In these cases, variation of the 2-naphthyl BCB ketone to more bulky 1-naphthyl one was permissible, forming the corresponding 2,5-diazabicyclo[5.1.1]nonane product 4ba in 57% yield. The phenyl BCB ketone was suitable for this reaction, and the target product 4ca was isolated in 75% yield. With the electron-rich p-methoxyphenyl BCB ketone, the desired product 4da was obtained in excellent yield (86%). Halides in the para-position of the BCB phenyl group were well tolerated, which could serve as a useful handle for diversification by cross-coupling reactions, and the expected 2,5diazabicyclo[5.1.1]nonanes were formed in moderate to good yields: 68% (p-fluoro, 4ea), 50% (p-chloro, 4fa), 45% (p-bromo, 4ga) and 35% (p-iodo, 4ha). The even more electron-deficient and unstable ptrifluoromethylphenyl BCB ketone was also compatible with this transformation, affording product 4ia in 67% yield. Both m-methoxy and o-methyl phenyl BCB ketones were viable substrates, resulting in the aimed products 4ja and 4ka in 86% and 43% yields, respectively. Moreover, BCB ketones bearing a multi-substituted phenyl or heteroaromatic (furan and thiophene) group all participated well in the reaction to furnish the corresponding products 4la-oa in 52-85% yields. Along with aryl BCB ketones, alkyl ones were suitable reaction partners as well (4pa-ra). Thus, the n-butyl-, sterically more hindered n-octyl-and cyclopentyl-substituted BCB ketones reacted efficiently to afford the aimed products: 69%