Pyrroles deuterium exchange studies

Cations (12), (13), and (14) represent the three ways in which proton may add to pyrrole. Twenty-five years ago, Koizumi and Titani earned out a series of deuterium exchange studies and... 

In a study of the synthesis of marine 2-aminoimidazole alkaloids, the aminal C-N bond of bicyclic 898 was cleaved regioselectively to form the allylic amine 899. Deuterium exchange results in H-1, H-2, and H-5, but not H-7 exchange, although the C(6)-C(7) double bond underwent isomerization 901. This is atributed to the assistance of the carbamoyl group that formed the oxazoline 900. Hydrolysis of the carbamate group of 899 under basic conditions affords either pyrrole 902 or pyridine 903 (Scheme 218) <2004OL3933>. 

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