title: Reaction of acetylenic esters and N-functionalized phosphazenes. 1,2-versus 1,4-addition of N-vinylic phosphazenes.
abstract: Reaction of phosphazenes derived from aminophosphonates with acetylenic esters leads to conjugated phosphorus ylides. The formation of these stabilized ylides is explained through a [2 + 2] cycloaddition reaction of the P = N linkage of the phosphazene (1,2-addition) and the triple bond of the acetylenic ester followed by ring opening of the azaphosphete intermediate. However, in the case of N-vinylic phosphazenes, the phosphazenes derived from triphenyl- and trimethyl-phosphine react as enamines (1,4-addition) with diacetylenic esters, whereas in phosphazenes derived from trimethylphosphine a 1,2-addition of ethyl propiolate to the P = N linkage of the phosphazene is produced.
authors.affiliation: Departamento de Química Orgánica I, Facultad de Farmacia, Universidad del País Vasco, Apartado 450, 01080, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Palacios
authors.forename: Concepción
authors.initials: C
authors.lastname: Alonso
authors.forename: Jaione
authors.initials: J
authors.lastname: Pagalday
authors.forename: Ana María
authors.initials: AM
authors.lastname: Ochoa de Retana
authors.forename: Gloria
authors.initials: G
authors.lastname: Rubiales