Two chemodivergent anionic domino processes from cyclic α-nitroketones and aromatic aldehydes

Treatment of cyclic α-nitroketones and aromatic 1,2-dialdehydes with DBU in tetrahydrofuran containing small amounts of water proceeded through two chemodivergent one-pot domino pathways, whose outcome depended on the ring size of the starting nitroketone. Thus, α-nitrocyclohexanone underwent diastereoselective α′-arylmethylenation reactions through a nitroaldol/aldol/reverse nitroaldol mechanism. On the other hand, α-nitrocycloheptanone and α-nitrocyclooctanone afforded 2-nitroindane-1,2-diols containing three contiguous stereocenters in a highly diastereoselective fashion through a nitroaldol/retro-Dieckmann/intramolecular nitroaldol process.