Beilstein J. Org. Chem.2014,10, 848–857, doi:10.3762/bjoc.10.81
; cyclization; Diels–Alder; inverse electron demand; N-acyliminium ion; tert-enamide; Introduction
Fused indoline, isoindoline, quinoline and isoquinoline substructures are found in many natural products and bioactive synthetic compounds (Figure 1). For example, nuevamine is a naturally-occurring isoindolo[1,2
reported reaction conditions for imino [4 + 2] Diels–Alder reactions [13][14] were employed here for the electrocyclization of N-acyliminium ions from N-aryl-3-hydroxyisoindolinones and tert-enamide analogues namely N-vinylpyrrolidone and N-vinylcaprolactam as the electron-rich dienophiles. Sixteen
position. The polarized form of the tert-enamide dienophile, on the other hand, will have a positive and negative charge on carbons α and β to N, respectively. Such polarization can only lead to the regioisomer with the substitution at position 5 of the isoindoloquinoline ring.
Even with this
PDF
Graphical Abstract
Figure 1:
Pyridoisoindole frameworks (highlighted) in bioactive molecules and compounds under present investi...