title: Synthesis and Reactivity of New 1,4-Bis(alkylthio)-3,6-diarylthieno[3,4-c]thiophene Derivatives.
abstract: 1,4-Bis(tert-butylthio)-3,6-diphenyl- and 3,6-di(2-thienyl)thieno[3,4-c]thiophenes (2a,b)were synthesized from 2-(tert-butylthio)-3-phenyl- and 3-(2-thienyl)cyclopropenethiones (1a,b) and triphenylphosphine in dry benzene at 50 degrees C, although similar treatment of 2,4,6-triisopropylphenyl, N,N-diethylamino, pyrrolidino, and diphenyl-substituted cyclopropenethiones (1c-h) did not result in the production of the corresponding thieno[3,4-c]thiophene derivatives. The possible reaction pathway for the formation of 2a,b is described. The protonation of 2a with trifluoroacetic acid (TFA) gave 4-(tert-butylthio)-3,6-diphenylthieno[3,4-c]thiophene-1(3H)-thione (13a), the treatment of which with sodium hydride and then isopropyl iodide led to 4-(tert-butylthio)-3,6-diphenyl-1-(isopropylthio)thieno[3,4-c]thiophene (16) by the regeneration of the thieno[3,4-c]thiophene ring system, this making possible the synthesis of other alkylthio-substituted thieno[3,4-c]thiophene derivatives. The reactions of 2a,b with N-phenylmaleimide (NPM) gave predominantly the endo-cycloadducts (17a,b) at the 1- and 3-positions, and that of 2a with dimethyl acetylenedicarboxylate (DMAD) led to the benzo[c]thiophene derivative (19) by desulfurization.
authors.affiliation: Department of Applied Chemistry, College of Engineering, Osaka Prefecture University, Sakai, Osaka 599, Japan and Department of Applied Physics and Chemistry, The University of Electro-Communications, Tokyo 182, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Matsumura
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yagyu
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mizuno
authors.forename: Hiroo
authors.initials: H
authors.lastname: Inoue
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Takada
authors.forename: Masanori
authors.initials: M
authors.lastname: Yasui
authors.forename: Fujiko
authors.initials: F
authors.lastname: Iwasaki