Synthesis of Pyrimidines and Quinazolines via Acceptorless Dehydrogenative Coupling Catalyzed by PNN‐Pd Complex

Abstract In this study, we report the catalytic application of Pd II PNN [PNN: 2,6‐{(R 2 P)N(H)(C 5 H 3 N)(C 2 HN 3 C 6 H 5 )}] ( L1 R = Ph; L2 R = t Bu) pincer complexes ( Pd1 – Pd4 ) for the sustainable and cost‐effective synthesis of pharmacologically important pyrimidines and quinazolines by acceptorless dehydrogenative coupling of alcohols. Among four mixed donor PdII aromatized and dearomatized complexes, [PdCl{ R P H NN‐κ 3 ‐P,N,N]Cl and [PdCl{ R PNN}‐κ 3 ‐P,N,N] (R = Ph or t Bu), tert‐butylphosphinyl complex was found to be more efficient in the catalytic reactions. A wide range of substituted pyrimidine (45 examples) derivatives was synthesized from amidine, benzyl alcohols and ketones using Pd2 (0.1 mol%) in toluene at 110 °C. Further, the catalyst was found to be effective for the synthesis of quinazolines (22 examples) using 2‐aminobenzyl alcohols and benzonitriles. HRMS and NMR studies confirmed reactions proceeding through Pd‐alkoxide and Pd‐hydride intermediates.