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
Author(s)
Date issued
2012
In
Organometallics
Vol
15
No
31
From page
5427
To page
5437
Subjects
ruthenium chloride phosphine complex reaction diphenyl phosphino benz oxazine diphenylphosphinophenyl dihydrobenzooxazine reaction ruthenium chloride phosphine complex styrene cyclopropanation diastereoselectivity diphenylphosphinobenzoxazine ruthenium catalyzed crystal mol structure diphenylphosphinobenzoxazine ruthenium complex mol structure calcn diphenylphosphinobenzoxazine ruthenium complex
Abstract
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)]
Publication type
journal article