... Journal of the ... J. Am. Chem. Soc. ... naphthalene (proton sponge) was unreactive toward 2, the bicycloamines 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) reacted with 2 to give salts that were insoluble in nonpolar organic solvents and ...