Synthesis and conformational properties of 5,7-disubstituted [3.3] Metacyclo (2,5) thiophenophane-1,12-diones

✍ Scribed by Yuji Miyahara; Takahiko Inazu; Tamotsu Yoshino

• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 235 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)99899-x

✦ Synopsis

The title compounds showed unique conformational equilibria which were dependent upon the substituents in the 5,7-positions, the predominant conformers being in a syn O,S,Ocis,cis conformation with a highly deformed thiophene-2,5-dicarbonyl moiety. --0 As reported previously, [3.3](2,51furano(2,5lthiophenophane-l,lldione _5. shows a yellow band arising from the charge-transfer 0 0 S interaction between its electron-rich furan and electron-deficient 2,5_diacylthiophene moieties'. While Lshows only a slight change in 0 its NMR spectrum over a wide temperature range, [3.3]metacyclo(2,51-L thiophenophane-1,12-dione 2 exhibited unexpected DNMR spectra. We wish to report here the synthesis of 2 and its derivatives Ewith substituents Y, to simplify the NMR spectra, at the 5,7-positions and their unique conformational properties as determined by the DNMR spectroscopy and the X-ray crystallography.

' 3) HX (X=Cl,Br)