Abstract According to the 1 H and 13 C NMR data, 3-arylpropynoic acids and their esters XC 6 H nC≡ C-CO 2 R (R= H, Me, Et) having electron-withdrawing substituents in the benzene ring (X= NO 2, CN, COMe, CO 2 Me) exist in HSO 3 F at− 80 to 0° C as XC 6 H nC≡ CC+(OH) OR ions. Derivatives with other substituents (X= H, F, Me, MeO) in HSO 3 F or CF 3 SO 3 H above− 40° C undergo protonation at the acetylenic carbon atom neighboring to ...
[Hollick, Jonathan J.; Golding, Bernard T.; Hardcastle, Ian R.; Martin, Niall; Richardson, Caroline; Rigoreau, Laurent J. M.; Smith, Graeme C. M.; Griffin, Roger J. Bioorganic and Medicinal Chemistry Letters, 2003 , vol. 13, # 18 p. 3083 - 3086]
