3] sigmatropic rearrangement. Reaction of 4 with diethylzinc in the presence of tetrakis(triphenylphosphine) palladium gave 1-alkyl- or 1-aryl-2-chloro-3-fluoropenta-1,3-dienes in moderate to good yields through a CC bond formation followed by dehydrofluorination.
We have reported the Grignard reaction of Halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane (1), with ketones gave unexpected products, α-(1-bromo-1-chloro-2,2,2-trifluoroethyl)alcohols (4) at a low temperature. However, this reaction hardly proceeded with aldehydes. Now, we found the reaction of 1 with aldehydes in the presence of zinc gave not only products of type 4, but α-(1-chloro-2,2,2-trifluoroethyl)alcohols
Practical, Stereocontrolled Synthesis of Polyfluorinated Artificial Pyrethroids
作者:Makoto Fujita、Kiyosi Kondo、Tamejiro Hiyama
DOI:10.1246/bcsj.60.4385
日期:1987.12
Practical and stereocontrolled approaches to polyfluorinated synthetic pyrethroids based on aldehyde addition of CF3CCl2ZnCl are described. The zinc reagent was allowed to react with 3-formyl-2,2-dimethylcyclopropanecarboxylates (6) to give the corresponding adducts. These were acetylated and then reduced again with zinc to afford (1R*, 3S*)-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylates (12). The (1R*, 3R*)-isomer was derived from 2,2-dichloro-1,1,1-trifluoro-5-methyl-4-hexen-3-ol by diazoacetylation, Cu(II)-catalyzed intramolecular carbene addition, and finally by the zinc reduction. An alternative access to 12 and its halogen homologues of the (Z)-pyrethroids involves addition of 1-halo-2,2-difluoroethenyl group across the CHO group of 6 and subsequent regio- and stereoselective halogenation.
reaction of halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane (1), with aldehydes and ketones in the presence of bases was found to give 1-alkyl- or 1-aryl-2-bromo-2-chloro-3,3,3-trifluoropropanols (2) or 2-chloro-3,3-difluoro-2-propenols (3) selectively in good to moderate yields depending on the bases and reaction conditions.