Chromium complexes of three new ligands, Ph2PN(Me)(CH2)2-X [X = NMe2 (PNN); PPh2 (PNP); Py (PNPy)], have been examined vis-à-vis their ability to promote ethylene tetramerization, (PNN)CrCl3(L) [L = THF (1); CH3CN (2)], (PNPy)CrCl3(L) [L = THF (3); CH3CN (4)], and (PNP)CrCl3(THF) (5). In the case of 2 and 4, it was possible to grow crystals suitable for X-ray diffraction. The reaction of 3 with Et3Al afforded the dinuclear [(HN(Me)(CH2)2Py)CrCl2Et]2 (6) containing a trivalent chromium connected to an Et group. During the alkylation though, the ligand has been fragmented with removal of the side arm and protonation of the N atom of the remaining NP residue. All the complexes have been tested for ethylene oligomerization activity. Complex 1 displayed the highest selectivity for 1-octene, upon activation with DMAO in MeCy. Contrary to expectations, complex 6 is not a self-activating catalyst.

Gurnham, J.; Liu, B.; Duchateau, R.; Gambarotta, S.; Korobkov, I.

Ionic diamine rhodium complex (1) catalyzes the reductive N-cyclization of 2-vinylnitroarenes using carbon monoxide as a reducing agent to afford functionalized indoles. The catalytic system allows direct access to indoles with ester and ketone groups at the 2- or 3-position, in good yields.

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Ionic Diamine Rhodium Complex Catalyzed Reductive N-Heterocyclization of 2-Nitrovinylarenes. -In the presence of the rhodium catalyst, a number of 2-nitrovinylarenes undergoes reductive cyclization to afford indoles. -(OKURO, K.; GURNHAM, J.; ALPER*, H.; J. Org. Chem. 76 (2011) 11, 4715-4720, http://dx.doi.org/10.1021/jo200320k ; Dep. Chem., Univ. Ottawa, Ottawa, Ont. K1N 6N5, Can.; Eng.) -Jannicke

A simple protocol allows the transformation of substrates (I) in the presence of carbon monoxide to yield the corresponding 2H‐indazoles.