Access to the 2H-Tetrahydro-4,6-dioxo-1,2-oxazine Ring System from Nitrone via a Tandem Nucleophilic Addition and Transesterification Reaction.

A general and efficient synthesis of the 2H-tetrahydro-4,6-dioxo-1,2-oxazine ring system through a tandem nucleophilic addition and transesterification reaction is described. The reaction is highly functional-group-tolerant and proceeds under mild conditions, affording the corresponding products in good to excellent yields. This method represents the first general synthetic route to access this heterocyclic scaffold, which exists in the complex natural products alchivemycin A and B with significant antibiotic activities.