Synthesis of benzofused 1,4-azaborinols via [4 + 2] annulation strategy and its application in indole synthesis

We disclose herein, the first general synthesis of benzofused 1,4-azaborinols via [4 + 2] annulation strategy. These compounds have been synthesised from 2-amino phenylboronic acids/boronates and alkynes in excellent yields. Additionally, we demonstrate their synthetic application by reporting the first transformation of benzofused 1,4-azaborinols into functionalized indoles.