We report a new approach for a highly regioselective synthesis of isoquinolones from various substituted benzamides and alkynes.

A highly regioselective synthesis of pyrido[2,1‐a]isoindolium salts from 2‐arylpyridines and two equivalents of electron‐deficient alkenes catalyzed by rhodium is demonstrated. The reaction was carried out in aqueous medium at 110 °C using inexpensive oxygen as oxidant. Reverse aza‐Michael addition of the isoindolium salt occurs when the salt was treated with base to give a β‐disubstituted alkene product. A reaction mechanism involving an ortho C–H olefination of 2‐arylpyridine by alkene, intramolecular aza‐Michael addition, deprotonation at the β‐carbon of the alkene fragment followed by another Michael addition to give the final product is proposed.magnified image

Palladium-catalyzed cycloaromatization of N-acyl-2-aminobiaryls, through a sequence of ortho CÀH bond activation/alkyne insertion/meta CÀH bond activation/alkyne insertion, was developed. An efficient synthesis of multiaryl-substituted naphthalenes, N-[2-(5,6,7,8-tetraarylnaphthalen-1yl)aryl]acetamides, was demonstrated using molecular oxygen as the sole oxidant. Furthermore, through Buchwald's synthetic protocol, two compounds were converted into corresponding fluorescent carbazoles in 30-40% yield by intramolecular CÀN bond formation.

The synthesis of phenanthridinones via denitrogenative annulation of 1,2,3‐benzotriazin‐4‐(3H)‐ones with arynes catalysed by Ni(0)/dppm was successfully developed. A variety of phenanthridinones were prepared in good to excellent yields. Based on this method, nature product, N‐methylcrinasidine, was synthesized.magnified image

Denitrogenative ortho-arylation, vinylation and methylation of 1,2,3-benzotriazin-4-(3H)-ones with organic boronic acids catalyzed by nickel complexes to give a wide range of o-substituted benzamides were demonstrated. Further, the catalytic reaction is successfully applied to the synthesis of the popular hypertensive drugs losartan and irbesartan in high yields.