کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5270648 | 1385422 | 2011 | 5 صفحه PDF | دانلود رایگان |
Bromophilic attack by the transition metal carbonyl anion, [Re(CO)5]Na (pKa = 21.1), on 2-(1-bromoalkylidene)thiazolidin-4-ones is significantly faster than abstraction of an acidic lactam hydrogen (pKa â¼17-18), when the generated carbanion is stabilized by an α-CN or α-PhCO group. The bromophilic reaction of 2-(1-bromoalkylidene)thiazolidin-4-one, having an α-CN electron-withdrawing group, resulted in formation of a new metallacyclic anionic complex. With less reactive vinyl bromides, containing an α-CONHPh or α-CO2Et group, only deprotonation is observed. The role of the metal carbonyl anion is highlighted by a comparison with the 9-methylfluorenide carbanion (pKa of 9-methylfluorene is 22.3), which reacts exclusively via a deprotonation pathway.
Bromophilic attack by the metal carbonyl anion, [Re(CO)5]â Na+; pKa of [Re(CO)5]HÂ =Â 21.1, on 2-(1-bromoalkylide-ne)thiazolidin-4-ones (ZÂ =Â CN and COPh) is significantly faster than abstraction of an acidic lactam hydrogen (pKa â¼17-18).
Journal: Tetrahedron Letters - Volume 52, Issue 1, 5 January 2011, Pages 29-33