Conformational behaviour of medium-sized rings. Part 10. Dithiosalicylides and trithiosalicylides

G. Bruce Guise, W. David Ollis*, Judith A. Peacock, Julia Stephanidou Stephanatou, J. Fraser Stoddart

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The trithiosalicylide derivatives (8)–(11) have been synthesised and shown by temperature-dependent 1H n.m.r. spectroscopy to exist in solution as ring inverting (35a) ⇌ (35b) enantiomeric helical conformations with trans-thioester linkages. The free energies of activation for these conformational changes are ca. 10 kcal mol−1higher than those for the similar process in the corresponding trisalicylides. In contrast with the trisalicylides, the trithiosalicylides can only ring invert between enantiomeric helical conformations via intermediates containing a cis-thioester linkage. The dithiosalicylide derivatives (3)–(7) have been synthesised; the temperature dependence of the 1H n.m.r. spectrum of di-o-thiothymotide (7) has been interpreted in terms of ring inversion (40a) ⇌ (40b) between enantiomeric boat conformations. Comparison of the ΔGvalue of 24.6 kcal mol−1for this conformational change with that of 17.7 kcal mol−1previously obtained for di-o-thymotide (41) suggests that cis-thioester linkages are subject to more resonance stabilisation than are cis-ester linkages.

Original languageEnglish (US)
Pages (from-to)1637-1648
Number of pages12
JournalJournal of the Chemical Society, Perkin Transactions 1
DOIs
StatePublished - 1982

ASJC Scopus subject areas

  • Chemistry(all)

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