The acetic acid catalyzed three-component reaction of pyrrolidine, aromatic aldehydes, and 3-arylideneoxindolin-2-ones in refluxing toluene afforded functionalized 7′arylidenespiro[indoline-3,1′-pyrrolizines] in good yields and with high diastereoselectivity. The similar three-component reaction with 2-arylidene-1,3-indanediones also gave 7′arylidenespiro[indene-2,1′-pyrrolizines] in good yields. However, the reaction with 3-phenacylideneoxindoles resulted in a mixture of spiro[indoline-3,1′-pyrrolizines] and 7′-arylidenesubstituted spirooxindoles in moderate yields. The reaction mechanism included generation of azomethine ylides, β-C−H functionalization of pyrrolidine, and sequential [3 + 2] cycloaddition. The obtained spirooxindole derivatives were investigated by in vitro evaluation against mouse colon cancer cells CT26 and human liver cancer cells HepG2 by MTT assay.
A highly regioselective Cu-catalyzed difunctionalization of quinolinium and benzothiazolim salts was developed with ether and halide (X = Br, Cl) as the halogen source under mild conditions.
The acetic acid catalyzed three-component reaction of pyrrolidine, aromatic aldehydes and 4-arylidene-5-methyl-2-phenylpyrazol-3-one in refluxing toluene gave functionalized 7'-(E)benzylidenespiro[pyrazole-4,1'-pyrrolizines] in good yields and with high diastereoselectivity. The similar reaction with 2arylidene-N,N'-dimethylbarbiturates resulted in mixture of Z/Eisomers of 7'-arylidenespiro[pyrimidine-5,1'-pyrrolizines] in good yields. However, the three-component with N-phenylmaleimides and sequential oxidation with DDQ reaction gave 8-(E)-arylidenedihydropyrrolo[3,4-a]pyrrolizines in satisfactory yields. The reaction mechanism included sequential β-CÀ H functionalization of pyrrolidine, generation of conjugated azomethine ylides, and sequential [3 + 2] cycloaddition with active alkenes.
The catalyst-free domino reaction
of α,β-unsaturated
N
-alkyl or
N
-arylaldimines with two molecules
of 2-arylidene-1,3-indanediones in dry acetonitrile resulted in polysubstituted
spiro[indene-2,3′-indeno[2′,1′:5,6]pyrano[2,3-
b
]pyridines] in moderate to good yields and with high diastereoselectivity.
The reaction mechanism included sequential aza/oxa-Diels–Alder
reactions via both endo-transition states. On the other hand, the
catalyst-free domino reaction of α,β-unsaturated
N
-arylaldimines with 2,2′-(arylmethylene)bis(1,3-indenediones)
afforded the mixed diastereoisomeric dispiro[indene-2,1′-cyclohexane-3′,2″-indene]
derivatives in satisfactory yields. The reaction mechanism of this
formal [3 + 3] cycloaddition was believed to proceed with sequential
nucleophilic 1,4-/1,2-additions.
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