Studies On Cyclocondensation And Dehydration Of Propargyl Alcohols

With the decrease of resource on earth and the deterioration in environment, the concept of atom economy in organic synthesis has got extensive research and attention, which is the key point in recent organic synthesis research. Atom economy reactions can make the best use of raw materials and produce the least pollution. Development of atom economy in organic synthesis reactions has important academic value and application prospect.Heterocyclic oxygen compounds are of great significance because the biological activity and drug function of many natural products are relevant to the structural unit with oxygen atoms. Therefore developing new, environment-friendly and efficient methods for synthesis of oxygen heterocyclic compounds has become one of the most important research topics in organic synthesis.Low-valent rhenium complexes are moisture-and air-tolerant compounds, which can be employed as Lewis acid catalysts. This paper shows that2,2-dimethylchromene derivatives can be synthesized by the Re(CO)5Br catalyzed cyclodehydration of phenols with2-methylbut-3-yn-2-ol. The procedure is simple and mild without any need of deoxygenization and dehydration of reaction system.Conjugated enyne compounds not only have properties of isolated alkenes and alkynes, but also have the special properties. These compounds are important raw materials or intermediates in organic synthesis and therefore widely used in pesticides and drugs synthesis. This paper shows that conjugated enynes can be synthesized by dehydration of alkynyl alcohols, with POC13as dehydrating agent and pyridine as the solvent, at90℃for eight hours, the isolated yield can reach more than70%. This reaction system is characterized by simple operation, high efficiency, and single product.