Studies on Hetero-Cage Compounds. II. pKa Studies on the 3,10-Diazabicyclo[4.3.1]decane System

Abstract
The pKa values of pseudopelletierine (1), 10-methyl-3,10-diazabicyclo[4.3.1]decan-4-one (2), 10-methyl-3, 10-diazabicyclo[4.3.1]decane (3), 6,8-exo-ethanopseudopelloetierine (4), 7,9-exo-ethano derivatives 5 and 6 of 2 and 3 were measured potentiometrically in water-methyl cellosolve (20 : 80 v/v) at 20°C. The conformational problems in the 3,10-diazabicyclo[4.3.1]decane system were discussed based on the observed pKa′ (pKmcs) values. The characteristic conformational behavior of the monocation (7) of 3 was suggested by the higher value of its pKmcs than of 6.