A general catalyst for Buchwald-Hartwig amination to prepare secondary five-membered heteroaryl amines with breaking the base barrier

The scope limitation of substrates especially for five-member heteroaryl substrates often presenting in medical and bioactive molecules, along with high palladium loadings and sometimes needing strong bases, perplexes the application of the palladium-catalyzed CN cross-coupling reactions. The terphenyl phosphine TXPhos supporting palladium catalyst [(TXPhos)(allyl)PdCl] dramatically broadened the existing scope of five-membered heteroaryl substrates and made the weak bases KHCO3 and KOAc become general and optimal choices. Therefore, the barrier of bases has been broken and an attractive protocol for the preparation of secondary five-membered heteroaryl amines via the palladium-catalyzed CN cross-coupling reaction has been established.