Synthesis Of Furan-2(5H)-ones And 2H-pyran-2-ones By Base-Mediated Tandem Reaction Of Alkynes

The furanones and pyranones are very important classes of heterocycles widely found in many naturally occurring products and biologically active compouds, and these compounds display many bioactivities, such as sterilization, anticancer activity, antioxidation and antibrowning. Furanone compounds are used as flavoring agents in food, tobacco and beverage. Pyranone compounds are known as a set of new drugs for anti-AIDS. Due to their broad range of pharmacological activities, considerable effort has been devoted to the development of new and efficient methods for the synthesis of furanones and pyranones derivatives.The domino reaction is one of the most powerful synthetic tools for the rapid and efficient assembly of various cyclic and polycyclic structures. Base-mediated tandem reaction with high atom economy and environmental friendliness has been developed for the cheap and efficient synthesis of heterocyclic compounds. This dissertation focuses on the development of novel methods for the furanones and pyranones derivatives preparation through base-mediated tandem reaction of alkynes.1. A novel and selective protocol has been presented for the synthesis of 4,5-disubstiuted furan-2(5H)-ones by base-mediated intramolecular tandem acyl shift/ nucleophile addition/ cyclization/ decarbonylation reactions of various alkynes. In the present of KOAc, a variety of alkynes underwent the reaction to afford the corresponding furanones in moderate to good yields. Mechanism involving an acyl shift process was proposed for this transformation on the basis of the observed isotope effect values.2. The first example of synthesizing 4,5,5-trisubstiuted furan-2(5H)-ones by bases-mediated tandem acyl migration/carbon nucleophilic cyclization/decarbonylation/Michael addition Reactions of alkynes with alkenes has been developed. In the present of KOAc and CsF, a variety of alkynes underwent the domino reaction with alkenes to afford the corresponding products in moderate yields.3. A newly selective method has been developed for the synthesis of 4,5,6-trisubstiuted 2H-pyran-2-ones by base-mediated tandem nucleophile addition/ cyclization reactions of various alkynes. In the present of KOAc and CsF, a variety of alkynes underwent the reaction to afford the corresponding pyranones in moderate yields.