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Conformation Analysis of the 8-Membered Ring of 12H-Dibenzo [d, g] [1, 3, 2] dioxathiocines: Symmetric and Asymmetric Conformations

✍ Scribed by P. Hug; Sandra Kolly; Hansrudolf Meier; Rita Pitteloud; Dieter Poppinger; Grety Rihs; Günther Rist

Publisher
John Wiley and Sons
Year
1990
Tongue
German
Weight
402 KB
Volume
73
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The 12__H__‐dibenzo [d, g] dioxathiocines 2 and 4 are prepared by condensation of the corresponding bis[phenols] 1 and 3 with SOCl~2~ and SCl~2~, respectively. X‐Ray analysis reveals the presence of the boat‐chair (BC) form as the only conformer in the solid state of the cyclic thiodioxy derivative 4a, whereas the sulfinyldioxy compound 2a exists in the asymmetric axial boat (B) form, i. e. with endo (axial) orientation of the exocyclic O‐atom. Conformational analysis using ^1^H‐NMR spectroscopy indicates the presence of a boat form for compounds 2, whereas compounds 4 again exist in the boat chair form. A comparison of ^1^H‐NMR and thermodynamic parameters with those of the cyclic sulfinyldioxy compound 5 with an equilibrium between e‐BC and a‐BC form (i.e. BC form with equatorial and axial orientation of the exocyclic O‐atom) is made.

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