Multicomponent Synthesis of Triazoloquinazolines

Significance

Reported is the synthesis of triazoloquinazolines by a multicomponent reaction of quinazolines, aldehydes, and N-isocyaniminotri­phenylphosphorane. A plausible mechanism is proposed which rationalizes both the formation of the desired product and the triphenylphosphine oxide byproduct. Although the N-isocyaniminotri-phenylphosphorane starting material is commercially available, it is somewhat expensive. How­ever, it is inexpensively made by the reaction of ­hydrazine carboxaldehyde and triphenylphosphine. Although this reagent is not often used as a starting material in organic synthesis, it has ­recently been gaining popularity in this type of ­cyclization.