BULLETIN DES SOCIETES CHIMIQUES BELGES, vol.102, no.7, pp.467-477, 1993 (SCI-Expanded)
In this study, the reactivities of 1-(2,4-dinitrophenyl)-, 1-(4,6-dimethylpyrimidin-2-yl)-, and 1-(5-nitro-2-pyridyl)-pyridinium-3-olates were tested upon various inductively and mesomerically electron rich dipolarophiles. N-substituted pyridinium-3-olates react across the 2,6-positions with 2pi-dipolarophiles whereas 4pi-dipolarophiles added across both 2,6 and 2,4 positions of the betaines.