Chromatographically separable rotamers of an unhindered amide.
Surprisingly stable formamide rotamers were encountered in the tetrahydroisoquinoline and morphinan series of alkaloids. We investigated the hindered rotation around the amide bond by dynamic high-performance liquid chromatography (DHPLC) and kinetic measurements of the interconversion of the rotamers which can readily be separated by HPLC as well as TLC. The experimental results of the different methods were compared to each other as well as to results obtained by DFT calculations.
Institut für Organische Chemie, Johannes Gutenberg Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Mario
M
Geffe
Institut für Organische Chemie, Johannes Gutenberg Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Lars
L
Andernach
Organisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Oliver
O
Trapp
Institut für Organische Chemie, Johannes Gutenberg Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Till
T
Opatz
amides; density functional calculations; dynamic HPLC; rotamers; thermodynamics