10-Fluoro-all-trans-α-retinal

Abstract

Abstract. C20H27FO , M r = 302.41, monoclinic, P2~/c, a=6.105(5), b=21.673(22), c=13.925(7)/~, fl = 96.66 (5) ° , V= 1830 (2),~3, Z=4, Dx= 1.10, D m = 1.09 (1) gcm -3, ~(Mo Ka) = 0.71073/~, /1 = 0.68 cm -~, F(000) = 656, T= 298 K, R = 0.062, wR =0.046 for 1797 unique observed reflections. The principal distortions in the polyene portion of the molecule can be seen in the angles opposite the methyl groups (119.9 and 121.7 °, a steric effect) and that opposite fluorine (131.9 ° , an inductive effect). The hexene ring is in the half-chair form, and its double bond is not in conjugation with the all-trans chain.

The First Structure of a Vicinal (E)-Fluoroselenoolefin: (E)-(5-Fluoro-4-octen-4-yl)dimethylselenonium Picrate

“…The C5--F bond length in (8) corresponds well with that in l O-fluoro-all-trans-a-retinal (1.381 ,~;Ratnapala & Serf, 1988) and in 2-cyclohexylidene-2-fluoroacetic acid (1.369 A; Abraham et al, 1986). Thus, it is somewhat longer than in potassium hydrogen difluoromaleate and potassium hydrogen difluorofumarate (1.342 and 1.338 A, respectively; Mattes & G6hler, 1980) or (E)-Ifluoro-2-bromovinyl phenyl sulfone (1.301/~; Shainyan & Belskii, 1991).…”

“…This corresponds to the situation in other fluoroolefins, e.g. lO-fluoro-all-trans-c~-retinal (117.4, 110.7, 131.9°;Ratnapala & Serf, 1988), potassium hydrogen difluoromaleate (116.8, 111.9, 131.4°; Mattes & G6hler, 1980) and 2-cyclohexylidene-2-fluoroacetic acid (118.9, 110.1, 130.1 o; Abraham et al, 1986).…”

“…Thus, it is somewhat longer than in potassium hydrogen difluoromaleate and potassium hydrogen difluorofumarate (1.342 and 1.338 A, respectively; Mattes & G6hler, 1980) or (E)-Ifluoro-2-bromovinyl phenyl sulfone (1.301/~; Shainyan & Belskii, 1991). The fluorovinyl double bond, C~5, is somewhat longer than the corresponding bond in lO-fluoro-all-trans-a-retinal (1.322A;Ratnapala & Serf, 1988) and potassium hydrogen difluorofumarate (1.307,~; Mattes & G6hler, 1980). However, it is significantly longer than in the above-mentioned difluoroethenediyl diphosphonate (1.289,~; Su et al, 1990) and (E)-1-fluoro-2-bromovinyl phenyl sulfone (1.301,4,; Shainyan & Belskii, 1991).…”

“…1). The few known monofluoroalkene reference structures are: (Ratnapala & Serf, 1988), 2-cyclohexylidene-2-fluoroacetic acid (Abraham, Ellison, Schonholzer & Thomas, 1986) and (E)-l-fluoro-2-bromovinyl phenyl sulfone (Shainyan & Belskii, 1991). Moreover, the following difluoroalkene structures have been described: zinc trans-l,2-difluoroethenediyldiphosphonate (Su et al, 1990), potassium hydrogen difluoromaleate and potassium hydrogen difluorofumarate (Mattes & G6hler, 1980), and 1,2-difluoro-2-(pentafluorosulfanyl)vinyltrimethylphosphonium tetrafluoroborate (Wessolowski et al, 1992).…”

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

“…A search in the Cambridge Structural Database (CSD), Version 5.31, November 2009; Allen, 2002 [10] for H vinyl Á Á ÁF vinyl intermolecular interactions yielded only three instances with the HÁ Á ÁF distance less than van der Waal contact plus 0.1 Å [11][12][13].…”