utilization of decomposition products of PFECAs. We report herein a new series of deoxyfluorination reagents featuring OCF2 functional groups derived from certain PFECAs. Alkyl fluorides were generated from various alcohols in ≤97% yield by these novelreagents. The mechanistic experiment verified in situgeneration of carbonic difluoride (COF2).
1,1,2,2-Tetrafluoroethyl-N,N-dimethylamine: a new selective fluorinating agent
作者:Viacheslav A. Petrov、Steve Swearingen、Wonpyo Hong、W. Chris Petersen
DOI:10.1016/s0022-1139(01)00372-4
日期:2001.6
The title compound has been prepared in 96–98% yield by the reaction of tetrafluoroethylene and dimethylamine. 1,1,2,2-Tetrafluoroethyl-N,N-dimethylamine (1) is found to be an effective reagent for the conversion of alcohols into alkyl fluorides. Reaction of 1 and primary alcohols proceeds with high yield formation of the corresponding alkyl fluorides at elevated temperature. However, the reaction
Stereochemistry of the fluorination of an alcohol with phenyltetrafluorophosphorane was investigated in the case of steroidal alcohols. 5α-Cholestan-3β-ol and 3α-ol gave 3α- and 3β-fluoro-5α-cholestane, respectively, which suggests that the fluorination proceeded through SN2 mechanism ; while, cholesterol and 3β-acetoxy-5-bromo-5α-cholestane-6β-ol gave fluoro compounds with retention of configuration, which shows that a neighboring group may have participated in stabilizing the carbonium intermediate in special cases. Diphenyltrifluorophosphorane gave similar results.
13C-19F couplings and 19F NMR shifts of cycloalkyl, bicycloalkyl and steroid monofluoro compounds
作者:H.-J. Schneider、W. Gschwendtner、D. Heiske、V. Hoppen、F. Thomas
DOI:10.1016/0040-4020(77)84058-1
日期:1977.1
investigated with 20 alicyclic compounds. One bond couplings, ranging from 168 to 214 Hz, can be represented as a function of the corresponding 13C-H coupling constants. For comparison 13C-1H couplings are determined for norboraane and adamantane and indicate considerable s character at the bridgehead C-H bond of the latter compound. One bond and geminal couplings (ranging from 18 to 24 Hz) are found to