(1E,3E,5E)-1,2,3,4,5,6-Hexafluoro-1,6-diphenylhexatriene

Abstract

The title triene, C(18)H(10)F(6), was prepared via the Pd(0) coupling reaction of (E)-(1,2-difluoro-1, 2-ethenediyl)bis(tributylstannane) with (Z)-beta-iodo-alpha, beta-difluorostyrene in N,N'-dimethylformamide/tetrahydrofuran. The crystal structure shows the product to be the 1E,3E,5E isomer. Due to steric interactions between F atoms, the double bonds are not coplanar. The planes defined by the two terminal double bonds are almost perpendicular.

Stereospecific preparation of (1E,3E,5E)-3.4-difluoro-1,6-diphenylhexatriene and (2E,4E,6E)-diethyl-4,5-difluoroocta-2,4,6-trienedioate

“…In the examples cited in references [1][2][3][4][5], the coupling partner with 1 was either a fluorine-containing vinyl iodide or an aryl iodide. To illustrate that a non-fluorine-containing vinyl halide would enable one to stereospecifically prepare a mixed polyene system and to demonstrate that a vinyl iodide was not a necessary requirement for the vinyl halide component, we utilized b-bromo styrene as the vinyl halide precursor.…”

“…With a vinyl halide, such as iodotrifluoroethene, 1 with Pd(0) catalysis, gave the first direct route to (E)-1,3,5-octafluorohexatriene [4]. Similarly, Gao prepared (1E,3E,5E)-1,2,3,4,5,6,hexafluoro-1,6-diphenylhexatriene via Pd(0) coupling of 1 with (Z)-1-iodo-2-phenyl-1,2-difluoroethene [5].…”

Preparation of E-(1,2-difluoro-1,2-ethenediyl)bis(tributylstannane)

“…Metallation of (Z)-1,2-Difluoroethenyltributylstannane is straightforward. This bisstannane can be selectively reacted with vinyl halides [2][3][4], aryl halides [5] to yield isomerically pure fluorinated stilbenes and polyenes [6]. Recently, this procedure has been applied for the preparation of poly(-arylenevinylenes) with fluorinated vinyl units.…”

“…It was transferred via a syringe. 4 Tetrahydrofuran (THF) was dried by distillation from sodium benzophenone ketyl. 5 F 2 C5 5CFCl was first condensed from a commercial cylinder into a glass trap, which was cooled with dry ice.…”

The stereospecific preparation of (E)-1,2-difluoro-1,2-disubstituted alkenes

“…As we have demonstrated several times [2][3][4][5][6][7][8][9][10][11][12][13], fluorinecontaining vinylstannanes readily undergo Stille-Liebeskind coupling with aryl iodides. The preferred conditions utilize Pd(PPh 3 ) 4 /Cu(I)I/DMF.…”