In search of optically active γ-keto acetylenes via regioselective coupling of allenylidene groups and cyclic enolates

Article abstract of DOI:10.1021/om0202928

An efficient synthetic approach of γ-keto acetylenes based on the regio- and diastereoselective propargylic alkylation of 2-propyn-1-ols with methyl ketones was discussed. The synthetic methodology constituted an alternative to the well-known Nicholas cou

Full text of DOI:10.1021/om0202928

3716
Organometallics 2002, 21, 3716-3726
In Sea r ch of Op tica lly Active γ-Keto Acetylen es via
Regioselective Cou p lin g of Allen ylid en e Gr ou p s a n d
Cyclic En ola tes
Victorio Cadierno, Salvador Conejero, M. Pilar Gamasa, and J ose´ Gimeno*
Departamento de Quı´mica Orga´nica e Inorga´nica, Instituto Universitario de Quı´mica
Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC), Facultad de Qu´ımica,
Universidad de Oviedo, E-33071 Oviedo, Spain
Larry R. Falvello
Universidad de Zaragoza, Departamento de Qu´ımica Inorga´nica, Plaza San Francisco s/ n,
E-50009 Zaragoza, Spain
Rosa M. Llusar
Departament de Ciencies Experimentals, Campus Riu Sec, Universitat J aume I, POB 224,
E-12071 Castello´n, Spain
Received April 15, 2002
(Indenyl)ruthenium(II) allenylidene complexes [Ru{dCdCdC(R)Ph}(η5-C9H7)(PPh3)2][PF6]
(R ) Ph (1), H (2)) regioselectively react with enolates derived from cyclopentanone and
cyclohexanone at the Cγ atom to yield the σ-alkynyl derivatives [Ru{CtCC(R)Ph(CHCOCH2-
(CH2)nCH2)}(η5-C9H7)(PPh3)2] (R ) Ph, n ) 1 (3a ), 2 (3b); R ) H, n ) 1 (4a ), 2 (4b)).
Protonation of these species at Câ of the alkynyl chain with HBF4 affords vinylidene complexes
5a ,b and 6a ,b, which can easily be demetalated with acetonitrile to yield the γ-keto acetylenes
HCtCC(R)Ph(CHCOCH2(CH2)nCH2) (7a ,b and 8a ,b). Compounds 4a ,b, 6a ,b and 8a ,b,
derived from the monosubstituted allenylidene complex 2, have been obtained as nonsepa-
rable mixtures of two diastereoisomers. The optically active allenylidene [Ru{dCdCd
C(C9H16)}(η5-C9H7)(PPh3)2][PF6] (10) (C(C9H16) ) (1R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-
ylidene) undergoes a selective exo addition of the cyclopentanone enolate to afford the
σ-alkynyl diastereoisomers [Ru{CtCC(C9H16)(CHCOCH2CH2CH2)}(η5-C9H7)(PPh3)2] (11a ,b).
Demetalation of 11a and 11b, via their corresponding vinylidenes, allows the preparation
of optically pure terminal alkynes HCtCC(C9H16)(CHCOCH2CH2CH2) (13a ,b, respectively).
The oxacycloalkenyl derivative [Ru{CdC(H)C(C9H16)CdC(CH2CH2CH2)O}(η5-C9H7)(PPh3)2]
(14) has been obtained by treatment of 11a or 11b with a catalytic amount of AlCl3.
Protonation of 14 affords the corresponding cyclic carbene 15. The reactivity of allenylidene
complexes 1, 2, and 10 toward lithium enolates derived from the optically active ketones
(R)-(-)-carvone and (R)-(+)-pulegone has been also explored. For diphenylallenylidene 1
diastereoselective additions are observed, yielding the optically pure σ-alkynyl complexes
16 and 19, respectively. While attempts to demetalate 19 failed, demetalation of 16 yields
the optically pure γ-keto alkyne HCtCCPh2(C10H13O) (18) in excellent yield. The crystal
structures of compounds 11b and 14 have been determined by X-ray diffraction.
In tr od u ction
In the context of our studies on the chemistry of
allenylidene ruthenium(II) complexes, we have recently
reported an efficient synthetic approach of γ-keto acety-
lenes based on the regio- and diastereoselective propar-
gylic alkylation of 2-propyn-1-ols with methyl ketones
mediated by the (indenyl)ruthenium(II) moiety [Ru(η5-
C9H7)(PPh3)2]+ (see eq 1).1
The following processes are involved in this synthetic
route (see Scheme 1): (i) initial formation of allenylidene
complexes A as the result of the metal-mediated dehy-
dration of propargylic alcohols HCtCCR1R2(OH),2,3 (ii)
* To whom correspondence should be addressed. E-mail: jgh@
sauron.quimica.uniovi.es.
(1) Cadierno, V.; Conejero, S.; Gamasa, M. P.; Gimeno, J .; Pe´rez-
Carren˜o. E.; Garc´ıa-Granda, S. Organometallics 2001, 20, 3175.
10.1021/om0202928 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/02/2002

Optically Active γ-Keto Acetylenes
Organometallics, Vol. 21, No. 18, 2002 3717
Sch em e 1
regioselective nucleophilic addition of lithium enolates
at the electrophilic Cγ atom of these metallacumulenes
to give neutral keto alkynyl derivatives B,4 (iii) selective
Câ protonation of the σ-alkynyl complexes to afford the
corresponding vinylidenes C,5 and finally (iv) a vinyli-
dene-π-terminal alkyne tautomerization in refluxing
acetonitrile to generate transient π-alkyne complexes
which readily exchange the coordinated alkyne by
acetonitrile, leading to the free γ-keto acetylenes D. The
metal fragment is quantitatively recovered as the ac-
etonitrile complex [Ru(NtCMe)(η5-C9H7)(PPh3)2]+.
This synthetic methodology constitutes an alternative
to the well-known Nicholas coupling of 2-propyn-1-ol
derivatives with ketones containing R-hydrogens via
[Co2(CO)6]-stabilized propargylium cations.6 Interest-
ingly, Hidai and co-workers have recently reported a
related ruthenium-catalyzed propargylic alkylation of
monosubstituted propargylic alcohols with ketones to
afford γ-keto acetylenes.7 Remarkably, although the
detailed reaction mechanism of this catalytic process is
still unknown, the nucleophilic attack of an enolate
carbon on the electrophilic Cγ atom in allenylidene
intermediates has been proposed as the key step of the
catalytic cycle.
To extend the scope of our synthetic approach, in this
paper we report the efficient synthesis of novel optically
active terminal alkynes which are prepared via regio-
selective reactions of the allenylidene derivatives [Ru-
{dCdCdC(R)Ph}(η5-C9H7)(PPh3)2][PF6] (R ) Ph, H)3a
and [Ru{dCdCdC(C9H16)}(η5-C9H7)(PPh3)2][PF6] (C(C9-
H
16) ) (1R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-ylidene)1
with enolates derived from prochiral (i.e. cyclopentanone
and cyclohexanone) and chiral (i.e. (R)-(-)-carvone and
(R)-(+)-pulegone) cyclic ketones. The presence of prochiral
or stereogenic centers in the allenylidene precursors
permits the elucidation of the stereoselectivity of these
nucleophilic additions. Part of this work has been
communicated in a preliminary report.3d
(2) For comprehensive reviews on the synthesis and reactivity of
allenylidene complexes see: (a) Werner, H. Chem. Commun. 1997, 903.
(b) Bruce, M. I. Chem. Rev. 1998, 98, 2797. (c) Touchard, D.; Dixneuf,
P. H. Coord. Chem. Rev. 1998, 178-180, 409. (d) Cadierno, V.; Gamasa,
M. P.; Gimeno, J . Eur. J . Inorg. Chem. 2001, 571.
(3) For papers dealing with the synthesis and reactivity of (indenyl)-
ruthenium(II) allenylidenes [Ru(dCdCdCR1R2)(η5-C9H7)(PPh3)2]+
see: (a) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Cueva,
M.; Lastra, E.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-Carren˜o. E. Orga-
nometallics 1996, 15, 2137. (b) Cadierno, V.; Gamasa, M. P.; Gimeno,
J .; Borge, J .; Garc´ıa-Granda, S. Organometallics 1997, 16, 3178. (c)
Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lo´pez-Gonza´lez, M. C.; Borge,
J .; Garc´ıa-Granda, S. Organometallics 1997, 16, 4453. (d) Cadierno,
V.; Gamasa, M. P.; Gimeno, J .; Pe´rez-Carren˜o, E.; Ienco, A. Organo-
metallics 1998, 17, 5216. (e) Cadierno, V.; Gamasa, M. P.; Gimeno, J .;
Pe´rez-Carren˜o, E.; Garc´ıa-Granda, S. Organometallics 1999, 18, 2821.
