Resumen de Transformations promoted by the hypervalent iodine reagents

Zhiyu Jia

• ABSTRACT The group¿s interest in the use of hypervalent iodine reagents for direct arene functionalization has led us to discover that a combination phenyliodine(bis-trifluoroacetate), PIFA, with simple alkali metal chlorides can be used to carry out chlorination of aromatic hydrocarbons in really mild conditions. Initially, a model reaction of the mono-chlorination of mesitylene (Scheme 1) was optimized. We then went on to explore the halogenation of other arenes. This work constitutes the first objective of the present doctoral thesis. More recently, as second main objective of this work, we studied and found that PIFA reacts directly with ß-diketones, ß-ketoesters and 2-oxocyclohexanecarbonitrile to give an ¿-arylation product, with a unique feature that the newly incorporated arene retains the iodine atoms ortho to the new C-C bond (Scheme 2). Given the synthetic potential of this reaction, we focused on improving the yields and the scope of this methodology and on preliminary mechanistic assays. The method is complementary to the metal-catalyzed ¿-arylation where C-I bond is converted into C-C. Our mechanistic hypothesis (unconfirmed) is a [3,3] sigmatropic rearrangement (¿iodonium Claisen¿) of the species 4 (Scheme 2) formed through the condensation of PIFA and 1-3-enol. The presence of the o-iodine on the aromatic ring of 1, 2 and 3 allows for easy access to derivatives.