Bis(hydroxy-isoindolinone)s: Synthesis, Stereochemistry, Polymer Chemistry, and Supramolecular Assembly

Synthesis and Reactivity of Dipalladated Derivatives of Terephthalaldehyde

The polynuclear complex [{μ-C1,C4,N,N″-C6H2{C(H)=N(nBu)}2-2,5}{Pd(μ-OAc)}]2 (I) reacts with tbbpy (4,4'-di-tert-butyl-2,2'-bipyridine) and TlOTf to form the dinuclear complex [{μ-C1,C4,N,N″-C6H2{C(H)=N(nBu)}2-2,5}{Pd(tbbpy)}2] (1). The hydrolysis of I with acetic acid in a 5:1 acetone/water mixture, in the presence of two equivalents of tbbpy and excess NaX (X = Br, I), yields the dipalladated terephthalaldehyde complexes [C6H2{PdX(tbbpy)}2-1,4-(CHO)2-2,5] [X = Br (2a), X = I (2b)], which are the first fully characterized complexes of this type. The reaction of 2a,b with CO results in the insertion of CO into both aryl-Pd bonds, forming [C6H2{C(O){PdX(tbbpy)}}2-1,4-(CHO)2-2,5] [X = Br (3a), X = I (3b)], which are the first examples of complexes with CO inserted into two separate aryl-metal bonds involving the same ligand. The bromo complex 2a reacts with excess XylNC in acetone, causing the precipitation of the dinuclear complex 2,3,6,7-tetrahydrobenzo[1,2-c:4,5-c']dipyrrole-1,5-dione-2,6-dixylyl-3,7-bis{=C(NHXyl)-C(=NXyl)-[PdBr(CNXyl)2]} (4), which is the result of the insertion of three molecules of the isocyanide into each aryl-Pd bond and the nucleophilic attack of one of them at each formyl group. When complex 4 reacts with TlOTf and residual water in 1,2-dichloroethane at 70 °C, depalladation occurs, and the organic compound 2,3,6,7-tetrahydrobenzo[1,2-c:4,5-c']dipyrrole-1,5-dione-2,6-dixylyl-3,7-bis{=C(NHXyl)-C(O)NHXyl} (5) can be isolated. The crystal structures of 1·4CHCl3, 4·2CH2Cl2·3hexane, and 5·2CDCl3 have been determined by X-ray crystallography.

Facile synthesis of 11-aryl-6H-isoindolo[2,1-a]indol-6-ones via hypervalent iodine(iii)-promoted cascade cyclization

An efficient method was developed for the synthesis of a tetracyclic fused indole and isoindoline ring system, under metal-free conditions.