(f) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lastra, E. J . Chem. Soc.,
Dalton Trans. 1999, 3235. (g) Cadierno, V.; Conejero, S.; Gamasa, M.
P.; Gimeno, J . J . Chem. Soc., Dalton Trans. 2000, 451. (h) Cadierno,
V.; Conejero, S.; Gamasa, M. P.; Gimeno, J .; Rodr´ıguez, M. A.
Organometallics 2002, 21, 203.
(4) Other regioselective nucleophilic additions of enolates derived
from methyl ketones at Cγ in allenylidene complexes, i.e. [Ru(dCd
CdCPh2)(η5-C5H5)(CO)(PiPr3)]+, [Os(dCdCdCPh2)(η5-C5H5)(PiPr3)2]+,
[Re(dCdCdCPh2)(CO)2{MeC(CH2PPh2)3}]+, and [Ru(dCdCdCPh2)(η5-
C5Me5)(iPr2PCH2CH2PiPr2)]+, have been reported: (a) Esteruelas, M.
A.; Go´mez, A. V.; Lo´pez, A. M.; Modrego, J .; On˜ate, E. Organometallics
1997, 16, 5826. (b) Baya, M.; Crochet, P.; Esteruelas, M. A.; Gutie´rrez-
Puebla, E.; Lo´pez, A. M.; Modrego, J .; On˜ate, E.; Vela, N. Organome-
tallics 2000, 19, 2585. (c) Mantovani, N.; Marvelli, L.; Rossi, R.;
Bianchini, C.; de los Rios, I.; Romerosa, A.; Peruzzini, M. J . Chem.
Soc., Dalton Trans. 2001, 2353. (d) Bustelo, E.; J ime´nez-Tenorio, M.;
Mereiter, K.; Puerta, M. C.; Valerga, P. Organometallics 2002, 21, 1903.
(5) For reviews on the synthesis and reactivity vinylidene complexes
see: (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) Werner, H. J .
Organomet. Chem. 1994, 475, 45. (c) Bruneau, C.; Dixneuf, P. H. Acc.
Chem. Res. 1999, 32, 311. (d) Puerta, M. C.; Valerga, P. Coord. Chem.
Rev. 1999, 193-195, 977.
Resu lts
Rea ction s of Allen ylid en e Com p lexes w ith En o-
la t es Der ived fr om P r och ir a l Cyclic Ket on es.
Lithium enolates of cyclopentanone and cyclohexanone
(prepared in situ from the corresponding ketone and
LDA in THF at -20 °C) add regioselectively at the Cγ
atom of the cumulenic chain in complexes [Ru{dCdCd
C(R)Ph}(η5-C9H7)(PPh3)2][PF6] (R ) Ph (1), H (2)),3a to
afford the neutral σ-alkynyl derivatives [Ru{CtCC(R)-
Ph(CHCOCH2(CH2)nCH2)}(η5-C9H7)(PPh3)2] (3a ,b and
4a ,b) isolated as air-stable yellow solids in 63-89% yield
after chromatographic workup (Scheme 2).
(6) For reviews on the Nicholas reaction see: (a) Nicholas, K. M.
Acc. Chem. Res. 1987, 20, 207. (b) Melikyan, G. G.; Nicholas, K. M. In
Modern Acetylene Chemistry; Stang, P. J ., Diederich, F., Eds.; VCH:
New York, 1995. (c) Caffyn, A. J . M.; Nicholas, K. M. In Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, G. A., Wilkinson, G.,
Eds.; Pergamon: New York, 1995; Vol. 12, Chapter 7.1. (d) Mu¨ller, T.
J . J . Eur. J . Org. Chem. 2001, 2021.
(7) (a) Nishibayashi, Y.; Wakiji, I.; Ishii, Y.; Uemura, S.; Hidai, M.
J . Am. Chem. Soc. 2001, 123, 3393. Related ruthenium-catalyzed
propargylic substitutions with heteroatom-centered nucleophiles have
been also reported: (b) Nishibayashi, Y.; Wakiji, I.; Hidai, M. J . Am.
Chem. Soc. 2000, 122, 11019.

3718 Organometallics, Vol. 21, No. 18, 2002
Cadierno et al.
Sch em e 2
Sch em e 3
1
Spectroscopic data (IR and H, 31P{1H}, and 13C{1H}
NMR) of 3a ,b and 4a ,b support the proposed formula-
tions (see the Experimental Section and Tables S1 and
S2, provided as Supporting Information). In particular,
(i) the IR spectra show the expected ν(CdO) and ν(Ct
C) absorption bands in the ranges 1708-1736 and
2072-2093 cm-1, respectively, and (ii) the 13C{1H} NMR
spectra display typical Ru-CRtCâ signals at δ 92.47-
95.59 (dd, 2J CP ) 22.2-26.2 Hz, CR) and 108.60-114.05
(s, Câ). Complexes 4a ,b have been isolated as a non-
separable mixture of two diastereoisomers (ca. 2:1 ratio),
as inferred by NMR spectroscopy.
pared (92 and 88% yields, respectively) and isolated as
nonseparable mixtures of two diastereoisomers (ca. 2:1
ratio). Complexes 5a ,b and 6a ,b have been fully char-
acterized by means of standard spectroscopic techniques
and elemental analysis (see the Experimental Section
and Tables S3 and S4, provided as Supporting Informa-
tion). In a second step acetonitrile solutions of vinyli-
denes 5a ,b and 6a ,b were heated under reflux, resulting
in the liberation of the γ-keto acetylenes 7a ,b and 8a ,b
(as a mixture of two diastereoisomers in ca. 2:1 ratio)
(78-83% isolated yields), and formation of the solvato
complex [Ru(NtCMe)(η5-C9H7)(PPh3)2][BF4] (9).8 Rel-
evant spectroscopic features of 7a ,b and 8a ,b are (i) (1H
NMR) the singlet (7a ,b) or doublet (8a ,b; J HH ) 2.6-
3.3 Hz) signal for the acetylenic proton (δ 2.22-2.70;
see Table S5 provided as Supporting Information) and
(ii) (13C{1H} NMR) characteristic singlet resonances for
the HCtC carbons, which appear in the ranges 70.31-
75.22 and 83.16-85.66 ppm, respectively (see Table S6,
provided as Supporting Information).
As expected on the basis of our previous results,1
demetalation of 3a ,b and 4a ,b proceeds cleanly, yielding
the terminal alkynes HCtCC(R)Ph(CHCOCH2(CH2)n-
CH2) (7a ,b and 8a ,b) in good overall yields (Scheme 2).
Thus, in the first step the air-stable vinylidene deriva-
tives [Ru{dCdC(H)CPh2(CHCOCH2(CH2)nCH2)}(η5-
C9H7)(PPh3)2][BF4] (5a ,b) were prepared by treatment
of 3a ,b with HBF4 (96 and 97% yields, respectively).
Similarly, vinylidene complexes 6a ,b have been pre-
(8) Terminal alkynes 8a ,b have been previously reported; see ref
7a and: Saha, M.; Nicholas, K. M. Isr. J . Chem. 1984, 24, 105.

Optically Active γ-Keto Acetylenes
Organometallics, Vol. 21, No. 18, 2002 3719
F igu r e 1. ORTEP view of the structure of the σ-alkynyl
F igu r e 2. ORTEP view of the structure of the alkenyl
complex [Ru{CdC(H)C(C9H16)CdC(CH2CH2CH2)O}(η5-C9-
complex [Ru{CtCC(C9H16)(CHCOCH2CH2CH2)}(η5-C9H7)-
(PPh3)2] (11b). Aryl groups of the triphenylphosphine
ligands have been omitted for clarity. Thermal ellipsoids
are drawn at 30% probability. Selected bond lengths (Å)
and angles (deg): Ru-C* ) 1.948(5); Ru-P(1) ) 2.290(2);
Ru-P(2) ) 2.314(2); Ru-C(46) ) 2.027(7); C(46)-C(47) )
1.223(9); C(47)-C(48) ) 1.504(9); C(48)-C(49) ) 1.62(1);
C(48)-C(53) ) 1.61(1); C(48)-C(58) ) 1.573(9); C(59)-O(1)
) 1.214(8); C*-Ru-P(1) ) 124.69(19); C*-Ru-P(2) )
124.42(18); C*-Ru-C(46) ) 115.2(3); P(1)-Ru-P(2) )
99.84(8); C(46)-Ru-P(1) ) 93.9(2); C(46)-Ru-P(2) ) 90.0-
(2); Ru-C(46)-C(47) ) 168.1(7); C(46)-C(47)-C(48) )
172(1). C* denotes the centroid of the indenyl ring (C(5),
C(6), C(7), C(8), C(9)).
