Isothioureas tethered to bridged-bicyclic tertiary allylic amines can be converted to carbodiimides through reaction with Hg(II) salts. Intramolecular cyclization of the tethered tertiary allylic amines to the carbodiimides afford zwitterionic intermediates that undergo 1,3-diaza-Claisen rearrangements, affording highly substituted tricyclic guanidines.
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