This HOT paper by Graham Hutchings and co-workers describes a cautionary tale of solubility, as the group discovered a systematic error in HPLC measurements of the enantiomeric excess of N-arene-sulfonyl-2-phenylaziridines.
They showed that the heterogeneous or homogeneous copper-catalysed synthesis of N-arene-sulfonyl-2-phenlaziridines mainly yields the R enantiomer. However previous reports significantly over-estimate the percentage enantiomeric excess when hexane was used as the HPLC injection solvent, due to the formation of an insoluble racemic phase.
The group has improved their analytical procedure to afford the correct value, but advise that previous reports on the
enantioselectivity of copper-catalysed aziridination reactions ‘should be regarded with caution if the analytical
procedure involved HPLC’.
Both reviewers thought this well-presented study is of importance to the field. Download it today – it’s now free to access until 8th February.
Laura Jeffs, Damien Arquier, Benson Kariuki, Donald Bethell, Philip C. Bulman Page and Graham J. Hutchings
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C0OB00724B, Paper