H7)(PPh3)2] (14). Aryl groups of the triphenylphosphine
ligands have been omitted for clarity. Thermal ellipsoids
are drawn at 30% probability. Selected bond lengths (Å)
and angles (deg): Ru-C* ) 1.976(7); Ru-P(1) ) 2.306(2);
Ru-P(2) ) 2.314(2); Ru-C(46) ) 2.063(6); C(46)-C(47) )
1.333(8); C(46)-O(1) ) 1.428(8); C(53)-O(1) ) 1.361(7);
C(53)-C(49) ) 1.335(8); C*-Ru-P(1) ) 120.97(15); C*-
Ru-P(2) ) 124.33(14); C*-Ru-C(46) ) 119.6(2); P(1)-
Ru-P(2) ) 103.72(8); C(46)-Ru-P(1) ) 93.0(2); C(46)-
Ru-P(2) ) 86.5(2); Ru-C(46)-C(47) ) 128.5(5); Ru-
C(46)-O(1) ) 113.8(4); C(46)-O(1)-C(53) ) 116.0(5);
O(1)-C(53)-C(49) ) 128.3(6); C(52)-C(53)-C(49) ) 128.3-
(6). C* denotes the centroid of the indenyl ring (C(5), C(6),
C(7), C(8), C(9)).
The reactivity of the optically active allenylidene
complex [Ru{dCdCdC(C9H16)}(η5-C9H7)(PPh3)2][PF6]
(C(C9H16) ) (1R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-
ylidene) (10)1 toward lithium enolates derived from
cyclopentanone and cyclohexanone has been also ex-
plored. While 10 remains unchanged upon addition of
a large excess of the cyclohexanone enolate, it readily
reacts with a slight excess (ca. 3:1) of the cyclopentanone
enolate, affording the corresponding σ-alkynyl deriva-
tive 11 (Scheme 3).
acetylenes 13a and 13b (98 and 92% yields, respectively;
see Scheme 3).10
Assuming the preferred exo addition in 10,1 the major
diastereoisomer 11a should have an S configuration at
C(58) (see Figure 1). In agreement with this, we have
found that the treatment of 11a and 11b with a catalytic
amount of AlCl3, in dichloromethane at room temper-
ature, yields in both cases the oxacycloalkenyl derivative
14, as the result of the intramolecular cyclization of the
keto alkynyl unit (94% yield, see Scheme 4).11 Com-
pound 14 exhibits analytical and spectroscopic data in
accord with the proposed formulation (see the Experi-
mental Section). Moreover, an unambiguous character-
ization by single-crystal X-ray analysis was undertaken
(see Figure 2).9 The molecule exhibits the usual pseudo-
octahedral three-legged piano-stool geometry with the
indenyl ligand in the usual η5 coordination mode. The
interligand angles P(1)-Ru-P(2), C(46)-Ru-P(1), and
C(46)-Ru-P(2) and those between the centroid C* and
the legs show values typical of a pseudooctahedron (see
caption for Figure 2). The most interesting features of
the structure are those concerning the alkenyl ligand.
Alkynyl complex 11 has been obtained as a mixture
of two diastereoisomers (ca. 2:1 ratio) which are easily
separated by column chromatography on neutral Al2O3
(11a , 48% yield; 11b, 24% yield). Their analytical and
spectroscopic data are fully consistent with the proposed
formulation (see the Experimental Section). Since the
configuration of the new chiral carbon atoms could not
be elucidated from the NMR data, a single-crystal X-ray
structural determination was carried out for the minor
diastereoisomer 11b. An ORTEP view of the molecular
geometry is shown in Figure 1. Selected bond distances
and angles are collected in the caption9 and are in
general comparable to those reported for the related
σ-alkynyl derivative [Ru{CtCC(C9H16)(CH2COiPr)}(η5-
C9H7)(PPh3)2].1 The structure shows that (i) the addition
of the enolate fragment takes place on the less sterically
demanding exo face of the allenylidene chain in [Ru-
{dCdCdC(C9H16)}(η5-C9H7)(PPh3)2][PF6] (10) and (ii)
the absolute configuration for the new stereogenic
carbon atom C(58) is R. As expected, demetalation of
11a and 11b, via vinylidene intermediates 12a and 12b,
allowed the preparation of the optically pure γ-keto
(10) The vinylidene complex 12b has been characterized only by 31P-
2
{1H} NMR spectroscopy (δ 36.07 and 38.16 (d, J PP ) 21.6 Hz) ppm),
since it is very unstable both in solution and in the solid state,
generating complicated mixtures of uncharacterized products. Pro-
tonation of 11b with 1 equiv of HBF4‚Et2O in acetonitrile yields directly
the terminal alkyne 13b and the acetonitrile complex 9 (see the
Experimental Section).
(11) (a) Lewis acid catalyzed intramolecular heterocyclization of
alkynes is a well-known method for the synthesis of unsaturated
heterocycles. See for example: Hardig, K. E.; Tiner, T. H. In Compre-
hensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon
Press: Oxford, U.K., 1991; Vol. 4, p 363. (b) We have recently reported
(9) The crystals measured present two molecules in the asymmetric
unit with very similar structural parameters. For brevity, only the bond
distances and angles of one of them are listed in the caption.
related cyclizations on the complexes [Ru{CtCCR1R2(CH2COR3)}(η5-
i
C9H7)(PPh3)2] (R1 ) R2 ) Ph, R3 ) Ph, Pr; CR1R2 ) C(C9H16), R3
)
Ph).1

3720 Organometallics, Vol. 21, No. 18, 2002
Cadierno et al.
Sch em e 4
Sch em e 5
Thus, the Ru-C(46) bond length (2.063(6) Å) falls in
the range 2.03-2.11 Å typical of a Ru-C(sp2) single
bond.12 Similarly, the C(46)-O(1) (1.428(8) Å) and
C(53)-O(1) (1.361(7) Å) distances compare well with
those reported for other (oxacycloalkenyl)ruthenium(II)
derivatives,12f and the C(46)-C(47) bond length (1.333-
(8) Å) shows also a coherent value for a CdC bond. The
alkenyl function is located in an endo disposition with
respect to the chiral auxiliary (1R)-1,3,3-trimethylbicyclo-
[2.2.1]hept-2-ylidene, as was expected from the exo
addition of the enolate group.
Treatment of 14 with HBF4, in THF at -20 °C, leads
to the novel optically active oxacycloalkylidene complex
15 in 84% yield (Scheme 4). Significantly, the 13C{1H}
NMR spectrum gives clear evidence of the formation of
a carbene moiety, displaying a typical low-field reso-
nance for the RudCR carbon atom at δ 299.49 (dd,
2J CP ) 14.3 and 10.7 Hz). Electrophilic additions at Câ
of alkenyl groups to give carbene species are well
documented.13,14
Rea ction s of Allen ylid en e Com p lexes w ith En o-
la tes Der ived fr om Ch ir a l Cyclic Keton es. The
efficient access to terminal alkynes 7a ,b, 8a ,b, and
13a ,b from prochiral ketones (Schemes 2 and 3)
prompted us to use the enolates derived from the
commercially available chiral ketones (R)-(-)-carvone
and (R)-(+)-pulegone in order to obtain the correspond-
ing γ-keto alkynes bearing new stereogenic centers.
(a ) Syn th esis of th e σ-Alk yn yl P r ecu r sor s. Treat-
ment of (R)-5-isopropenyl-2-methyl-2-cyclohexenone ((R)-
(-)-carvone) with LDA, in THF at -20 °C, and subse-
quent addition of 1 equiv of the complex [Ru(dCdCd
CPh2)(η5-C9H7)(PPh3)2][PF6] (1) gives diastereoselectively,
as determined by NMR spectroscopy, the σ-alkynyl
derivative 16 (78% yield) (Scheme 5).
Similarly, complex 1 reacts with the enolate derived
from (R)-2-isopropylidene-5-methylcyclohexanone (pre-
pared in situ by treatment of (R)-(+)-pulegone with LDA
in THF at -78 °C) to give the corresponding σ-alkynyl
(12) See for example: (a) Bruce, M. I.; Catlow, A.; Humphrey, M.
G.; Koutsantonis, G. A.; Snow, M. R.; Tiekink, E. R. T. J . Organomet.
Chem. 1988, 338, 59. (b) Torres, M. R.; Santos, A.; Perales, A.; Ros, J .
J . Organomet. Chem. 1988, 353, 321. (c) Romero, A.; Santos, A. Vegas,
A. Organometallics 1988, 7, 1988. (d) Lo´pez, J .; Santos, A.; Romero,
A.; Echevarren, A. M. J . Organomet. Chem. 1993, 443, 221. (e)
Bohanna, C.; Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.
