Direct, Asymmetric Synthesis of Carbocycle?Fused Uracils via [4+2] Cycloadditions: a Noncovalent Organocatalysis Approach

The peculiar versatility of remotely enolizable 6-methyluracil-5-carbaldehydes as useful vinylogous pronucleophiles in direct, asymmetric [4+2] cyclizations with suitable nitroolefins has been demonstrated. Under the strategic exploitation noncovalent bifunctional organocatalysis, a dearomative remote enolization strategy was implemented, to generate oQDM-type dienolate intermediates that were efficiently and stereoselectively trapped by either aromatic or aliphatic nitroolefins. A series functionalized, chiral carbocycle-fused uracils embedding three contiguous stereocenters thus collected one step good yields, generally levels enantioselectivity, complete diastereocontrol. Furthermore, ability provide enantiopure products via simple one-cycle recrystallizations possibility further functionalize these scaffolds without losing their integrity