Pd-catalyzed oxidative amination of 2-alkenylquinazolin-4(3 H )-ones: synthesis of methylene and vinyl derivatives of pyrrolo(pyrido)[2,1- b ]quinazolinones.

When treated with the catalytic system Pd(OAc) 2 /PPh 3 /Cs 2 CO 3 /benzoquinone in dioxane or Pd(PPh 3 ) 2 Cl 2 / t -BuONa/Cs 2 CO 3 /benzoquinone in toluene, 2-butenylquinazolin-4(3 H )-ones undergo intramolecular aza-Wacker cyclization to give methylene-substituted pyrrolo(pyrido)[2,1- b ]quinazolinones. The latter catalytic system is also efficient in the reaction of pentenyl(hexenyl)quinazolin-4(3 H )-ones but, in these cases, the aminopalladation of C-H multiple bonds significantly competed with allylic C(sp 3 )-H bond activation which leads to hitherto unknown vinyl-substituted pyrrolo(pyrido)[2,1- b ]quinazolinones.