Organometallics 1995, 14, 4685. (f) Esteruelas, M. A.; Go´mez, A. V.;
Lo´pez, A. M.; On˜ate, E.; Ruiz, N. Organometallics 1998, 17, 2297. (g)
Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; On˜ate, E. Organome-
tallics 1998, 17, 3567. (h) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A.
M.; On˜ate, E.; Ruiz, N. Organometallics 1999, 18, 1606. (i) Cadierno,
V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.; Pe´rez-Carren˜o,
E.; Garc´ıa-Granda, S. Organometallics 2001, 20, 5177.
(13) For theoretical calculations on transition-metal alkenyl com-
plexes see: Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.
(14) Transformations of (indenyl)ruthenium(II) alkenyl derivatives
into carbene complexes are reported in: (a) Bassetti, M.; Casellato,
P.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.; Mart´ın-Vaca,
B. Organometallics 1997, 16, 5470. (b) Gamasa, M. P.; Gimeno, J .;
Mart´ın-Vaca, B. M. Organometallics 1998, 17, 3707. (c) Bieger, K.; D´ıez,
J .; Gamasa, M. P.; Gimeno, J .; Pavlista, M.; Rodr´ıguez-AÄ lvarez, Y.;
Garc´ıa-Granda, S.; Santiago-Garc´ıa, R. Eur. J . Inorg. Chem. 2002,
1647. See also ref 1.

Optically Active γ-Keto Acetylenes
Organometallics, Vol. 21, No. 18, 2002 3721
Sch em e 6
Sch em e 7
chromatography or fractional crystallization failed.
Moreover, no reaction has been observed between [Ru-
{dCdCdC(C9H16)}(η5-C9H7)(PPh3)2][PF6] (10) and the
lithium enolate derived from (R)-(-)-carvone.
(b) Syn th esis of th e Ter m in a l Alk yn es. The ter-
minal alkyne 18 has been obtained (83% yield) optically
pure after protonation of 16 with HBF4 and subsequent
treatment of the resulting vinylidene derivative 17 with
acetonitrile (Scheme 5). Analytical and spectroscopic
data of 17 and 18 are in accord with the proposed
formulations, being comparable with those observed for
the related vinylidenes 5a ,b and 6a ,b and terminal
alkynes 7a ,b and 8a ,b (see the Experimental Section).
On the basis of the absolute configuration found for the
σ-alkynyl precursor 16,3d an R configuration is proposed
for the corresponding new stereogenic centers in 17 and
18. Unfortunatelly, all attempts to liberate the corre-
sponding chiral γ-keto acetylene from σ-alkynyl com-
plexes 19-21 failed, giving the starting materials, i.e.
(R)-(+)-pulegone and allenylidene complexes 1 and 10,
respectively. This probably results from the selective
protonation of the keto group in 19-21.
derivative 19 in a diastereoselective manner (77% yield;
Scheme 6). When the in situ formation of the enolate
takes place at -20 °C (instead of -78 °C) and the
reaction with complex 1 is performed at this tempera-
ture, σ-alkynyl complexes 19 (39% yield) and 20 (26%
yield) are obtained after chromatographic workup on
neutral Al2O3 (Scheme 6). These complexes arise from
the competitive deprotonation at CH2CdO vs CH3 of (R)-
(+)-pulegone. Compounds 16, 19, and 20 have been
analytically and spectroscopically characterized (see the
1
Experimental Section). The H NMR spectra of 16 and
19 exhibit a doublet signal for the CHCdO proton at
4.30 (J HH ) 4.8 Hz) and 3.53 (J HH ) 4.4 Hz) ppm,
respectively. On the basis of these data and the X-ray
crystal structure of 16, which shows an anti disposition
of the two CH protons of the cyclohexenone ring (i.e. R
configuration for Cδ),3d an R configuration is also
assigned to the new stereogenic center in 19. The 13C-
{1H} NMR spectrum of 20 is very informative, since it
shows the presence of only two methyl groups (δ 22.63
and 24.06) and four CH2 carbon resonances (δ 29.34,
33.99, 47.68, and 52.53) (assigned using DEPT experi-
ments), in accord with the proposed formulation.
Discu ssion
Ster eoselectivity of th e Nu cleop h ilic Ad d ition s:
F or m a tion of Op tica lly Active σ-Alk yn yl Com -
p lexes. Previous studies from our laboratory have
demonstrated the ability of (indenyl)ruthenium(II)
allenylidene complexes [Ru(dCdCdCR1R2)(η5-C9H7)-
(PPh3)2]+ to undergo regioselective nucleophilic addi-
tions, leading to the σ-alkynyl species [Ru{CtCCR1R2-
(Nu)}(η5-C9H7)(PPh3)2].3 In accordance with this behavior
the addition of methyl enolates leads to keto-function-
alized σ-alkynyl derivatives [Ru{CtCCR1R2(CH2COR3)}-
(η5-C9H7)(PPh3)2].1 As expected, the addition of the
enolates derived from the prochiral cyclic ketones cy-
clopentanone and cyclohexanone to the allenylidenes 1
and 2 proceeds regioselectively to give σ-alkynyl com-
plexes 3a , 4a and 3b, 4b, respectively (Scheme 2).
Similarly, the chiral allenylidene complex 10 undergoes
the regioselective addition of the enolate derived from
cyclopentanone to give the σ-alkynyl complex 11, al-
though no reaction is observed with the cyclohexanone
enolate (Scheme 3). This difference is probably produced
by the effect of the steric hindrance between the chiral
auxiliary (1R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-ylidene
and the incoming bulkier enolate, which prevents the
nucleophilic addition. Although the cyclopentanonic
fragment adds stereoselectively through the exo face of
In contrast to complex 1, the reaction of the chiral
allenylidene complex [Ru{dCdCdC(C9H16)}(η5-C9H7)-
(PPh3)2][PF6] (10) with the resulting (R)-(+)-pulegone
enolates (prepared in situ at -20 °C) is chemoselective,
affording the σ-alkynyl derivative 21 (51% yield; Scheme
7). On the basis of the stereochemistry found for the
novel stereogenic carbon atom in the analogous σ-alky-
nyl complexes 11a and 11b, an exo addition is also
proposed for the formation of complex 21. Analytical and
spectroscopic data for 21 confirm the proposed formula-
tion (see the Experimental Section). Since these data
can be compared to those observed for the analogous
complex 20, complex 21 will not be discussed further.
Although the allenylidene complex [Ru{dCdCdC(H)-
Ph}(η5-C9H7)(PPh3)2][PF6] (2) also reacts with the eno-
lates derived from (R)-(-)-carvone and (R)-(+)-pulegone,
the reactions lead to complex mixtures of unidentified
1
species, as inferred by 31P{1H} and H NMR spectros-
copy. All attempts to purify these mixtures by column

3722 Organometallics, Vol. 21, No. 18, 2002
Cadierno et al.
the chiral auxiliary, which is less hindered, the forma-
tion of 11 as a mixture of two diastereoisomers in a ca.
2:1 ratio shows that the overall diastereoselectivity of
the nucleophilic addition is only moderate (33.3% de).
This seems to indicate that the allenylidene substituent
C9H16 presents a poor chiral induction with respect to
the incoming cyclic enolate. A similar chiral induction
is also observed in the monosubstituted allenylidene 2,
since two σ-alkynyl diastereoisomers are also obtained
for complexes 4a ,b. It is noteworthy that the σ-alkynyl
complex 11 undergoes a Lewis acid promoted intramo-
lecular cyclization of the keto alkynyl ligand to afford
the optically active oxacycloalkenyl derivative 14 and
the cyclic carbene 15 (Scheme 4).1 The formation of
these species clearly evidences the utility of transition-
metal allenylidenes as building blocks for the prepara-
tion of complex molecules.2
In summary, novel γ-keto-functionalized terminal
alkynes, some of them optically pure, have been pre-
pared in good yields through regio- and stereoselective
nucleophilic additions to appropriate allenylidene com-
plexes. This efficient synthetic protocol follows previ-
ously reported examples which prove the utility of
allenylidene complexes for the selective generation of
C-C bonds.
