title: Nonsymmetrical 3,4-dithienylmaleimides by cross-coupling reactions with indium organometallics: synthesis and photochemical studies.
abstract: The synthesis and photochemical study of novel nonsymmetrical 1,2-dithienylethenes (DTEs) with a maleimide bridge have been carried out. The synthetic approach to the DTEs was based on successive selective palladium-catalyzed cross-coupling reactions of 5-susbtituted-2-methyl-3-thiophenyl indium reagents with 3,4-dichloromaleimides. The required organoindium reagents were prepared from 2-methyl-3,5-dibromothiophene by a selective (C-5) coupling reaction with triorganoindium compounds (R3 In) and subsequent metal-halogen exchange. The coupling reactions usually gave good yields and have a high atom economy with substoichiometric amounts of R3 In. The results of photochemical studies show that these novel dithienylmaleimides undergo a photocyclization reaction upon irradiation in the UV region and a photocycloreversion after excitation in the visible region, thus they can be used as photochemical switches. ON-OFF operations can be repeated in successive cycles without appreciable loss of effectiveness in the process.
authors.affiliation: Departamento de Química Fundamental and Centro de Investigaciones Científicas Avanzadas (CICA), Universidade da Coruña, 15071A Coruña (Spain), Fax: (+34) 981167065.
authors.forename: Angeles
authors.initials: A
authors.lastname: Mosquera
authors.forename: M Isabel
authors.initials: MI
authors.lastname: Férnandez
authors.forename: Moisés
authors.initials: M
authors.lastname: Canle Lopez
authors.forename: José
authors.initials: J
authors.lastname: Pérez Sestelo
authors.forename: Luis A
authors.initials: LA
authors.lastname: Sarandeses
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D007204:Indium / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes
chemical_list: D008301:Maleimides; D009942:Organometallic Compounds; D007204:Indium; C043592:maleimide
keywords: CC coupling; indium; palladium catalysis; photochemical reactions; photochromism