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Synthesis 2003(13): 2089-2095
DOI: 10.1055/s-2003-41451
PAPER
© Georg Thieme Verlag Stuttgart · New York

An Improved Synthesis and Structural Characterisation of 2-(4-Acetylthiophenylethynyl)-4-nitro-5-phenylethynylaniline: The Molecule Showing High Negative Differential Resistance (NDR)

Changsheng Wanga, Andrei S. Batsanova, Martin R. Bryce*a, Ian Sageb
a Department of Chemistry, University of Durham, Durham, DH1 3LE, UK
Fax: +44(191)3844737; e-Mail: m.r.bryce@durham.ac.uk;
b QinetiQ, St Andrews Road, Malvern, Worcestershire WR14 3PS, UK
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Publication History

Received 28 May 2003
Publication Date:
10 September 2003 (online)

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Abstract

2-(4-Acetylthiophenylethynyl)-4-nitro-5-phenyl-ethynyl-aniline (11) has been synthesised by an improved route, which has many advantages over the literature procedure. A key intermediate is 2-ethynyl-4-nitro-5-phenylethynylaniline (6) which is obtained from 2,5-dibromoacetanilide (5 steps, 68% overall yield). Reaction of 6 with 1-acetylthio-4-iodobenzene under Sonogashira coupling conditions affords 11 (56%). Compound 11 is characteris­ed by CHN analysis, mass spectrometry and 1H and 13C NMR spectroscop­y. The crystal structures of 2-bromo-4-nitro-5-phenylethynylani­line (4), 2-(3-hydroxy-3-methylbutynyl)-4-nitro-5-phenyl­ethynylaniline (5) and 2-[(4-methoxybenzylthio)phenylethynyl]-4-nitro-5-phenylethynylaniline (15), have been determined, by which the regiochemical structure of 11 is also proved. The intramolecul­ar contacts O(1)···C(7) of 2.692(2) Å in 4 and 2.677(2) Å in 15 are considerably shorter than the standard van der Waals O···C contact of 3.24 Å.

Key words

2-(4-acetylthiophenylethynyl)-4-nitro-5-phenylethynyl-aniline - negative differential resistance - molecular wires - Sono­gashira coupling