Exp er im en ta l Section
Synthetic procedures were performed under an atmosphere
of dry nitrogen using vacuum line and other standard Schlenk
techniques. All reagents were obtained from commercial
suppliers and used without further purification. Solvents were
dried by standard methods and distilled under nitrogen before
use. Compounds [Ru{dCdCdC(R)Ph}(η5-C9H7)(PPh3)2][PF6]
(R ) Ph (1), H (2))3a and [Ru{dCdCdC(C9H16)}(η5-C9H7)-
(PPh3)2][PF6] (10)1 were prepared by following the methods
reported in the literature. Infrared spectra were recorded on
a Perkin-Elmer 1720-XFT spectrometer. Conductivities were
measured at room temperature, in ca. 10-3 mol dm-3 acetone
solutions, with a J enway PCM3 conductimeter. The C and H
analyses were carried out with a Perkin-Elmer 2400 micro-
analyzer. Optical rotations (R) were measured on a Perkin-
Elmer 343 polarimeter. High-resolution mass spectra were
recorded using a MAT-95 spectrometer. FAB mass spectra
were recorded using a VG-Autospec spectrometer operating
in positive mode; 3-nitrobenzyl alcohol (NBA) was used as the
matrix. NMR spectra were recorded on a Bruker DPX300
instrument at 300 MHz (1H), 121.5 MHz (31P), or 75.4 MHz
(13C) using SiMe4 or 85% H3PO4 as standard. DEPT experi-
ments have been carried out for all the compounds reported
in this paper. 31P{1H}, 1H, and 13C{1H} NMR spectroscopic data
for 3a ,b through 8a ,b are collected in Tables S1-S6, which
have been provided as Supporting Information.
To increase the stereoselectivity of the nucleophilic
additions, a different approach was undertaken by using
chiral enolates derived from (R)-(-)-carvone and (R)-
(+)-pulegone. These nucleophiles react with the diphen-
ylallenylidene 1 to give diastereoselectively the chiral
σ-alkynyl complexes 16 and 19, respectively (Schemes
5 and 6). The absolute configuration of the new stereo-
genic carbon atom (R as determined by X-ray diffraction
analysis on 16)3d seems to be the result of a sterically
controlled addition, since the isopropenyl (16) and
methyl (19) substituents of the cyclohexenone rings (Cꢀ)
are located far away from the bulky CPh2 moiety of the
alkynyl chain. The influence of the steric hindrance
between the incoming nucleophile and the allenylidene
substituents is also clearly evidenced in the reaction of
the chiral allenylidene 10 and the enolate derived from
(R)-(+)-pulegone (Scheme 7). Despite the fact that at
-20 °C the formation of the enolate is not chemoselec-
tive, giving rise to a mixture of two species (resulting
from a competitive CH2 vs CH3 deprotonation), the
addition occurs in a chemioselective manner, affording
the isopropylidene-substituted isomer 21. This is prob-
ably the result of the steric demands of the chiral
auxiliary in the allenylidene chain, which prevents the
addition of the other form of the enolate. The inertness
of 10 toward the (R)-(-)-carvone enolate can be also
explained on the basis of these steric demands.
The numbering for the indenyl skeleton is as follows:
Syn th esis of th e σ-Alk yn yl Com p lexes [Ru {CtCC(R)-
P h (CHCOCH2(CH2)n CH2)}(η5-C9H7)(P P h 3)2] (n ) 1, R )
P h (3a ), H (4a ); n ) 2, R ) P h (3b), H (4b)). A solution of
the corresponding lithium enolate (prepared in situ by treat-
ment of the corresponding ketone (1 mmol) with LDA (0.179
g, 1 mmol) in 10 mL of THF at -20 °C for 30 min) was added
at -20 °C to a solution of [Ru{dCdCdC(R)Ph}(η5-C9H7)-
(PPh3)2][PF6] (R ) Ph (1), H (2); 1 mmol) in 30 mL of THF.
The mixture was warmed to room temperature, and the
solvent was then removed in vacuo. The resulting solid residue
was dissolved in dichloromethane (ca. 5 mL) and transferred
to a silica gel chromatography column. Elution with a hexane/
diethyl ether mixture (2/1) gave a yellow band from which
σ-alkynyl complexes 3a ,b and 4a ,b were isolated as yellow
solids after solvent removal. Complexes 4a ,b have been
obtained as a nonseparable mixture of diastereoisomers in ca.
2:1 ratio. 3a : yield 89% (0.902 g); IR (KBr, cm-1) ν 1736 (Cd
O), 2072 (CtC). Anal. Calcd for RuC65H54P2O (1014.16): C,
76.98; H, 5.36. Found: C, 77.12; H, 5.12. 3b: yield 69% (0.709
g); IR (KBr, cm-1) ν 1715 (CdO), 2077 (CtC). Anal. Calcd for
RuC66H56P2O (1028.18): C, 77.09; H, 5.49. Found: C, 77.21;
H, 5.60. 4a : yield 69% (0.647 g); IR (KBr, cm-1) ν 1735 (Cd
O), 2090 (CtC). Anal. Calcd for RuC59H50P2O (938.06): C,
75.54; H, 5.37. Found: C, 76.12; H, 5.20. 4b: yield 63% (0.600
g); IR (KBr, cm-1) ν 1708 (CdO), 2093 (CtC). Anal. Calcd for
RuC60H52P2O (952.08): C, 75.69; H, 5.50. Found: C, 75.80; H,
5.39.
Dem eta la tion Rea ction s: Syn th esis of Op tica lly
Active Ter m in a l Alk yn es. We have recently reported
an efficient synthetic approach to terminal functional-
ized alkynes starting from (allenylidene)ruthenium(II)
complexes.3e Using the well-established sequence of
reactions in this methodology (Scheme 1), novel γ-keto
acetylenes have been prepared starting from the afore-
mentioned σ-alkynyl derivatives 3a ,b, 4a ,b, 11a ,b, and
16. These are transformed in a first step into the
corresponding vinylidenes, which generate, by demeta-
lation in refluxing acetonitrile, the desired terminal
alkynes (Schemes 2, 3, and 5). Thus, optically active
γ-keto alkynes 13a ,b and 18, which represent a series
of unusual examples containing up to four chiral
centers, are obtained in good yields. Unfortunately, the
competitive protonation of the keto alkynyl groups at
the carbonyl function vs the formation of vinylidene
complexes (protonation of 19-21) constitutes a draw-
back which impedes the isolation of the desired optically
active γ-keto acetylenes derived from (R)-(+)-pulegone.

Optically Active γ-Keto Acetylenes
Organometallics, Vol. 21, No. 18, 2002 3723
Syn th esis of th e Vin ylid en e Com p lexes [Ru {dCdC(H)-
and 111.41 (s, C-3a and C-7a), 115.60 (s, Câ), 123.09, 124.94,
and 125.83 (s, C-4, C-5, C-6 or C-7), 127.15-140.18 (m, Ph
and C-4, C-5, C-6 or C-7), 216.59 (s, CdO) ppm; ∆δ(C-3a,7a)
) -20.02. Anal. Calcd for RuC62H60P2O (984.18): C, 75.66; H,
6.14. Found: C, 76.42; H, 6.02. Minor diastereoisomer (11b):
yield 24% (0.236 g); IR (KBr, cm-1) ν 2064 (CtC), 1724 (CdO).
31P{1H} NMR (C6D6) δ 52.74 and 53.72 (d, 2J PP ) 34.9 Hz) ppm.
1H NMR (C6D6) δ 0.97, 1.05, and 1.25 (s, 3H each, CH3), 1.15,
1.45, 1.71, and 1.90 (m, 2H each, CH2), 2.20 (m, 1H, CHCd
O), 2.37 (m, 4H, CH2), 2.97 (m, 1H, CH), 4.48 and 4.71 (br, 1H
each, H-1 and H-3), 5.38 (br, 1H, H-2), 6.12 and 6.31 (d, 1H
each, J HH ) 7.6 Hz, H-4, H-5, H-6, or H-7), 6.73-7.25 (m, 32H,
Ph and H-4, H-5, H-6, or H-7) ppm; 13C{1H} (C6D6) δ 19.33,
28.33, and 28.91 (s, CH3), 20.33, 24.51, 32.64, 37.51, 41.14,
and 41.44 (s, CH2), 46.69 and 53.50 (s, C), 50.49 (s, CH), 56.71
(s, CHCdO), 59.07 (s, Cγ), 73.14 (d, 2J CP ) 4.5 Hz, C-1 or C-3),
C(R)P h (CHCOCH2(CH2)n CH2)}(η5-C9H7)(P P h 3)2][BF 4] (n
) 1, R ) P h (5a ), H (6a ); n ) 2, R ) P h (5b), H (6b)). A
dilute solution of HBF4‚Et2O in diethyl ether was added
dropwise at -20 °C to a stirred solution of the corresponding
σ-alkynyl complex 3a ,b and 4a ,b (1 mmol) in 100 mL of diethyl
ether. Immediately, an insoluble solid precipitated, but the
addition was continued until no further solid was formed. The
solution was then decanted and the brown solid washed with
diethyl ether (3 × 20 mL) and vacuum-dried. Complexes 6a ,b
have been obtained as a nonseparable mixture of diastereo-
isomers in ca. 2:1 ratio. 5a : yield 96% (1.058 g); IR (KBr, cm-1
)
ν 1059 (BF4-), 1730 (CdO); conductivity (acetone, 20 °C; Ω-1
cm2 mol-1) 107. Anal. Calcd for RuC65H55F4P2BO (1101.97):
C, 70.84; H, 5.03. Found: C, 71.03; H, 4.98. 5b: yield 97%
(1.082 g); IR (KBr, cm-1) ν 1057 (BF4-), 1702 (CdO); conduc-
tivity (acetone, 20 °C; Ω-1 cm2 mol-1) 112. Anal. Calcd for
RuC66H57F4P2BO (1115.99): C, 71.03; H, 5.14. Found: C, 71.40;
H, 5.20. 6a : yield 92% (0.944 g); IR (KBr, cm-1) ν 1060 (BF4-),
1732 (CdO); conductivity (acetone, 20 °C; Ω-1 cm2 mol-1) 109.
