Investigating the synthesis of unsymmetrical tetrathiafulvalene derivatives: Improved yields by the hidden equivalent method

✍ Scribed by Richard D. McCullough; Melissa A. Petruska; John A. Belot

• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 827 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00557-8

✦ Synopsis

An improved synthesis of unsymmetrical tetrathiafulvalenes (TTFs) (5 a-c, 5 f-g, 7) is presented which results in higher yields of unsymmetrical TTFs when compared to existing methods. The synthetic method consists of pre-equilibration of thiones containing electron withdrawing groups with P(OEt)3 at the minimum temperature where a reaction occurs as determined by 31 p NMR, followed by the slow addition of the thiones to be coupled (typically containing electron donating substituents) and a second equivalent of P(OEt)3. The reaction is allowed to react for some time and a third equivalent of P(OEt)3 is then added. It was also found that the purification of unsymmetrical TTF, 5a, can be greatly simplified by selective precipitation of the symmetrical TTF tetraester (5d) allowing for the rapid synthesis of 5a in multigram quantities. In addition our studies have led to some mechanistic insights of the reaction.