Fluorinated vinylzinc reagent preparation

Table 4. Preparation of Fluorinated Vinylzinc Reagents from (F)-Vinyl Halides and Zinc Metal [110]...

Fluorinated vinylzinc reagents can be prepared by three methods (1) capture of the corresponding vinyllithium reagents at low temperatures with a zinc salt (2) capture of the corresponding vinyllithium reagent in situ with a zinc salt at ambient temperatures or (3) direct insertion of zinc into the carbon-halogen bond of a fluorinated vinyl halide. 

Related methodology has been utilized to prepare fluoroenynes either by coupling fluorinated vinyl halides with an acetylenic zinc reagent or via coupling of a fluorinated vinylzinc reagent with l-iodo-l-alkynes2,11, as illustrated in equations 17-21. 

The partially fluorinated vinylzinc reagent, reported by Shi and coworkers, has been utilized to prepare the fluoro analog of Naproxen and for the key intermediate for a novel synthetic pyrethroid (equations 67 and 68)44. 

Similar to the zinc insertion methodology for the preparation of fluorinated vinylzinc reagents (Section II.C), zinc reacts quantitatively with bromo- and iodopentafluorobenzene in coordinating solvents such as THF, Et20, DME, DG (diglyme), DMF, DMAC and DMSO to give bis(pentafluorophenyl)zinc (equation 72)68. These workers also obtained equilibrium constants for the Schlenk equilibrium between the mono/bis species via 19F NMR spectra. 

Fluorinated vinylzinc reagents have been prepared by two methods ... 

The preparation of fluorinated dienes is particularly advantageous via the palladium catalyzed coupling protocol. By proper selection of the appropriate vinylzinc reagent and vinyl iodide, a wide variety of fluorinated dienes can be stereospecifically prepared, as illustrated in equation 22. 

Table 7. Preparation of Fluorinated Vinylcopper Reagents via Exchange of Cu(I) Halides with Fluorine-Containing Vinylzinc or Cadmium Compounds [145]...

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