Anders, Ernst; Opitz, Andreas; Boese, Roland:

The first x-ray structures of N-lithiated 4-alkylidene-1,4-dihydropyridines [{4-(CH3CR)C5H4N}Li(TMEDA)]2: comparison of the x-ray and MNDO geometries and investigation of lithium coordination in solution.

In: Chemische Berichte (Chem.Ber.), Jg. 125 (1992) ; Nr. 5, S. 1267-1271
ISSN: 0009-2940
Zeitschriftenaufsatz / Fach: Chemie
4-Ethyl- and isopropylpyridine reacted with LDA and TMEDA to give title compds. I (R = H, Me), which were subjected to x-ray anal. The structural parameters of the heterocyclic moieties of I are typical of N-lithiated 4-alkylidene-1,4-dihydropyridines. MNDO geometries compare quite well with x-ray structure of I (R = H). The lithium atom of I (R = H) in soln. prefers the same type of coordination as in the crystal. Two-dimensional 6Li,1H-HOESY showed Li contacts only to ortho-hydrogen atoms. I (R = H) reacts exclusively as a C nucleophile, whereas I (R = Me) reacts exclusively as a N nucleophile.