Rh(iii)-catalyzed substrate-dependent oxidative (spiro)annulation of isoquinolones with diazonaphthoquinones: selective access to new spirocyclic and oxepine-fused polycyclic compounds

Abstract

Reported herein is a practical and selective assembly of novel isoquinolone-containing spirocyclic and oxepine-fused polycyclic skeletons through a rhodium(III)-catalyzed oxidative [4 + 1] spiroannulation or formal [4 + 3] annulation reactions of diverse NH-isoquinolones with diazonaphthalen-2(1H)-ones. Intriguingly, when 3,4-disubstituted or 3-aryl substituted isoquinolones were employed, diazonaphthalen-2(1H)-ones acted as C1 synthons to deliver spiro isoquinolone compounds in up to 98% yield. Whereas, with 3-heteroaryl substituted isoquinolones, this rhodium-catalyzed transformation switched to a formal [4 + 3] annulation to afford oxepine-fused polycyclic compounds in moderate yields. The present protocol features wide substrate scope, simple operation procedures, and excellent regioselectivity. Moreover, the further transformations of the obtained products showcased the potential applications of this synthetic protocol.