a novel furan synthesis

✍ Scribed by S. Bartlett; R.D. Chambers; N.M. Kelly

• Book ID: 104225538
• Publisher: Elsevier Science
• Year: 1980
• Tongue: French
• Weight: 75 KB
• Volume: 21
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)92808-9

✦ Synopsis

y-ray induced addition of acetaldehyde to perfluoro-3,4-dimethyl-3-hexene gives a product which, in two novel steps, may be converted to a fluorinated furan.

In pursuing the unusual chemistry of fluorinated olefins of the type (RF)2C=C(RF)2 ' (where RF is a perfluoroalkyl group) we find that free-radical addition of acetaldehyde to perfluoro-3,4-dimethyl-3-hexene (1) occurs in very high yield, by y-ray initiation giving compound (2).

Reaction of (2) with tri-n-butylamine in tetraglyme induced a novel cyclisation, which is shown in the Reaction Scheme. This cyclisation step is interesting because it involves exclusive attack through oxygen (3a), rather than carbon (3b) in the enolate anion.

6-6+ Consequently, this step is a useful demonstration of the 'hardness' of a site F--C=C towards nucleophilic attack.

Pyrolysis of the cyclic compound (4) led to an efficient 1,3-sigmatropic shift of pentafluoroethyl, giving the new fluorinated furan (5). The chemistry of (5) and its precursors (2) and ( ) is under investigation. Surprisingly, photolysis of (5) did not give ring opening, which has been reported for other fluorinated furans, 2 but instead, loss of hydrogen fluoride, giving derivatives ( ) and ( ).

CF,. CF_ CF, CF_