The Synthesis Of Hydrogenated Pyrone Derivatives By The Cycloaddition Of Alkynes, 1,3-Diketone And CO

Atom-economic reaction can maximally transfer the starting material into the desired product, and is one of the ideal reactions in environment-friendly organic synthesis. In this dissertation, a three-component cyclocarbonylative reaction of terminal alkynes, 1,3-diketones and carbon monoxide has been investigated to develop an atom-economic synthetic method for the synthesis of O-heterocyclic compound.(1) The straightforward synthesis of 3,4,7,8-tetrahydro-2H-chromene- 2,5(6H)-dione by a [3+2+1] cyclocarbonylative coupling of aromatic terminal alkynes, 1,3-cyclohexanediones and CO catalyzed by Pd(PPh3)4 has been developed. It has also found that neither aliphatic alkynes nor internal alkynes can undergo the similar reaction. Moreover, aromatic terminal alkynes can not react with linear 1,3-diketones such as indanone, acetylacetone.(2) Under the similar reaction conditions, using DMF as solvent, 2-methyl-1-buten-3-yne, 1,3-cyclohexanediones and CO also proceeds the same cyclocarbonylative reaction to afford 3-alkylidene-3,4,7,8-tetrahydro- 2H-chromene-2,5(6H)-dione derivatives.(3) Unlike aromatic terminal alkynes, 2-methyl-1-buten-3-yne can reacts with linear 1,3-diketones to afford 3-alkylidene 3,4-dihydro-2H-pyran-2-one in moderate yields after 4 days.The presented catalytic system has the advantages of mild conditions, high selectivity and yield. The present research work not only provides a new atom-economic reaction for synthesis of O-heterocyclic compounds, but also extended the application of alkynes and 1,3-diketones in the synthesis of heterocyclic synthesis.