Study On The Tandem Cyclization Of α-carbonyl Acids And Alkynes

Cyclolactones are very important heterocyclic compounds,are widely found in natural products and drug molecules.Cyclolactone skeleton has unique biological activity and also is an important intermediate in the synthesis of drug molecules.Therefore,great attentions have been paid by chemists to the construction of the skeleton of cyclolactones.Although many achievements have been made,some key and challenging problems remain,such as the availability of starting materials,shorted reaction procedure,atom economy,harsh reaction conditions,and limited substrate scopes.Therefore,the development of mild and environmentally friendly methods for the selective synthesis of substituted cyclolactone compounds is desirable.In this context,phenantholactone and spironolactone were synthesized under mild conditions by usingα-carbonyl acid and alkyne as starting materials.The main contents are as follows:(1)We have developed a photoinduced transformation of α-carbonyl acid and substituted acetylene to selectively synthesize phenolactone compounds.Under the condition of no additional photosensitization and oxidant,the target product was synthesized with good to excellent yield.This reaction has the advantages of mild reaction conditions,simple operation,wide range of substrate and hydrogen as the only by-product.The mechanistic studies showed that the reaction underwent photoinduced free radical addition/cyclization and hydrogen evolution cascade processes.(2)We have reported a mothed for synthesis of spironolactones from easily availableα-carbonyl acids and 1,3-enynes in the presence of boron trifluoride ether.This method provides a novel,simple and efficient passway for the preparation of functionalized spironolactone with good to excellent yield.