Study On Copper-mediated Cyclization Of Alkynes For The Synthesis Of 1-naphthols

1-Naphthols are important class of organic compounds that not only are used in organic synthesis,but they are also an important structural motif in numerous pharmaceuticals and natural products.In the past decade,the traditional synthesis methods have made much progress,which include: Diels–Alder reactions,transition-metal-mediated cyclizations,ring rearrangements or expansions,and Lewis acid catalyzed cyclizations.Nevertheless,the present synthetic methods to1-naphthols generally suffer from harsh conditions,low yield,employment of highly functionalized starting materials,preciouscatalysts,multiple synthetic steps and lack of substrate widespread.To address these limitations and to realize the construction of naphthols in an economic and green fashion,development of efficient methods using readily available starting materials and cheaper catalyst is of great significance.In this paper,two methods for the synthesis of 1-naphthols were developed using a copper-base catalyst system.The specific contents and research results are as follows:1.Copper-mediated cyclization of o-bromoaryl ketones with terminal alkynes for the synthesis of 1-naphthols.Highly regioselective synthesis of 1-naphthols compounds mediated by CuI,using readily available o-bromoacetophenones and terminal alkynes as starting materials.The reaction uses water as a solvent.The range of the alkyne is not limited to the phenyl-substituted terminal alkyne acetylene,the heteroaryl substitution,the alkenyl substitution,the chain terminal alkyne and biologically active estradiol ketone are also well suited for this system.The obtained 1-naphthol product was further expanded to synthesize a derivative of the insecticide,carbaryl.2.Copper-catalyzed cyclization of o-alkynyl aromatic ketones toward1-naphthols.CuI catalyzesd cyclization of o-alkynyl aryl ketone compounds toward1-naphthols.The reaction requires only 0.1% CuI as catalyst and water as solvent.The reaction operation is simple,and 1-naphthol is synthesized in a green and efficient manner.Innovatively proposed a copper-base system to catalyze the C-6-endo-dig cyclization of o-alkynyl aromatic carbonyl compounds to synthesize1-naphthol,which has potential applications in the industry.