The Photohydration of N-Glycosylpyridinium Salts and of Related Pyridinium N,O-Acetals

The photolysis of N-MEM-pyridinium chloride (1e) in alkaline H2O gave N-MEM-6-azabicyclo[3.1.0]hexenol (2e). With benzoic acid in CHCl3, this bridged aziridine gave a complex aminal 7 reminiscent by its C2 symmetry of Trögerʹs base. Photolysis of α-d-glucopyranosyl pyridinium chloride (α-12) gave a 1:1 mixture of the corresponding α-d-glucopyranosyl aziridines (α-13/α-14), which were separated, after peracetylation, by crystallisation. The absolute configuration of one of the bridged aziridines (α-16) was established by X-ray analysis.