Progress In The Study Of Synthesis Methods On Benzofuran And Quinazoline Compounds With Paraformaldehyde

Heterocycles are ubiquitous in natural products and pharmaceutical molecules,they have excellent biological activity and important application value,often used for the preparation of specific polymers,dyes and biologically active molecules.Therefore,the exploration and development of new methods for synthesis of heterocyclic compounds is one of the focuses of organic synthesis chemistry.Paraformaldehyde(PFA)and formalin are versatile one-carbon homologation reagents,and PFA as the polymer form of formaldehyde has the advantages of easy transportation,handling,storage and use,so it has aroused great interest of researchers.The development new synthesis of 2-aroylbenzofuran and 2-arylquinazoline compounds using paraformaldehyde as the carbon source was described in this paper.1.We developed a straightforward and efficient access to 2-aroylbenzofurans from 2-bromophenols,phenacyl bromides and paraformaldehyde through palladium-catalyzed transformations.The cheap and stable paraformaldehyde served as the carbon source via an in situ formylation reaction.The system has good compatibility with functional groups,such as halogen and trifluoro-methyl were well tolerated under the reaction conditions.This three-component approach provides a new route for the synthesis of 2-aroyl substituted benzothiophenes.2.We developed a novel approach for the synthesis of 2-arylquinazolines under transition-metal-free conditions.The stable and low toxicity paraformaldehyde is used as the one-carbon source to construct heterocycles.The reaction system has good atom economy and compatibility of functional groups,halogen and heterocycles were well tolerated under the reaction conditions.This novel method provides a new route for the synthesis of 2-arylquinazolines.