Catalytic 1,2-dihydronaphthalene and -aryl-diene synthesis Co-Carbene radical and -quinodimethane intermediates.

Catalytic synthesis of substituted 1,2-dihydronaphthalenes metalloradical activation of -styryl -tosyl hydrazones (()-2-(prop-1-en-1-yl)benzene--tosyl hydrazones) is presented, taking advantage of the intrinsic reactivity of a cobalt(iii)-carbene radical intermediate. The method has been successfully applied to a broad range of substrates with various substituents at the aromatic ring, producing the desired ring products in good to excellent isolated yields for substrates with an = COOEt substituent at the vinylic position (∼70-90%). Changing the moiety from an ester to other substituents has a surprisingly large influence on the (isolated) yields.

Nitrene Radical Intermediates in Catalytic Synthesis.

Nitrene radical complexes are reactive intermediates with discrete spin density at the nitrogen-atom of the nitrene moiety. These species have become important intermediates for organic synthesis, being invoked in a broad range of C-H functionalization and aziridination reactions. Nitrene radical complexes have intriguing electronic structures, and are best described as one-electron reduced Fischer type nitrenes.

Cobalt-Porphyrin-Catalysed Intramolecular Ring-Closing C-H Amination of Aliphatic Azides: A Nitrene-Radical Approach to Saturated Heterocycles.

Cobalt-porphyrin-catalysed intramolecular ring-closing C-H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines, imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air- and moisture-stable catalyst. Kinetic studies of the reaction in combination with DFT calculations reveal a metallo-radical-type mechanism involving rate-limiting azide activation to form the key cobalt(III)-nitrene radical intermediate.

Catalytic Synthesis of N-Heterocycles via Direct C(sp)-H Amination Using an Air-Stable Iron(III) Species with a Redox-Active Ligand.

Coordination of FeCl to the redox-active pyridine-aminophenol ligand NNO in the presence of base and under aerobic conditions generates FeCl(NNO) (1), featuring high-spin Fe and an NNO radical ligand. The complex has an overall S = 2 spin state, as deduced from experimental and computational data. The ligand-centered radical couples antiferromagnetically with the Fe center.

Encapsulated cobalt-porphyrin as a catalyst for size-selective radical-type cyclopropanation reactions.

A cobalt-porphyrin catalyst encapsulated in a cubic M8 L6 cage allows cyclopropanation reactions in aqueous media. The caged-catalyst shows enhanced activities in acetone/water as compared to pure acetone. Interestingly, the M8 L6 encapsulated catalyst reveals size-selectivity.

Encapsulation of metalloporphyrins in a self-assembled cubic M8L6 cage: a new molecular flask for cobalt-porphyrin-catalysed radical-type reactions.

The synthesis of a new, cubic M8L6 cage is described. This new assembly was characterised by using NMR spectroscopy, DOSY, TGA, MS, and molecular modelling techniques. Interestingly, the enlarged cavity size of this new supramolecular assembly allows the selective encapsulation of tetra(4-pyridyl)metalloporphyrins (M(II)(TPyP), M = Zn, Co).