Unusual Hetarynic Condensation of 3-Bromo-2-ethoxypyridine with Diisopropyl Ketone Enolate in the Presence of a Complex Base

The crystal structure analysis of 1,8-diethoxy-9,10-dihydro-9-isopropyl-10,10-dimethyl-2,7-diaza-9-anthrol, C₂₁H₂₈N₂O₃, obtained from the condensation of 3-bromo-2-ethoxypyridine with diisopropyl ketone enolate in the presence of the complex base NaNH₂.^tBuONa, shows the tricyclic nature of the compound and allows interpretation of the reaction mechanism. The structure and conformation of the two independent molecules present in the asymmetric unit are compared with molecular modelling results.

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