Kinetic formation and equilibration of isomeric ketone dimethylhydrazone lithio anions Academic Article uri icon

abstract

  • Deprotonation of (Z)-[1-13C]-3-pentanone dimethylhydrazone (DMH) ((Z)-l) by lithium diethylamide and lithium diisopropylamide in THF was studied by 13C NMR spectroscopy. Low regioselectivity was observed, and no isomerization of (Z)-l to (E)-1 occurred during the deprotonation reaction.Proton-transfer reactions between 3-pentanone DMH (6), heptanal DMH (7), and 3-heptanone DMH (10) and the DMH lithio anions formed by deprotonation of these DMH's at 0 °C were studied by alkylation and GC analysis of the alkylated products. These reactions occurred with half-lives of 2 to 8 h, while the deprotonation of ketone DMH's with lithium dialkylamide bases was complete within 0.5 h at0 °C. These results show that there is little preference for deprotonation syn or anti to the lone pair of the C=N nitrogen in otherwise equivalent methylene groups in acyclic ketone DMH's. © 1980, American Chemical Society. All rights reserved.

author list (cited authors)

  • Ludwig, J. W., Newcomb, M., & Bergbreiter, D. E.

citation count

  • 19

publication date

  • November 1980