1194 Organometallics, Vol. 27, No. 6, 2008
Mothes et al.
variations in the nature of the substituents on the phosphorus,
the central methylenic carbon, or the pyridyl group and was
even found convenient for the synthesis of optically active
versions based on P-chiral or C-chiral centers.8b–d
The readily accessible complex RuCl2(PPh3)3 was selected
as a convenient starting compound for our investigations on
account of its well-established substitutional lability, cor-
roborated here by new observations disclosed below.
The present paper describes the directed synthesis and full
characterization of new members of the extended family of 16
e- phosphinopyridine type complexes RuCl2(Lnx)(PPh3) (Lnx
) R2PCH2(C5H2R′R′′N)) differing in the nature of substituents
on the phosphorus atom (superscript label n in Lnx defined as
n ) 1 for R ) Ph, n ) 2 for R ) Cy) and on the pyridyl group
(superscript label x in Lnx defined as x ) a for picolyl, noted
pic, and x ) b for quinolyl, noted quin).9 It also presents a
hitherto unknown aspect of their reactivity toward a diazoalkane,
suggesting a realistic rational pathway for the “in situ” genera-
tion of an active olefin metathesis catalyst. Possibilities and
limitations of these complexes as readily available catalyst
precursors for the ROMP of norbornene10 or the transfer
hydrogenation of ketones11 are discussed on the basis of
preliminary catalytic tests.
A convenient modular approach to a palette of such pyridine-
functionalized phosphine ligands was developed some years ago
in our laboratory and applied to the synthesis of a number of
their Ru and Rh complexes.8 The procedure allowed multiple
(1) (a) For reviews on olefin metathesis, see: Handbook of Metathesis;
Grubbs, R. H., Ed.; Wiley-VCH: Weinheim, Germany, 2003. (b) Hoveyda,
A. H.; Gillingham, D. G.; Van Veldhuizen, J. J.; Kataoka, O.; Garber, S. B.;
Kingsbury, J. S.; Harrity, J. P. A. Org. Biomol. Chem. 2004, 2, 1. (c)
Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592.
(d) Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003, 42, 1900. (e)
Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18. (f) Fürstner, A.
Angew. Chem., Int. Ed. 2000, 39, 3012.
(2) (a) For selected specific examples of advanced new generations of
olefin metathesis catalysts, see: Sanford, M. S.; Love, J. A.; Grubbs, R. H.
Organometallics 2001, 20, 5314. (b) Love, J. A.; Morgan, J. P.; Trnka,
T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002, 41, 4035. (c) Garber,
S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc.
2000, 122, 8168. (d) Van Veldhuizen, J. J.; Garber, S. B.; Kingsbury, J. S.;
Hoveyda, A. H. J. Am. Chem. Soc. 2002, 124, 4954. (e) Wakamatsu, H.;
Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 2403. (f) Dunne, A. M.;
Mix, S.; Blechert, S. Tetrahedron Lett. 2003, 44, 2733. (g) Grela, K.;
Harutyunyan, S.; Michrowska, A. Angew. Chem., Int. Ed. 2002, 41, 4038.
(h) Michrowska, A.; Bujok, R.; Harutyunyan, S.; Sashuk, V.; Dolgonos,
G.; Grela, K. J. Am. Chem. Soc. 2004, 126, 9318. (i) Harutyunyan, S.;
Michrowska, A.; Grela, K. In Catalysts for Fine Chemical Synthesis;
Roberts, S. M., Whittall, J., Mather, P., McCormack, P., Eds.; Wiley-
Interscience: New York, 2004; Vol. 3, p 169. (j) Grela, K.; Michrowska,
A.; Bieniek, M. Chem. Rec. 2006, 6, 144. (k) Yang, L.; Mayr, M.; Wurst,
K.; Buchmeister, M. R. Chem.-Eur. J. 2004, 10, 5761. (l) Fürstner, A.;
Thiel, O. R.; Lehmann, C. W. Organometallics 2002, 21, 331. (m) Slugovc,
C.; Perner, B.; Stelzer, F.; Mereiter, K. Organometallics 2004, 23, 3622.
(n) Romero, P. E.; Piers, W. E.; McDonald, R. Angew. Chem., Int. Ed.
