Synthesis of 2,3-Dihydroselenophene and Selenophene Derivatives by Electrophilic Cyclization of Homopropargyl Selenides

The synthesis of several highly functionalized 2,3-dihydroselenophenes from homopropargyl selenides via electrophilic cyclization is described. Electrophiles such as 12, ICI, and PhSeBr were used in a simple process employing CH2Cl2 as solvent at room temperature, which gave the cyclized products in high yields. 4-lodo-2,3-dihydroselenophenes obtained by this methodology were submitted to a dehydrogenation reaction using 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) to give 3-iodoselenophenes. 4-lodo-5-phenyl-2,3-dihydroselenophene was also submitted to the thiol copper-catalyzed and Heck-type reactions giving the desired products under mild reaction conditions.