Relative acidities and structure analysis of cis and trans isomers of 1,5-oxazaspiro[5.5] undecane derivatives by multinuclear magnetic resonance.

The relative acidities of the cis and trans isomers of a series of 1,5-oxazaspiro[5.5]undecane derivatives were determined by measuring DeltapK in acid-base titrations followed by (1)H NMR. Relative structural stabilities were determined by measuring substituent chemical shift and gamma-gauche effects in (13)C, (15)N, and (17)O NMR.