Reactions of trifluoromethyl and pentafluorophenyl isocyanide with double and triple bonds.

Abstract

Whereas the ligand behaviour of trifluoromethyl isocyanide has been studied intensively during the last years, the organic chemistry of CNCF 3 is much less developed. Herein we report the cycloaddition reactions of CNCF 3 with PP double bonds, CC and CS triple bonds. Diphosphenes react with CNCF 3 depending on the substituents at the phosphorus atom. With the [(CH 3) 3Si]C substituent the [2+1]-cycloaddition product is formed. However, changing the substituent to 2,4,6-C 6H 2 (t-C 4H 9) 3 a five membered heterocyclic compound is obtained containing an exocyclic PC double bond. The reaction of CF 3NC with alkynes yields bis(imino)cyclobuten derivatives as the stable products. Reaction of the CS triple bond of F 3 SCRf (Rf  CF3, SF 5) with the fluorinated isocyanides yield the alkylidyne sulfur difluorides R f ′NC(F)C(R f)SF 2 (R f ′  CF 3, C 6F 5) as a mixture of isomeres. With the SF 5 and C 6F 5 substituents, however, a single isomere can be detected by NMR spectroscopy, whose structure has been elucidated by X-ray crystallography.