Palladium‐Catalyzed Acylation Reactions: A One‐Pot Diversified Synthesis of Phthalazines, Phthalazinones and Benzoxazinones

A sequential one‐pot strategy for the diversified synthesis of phthalazines, phthalazinones and benzoxazinones was presented. This strategy proceeds through [Pd]‐catalyzed acylation and nucleophilic cyclocondensation with dinucleophilic reagents. This process was based on direct coupling with simple bench‐top aldehydes without the assistance of directing group and without activating the carbonyl group. The process is highly advantageous because it employs simple nitrogen‐based nucleophiles, and non‐toxic and readily accessible aldehydes as the carbonyl source. Most importantly, the strategy was applied to the one‐pot synthesis of PDE‐4 inhibitor.