A Forgotten Chiral Spiro Compound Revisited: 3,3'‐Dimethyl‐3H,3'H‐2,2'‐spirobi[[1,3]benzothiazole] |
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| Authors: | Angélique Lindamulage De Silva Vesna Risso Marion Jean Michel Giorgi Valérie Monnier Jean‐Valère Naubron Nicolas Vanthuyne Daniel Farran Christian Roussel |
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| Institution: | 1. Aix Marseille Université, Centrale Marseille, CNRS, Marseille, France;2. Spectrop?le, Aix Marseille Université, Marseille, France |
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| Abstract: | The title compound was obtained as a side product during dimerization‐oxidation steps of the carbene generated from N‐methylbenzothiazolium iodide. Chromatography on (S,S)‐Whelk O1 column showed on cooling a typical plateau shape chromatogram indicating an exchange between two enantiomers on the column. The thermal barrier to racemization was determined (85 kJ.mol?1 at 10 °C) by dynamic high‐performance liquid chromatography (DHPLC).The absolute configuration of the first (M) and second eluted (P) enantiomers on the (S, S)‐Whelk O1 column was established by comparing the reconstructed circular dichroism (CD) spectra from the CD detector signal and the calculated CD spectrum of the (P) enantiomer. Mass spectrometry revealed that 3,3'‐dimethyl‐3H,3'H‐2,2'‐spirobi1,3]benzothiazole] can be viewed as a masked thiophenate attached to a benzothiazolium framework. Chirality 27:716–721, 2015. © 2015 Wiley Periodicals, Inc. |
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| Keywords: | axial chirality racemization barrier spiro heterocycle carbene dimerization oxidation of carbene dimer |
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