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Ruthenium(II) Complexes Bearing a Ligand Derived from P,N- or P,N,O-Diphenylphosphinobenzoxazine: Synthesis, X-ray Characterization, and cis Diastereoselectivity in Styrene Cyclopropanation

Auteur(s)
Ardizzoia, G. Attilio
Brenna, Stefano
Durini, Sara
Date de parution
2012
In
Organometallics
Vol.
15
No
31
De la page
5427
A la page
5437
Mots-clés
Résumé
A phosphino-oxazine based ligand (L; 2-(2-(diphenylphosphino)phenyl)-2,4-dihydro-1H-benzo[d][1,3]oxazine) showing a temp.-dependent equil. between a closed bidentate (LPN) and an opened tridentate (LPNO) form, has been synthesized and its coordination behavior toward ruthenium(II) centers studied. Under different exptl. conditions, two different species bearing the ligand in either its bidentate or tridentate coordination mode were isolated by reaction with Ru(PPh3)3Cl2. These species, resp. formulated as [Ru(PPh3)(LPNO)Cl2] (1) and [Ru(PPh3)(LPN)Cl2] (2), were fully characterized via NMR in soln. and by an x-ray structural detn. Notably, compd. 2 reacts with an excess of Et diazoacetate (EDA) in CH2Cl2 to give a stable ?3-diethyl maleate complex, [Ru(LPN)(cis-EtO(O)CCH:CHC(O)OEt)Cl2] (3). The crystal structure of 3 has also been detd. Substitution reactions with 4-picoline (4-Me-py) performed on 1 led to two new complexes: the neutral complex [Ru(4-Me-py)(LPNO)Cl2] (5) and the salt [Ru(4-Me-py)2(LPNO)Cl](Cl) (6a). The latter compd. catalyzed the intermol. cyclopropanation of styrene with EDA in high yields and with elevated cis diastereoselectivity (i.e., cis/trans = 80/20). [on SciFinder(R)]
Identifiants
https://libra.unine.ch/handle/123456789/19262
Type de publication
journal article