Under the cooperative catalysis of NHC/Lewis acid, the mild, straightforward [4 + 2] annulation of α-bromo-α,β-unsaturated aldehydes bearing γ-H with isatin derivatives gave spirocyclic oxindole-dihydropyranones stereoselectively. This approach is particularly attractive due to the concise construction, avoidance of external oxidants, and the potential utilization value of final products in molecular biology and pharmacy.

Smooth as isatin! A straightforward synthesis of spirocyclic oxindole–dihydropyranones through an N‐heterocyclic‐carbene‐catalyzed [4+2] annulation of α‐bromo‐α,β‐unsaturated aldehydes or α,β‐dibromoaldehyde bearing γ‐H with isatin derivatives under mild reaction conditions is disclosed (see scheme). The concise construction, ready availability of the starting materials, avoidance of external oxidants, and the potential utilization value of final products in molecular biology and pharmacy makes this approach particularly attractive.

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This manuscript discloses an efficient construction of the spirocyclic oxindole-dihydropyranone scaffold via the N-heterocyclic carbene (NHC)-catalyzed oxidative γ-functionalization of α,β-unsaturated aldehydes bearing γ-H with isatin derivatives. The ready availability of the starting materials, easy work-up, mild reaction conditions and the potential utilization value of the products make this strategy attractive.

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