Synthesis of Anti-[2.2](2-Phenylthiazolophane): A New Heterocyclic Biphenylophane †

Abstract

Synthesis of a heterocyclic variant of the biphenylophanes, namely anti-[2.2](2-phenylthiazolophane) (1), is described via a sequence involving the pyrolysis of an intermediate bis-lactone (8). Dynamic ¹H NMR analysis revealed both the bis-lactone 8 and the target heterophane 1 to be conformationally mobile on the NMR time scale at temperatures down to −55 °C.

Keywords

cyclophanes thiazoles lactones decarboxylation flash vacuum pyrolysis

References

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When ¹H NMR of 1 was recorded in CDCl₃ containing a drop of CF₃CO₂H, there was observed downfield shifts of the protons associated with both the phenyl (δ 7. 1 and 7. 43) as well as the thiazole ring (δ 7. 54) as a consequence of the presence of the positive charge on the thiazole rings. Furthermore, a single set of absorptions for these protons strongly indicated bis-protonation of heterophane 1 in the presence of CF₃CO₂H.