A direct synthesis method towards spirocyclic indazole derivatives via Rh(iii)-catalyzed C–H activation and spiroannulation

Abstract

A rhodium(III)-catalyzed [4+1] spiroannulation of N-aryl phthalazine-diones (pyridazine-diones) with diazo compounds to construct spirocyclic indazole derivatives with diverse structures is described. The corresponding spiroannulation products were obtained in moderate to...

Rh(iii)-catalyzed substrate-dependent oxidative (spiro)annulation of isoquinolones with diazonaphthoquinones: selective access to new spirocyclic and oxepine-fused polycyclic compounds

“…On the basis of the above observations and previous reports, 8,12,14 possible pathways for this (spiro)annulation reaction are suggested in Scheme 5. Initially, the active Rh( iii )-species reacts with 1a to release a five-membered rhodacycle A and two molecules of HX through a selective C–H and N–H bond cleavage.…”

“…13 Later, a new rhodium-catalyzed oxidative spiroannulation using diazonaphthalen-2(1 H )-ones as C1 synthons was developed for the direct synthesis of diverse spirocyclic indazole derivatives, as reported by Yu's group (Scheme 1, eqn (4)). 14 Motivated by the elegant achievements and as a continuation of our research interest in exploring novel transition metal-catalyzed chelation-assisted oxidative (spiro)annulation reactions, 15 we disclose herein a Rh( iii )-catalyzed tunable oxidative [4 + 1] spiroannulation or formal [4 + 3] annulation reaction of NH -isoquinolones with 1-diazonaphthalen-2(1 H )-ones thus leading to diverse isoquinolone-containing spirocyclic or oxepine-fused polycyclic compounds simply by employing the corresponding isoquinolone substrates (Scheme 1, eqn (5)).…”

C–H activation-initiated spiroannulation reactions and their applications in the synthesis of spirocyclic compounds

“…To get fused spirocyclic indazole derivatives, Yu et al realized a CHA-initiated spirocyclization reaction of N -aryl phthalazinediones with quinone diazides or diazo oxindoles (Scheme 30). 24 Similarly we have developed a [5 + 1] spiroannulation of aryl azomethine imines with cyclic diazo compounds 25 b and a [4 + 1] spiroannulation of 3-phenyl substituted NH-isoquinolones with diazonaphthoquinones (Scheme 31). 25 a…”

Recent advances in transition-metal-catalyzed carbene insertion to C–H bonds

“…By means of 2-phenyl-2,3-dihydrophthalazine-1,4-dione and derivatives 200 as the C–H substrates, a Rh( iii )-catalyzed carbene insertion to aromatic C–H/annulation cascade occurred to form spirocyclic indazole derivatives 202 in moderate to excellent yields (40–93%) (Scheme 64). 251 Initially, the active catalyst Cp*Rh(OAc) 2 is possibly generated through in situ anion exchange of the precatalyst in the presence of AgOAc, followed by N-heterocycle-directed C–H cleavage to produce the five-membered rhodacycle intermediate int-202a as well as one molecule of acetic acid. Subsequent coordination and release of dinitrogen of 1-diazonaphthalen-2( 1H )-one ( 201a ) forms the rhodacycle carbene species int-202b .…”