Anal. Calcd for RuC59H51F4P2BO (1025.87): C, 69.07; H, 5.01.
Found: C, 69.28; H, 5.17. 6b: yield 88% (0.915 g); IR (KBr,
cm-1) ν 1059 (BF4-), 1701 (CdO); conductivity (acetone,
20 °C; Ω-1 cm2 mol-1) 111. Anal. Calcd for RuC60H53F4P2BO
(1039.89): C, 69.30; H, 5.13. Found: C, 69.68; H, 5.21.
2
2
73.51 (br, C-1 or C-3), 85.42 (dd, J CP ) 22.3 Hz, J CP ) 22.3
Hz, Ru-CR), 95.28 (s, C-2), 109.37 and 110.55 (s, C-3a and
C-7a), 116.17 (s, Câ), 122.89, 123.80, 125.07, and 125.63 (s, C-4,
C-5, C-6 and C-7), 126.91-139.11 (m, Ph), 219.96 (s, CdO)
ppm; ∆δ(C-3a,7a) ) -20.74. Anal. Calcd for RuC62H60P2O
(984.18): C, 75.66; H, 6.14. Found: C, 75.53; H, 6.27.
Syn th esis of th e Vin ylid en e Com p lex [Ru {dCdC(H)C-
(C9H16)(CHCOCH2CH2CH2)}(η5-C9H7)(P P h 3)2][BF 4] (12a ).
Complex 12a , isolated as a brown solid, was obtained as
described for 5a ,b and 6a ,b starting from the σ-alkynyl
complex 11a (0.984 g, 1 mmol): yield 92% (0.986 g); IR (KBr,
cm-1) ν 1720 (CdO), 1057 (BF4-); conductivity (acetone, 20 °C;
Ω-1 cm2 mol-1) 109; 31P{1H} NMR (CDCl3) δ 35.19 and 38.48
Syn th esis of th e Ter m in a l Alk yn es HCtCC(R)P h -
(CHCOCH2(CH2)n CH2) (n ) 1, R ) P h (7a ), H (8a ); n ) 2,
R
) P h (7b), H (8b)). A solution of the corresponding
vinylidene complex 5a ,b and 6a ,b (1 mmol) in acetonitrile (30
mL) was heated under reflux for 30 min. The solution was then
evaporated to dryness and the resulting solid residue extracted
with diethyl ether (ca. 50 mL) and filtered. A yellow solid
containing mainly the nitrile complex [Ru(NtCMe)(η5-C9H7)-
(PPh3)2][BF4] (9) remains insoluble. The extract was evapo-
rated to dryness and the crude product purified by column
chromatography on silica gel with a hexane/diethyl ether
mixture (6/1) as eluent. Evaporation of the solvents gave
terminal alkynes 7a ,b and 8a ,b as white solids. Compounds
8a ,b have been obtained as a nonseparable mixture of dia-
stereoisomers in a ca. 2:1 ratio. 7a : yield 79% (0.216 g). Anal.
Calcd for C20H18O (274.36): C, 87.55; H, 6.61. Found: C, 87.28;
2
1
(d, J PP ) 23.0 Hz) ppm; H NMR (CDCl3) δ 0.42, 0.82, and
1.31 (s, 3H each, CH3), 1.13, 1.52, 1.71, 1.86, and 2.00 (m, 2H
each, CH2), 2.12 (m, 3H, CH2 and CHCdO), 2.31 (m, 1H, CH),
5.22 (s, 1H, RudCdCH), 5.32 (d, 1H, J HH ) 8.3 Hz, H-4, H-5,
H-6, or H-7), 5.57 (br, 2H, H-1 and H-3), 5.60 (d, 1H, J HH
)
9.1 Hz, H-4, H-5, H-6, or H-7), 6.10 (br, 1H, H-2), 6.82-7.50
(m, 32H, Ph and H-4, H-5, H-6, or H-7) ppm; 13C{1H} NMR
(CD2Cl2) δ 20.81, 30.55, and 32.17 (s, CH3), 22.27, 27.36, 33.34,
39.11, 40.20, and 42.84 (s, CH2), 46.96 and 54.77 (s, C), 51.52
(s, CH), 61.10 (s, CHCdO), 65.31 (s, Cγ), 81.92 and 84.04 (d,
2
2J CP ) 8.7 Hz, C-1 and C-3), 99.19 (d, J CP ) 3.3 Hz, C-2),
2
111.43 (s, Câ), 114.81 (d, J CP ) 3.3 Hz, C-3a or C-7a), 123.02
(s, C-3a or C-7a), 123.95 and 127.21 (s, C-4, C-5, C-6, or C-7),
H, 6.70. 7b: yield 80% (0.230 g). Anal. Calcd for C21H20
O
130.28-135.84 (m, Ph and C-4, C-5, C-6, or C-7), 222.97 (s,
(288.39): C, 87.46; H, 6.99. Found: C, 87.21; H, 6.83. 8a : yield
83% (0.164 g). Anal. Calcd for C14H14O (198.26): C, 84.81; H,
7.11. Found: C, 84.74; H, 7.23. 8b: yield 78% (0.165 g). Anal.
Calcd for C15H16O (212.28): C, 84.87; H, 7.59. Found: C, 84.93;
H, 7.42.
2
2
CdO), 326.99 (dd, J CP ) 19.1 Hz, J CP ) 13.6 Hz, RudCR)
ppm; ∆δ(C-3a,7a) ) -11.78. Anal. Calcd for RuC62H61F4P2BO
(1071.99): C, 69.47; H, 5.73. Found: C, 68.34; H, 5.86.
Syn th esis of th e Ter m in a l Alk yn e HCtCC(C9H16)-
(CHCOCH2CH2CH2) (13a ). Compound 13a , isolated as a
white solid, was prepared as described for 7a ,b and 8a ,b
starting from the vinylidene 12a (room temperature; 30 min):
yield 98% (0.239 g); IR (KBr, cm-1) ν 3298 (H-Ct), 2096
(CtC), 1743 (CdO). 1H NMR (CDCl3) δ 0.84, 1.09, and 1.48
(s, 3H each, CH3), 0.99, 1.13, 1.30, and 1.88 (m, 2H each, CH2),
1.54-1.78 (m, 4H, CH2), 2.18 (s, 1H, tCH), 2.36 (dd, 1H,
J HH ) 13.2 Hz, J HH ) 7.5 Hz, CHCdO), 2.49 (m, 1H, CH) ppm;
13C{1H} NMR (CDCl3) δ 18.39, 28.47, and 28.63 (s, CH3), 20.73,
24.72, 30.44, 35.48, 36.79, and 40.92 (s, CH2), 45.20 (s, C), 50.80
(s, CH), 52.74 and 52.92 (s, C and Cγ), 60.41 (s, CHCdO), 72.94
(s, tCH), 88.47 (s, tC), 214.71 (s, CdO) ppm; [R]20D ) -102.5°
Syn th esis of th e σ-Alk yn yl Com p lex [Ru {CtCC(C9H16)-
(CHCOCH2CH2CH2)}(η5-C9H7)(P P h 3)2] (11). Complex 11
was prepared as described for 3a ,b and 4a ,b starting from
the allenylidene derivative [Ru{dCdCdC(C9H16)}(η5-C9H7)-
(PPh3)2][PF6] (10) (1.046 g, 1 mmol) and cyclopentanone (0.265
mL, 3 mmol). It was obtained as a mixture of two diastereo-
isomers which were separated by column chromatography on
Al2O3 (neutral; activity grade I) using a hexane/diethyl ether
mixture (3/1) as eluent (orange bands). Major diastereoisomer
(11a ): yield 48% (0.472 g). IR (KBr, cm-1) ν 2069 (CtC), 1739
2
(CdO). 31P{1H} NMR (C6D6) δ 52.28 and 54.41 (d, J PP ) 34.5
1
mL dm-1 g-1 (c ) 0.04 M in ethanol). Anal. Calcd for C17H24
O
Hz) ppm; H NMR (C6D6) δ 1.16, 1.18, and 1.83 (s, 3H each,
CH3), 1.24 (m, 4H, CH2), 1.53, 1.76, 1.88, and 2.18 (m, 2H each,
CH2), 2.50 (dd, 1H, J HH ) 13.8 Hz, J HH’ ) 7.2 Hz, CHCdO),
3.13 (m, 1H, CH), 4.63 and 5.17 (br, 1H each, H-1 and H-3),
5.85 (br, 1H, H-2), 6.00 (d, 1H, J HH ) 8.7 Hz, H-4, H-5, H-6,
or H-7), 6.65-7.63 (m, 33H, Ph and H-4, H-5, H-6 or H-7) ppm;
13C{1H} NMR (C6D6) δ 19.78, 29.27, and 30.08 (s, CH3), 21.04,
25.75, 31.53, 36.62, 37.30, and 41.39 (s, CH2), 46.35 and 54.38
(s, C), 51.53 (s, CH), 56.14 (s, Cγ), 62.77 (s, CHCdO), 74.18
(br, C-1 or C-3), 74.91 (d, 2J CP ) 5.4 Hz, C-1 or C-3), 83.76 (dd,
2J CP ) 22.4 Hz, 2J CP ) 22.4 Hz, Ru-CR), 96.56 (s, C-2), 109.94
(244.38): C, 83.55; H, 9.89. Found: C, 83.71; H, 9.66.
