Hypervalent iodine reagents solvent-free preparation

Solvent-free reactions have many advantages such as reduced pollution, lower costs and the simplicity of the processes involved [60]. The solvent-free preparation of several important hypervalent iodine reagents has been reported [61,62], [Hydroxy(sulfonyloxy)iodo]arenes (42) have been prepared in excellent yields by the solid-state reaction simply by grinding (diacetoxyiodo)arenes and appropriate sulfonic acids for several minutes in an agate mortar [61]. Tosyloxy- and mesyloxy benziodoxoles 44 can be prepared by a similar solvent-free procedure starting from 2-iodosylbenzoic acid (43) [61], Likewise, [hydroxy(phosphoryloxy)iodo]arenes 46 have been conveniently prepared by a solvent-free method from (diacetoxyiodo)arenes and phosphate esters 45 (Scheme 6.17) [62],... 

Several examples of solvent-free reactions of hypervalent iodine reagents under microwave irradiation conditions have been reported [2, 68-72], A solvent-less oxidation of 1,4-dihydropyridines to the respective pyridines can be performed using [bis(trifluoroacetoxy)iodo]benzene at room temperature under microwave irradiation conditions [68], Carbonyl compounds (aldehydes, ketones and esters) can be converted into the respective a-[(2,4-dinitrobenzene)sulfonyl]oxy carbonyl compounds by the reaction of the neat carbonyl compounds with [hydroxy(2,4-dinitrobenzenesulfonyloxy)iodo]benzene (HDNIB) under microwave irradiation in less than 40 s [69], Likewise, a-halocarbonyl compounds 55 can be conveniently prepared by sequential treatment of carbonyl compounds 54 with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation (MWI) conditions (Scheme 6.21) [70],... 

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