2004, 43, 6161. (o) Conrad, J. C.; Parnas, H. H.; Snelgrove, J. L.; Fogg, D.
J. Am. Chem. Soc. 2005, 127, 11882. (p) Conrad, J. C.; Fogg, D. E. Curr.
Org. Chem. 2006, 10, 185. (q) Bieniek, M.; Bujok, R.; Cabaj, M.; Lugan,
N.; Lavigne, G.; Artl, D.; Grela, K. J. Am. Chem. Soc. 2006, 128, 13652.
(r) Ritter, T.; Hejl, A.; Wenzel, A. G.; Funk, T. W.; Grubbs, R. H.
Organometallics 2006, 25, 5740.
Results and Discussion
Preparation of the Ligands. Both 2-[(diphenylphosphino)
methyl]pyridine and 2-[(diphenylphosphino)methyl]-6-meth-
ylpyridine (L1a) were previously prepared in good yields by
reaction of diphenylchlorophosphine with 2-pyridynylmethyl-
lithium and 6-methyl-2-pyridynylmethyllithium, respectively, at
low temperature.8 Such a procedure was extended here to the
synthesis of 2-[(diphenylphosphino)methyl]quinoline (L1b) from
Ph2PCl and 2-quinolynylmethyllithium, 2-[(dicyclohexylphos-
(7) (a) For various reviews and articles on the coordination chemistry
of phosphinopyridines and related P, N ligands, see: Newkome, G. R. Chem.
ReV. 1993, 93, 2067. (b) Espinet, P.; Soulantica, K. Coord. Chem. ReV.
1999, 193–195, 499. (c) Guiry, P. J.; Saunders, C. P. AdV. Synth. Catal.
2004, 346, 497. (d) Gomez, R.; Adrio, J.; Carretero, J. C. Angew. Chem.,
Int. Ed. 2006, 45, 7674. (e) Gianneschi, N. C.; Masar III, M. S.; Mirkin,
C. A. Acc. Chem. Res. 2005, 38, 825. (f) Chen, H.-P.; Liu, Y.-H.; Peng,
S.-M.; Liu, S.-T. Dalton Trans. 2003, 1419. (g) Speiser, F.; Braunstein, P.;
Saussine, L. Organometallics 2004, 23, 2625.
(3) (a) For selected applications of olefin metathesis, see: Nicolaou,
K. C.; Bulger, P. G.; Sarlah, D. Angew. Chem., Int. Ed. 2005, 44, 4490. (b)
Gradillas, A.; Perez-Castells, J. Angew. Chem., Int. Ed. 2006, 45, 6086. (c)
Watson, K. J.; Anderson, D. R.; Nguyen, S. T. Macromolecules 2001, 34,
3507. (d) Clavier, H.; Grela, K.; Kirschning, A.; Mauduit, M.; Nolan, S. P.
Angew. Chem., Int. Ed. 2007, 46, 6786.
(8) (a) Alvarez, M.; Lugan, N.; Mathieu, R. J. Chem. Soc., Dalton Trans.
1994, 2755. (b) Yang, H.; Alvarez, M.; Lugan, N.; Mathieu, R. J. Chem.
Soc., Chem. Commun. 1995, 1721. (c) Yang, H.; Lugan, N.; Mathieu, R.
Organometallics 1997, 16, 2089. (d) Yang, H.; Alvarez-Gressier, M.; Lugan,
N.; Mathieu, R. Organometallics 1997, 16, 1401. (e) Yang, H.; Lugan, N.;
Mathieu, R. C. R. Acad. Sci. Paris, 2, Sér. II 1999, 251–258. (f) Esquius,
G.; Pons, J.; Yanez, R.; Ros, J.; Mathieu, R.; Lugan, N.; Donnadieu, B. J.
Organomet. Chem. 2003, 667, 126.
(4) For a review, see: Mecking, S.; Held, A.; Bauers, F. M. Angew.
Chem., Int. Ed. 2002, 41, 544.
(5) (a) For examples of in situ generated catalytic systems where the
precatalyst is not a carbene complex, see: Herrmann, W. A.; Schattenman,
W. C.; Nuyken, O.; Glander, S. C. Angew. Chem., Int. Ed. Engl. 1996, 35,
1087. (b) Demonceau, A.; Stumpf, A. W.; Saive, E.; Noëls, A. F.
