The dimer of 1-(5-nitro-2-pyridyl)-3-oxidopyridinium and its reactions
Abstract
The betaine 1-(5-nitro-2-pyridyl)-3-oxidopyridinium reversibly forms a dimer which provides a convenient source of the reactive betaine monomer; olefinic dipolarophiles add readily at the 2,6-positions, 2,3-dimethylbutadiene reacts across the 2,4-positions and stereochemical integrity is preserved during the addition of maleic and fumaric esters.