Lactone

Lactone

RDCs are NMR-parameters, which can complement NOEs and J couplings, if relative configurations of stereogenic centres need to be determined. The α-methylen-γ-butyrolactone shown here was synthesized with high diasteredoselectivity in the Giannis group (Universität Leipzig). NOEs and J couplings, however, were not sufficient to determine the relative configuration of this flexible compound. Using RDCs the relative configuration could be determined unambiguously.

After the determining the relative configuration to be trans (left structure), we investigated whether also population information can be obtained from RDCs. We did so (together with the Maliniak group (Stockholm University) ) using two approaches (multi-conformer-single-tensor and multi-conformer-multi-tensor fit). The populations obtained matched well, also to the ones extracted from J couplings and via MP2.

In the meantime this molecule has become one of our favorite guinea pigs. We could show that under favorable circumstances local tensors can be used to relate stereogenic centres. This of course asks for quite a large number of RDCs (longe-range, etc.).

Publications

1 C. M. Thiele, A. Marx, R. Berger, J. Fischer, M. Biel, A. Giannis, Determination of the relative configuration of a five-membered ring compound using RDCs, Angew. Chem. 2006, 118, 4566-4571, Angew. Chem. Int. Ed. 2006, 45, 4455-4460.
2 C. M. Thiele, V. Schmidts, B. Böttcher, I. Louzao, R. Berger, A. Maliniak, B. Stevensson, On the Treatment of Conformational Flexibility when using Residual Dipolar Couplings for Structure Determination, Angew. Chem. 2009, 121, 6836-6840, Angew. Chem. Int. Ed. 2009, 48, 6708-6712.
3 C. M. Thiele, A. Maliniak, B. Stevensson, Use of Local Alignment Tensors for the Determination of Relative Configurations in Organic Compounds, J. Am. Chem. Soc. 2009, 131, 12878-12879.