Addition Reaction of Carboxylic Anhydrides to the Carbon-Nitrogen Double Bond of Unsubstituted Cyclic Imidates

Article abstract of DOI:10.1246/bcsj.55.1921

Acyclic and cyclic (SAn and GAn) carboxylic anhydrides were added at room temperature to the C=N bond of unsubstituted cyclic imidates of 2-oxazoline (OZO) and 5,6-dihydro-4H-1,3-oxazine (OZI) to give addition products quantitatively.In contrast to these findings, the reactions of acetyl halides with OZO and OZI yielded ring-opened products and the reactions of carboxylic anhydrides with 2-benzyl-2-oxazoline (BzOZO) afforded also the ring-opened products.The bicyclic addition product of OZO with SAn is equilibrated with a mixture of starting materials.The stereochemistry of addition products having a six-membered ring system is discussed.