Synthesis of iron thienyl complexes

Abstract

Dimetallation of thiophene (TH 2), bithiophene (BTH 2) and 3,6-dimethyl[3,2- b]thienothiophene (TTH 2) using a slight excess of butyl lithium, followed by the addition of [FeCp(CO) 2I], resulted in the formation of [2,5-{FeCp(CO) 2} 2T], 1 and [2-{FeCp(CO) 2}T]. The analogous reaction with bithiophene as precursor afforded similar products [2,2′-{FeCp(CO) 2} 2BT] 2 and [2-{FeCp(CO) 2}BTH] 3. In addition to the expected mono- ([2-{FeCp(CO) 2}-TTH] 4) and binuclear ([2,2′-{FeCp(CO) 2} 2-TT] 5) products, dimetallation of 3,6-dimethyl[3,2- b]thienothiophene and the subsequent reaction with [FeCp(CO) 2I] yielded carbonyl inserted mono-([2-{FeCp(CO) 2}C(O)-{TT} 2H] 6) and binuclear ([2-{FeCp(CO) 2}C(O)-{TT} 2-2′-{FeCp(CO) 2}] 7) carbon–carbon coupled products. The precursor [2,7-{SnMe 3} 2-TT] ( 8) was prepared and reacted with [FeCp(CO)(PEt 3)I] in the presence of a palladium catalyst to afford [2-{FeCp(CO)(PEt 3)}C(O)-{TT} 2-2′-{SnMe 3}] 10.