No abstract

The recent groundbreaking developments in the application of diaryliodonium salts in cross-coupling reactions has brought this class of previously underdeveloped reagents to the forefront of organic chemistry. With the advent of novel, facile, and efficient synthetic routes to these compounds, many more applications can be foreseen. Herein we provide an overview of the historical and recent advances in the synthesis and applications of diaryliodonium salts.

The first one-pot synthesis of neutral and electron-rich [hydroxy(tosyloxy)iodo]arenes (HTIBs) from iodine and arenes is presented, thereby avoiding the need for expensive iodine(III) precursors. A large set of HTIBs, including a polyfluorinated analogue, can be obtained from the corresponding aryl iodide under the same conditions. The reaction proceeds under mild conditions, without excess reagents, and is fast and high-yielding. Together, the two presented routes give access to a wide range of HTIBs, which are useful reagents in a variety of synthetic transformations.

The results of our research into the Bohlmann-Rahtz pyridine synthesis are summarized. The historic discovery of this reaction and its mechanism are discussed; followed by recent improvements in methodology, such as Brønsted and Lewis acid catalysis, microwave assistance, process in a continuous flow reactor, and incorporation into multicomponent and tandem reactions. Applications of these methods in the synthesis of pyrido[2,3-d]pyrimidines, combinatorial pyridine libraries, heterocyclic a-and gamino acids, a-helix mimetics, and complex natural products are discussed, along with a consideration of future perspectives.

Di-or trisubstituted pyrimidine libraries are prepared in good yield by the microwave irradiation of an alkynone and either an amidine or guanidine at 120 ± 150 8C in acetonitrile in the presence of sodium carbonate or at 100 8C after treatment with methanolic sodium methoxide in a sealed tube using a monomodal microwave synthesiser. These rapid and efficient methods often require no chromatographic purification and so are appropriate for automated combinatorial methodology and have been applied in the synthesis of a small library of potentially useful novel ligands for the estrogen receptor based on the pyrimidine template.