Expedient synthesis of new cinnoline diones by Ru-catalyzed regioselective unexpected deoxygenation-oxidative annulation of propargyl alcohols with phthalazinones and pyridazinones

Abstract

Ruthenium-catalyzed simple, cascade and one-pot synthesis of cinnoline-fused diones has been carried out by the C-H activation of phthalazinones/pyridazinones accomplished by the unusual deoxygenation of propargyl alcohols. The bond selectivity is accredited to the traceless directing nature of the hydroxyl group of propargyl alcohol. A sequential C-H activation, insertion and deoxy-oxidative annulation has been proposed based on the preliminary mechanistic study.

Palladium(II)/N‐Heterocyclic Carbene‐Catalyzed Regioselective Heteroannulation of Tertiary Propargyl Alcohols and o‐Haloanilines to form 2‐Alkenylindoles

“…Reports on metal‐NHC catalysts in Larock heteroannulation are scarce . Our group has previously reported the Ru(II)‐catalyzed regioselective deoxygenation–oxidative annulation of propargyl alcohols with phthalazinones and pyridazinones . Propargyl alcohols, known for their contributions in the synthesis of heterocyclic compounds, leave vast scope for the generation of new value‐added entities involving organometallics.…”

Ruthenium Catalyzed C−H Acylmethylation of N‐Arylphthalazine‐1,4‐diones with α‐Carbonyl Sulfoxonium Ylides: Highway to Diversely Functionalized Phthalazino‐fused Cinnolines

“…Consequently, reasonable traditional and eye‐catching modern strategies have been developed towards the synthesis of functionalized and fused phthalazine‐diones in the past decade. In this regard, transition‐metal‐catalyzed annulation of 2‐arylphthalazine‐1,4‐diones with different coupling partners, including internal alkynes, propargyl alcohols via C−H activation approach have attracted great interest in recent years –. Our group has also recently reported Rh III ‐catalyzed additive‐driven carbene insertion strategies for the synthesis hydroxy‐dihydroindazolo‐fused phthalazine‐diones and cinnoline‐fused phthalazine‐diones via annulation of α‐diazo carbonyl compounds with 2‐arylphthalazine‐1,4‐diones …”

Palladium‐Catalyzed Direct ortho‐C–H Bond Sulfonylation and Halogenation of Phthalazine‐1,4‐diones

“…To the best of our knowledge, pyridazinedione‐directed C–H functionalization has been mainly limited to C–C bonds formation with Ir, Rh, and Ru catalysts (Scheme ). In 2016, two groups of Gandhi and Perumal independently reported the using of phthalazindiones as easily accessible structures in the synthesis of phthalazino[2,3‐ a ]cinnolines via Ru and Rh catalyzed dehydrogenative coupling reactions, respectively (Scheme a and 1b). Gogoi disclosed a Ru II ‐catalyzed annulation reaction between 2‐phenylphthalazinediones and alkynes for the synthesis of substituted quinazolines (Scheme c) .…”