Part II: Diastereoselective Reactions Involving β‐Mono‐ and β,β′‐Disubstituted Alkylidene Oxindoles: Pondering Alkene Geometry

Abstract

Part II encompasses synthetic efforts towards the construction of acyclic and cyclic structures that contain carbon and heteroatoms by employing diastereoselective reactions of β,β′‐disubstituted alkylidene oxindole as the primary substrate. In addition to the construction of acyclic structures, carbocyclic and heterocyclic rings that contain three‐, five‐, six‐, and seven‐membered spirocycles or fused‐rings are also described. A few examples of the arylative cyclization of dienes have also been presented.

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

“…There is extensive application of 3-phenacylideneoxindoles generating diverse reaction strategies following the regioselective and diastereoselective synthesis of carbocyclic and heterocyclic frameworks [ 31 – 32 ]. During our preliminary investigations as shown in Table 1 , we commenced our study by reacting two equivalents of ( E )-3-(2-(4-chlorophenyl)-2-oxoethylidene)indolin-2-one ( 1a ) under reflux conditions with one equivalent of tosylhydrazine ( 2 ) as hydrogen source in ethanolic solution in the presence of K 2 CO 3 as base.…”

Ultrasound-Engineered fabrication of immobilized molybdenum complex on Cross-Linked poly (Ionic Liquid) as a new acidic catalyst for the regioselective synthesis of pharmaceutical polysubstituted spiro compounds

“…Addition of pyrazolone or β-enamino ester (D) onto intermediate (B) was carried out through addition to α,β‘ bond in the presence of electron withdrawing groups (EWG) (R‘,R‘‘= CN). Among mentioned regioselective mechanism, US strategy also leads to improvement selectivity in organic transformations [49] .…”

Spiro‐2‐oxindoles via 1,3‐dipolar cycloadditions. A decade update

“…The synthetic methodologies developed for the construction of 3‐methylene‐ and 3‐(monosubstituted)‐ alkylidene 2‐oxindoles, [25] as well as their usefulness in organic synthesis, [26,27] have been reviewed recently. Such trisubstituted alkenes constitute the ideal starting reagents for the construction of three‐ to seven‐membered 3‐spiro(carbo)‐ or 3‐spiro(hetero)‐cyclic indoles [15] .…”