Syn th esis of th e Ter m in a l Alk yn e HCtCC(C9H16)-
(CHCOCH2CH2CH2) (13b). A solution of the σ-alkynyl com-
plex 11b (0.984 g, 1 mmol) in 30 mL of acetonitrile was treated
at room temperature with a very dilute solution of HBF4‚Et2O
in diethyl ether (1 mmol). The reaction mixture was stirred
at room temperature for 30 min and then evaporated to
dryness. The yellow solid residue was transferred to a silica
gel chromatography column. Elution with a hexane/diethyl

3724 Organometallics, Vol. 21, No. 18, 2002
Cadierno et al.
ether mixture (6/1) gave 13b as a colorless oil: yield 92% (0.224
g); IR (KBr, cm-1) ν 3314 (H-Ct), 2102 (CtC), 1735 (CdO);
1H NMR (CDCl3) δ 0.95, 1.30, and 1.37 (s, 3H each, CH3), 1.13,
1.40, 1.52, 1.78, and 1.99 (m, 2H each, CH2), 2.01 (s, 1H, t
CH), 2.25-2.50 (m, 3H, CH2 and CHCdO), 2.61 (m, 1H, CH)
ppm; 13C{1H} NMR (CDCl3) δ 19.68, 27.39, and 27.67 (s, CH3),
20.32, 24.14, 31.39, 37.44, 40.24, and 41.66 (s, CH2), 46.40 (s,
C), 50.75 (s, CH), 52.98 and 54.97 (s, C and Cγ), 54.53 (s, CHCd
O), 73.73 (s, tCH), 88.68 (s, tC), 215.80 (s, CdO) ppm; HRMS
m/z calcd (found) for C17H24O, M+ 244.182 716 (244.184 215);
The product was purified by column chromatography on silica
gel with a hexane/diethyl ether mixture (4/1) as eluent.
Evaporation of the solvents gave complex 16 as an orange
solid: yield 78% (0.843 g); IR (KBr, cm-1) ν 2064 (CtC), 1652
2
(CdO). 31P{1H} NMR (C6D6) δ 51.56 and 52.05 (d, J PP ) 33.4
1
Hz) ppm; H NMR (C6D6) δ 1.48 and 1.74 (s, 3H each, CH3),
2.12 and 2.82 (m, 1H each, CH2), 4.30 (d, 1H, J HH ) 4.8 Hz,
CHCdO), 4.37 (m, 1H, CH), 4.58 (br, 1H, H-1 or H-3), 4.92
(m, 2H, H-1 or H-3 and dCH2), 5.04 (m, 2H, H-2 and dCH2),
5.45 (br, 1H, dCH), 5.84-7.89 (m, 44H, Ph, H-4, H-5, H-6,
and H-7) ppm; 13C{1H} NMR (C6D6) δ 17.04 and 22.36 (s, CH3),
[R]20 ) 74.2° mL dm-1 g-1 (c ) 0.04 M in ethanol).
D
27.58 (s, CH2), 45.17 and 55.92 (s, CH), 57.40 (s, Cγ), 73.07
Syn th esis of th e Alk en yl Com p lex [Ru {CdC(H)C-
(C9H16)CdC(CH2CH2CH2)O}(η5-C9H7)(P P h 3)2] (14). A solu-
2
and 73.61 (s, C-1 and C-3), 96.42 (s, C-2), 99.72 (dd, J CP
)
2
22.1 Hz, J CP ) 22.1 Hz, Ru-CR), 110.04 and 111.31 (s, C-3a
and C-7a), 111.58 (s, dCH2), 115.36 (s, Câ), 123.82-150.38 (m,
Ph, C-4, C-5, C-6, and C-7), 136.49 (s, CH)CCH3), 139.91 (s,
CHdCCH3), 148.94 (s, CH2dCCH3), 200.78 (s, CdO) ppm; ∆δ-
(C-3a,7a) ) -20.02. Anal. Calcd for RuC70H60P2O (1080.26):
C, 77.83; H, 5.59. Found: C, 77.95; H, 5.89.
tion of the σ-alkynyl complex 11a or 11b (0.984 g, 1 mmol) in
20 mL of dichloromethane was treated with AlCl3 (0.007 g,
0.05 mmol) at room temperature for 2 h. The solution was then
evaporated to dryness and the resulting solid residue extracted
with diethyl ether (ca. 100 mL) and filtered over Al2O3 (neutral;
activity grade I). Evaporation of the solvent gave complex 14
as a yellow solid: yield 94% (0.925 g); 31P{1H} NMR (CDCl3)
δ 49.43 and 50.24 (d, 2J PP ) 30.5 Hz) ppm; 1H NMR (CDCl3) δ
0.70, 0.90, and 1.13 (s, 3H each, CH3), 0.97, 1.27, 1.40, 1.68,
1.93, and 2.33 (m, 2H each, CH2), 2.10 (m, 1H, CH), 4.67 and
4.89 (br, 1H each, H-1 and H-3), 4.93 (s, 1H, dCH), 5.19 and
5.47 (m, 1H each, H-4, H-5, H-6, or H-7), 5.84 (br, 1H, H-2),
6.68-7.28 (m, 32H, Ph and H-4, H-5, H-6, or H-7) ppm; 13C-
{1H} NMR (CDCl3) δ 19.26, 26.55, and 28.50 (s, CH3), 19.83,
25.65, 30.00, 30.93, 35.26, and 41.57 (s, CH2), 48.55, 51.96,
Syn th esis of th e Vin ylid en e Com p lex [Ru {dCdC(H)-
CP h 2(C10H13O)}(η5-C9H7)(P P h 3)2][BF 4] (17). Complex 17,
isolated as a brown solid, was prepared as described for 5a ,b
and 6a ,b by starting from the σ-alkynyl derivative 16 (1.080
g, 1 mmol): yield 90% (1.051 g); IR (KBr, cm-1) ν 1685 (CdO),
1064 (BF4-); conductivity (acetone, 20 °C; Ω-1 cm2 mol-1) 113;
2
31P{1H} NMR ((CD3)2CO) δ 36.74 and 41.69 (d, J PP ) 23.0
Hz) ppm; 1H NMR ((CD3)2CO) δ 1.34 and 1.46 (s, 3H each,
CH3), 2.89 and 3.06 (m, 1H each, CH2), 4.10 (m, 1H, CH), 4.39
and 4.62 (s, 1H each, dCH2), 4.85 (br, 1H, CHCdO), 5.20-
5.60 (m, 6H, H-1, H-2, H-3, RudCdCH and H-4, H-5, H-6, or
H-7), 6.53-7.50 (m, 43H, Ph, dCH and H-4, H-5, H-6, or H-7)
ppm; 13C{1H} NMR ((CD3)2CO) δ 13.08 and 22.39 (s, CH3),
31.27 (s, CH2), 42.07 and 54.64 (s, CH), 62.87 (s, Cγ), 77.40
and 82.46 (s, C-1 and C-3), 98.25 (s, C-2), 110.93 (s, dCH2),
115.82 (s, Câ), 119.78 (s, C-3a and C-7a), 124.13, 125.48, 127.47,
and 127.68 (s, C-4, C-5, C-6, and C-7), 129.15-151.16 (m, Ph),
135.77 (s, CHdCCH3), 147.34 (s, CHdCCH3), 148.10 (s, CH2d
2
and 52.45 (s, C), 49.17 (s, CH), 73.62 (d, J CP ) 10.9 Hz, C-1
2
or C-3), 74.34 (d, J CP ) 9.5 Hz, C-1 or C-3), 102.09 (s, C-2),
109.54 (s, dCH), 109.79, 110.49, and 114.18 (s, C-3a, C-7a
and dC), 121.54, 123.20, 123.36, and 124.85 (s, C-4, C-5, C-6,
and C-7), 126.74-134.26 (m, Ph), 152.06 (s, dC-O), 160.80
(dd, 2J CP ) 20.2 Hz, 2J CP ) 15.9 Hz, Ru-CR) ppm. Anal. Calcd
for RuC62H60P2O (984.18): C, 75.66; H, 6.14. Found: C, 75.63;
H, 6.05.
