Organocatalytic (5+1) benzannulation of Morita–Baylis–Hillman carbonates: synthesis of multisubstituted 4-benzylidene pyrazolones

Abstract

4-Benzylidene pyrazolones are valuable scaffolds of numerous bioactive molecules, building blocks, ligands, dyes, and pigments. Therefore, the construction of 4-benzylidene pyrazolones with diverse substitution patterns is a desirable target of...

Cooperative photoactivation/Lewis base catalyzed [4 + 2] annulations of α-diazoketones andortho-amino MBH carbonates to access dihydroquinolinone frameworks

“…In the context of our long-standing interest in preparing drug-like frameworks, diverse pharmacophore architectures were prepared. 15 Based on previous studies on MBH carbonates, 16 which demonstrated impressive reactivity, compatibility, and potential versatility of these synthons, we envisaged that the combination of α-diazoketones and ortho-amino MBH carbonates in the cooperative catalysis of photoactivation/ Lewis base would enrich the synthetic tools of bioactive 3,4dihydroquinolinone frameworks existing in molecules with different activities. Significantly, the successful transformation highlights the promising potential of this powerful cooperative strategy (Scheme 1C).…”

Synthesis of 4‐Alkenylated Pyrazolinones by 2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ)‐Mediated Oxidative Coupling Reaction

“…[7] Other routes include the gold-catalyzed cascade reaction of difficult available N-propioloyl hydrazones, [8] the iodinepromoted domino Reaction of 2-hydroxy chalcones with 3-methyl-pyrazolinones, [9] the 1,4-diazabicyclo [2.2.2]octane (DABCO)-catalyzed (5 + 1) benzannulation of Morita-Baylis-Hillman carbonates with 2-allylidenemalononitriles. [10] However, these methods are mainly focused on the alkenylated pyrazolinones with single aryl/heteroaryl substituent. Especially, the alkenylated pyrazolinones bearing both aryl and vinyl substituents (highly substituted α,β,γ,δ-dienpyrazolinones) are scarcely reported.…”

“…The most popular way to access alkenylated pyrazolinones is the Knoevenagel condensation of pyrazolinones with aldehydes or ketones [7] . Other routes include the gold‐catalyzed cascade reaction of difficult available N‐propioloyl hydrazones, [8] the iodine‐promoted domino Reaction of 2‐hydroxy chalcones with 3‐methyl‐pyrazolinones, [9] the 1,4‐diazabicyclo [2.2.2]octane (DABCO)‐catalyzed (5+1) benzannulation of Morita‐Baylis‐Hillman carbonates with 2‐allylidenemalononitriles [10] . However, these methods are mainly focused on the alkenylated pyrazolinones with single aryl/heteroaryl substituent.…”

DABCO-Catalyzed Mono-/Diallylation of N-Unsubstituted Isatin N,N′-Cyclic Azomethine Imine 1,3-Dipoles with Morita-Baylis-Hillman Carbonates

“…MBH adducts contain the structural moieties of allylic alcohols or amines, Michael acceptors, and electron-withdrawing groups, which makes them valuable substrates for various types of reactions such as Michael addition, allylic substitution, cycloaddition reaction, Friedel-Crafts reaction, Claisen rearrangement, etc. [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. Based on our previous studies of 1,3-dipolar cycloaddition, Michael addition of azomethine ylides and azomethine imines and palladium-catalyzed tandem reaction to construct 3,3-disubstituted indolinones [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 ], herein we report the mono-/diallylation of isatin N , N ′-cyclic azomethine imines from the condensation of isatin and pyrazolidones with MBH carbonates.…”