Fluorinated Ylides and Related Compounds

Chain-extension reactions via insitu capture of the dibromofluoromethide ion with difluoromethylene fluoro-olefins

“…Tertiary phosphines react with fluorotrihalomethanes to form phosphonium salts. 11 The mechanism of phosphonium salt formation is not an SN 2 process, but involves halophilic attack on the halogen (other than fluorine) by the tertiary phosphines to form an ion-pair, followed by recombination of the ion-pair, as illustrated in Scheme 8. This mechanistic interpretation is supported by the observation that only the phosphonium salt is obtained when dry solvent is utilized (Path A); but the product is CFHX 2 when water or ethanol are present (Path B).…”

“…[11][12][13] Since the dibromofluoromethide ion 6 could be generated readily (from 5) by the process described in Scheme 8, it was of interest to determine whether the carbanion 6 generated in this manner could be captured by a fluoro-olefin faster than recombination of the ion-pair to form the phosphonium salt. The dibromofluoromethide ion 6 differs from chlorodifluoromethide 1 and bromodifluoromethide 3 in two important ways.…”

“…11,13 Thus, an alternative mechanism might involve attack by the ylide on the fluoro-olefin, as shown in Scheme 9.…”

The reduction of Ag(I) by α‐silylamines R2NCH2SiX3

“…This can be explained by the fact that it has a low ionization potential 78 and, simultaneously, easily forms phosphonium salts. 79 …”

A Facile Method for the Stereoselective Horner-Wadsworth-Emmons Reaction of Aryl Alkyl Ketones.

“…It is worth noting that the HWE reaction of ketone 3b with the o-tolyl group has not been observed to occur under NaH conditions, whereas the reaction readily proceeds under Sn(OSO 2 CF 3 ) 2 conditions (each entry 2 in Tables 1 and 2 10) an efficient fluorinating building-block, 11,12) also provided the excellent stereoselectivity in the HWE reaction under the Sn(OSO 2 CF 3 ) 2 conditions, as shown in Chart 3 and Table 3. (E)-a-Fluoro-a,b-unsaturated esters 5a, b, d-f were obtained as major products in each corresponding reaction (entries 1, 2, 4, 5, and 6 in Table 3).…”