Synthesis of 3-spirooxindole 3H-indoles through Rh(iii)-catalyzed [4 + 1] redox-neutral spirocyclization of N-aryl amidines with diazo oxindoles

Abstract

In this paper, an efficient synthesis of 3-spirooxindole 3H-indoles through the coupling and spirocyclization of N-aryl amidines with diazo oxindoles is presented. Mechanistically, the formation of the title products involves...

Ru(ii)-catalyzed regioselective [4 + 1] redox-neutral spirocyclization of aryl amidines with diazopyrazolones: direct access to spiro[indole-3,4′-pyrazol]-5′-ones

“…Then, Fan developed a Rh(III)catalyzed [4 + 1]/[4 + 1 + 1] spirocyclization with diazo compounds to synthesize benzoxazine-and indole-fused spirocycles. 15 In addition, Liu achieved a catalytic system-controlled strategy to construct tetraaza-spiroheterocycles and trizazaspiroheterocycles. 16 Even though great progress has been made, further exploration to access heterocyclic compounds with structural diversity is still highly desired.…”

A divergent construction of fused and bridged carbo-/heterocyclic scaffoldsviacascade reactions of aryl azomethine imines with vinyl cyclic carbonates

“…reported the reaction of an aryl azomethine imine with diazo phosphonate, from which pyrano[ de ]isochromene derivatives were obtained (Scheme 1g). 4 h As a continuation of our interest in this field, 5,6 we have developed a synthesis process of spirocyclic dihydrophthalazines through spiroannulation reactions of aryl azomethine imines with cyclic diazo compounds (Scheme 1h). 5 a Observing that the coupling partners (CPs) used in the above described cases were mostly limited to alkenes/alkynes and diazo compounds, we were interested in further exploration of the fascinating reactivity of aryl azomethine imines by extending the scope of the CPs.…”

A substrate-controlled Ru(ii)-catalyzed C–H activation/[5 + 2] annulation cascade and unusual acyl migration to synthesize diverse indoline scaffolds

“…For example, Ackermann 16 and Cheng 17 reported the C–H activation of N - t Bu benzamidines/[4 + 2] annulation with diazo compounds to construct substituted isoquinolines (Scheme 1a). Li 18 and Fan 19 constructed interesting indole skeletons from N -aryl benzamidines through a C–H activation/[4 + 1] annulation strategy. Interestingly, Fan 20 had also used the two substrates to realize the construction of complex spiroheterocycles through a C–H activation/[4 + 1 + 1] annulation cascade (Scheme 1b).…”