[1,5]-Oxy/Thio/Azole Sigmatropic Rearrangement versus Indolyl-Spirocyclization: Tandem Reactions of 2-Azidobenzoate with Isocyanides for Accessing Quinazolin-4(3<i>H</i>)-ones

A general protocol for the synthesis of a variety of functionalized quinazolinones has been developed through a sequential Pd-catalyzed coupling/1,5-alkyloxy/thio/azole shift/6π electrocyclization reaction of isocyanides and 2-carbonylaryl azides. When 3-(2-isocyanoethyl)indoles were utilized, an unusual competitive reaction between [1,5]-shift and indole-spirocyclization was observed, which renders a modular synthesis of quinazolinones and spiroindolenine-3,3'-pyrrolo[2,1-<i>b</i>]quinazolinones in a highly chemoselective manner.