Leveraging Cascade Alkynyl Prins Cyclization Towards the Stereoselective Synthesis of Spiro-Furan Quinazolinone Scaffolds.

A TfOH-promoted, metal-free protocol has been unveiled for the synthesis of spiro-furan quinazolinones employing alkynol urea derivatives utilizing alkynyl Prins cyclization reaction. This methodology produces highly functionalized spiro-heterocycles in excellent yields with exclusive E-selectivity under ambient conditions. Furthermore, late-stage modifications incorporate bromide and acetyl functionalities into the synthesized spiro-heterocycles. Highly functionalized spiro-furan quinazolinone scaffolds employing cascade alkynyl Prins cyclization reaction with an exocyclic double bond in excellent yields and exclusive selectivity are revealed.