Applications Of Phenyliodine(Ⅲ)-Bis(Trifluoroacetate)(PIFA) In The Synthesis Of Nitrogen-containing Heterocycles

Recently, hypervalent iodine reagents have been extensively used as the oxidationreagents in synthetic organic chemistry. One such reagent, phenyliodine(III)-bis(trifluoroacetate) (PIFA) has attracted considerable attention of research recently due to its ready availability, low toxicity, easy handling, and reactivity similar to that of heavy metal reagents. Such as Ti(Ⅲ),Hg(Ⅱ),Pb(Ⅳ). Its efficient utilization in the metal-free transformations relies on both the extremely mild reaction conditions required and its ability to oxidize chemoselectively a wide range of functionalities such as phenols, amines, sulfides, and carbonyl compounds. Tellitu and co-workers developed novel metal-free approaches to the synthesis of nitrogen-containing heterocycles using properly substituted amides and amines as synthetic precursors in which an intramolecular N-N, N-S, or N-C bond is formed through a PIFA-mediated oxidization process.α-Oxoketene dithioacetals are a kind of versatile intermediates used in organic synthesis. Base on its structure, it is widely used in organic synthesis. In the past decade, we have been devoting our efforts towards the synthesis and applications onα-oxoketene dithioacetals and achieved interesting results.Enaminones have emerged as versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident electrophilicity of enones. Their chemistry has been the focus of intense research for decades, particularly in heterocyclic synthesis, and continues to be an active area of research today. The pyrrole, oxazoles, pyridinones and quinolines have been prepared from enaminones. This work mainly based on the following two aspects:1.A facile and convenient one-pot synthesis of isothiazol-3-(2H)-ones is developed throughα-oxoketene dithioacetals and phenyliodine(III)-bis (trifluoroacetate) (PIFA). An intramolecular N-S bond is formed successfully. The use of innocuous oxidizer PIFA,simplicity of execution, ready availability of substrates,and potential products make this synthetic strategy much attractive.2.A convenient and efficient synthesis of highly substituted pyrrolin-4-ones is developed via the PIFA-mediated cyclization reactions of readily available. enaminones. This protocol is associated with readily available starting materials, mild conditions, good yields, and broad range of synthetic potential of the products. In summary, a facile and convenient synthesis of heterocyclic compounds is developed through a PIFA-mediated oxidization. The use of innocuous oxidizer PIFA, mild conditions, good yields, and broad range of synthetic potential of the products make this synthetic strategy much attractive.