Thienothiophenes. Part 2.1 Synthesis, metallation and bromine→lithium exchange reactions of thieno[3,2-b]thiophene and its polybromo derivatives
- 1 January 1997
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 22,p. 3465-3470
- https://doi.org/10.1039/a701877k
Abstract
Methods for the large-scale synthesis of thieno[3,2-b]thiophene [including a catalytic vapour-phase reaction (at 550 °C) between 2-(2-thienyl)ethanol and carbon disulfide], its 2-carboxylic acid and its 3,6-dibromo and 2,3,5,6-tetrabromo derivatives are reported. With 2 mol equiv. of butyllithium thieno[3,2-b]thiophene gives its 2,5-dilithiated derivative and its 3,6-dibromo derivative gives the 3,6-dilithiated compound. By quenching with suitable electrophilic reagents these dilithiated compounds have been converted into various 2,5- or 3,6-disubstituted thieno[3,2-b]thiophenes, respectively. Likewise 2,3,5,6-tetrabromothieno[3,2-b]thiophene has been converted into 2,5-disubstituted 3,6-dibromothieno[3,2-b]thiophenes.Keywords
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