Rhodium-Catalyzed Functionalization and Annulation of N-Aryl Phthalazinediones with Allyl Alcohols

A direct ortho-Csp²-H acylalkylation of 2-aryl-2,3-dihydrophthalazine-1,4-diones with unsubstituted and substituted allyl alcohols is achieved in high yields through Rh(III)-catalyzed C-H bond activation process. The additional employment of Cu(OAc)₂⋅2H₂O as an oxidant detour the reaction towards [4+1] annulation, producing 13-(2-oxopropyl)-13H-indazolo[1,2-b]phthalazine-6,11-diones in moderate yields. Interestingly, Lawesson's reagent-mediated conditions accomplished intramolecular cyclization in ortho-(formylalkylated)-2,3-dihydrophthalazine-1,4-diones to produce diazepino[1,2-b]phthalazine-diones in moderate yields. Furthermore, allyl alcohol showcased distinct reactivity in presence of different additives to produce ortho-allylated, oxidative and non-oxidative [4+2] annulated products.