Contribution of chiral HPLC in tandem with polarimetric detection in the determination of absolute configuration by chemical interconversion method: Example in 1-(thi)oxothiazolinyl-3-(thi)oxothiazolinyl toluene atropisomer series

We report the determination of the absolute configuration of eight stereoisomers in the series of chiral 1-(thi)oxothiazolinyl-3-(thi)oxothiazolinyl toluene atropisomers 1-3, from the known absolute configuration of one stereoisomer, determined by X-ray crystallography. The method uses the affiliation between signs of rotation of polarised light during chemical transformations which preserve the absolute configuration and also during rotation around a single pivot bond producing a compound of known configuration. The use of chiral HPLC in tandem with a chirality detector gives a decisive advantage since such correlation can be performed on a mixture of a very limited quantity of compounds, without tedious purification steps. The method shown as an example in this article, which uses chiral HPLC with chirality detection, may prove useful in many other cases where the determination of the absolute configuration is necessary and where a chemical interconversion method can be used on a microscale.