Use of Stable Amine-Capped Polyynes in the Regioselective Synthesis of Push–Pull Thiophenes

The reactions of a series of 1-halopolyynes
with secondary amines
led to novel amine end-capped polyynes exhibiting surprisingly high
stability toward moisture. The new compounds were characterized by
NMR spectroscopy, ESI-MS spectrometry, and X-ray single-crystal diffractometry.
The use of amine end-capped polyynes as precursors to substituted
push–pull thiophenes was next presented. The results show the
firstto the best of our knowledgetransformation of
ynamine to thiophene and the first regioselective transformation of
a longer polyynes to butadiyne-substituted thiophene. Photophysical
studies of the resulting compounds show that some of the substituted
thiophenes have high quantum yield photoluminescence upon UV light
irradiation.