Reaction of pyrrole anions with carbon disulfide. Synthesis of pyrrole-3-carbodithioates

2,5-Disubstituted pyrroles react with carbon disulfide in the system KOH-DMSO with selective formation of pyrrole-3-carbodithioate anions from which pyrrole-3-carbodithioates were prepared by ethylation in 36-61% yield. From 2-methyl-5-phenyl(2-furyl- or 2-thienyl)pyrroles only pyrrole-3-carbodithioates are formed, wi th no isomeric pyrrole-4-carbodithioates being present. The reaction direction depends on pyrrole ring substitution: unsubstituted pyrrole selectively forms pyrrole-1-carbodithioate, whereas 2-methyl-, 2,3- and 2,4-dimethylpyrroles give exclusively pyrrole-2-carbodithioates under the same conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.