A Forgotten Chiral Spiro Compound Revisited: 3,3'‐Dimethyl‐3H,3'H‐2,2'‐spirobi[[1,3]benzothiazole]

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'-spirobi[[1,3]benzothiazole] can be viewed as a masked thiophenate attached to a benzothiazolium framework.

Atropisomerism in a 10-Membered Ring with Multiple Chirality Axes: (3Z,9Z)-1,2,5,8-Dithiadiazecine-6,7(5H,8H)-dione Series

“…Display of the 11 (3 Z ,9 Z )-1,2,5,8-dithiadiazecine-6,7­(5 H ,8 H )-dione derivatives reported in the literature: 4 , − 5 , 6 , , 7 , , 8 , , 9 , , 10 , , 11 , 12 , 13 , and 14 …”

Bifunctionalization of styrene through ring-opening-recombination strategy of phenylpropathiazole salt

“…1 N -Alkylated benzothiazolium salts 2 derived from benzothiazolium are important synthetic precursors or intermediates in various reactions. 3 The ring-opening-recombination reaction has received special attention owing to its high efficiency and broad substrate scope (Scheme 1a). 4 In recent years, the N -alkylated benzothiazolium salt opening-recombination reaction has become a research focus, with emphasis on its mechanism, substrate scope, and practical applications.…”