Lewis Acid-promoted nucleophilic addition-cyclization of N, O-acetals with ynamides

February 22, 2024

• Title:       

  Lewis Acid-promoted nucleophilic addition-cyclization of N, O-acetals with ynamides

• Image Source:

  Synthesis of dihydro-[1,3]oxazino[4,3-a] isoindole and tetrahydroisoquinoline through Cu(OTf)₂-catalyzed reactions of N-acyliminium ions with ynamides

• Mark:

  Fig. 2

• Associated context:

  In recent years, we studied various nucleophilic reactions of N-acyliminium ions, and established facile approaches to pyrido or pyrrolo[1,2-c] [1,3]oxazin-1-ones and 3,4-dihydro-1,3-oxazin-2-ones by reacting with alkynes or ynamides (Fig. 2, 3-4). On the basis of our con-  tinuous efforts in N, O-acetals and ynamides, we envisioned that  the iminium ions derived from the N, O-acetals 6 and 7 could undergo a nucleophilic addition-cyclization process with ynamides  8 to give substituted dihydro-[1,3]oxazino[4,3-a] isoindole and tetrahydroisoquinoline skeletons, respectively (Fig. 2, 5).