Intramolecular cyclization of dinitriles via zirconocene(IV)-phosphorus exchange reactions: Synthesis of sigma(3),lambda(3)-1-phospha- and sigma(3),lambda(3)-1,4-diphospha-2,6-diazines

Dinitrile cyclization reactions leading to new six-membered heterocycles 1- sigma(3),lambda(3)-phospha-2,6-diazines 3a,b and 1,4-sigma(3),lambda(3)-dip hospha-2,6-diazines 6, 7, and 8 are presented. These syntheses involve dini trile derivatives, Schwartz reagent [Cp2ZrHCl](n), and phosphorus compounds as promoted cyclization reagents. An X-ray crystal structure of the 1,4-si gma(3),lambda(3)-diphospha-2,6-diazine 8 is reported.