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

Allylation of N-unsubstituted isatin N,N′-cyclic azomethine imines with Morita-Baylis-Hillman carbonates in the presence of 1–10 mol% DABCO in DCM at room temperature, rapidly gave N-allylated and N, β-diallylated isatin N,N′-cyclic azomethine imine 1,3-dipoles in moderate to high yields. The reaction features mild reaction conditions, easily practical operation, and short reaction times in most cases. Furthermore, the alkylated products were transformed into novel bicyclic spiropyrrolidine oxoindole derivatives through the [3+2] or [3+3]-cycloaddition with maleimides or Knoevenagel adducts.

K2CO3-Promoted Formal [3+3]-Cycloaddition of N-Unsubstituted Isatin N,N'-Cyclic Azomethine Imine 1,3-Dipoles with Knoevenagel Adducts

The synthesis of dicyclic spiropyridazine oxoindole derivatives by using [3+3]-cycloaddition of N-unsubstituted isatin N,N'-cyclic azomethine imine 1,3-dipoles was reported. The products bearing two consecutive stereocenters, including spiroquaternary stereocenters in one ring structure, can be effectively obtained in moderate to excellent yields (20-93%) and low to moderate diastereoselectivities (1:9-10:1 dr). The synthesized compounds (>35 examples) were characterized by single-crystal XRD, FTIR, NMR, and mass spectral analysis.

Rapid umpolung Michael addition of isatin N,N′-cyclic azomethine imine 1,3-dipoles with chalcones

3,3-Disubstituted oxindoles were prepared rapidly in moderate to excellent yields with promising dr values by the t-BuONa-promoted Michael addition.

An overview of the reactions involving azomethine imines over half a decade

Azomethine imines constitute a versatile class of 1,3-dipoles which was used extensively for biologically relevant N-heterocycle synthesis – a five-year recap.

A Role for Isatin Azomethine Imines as a Dipolarophile in Cycloaddition Reactions

An unusual [2 + 3] cycloaddition of isatin azomethine imines (AIs) and in situ generated azaoxyallyl cations has been developed. It is the first example where AIs serve as the [C,O] 2-atom synthon in organic synthesis. This work not only reveals a new role of isatin AIs in cycloaddition reaction but also provides an efficient access to unprecedented spiroheterocycle compounds.

1,3-Dipolar cycloaddition of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes catalyzed by DBU in water

A simple and green procedure was established by [3 + 3] cycloaddition reaction of isatin derived cyclic imine 1,3-dipoles with α,β-unsaturated aldehydes, giving the desired spiro heterocyclic oxindoles with aza-quaternary centers in good yields and diastereoselectivities. It should be noted that water can be employed as a suitable solvent for the improvement of diastereoselectivity.

A simple and green procedure was established by [3 + 3] cycloaddition reaction of isatin derived cyclic imine 1,3-dipoles with α,β-unsaturated aldehydes, giving spirooxindoles with aza-quaternary center in good yields and diastereoselectivities.

A [3 + 2] cycloaddition/C-arylation of isatin N,N′-cyclic azomethine imine 1,3-dipole with arynes

A [3 + 2] annulation/C-arylation reaction of 1,3-dipole 1 with arynes has been established for the synthesis of oxindole scaffolds.

Diverse reactivity of isatin-based N,N′-cyclic azomethine imine dipoles with arynes: synthesis of 1′-methyl-2′-oxospiro [indene-1,3′-indolines] and 3-aryl-3-pyrazol-2-oxindoles

Reaction of aryne with isatin based N,N′-cyclic AMI 1,3-dipole afforded 3,3-disubstituted oxindole while methyl substitution on the pyrrolidine ring of 1,3-dipole directed [3+2] cycloaddition products.

Rapid abnormal [3+2]-cycloaddition of isatin N,N′-cyclic azomethine imine 1,3-dipoles with chalcones

More than 35 new compounds were prepared rapidly in moderate to excellent yields with high diastereoselectivities by K₂CO₃-promoted abnormal 1,3-diploar cycloaddition of isatin N, N′-cyclic azomethine imines with chalcones.

Diastereoselective construction of a functionalized dihydro-pyridazine-based spirooxindole scaffold via C-3 umpolung of isatin N,N′-cyclic azomethine imine

This study demonstrates an abnormal [3+3] tandem Michael addition/N-cyclization of isatin N,N′-cyclic azomethine imine 1,3-dipoles and 2-arylidene malononitrile that diastereoselectively construct a dihydro-pyridazine-based spirooxindole.

Base-mediated [2 + 4] cycloadditions of in situ formed azaoxyallyl cations with N-(2-chloromethyl)aryl amides

A base-mediated [2 + 4] annulation of in situ formed azaoxyallyl cations with in situ generated aza-oQMs has been realized.