Constructing densely functionalized Hajos–Parrish-type ketones with six contiguous stereogenic centers and two quaternary carbons in a formal [2 + 2 + 2] cycloaddition cascade

摘要: A [2 + 2 2] annulation of 2-methylcyclopentane-1,3-dione and nitrostyrenes has been achieved via a cascade double Michael–Henry reaction that provides densely functionalized Hajos–Parrish-type ketones with two quaternary carbons six contiguous stereogenic centers. An uncommon intriguing example the high self-disproportionation enantiomers (SDE) in crystallization racemic 3i was observed. The spontaneous resolution mixture into its enantiopure forms regular without need to utilize chiral resolving agent or external stimuli achieved. structures appropriate derivatives, (±)-3a, (±)-5a, (±)-3f, (−)-3i, were further confirmed by their single-crystal X-ray crystallographic analyses.