The indium-mediated allylation of novel 3-(2-Boc-hydrazono)indolin-2-one derivatives, followed by a palladium-catalysed carboamination reaction, is described to afford unprecedented spirocyclic oxindoles in good yields.

We here describe the first Cu-catalysed, diastereoselective 1,2-addition of 1,1-diborylmethane to chiral ketimines for the synthesis of quaternary stereocenters and spiro compounds. The method provides easy access to a range...

Addressing the asymmetric synthesis of oxindole-based α-aminoboronic acids, instead of the expected products we disclosed the efficient homocoupling of oxindole-based N-tert-butanesulfinyl imines, with the generation of chiral, quaternary 1,2-diamines in a mild and completely stereoselective way. The obtained 3,3′-bisoxindole derivatives were fully characterized by NMR and single-crystal X-ray diffraction analysis and proved to be single diastereoisomers and atropisomers. A plausible mechanism for the one-pot Cu(II)-catalyzed Bpin addition to the isatin-derived ketimine substrate and subsequent homocoupling is described.

The reaction between hydrazonoyl chlorides and monosubstituted allenes in the presence of catalytic amounts of copper(I) chloride gives 1,3,5-substituted pyrazoles under mild conditions and very short reaction times.This site-and regioselective process involves first the complexation of copper(I) on the external double bond of the allene moiety, followed by nucleophilic attack on the central carbon atom of the so-formed copper(I)-complexed allene by the terminal nitrogen of the hydrazonoyl chloride. Subsequent ring closure to the target pyrazole ring is possible in the presence of electron-attracting groups on the allene moiety. A catalytic cycle has been proposed on the basis of the experimental results.Allenes can undergo a wide variety of reactions 1 including the celebrated Diels-Alder 1,2 and 1,3-dipolar 3 cycloadditions. To this latter respect, allenes are particularly interesting dipolarophiles as they have two sites of addition, for each of which two different dipole-dipolarophile orientations are possible. Several years ago, one of us was engaged in the synthesis of highly-functionalised pyrazoles by cycloaddition between allenes and nitrilimines, 4 -C≡N + -N -, owing to the fact that variously functionalised pyrazoles are interesting targets in medicinal chemistry as analgesic, antifungal, anti-inflammatory, antibacterial and antiviral agents. 5 Unfortunately, it was found that the obtainment of complex reaction mixtures was often the rule, i.e. the cycloaddition showed poor site-and regio-selectivity. Furthermore, the reaction outcome was strongly dependent on the electronic nature of the 1,3-dipole: while electron-rich nitrilimines gave fair results, the cycloaddition pathway appeared impervious with electron-poor nitrilimines. Since the in situ generation of the labile nitrilimine intermediate was accomplished by dehydrohalogenation of the corresponding hydrazonoyl chloride -C(Cl)=N-NHwith stoichiometric amounts of silver carbonate, 4,6 it is apparent that a site-and regio-selective approach to the pyrazole ring