Efficient synthesis of 2-iodo and 2-dicyanomethyl derivatives of thiophene, selenophene, tellurophene, and thieno[3,2-b]thiophene

An effective synthesis of 2-iodothiophene, 2-iodotellurophene, and 2-iodothieno[3,2-b]thiophene and a Pd-catalyzed carbon-carbon coupling reaction of these iodo derivatives as well as 2-iodoselenophene with malononitrile affording novel thienyl-, tellurienyl-, thieno[3,2-b]thienyl-, and selenienylmalononitrile are described. These heteroarylmalononitriles are important synthons for the preparation of 2-dicyanomethylene-2,5-dihydroheterophene chromophores.