Transition‐Metal‐Free Synthesis of 4‐Alkynylquinazolines.

Protocols have been developed that allow easy access to 4‐alkynylquinazolines under transition‐metal‐free conditions. The ring opening reaction of 4‐(benzofuran‐2‐yl)quinazolines obtained from the arylation of quinazolines with benzofuran is the first way to achieve 4‐alkynylquinazolines. Direct alkynylation of quinazolines with terminal alkynes in the presence of n‐BuLi and iodine or with alkynyl Grignard reagents is another strategy. Desilylation of 4‐((trimethylsilyl)ethynyl)quinazolines obtained by direct alkynation is the third approach to give 4‐alkynylquinazolines. It has also been shown that the protocols are applicable for scale‐up synthesis. [ABSTRACT FROM AUTHOR]