Macromolecules 1997, 30, 3127. (c) Bartz, M.; Küther, J.; Seshadri, R.;
Tremel, W. Angew. Chem., Int. Ed. 1998, 37, 2466. (d) Amoroso, D.; Fogg,
D. E. Macromolecules 2000, 33, 2815. (e) Jan, D.; Delaude, L.; Demonceau,
A.; Noëls, A. F. J. Organomet. Chem. 2000, 606, 55. (f) Sémeril, D.; Cléran,
M.; Bruneau, C.; Dixneuf, P. H. AdV. Synth. Catal. 2001, 343, 184. (g)
Castarlenas, R.; Fischmeister, C.; Dixneuf, P. New J. Chem. 2003, 27, 215.
(h) Matos, J. M. E.; Lima-Neto, B. S. J. Mol. Catal. A 2004, 222, 81. (i)
Matos, J. M. E.; Lima-Neto, B. S. Catal. Today 2005, 107–108, 282. (j)
Bernechea, M.; Lugan, N.; Gil, B.; Lalinde, E.; Lavigne, G. Organometallics
2006, 25, 684. (k) Castarlenas, R.; Vovard, C.; Fischmeister, C.; Dixneuf,
P. H. J. Am. Chem. Soc. 2006, 128, 4079. (l) Sauvage, X.; Borguet, Y.;
Noels, A. F.; Delaude, L.; Demonceau, A. AdV. Synth. Catal. 2007, 349,
255.
(9) The specific case of the ligand R2PCH2(C5H4N) based on an unsub-
stituted pyridyl group was not included in the present report, a complicating
factor being that relevant complexes RuCl2{ R2PCH2(C5H4N)}(PPh3) are
obtained as mixtures of inseparable isomers (Lugan, N.; Lavigne, G. Unpub-
lished observations).
(10) (a) For leading references on ROMP, see: Nguyen, S. T.; Johnson,
L. K.; Grubbs, R. H. J. Am. Chem. Soc. 1992, 114, 3974. (b) Lynn, D. M.;
Kanaoka, S.; Grubbs, R. J. Am. Chem. Soc. 1996, 118, 784. (c) Bielawski,
C. W.; Grubbs, R. H. Angew. Chem., Int. Ed. 2000, 39, 2903. (d) Choi,
T.-L.; Grubbs, R. H. Angew. Chem., Int. Ed. 2003, 42, 1743. (e) Haigh,
D. M.; Kenwright, A. M.; Khosravi, E. Macromolecules 2005, 38, 7571.
(f) Fogg, D. E.; Foucault, H. ComprehensiVe Organometallic Chemistry
III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier: Oxford, 2006. (g)
Camm, K. D.; Martinez Castro, N.; Liu, Y.; Czechura, P.; Fogg, D. E. J. Am.
Chem. Soc. 2007, 129, 4168.
(6) (a) Let us also state here the existence of the remarkably ingenuous
one-pot procedure for the synthesis of Grubbs catalyst: Wolf, J.; Stüer, W.;
Grünwald, C.; Werner, H.; Schwab, P.; Schulz, M. Angew. Chem., Int. Ed.
1998, 37, 1124. (b) Jung, S.; Brandt, C. D.; Wolf, J.; Werner, H. Dalton
Trans 2004, 375. (c) see also Louie, J.; Grubbs, R. H. Angew. Chem., Int.
Ed. 2001, 40, 247.
(11) (a) For review articles on transfer hydrogenation, see: Clapham,
S. E.; Hadzovic, A.; Morris, R. H. Coord. Chem. ReV. 2004, 248, 2201. (b)
Gladiali, S.; Alberico, E. Chem. Soc. ReV. 2006, 35, 226. (c) Samec, J. S. M.;
Bäckvall, J.-E.; Andersson, P. G.; Brandt, P. Chem. Soc. ReV. 2006, 35,
237. (d) Wu, X.; Xiao, J. Chem. Commun. 2007, 2449. (e) Palmer, M. J.;
Wills, M. Tetrahedron: Asymmetry 1999, 10, 2045.