Bromophilic attack by the transition metal carbonyl anion, [Re(CO)(5)]Na (pK(a) = 21.1), on 2-(1-bromoalkylidene)thiazolidin-4-ones is significantly faster than abstraction of an acidic lactam hydrogen (pK(a) similar to 17-18), when the generated carbanion is stabilized by an alpha-CN or alpha-PhCO group. The bromophilic reaction of 2-(1-bromoalkylidene)thiazolidin-4-one, having an alpha-CN electron-withdrawing group, resulted in formation of a new metallacyclic anionic complex. With less reactive vinyl bromides, containing an alpha-CONHPh or alpha-CO(2)Et group, only deprotonation is observed. The role of the metal carbonyl anion is highlighted by a comparison with the 9-methylfluorenide carbanion (pK(a) of 9-methylfluorene is 22.3), which reacts exclusively via a deprotonation pathway.
Keywords:
Halogenophilic reactions / Proton transfer / 2-(1-Bromoalkylidene)thiazolidin-4-ones / Metal carbonyl anions
TY - JOUR
AU - Sazonov, P. K.
AU - Džambaski, Zdravko
AU - Shtern, M. M.
AU - Marković, Rade
AU - Beletskaya, I. P.
PY - 2011
UR - http://cer.ihtm.bg.ac.rs/handle/123456789/927
AB - Bromophilic attack by the transition metal carbonyl anion, [Re(CO)(5)]Na (pK(a) = 21.1), on 2-(1-bromoalkylidene)thiazolidin-4-ones is significantly faster than abstraction of an acidic lactam hydrogen (pK(a) similar to 17-18), when the generated carbanion is stabilized by an alpha-CN or alpha-PhCO group. The bromophilic reaction of 2-(1-bromoalkylidene)thiazolidin-4-one, having an alpha-CN electron-withdrawing group, resulted in formation of a new metallacyclic anionic complex. With less reactive vinyl bromides, containing an alpha-CONHPh or alpha-CO(2)Et group, only deprotonation is observed. The role of the metal carbonyl anion is highlighted by a comparison with the 9-methylfluorenide carbanion (pK(a) of 9-methylfluorene is 22.3), which reacts exclusively via a deprotonation pathway.
PB - Pergamon-Elsevier Science Ltd, Oxford
T2 - Tetrahedron Letters
T1 - Reactions of transition metal carbonyl anions with 2-(1-bromoalkylidene)thiazolidin-4-ones: halogenophilic attack or deprotonation
VL - 52
IS - 1
SP - 29
EP - 33
DO - 10.1016/j.tetlet.2010.10.112
ER -
@article{
author = "Sazonov, P. K. and Džambaski, Zdravko and Shtern, M. M. and Marković, Rade and Beletskaya, I. P.",
year = "2011",
url = "http://cer.ihtm.bg.ac.rs/handle/123456789/927",
abstract = "Bromophilic attack by the transition metal carbonyl anion, [Re(CO)(5)]Na (pK(a) = 21.1), on 2-(1-bromoalkylidene)thiazolidin-4-ones is significantly faster than abstraction of an acidic lactam hydrogen (pK(a) similar to 17-18), when the generated carbanion is stabilized by an alpha-CN or alpha-PhCO group. The bromophilic reaction of 2-(1-bromoalkylidene)thiazolidin-4-one, having an alpha-CN electron-withdrawing group, resulted in formation of a new metallacyclic anionic complex. With less reactive vinyl bromides, containing an alpha-CONHPh or alpha-CO(2)Et group, only deprotonation is observed. The role of the metal carbonyl anion is highlighted by a comparison with the 9-methylfluorenide carbanion (pK(a) of 9-methylfluorene is 22.3), which reacts exclusively via a deprotonation pathway.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Tetrahedron Letters",
title = "Reactions of transition metal carbonyl anions with 2-(1-bromoalkylidene)thiazolidin-4-ones: halogenophilic attack or deprotonation",
volume = "52",
number = "1",
pages = "29-33",
doi = "10.1016/j.tetlet.2010.10.112"
}
Sazonov, P. K., Džambaski, Z., Shtern, M. M., Marković, R.,& Beletskaya, I. P. (2011). Reactions of transition metal carbonyl anions with 2-(1-bromoalkylidene)thiazolidin-4-ones: halogenophilic attack or deprotonation.
Tetrahedron Letters
Pergamon-Elsevier Science Ltd, Oxford., 52(1), 29-33.
https://doi.org/10.1016/j.tetlet.2010.10.112
Sazonov PK, Džambaski Z, Shtern MM, Marković R, Beletskaya IP. Reactions of transition metal carbonyl anions with 2-(1-bromoalkylidene)thiazolidin-4-ones: halogenophilic attack or deprotonation. Tetrahedron Letters. 2011;52(1):29-33
Sazonov P. K., Džambaski Zdravko, Shtern M. M., Marković Rade, Beletskaya I. P., "Reactions of transition metal carbonyl anions with 2-(1-bromoalkylidene)thiazolidin-4-ones: halogenophilic attack or deprotonation" Tetrahedron Letters, 52, no. 1 (2011):29-33,
https://doi.org/10.1016/j.tetlet.2010.10.112 .
