Protonation-triggered conformational modulation of an N,N'-dialkylbispidine: first observation of the elusive boat-boat conformer.
Modulation of the solution conformations of N,N'-bis(benzhydryl)bispidine has been achieved by protonation. Conformers have been characterized by NMR spectroscopy using nuclear Overhauser effects and residual dipolar couplings. In contrast to the preference for the chair-chair conformation for the free base and the monoprotonated species, the diprotonated bispidine is revealed to exist as a mixture of chair-boat and boat-boat conformers. While boat-boat conformers of bispidines have previously not been detected, they are here observed to constitute up to 70% of the bispidine population.
Department of Chemistry-BMC, Uppsala University, S-75123 Uppsala, Sweden.
Sara
S
Norrehed
Máté
M
Erdélyi
Mark E
ME
Light
Adolf
A
Gogoll
D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011522:Protons
D019086:Bridged Bicyclo Compounds, Heterocyclic; D011522:Protons; C495809:bispidine