2
2
CCH3), 206.05 (s, CdO), 358.29 (dd, J CP ) 15.8 Hz, J CP
)
14.3 Hz, RudCR) ppm; ∆δ(C-3a,7a) ) -10.92. Anal. Calcd for
RuC70H61F4P2BO (1168.04): C, 71.98; H, 5.26. Found: C, 72.23;
H, 5.29.
Syn th esis of th e Ca r ben e Com p lex [Ru {dCCH2C-
(C9H16)CdC(CH 2CH2CH2)O}(η5-C9H7)(P P h 3)2][BF 4] (15).
To a solution of the alkenyl complex 14 (0.984 g, 1 mmol) in
30 mL of THF was added dropwise, at -20 °C, an excess of a
diluted solution of HBF4‚Et2O in diethyl ether (3 mmol). The
resulting solution was stirred at room temperature for 30 min
and then concentrated to ca. 5 mL. Addition of diethyl ether
(ca. 100 mL) precipitated complex 15 as a brown solid, which
was washed with diethyl ether (3 × 20 mL) and vacuum-
dried: yield 84% (0.900 g); IR (KBr, cm-1) ν 1060 (BF4-);
conductivity (acetone, 20 °C; Ω-1 cm2 mol-1) 115; 31P{1H} NMR
Syn th esis of th e Ter m in al Alkyn e HCtCCP h 2(C10H13O)
(18). Compound 18, isolated as a white solid, was prepared
as described for 7a ,b and 8a ,b starting from the vinylidene
complex 17 (1.168 g, 1 mmol): yield 83% (0.282 g); IR (KBr,
cm-1) ν 3255 (H-Ct), 2115 (CtC), 1652 (CdO). 1H NMR
(CDCl3) δ 1.67 and 1.74 (s, 3H each, CH3), 2.15 (m, 1H, CH2),
2.67 (s, 1H, tCH), 3.02 (m, 2H, CH2 and CH), 3.72 (d, 1H,
J HH ) 1.0 Hz, CHCdO), 4.65 and 4.76 (s, 1H each, dCH2),
6.54 (br, 1H, dCH), 7.15-7.63 (m, 10H, Ph) ppm; 13C{1H}
NMR (CDCl3) δ 16.40 and 21.40 (s, CH3), 27.87 (s, CH2), 42.45
and 55.26 (s, CH), 53.14 (s, HCtCC), 76.53 (s, tCH), 85.73
(s, tC), 111.65 (s, dCH2), 126.74, 126.90, 127.56, 127.64,
127.73, and 128.31 (s, CH of Ph), 136.10 (s, CHdCCH3), 142.66
and 143.00 (s, C of Ph), 142.83 (s, CHdCCH3), 148.48 (s, CH2d
1
(CDCl3) δ 41.37 and 46.58 (br) ppm; H NMR (CDCl3) δ 0.54,
0.86, and 1.31 (s, 3H each, CH3), 1.06, 1.25, 1.55, and 2.22 (m,
2H each, CH2), 1.74-1.82 (m, 4H, CH2), 1.95 (m, 1H, CH), 4.17
(m, 2H, dCCH2), 5.18 (br, 1H, H-2), 5.50 (br, 2H, H-1 and H-3),
6.32 (m, 4H, H-4, H-5, H-6, and H-7), 7.06-7.48 (m, 30H, Ph)
ppm; 13C{1H} NMR (CDCl3) δ 18.10, 28.41, and 28.53 (s, CH3),
19.60, 24.80, 29.25, 31.27, 33.96, and 41.55 (s, CH2), 45.07,
50.01, and 52.37 (s, C), 48.89 (s, CH), 59.85 (s, dCCH2), 78.20
(br, C-1 and C-3), 97.76 (s, C-2), 111.21 (s, dCH), 120.24 (s,
C-3a and C-7a), 121.28, 125.43, and 127.19 (s, C-4, C-5, C-6,
or C-7), 128.08-134.31 (m, Ph and C-4, C-5, C-6, or C-7),
151.58 (s, dC-O), 299.49 (dd, 2J CP ) 14.3 Hz, 2J CP ) 10.7 Hz,
RudCR) ppm; ∆δ(C-3a,7a) ) -10.46; mass spectrum (FAB,
m/e) for RuC62H61F4P2BO (1071.99) [M+] 986, [M+ - PPh3] 724,
[{Ru(η5-C9H7)(PPh3)}+] 479. Complex 15 was too sensitive to
moisture and oxygen to give satisfactory elemental analyses.
Syn th esis of th e σ-Alk yn yl Com p lex [Ru {CtCCP h 2-
(C10H13O)}(η5-C9H7)(P P h 3)2] (16). Complex 16 was prepared
as described for 3a ,b and 4a ,b by starting from the alle-
nylidene derivative [Ru(dCdCdCPh2)(η5-C9H7)(PPh3)2][PF6]
(1; 1.076 g, 1 mmol) and (R)-(-)-carvone (0.156 mL, 1 mmol).
CCH3), 198.22 (s, CdO) ppm; [R]20 ) -179.9° mL dm-1 g-1
D
(c ) 0.04 M in ethanol). Anal. Calcd for C25H24O (340.46): C,
88.19; H, 7.10. Found: C, 87.92; H, 7.23.
Syn th esis of th e σ-Alk yn yl Com p lex [Ru {CtCCP h 2-
(C10H15O)}(η5-C9H7)(P P h 3)2] (19). A solution of (R)-(+)-
pulegone (0.162 mL, 1 mmol) in 10 mL of THF was treated,
at -78 °C, with LDA (0.179 g, 1 mmol) for 30 min and then
transferred to a solution of [Ru(dCdCdCPh2)(η5-C9H7)(PPh3)2]-
[PF6] (1; 1.076 g, 1 mmol) in 50 mL of THF. The mixture was
warmed to room temperature, and the solvent was then
removed in vacuo. The resulting solid residue was dissolved
in dichloromethane (ca. 5 mL) and transferred to a silica gel
chromatography column. Elution with a hexane/diethyl ether
mixture (4/1) gave an orange band from which the σ-alkynyl
complex 19 was isolated after solvent removal: yield 77%
(0.833 g); IR (KBr, cm-1) ν 2073 (CtC), 1694 (CdO). 31P{1H}

Optically Active γ-Keto Acetylenes
Organometallics, Vol. 21, No. 18, 2002 3725
2
NMR (C6D6) δ 51.54 and 52.12 (d, J PP ) 33.5 Hz) ppm; 1H
NMR (C6D6) δ 0.79 (d, 3H, J HH ) 6.6 Hz, CHCH3), 1.23, 1.75,
2.21, and 2.45 (m, 1H each, CH2), 1.50 and 2.00 (s, 3H each,
dC(CH3)2), 2.95 (m, 1H, CHCH3), 3.53 (d, 1H, J HH ) 4.4 Hz,
CHCdO), 4.68 and 4.96 (br, 1H each, H-1 and H-3), 5.74 (br,
1H, H-2), 6.31-7.72 (m, 44H, Ph, H-4, H-5, H-6, and H-7) ppm;
13C{1H} NMR (C6D6) δ 21.87, 22.95 and 23.60 (s, CH3), 27.28
and 31.53 (s, CH2), 34.60 and 65.02 (s, CH), 56.60 (s, Cγ), 74.81
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for Com p lexes 11b a n d 14a
11b
14
empirical formula
fw
T, K
C
64.5H66OP2Ru
C62H60OP2Ru
984.11
150(1)
1020.19
293(2)
λ, Å
0.710 73 (graphite monochromated)
cryst syst
space group
a, Å
orthorhombic
P212121
21.096(15)
16.632(12)
30.39(2)
90
monoclinic
P21
2
2
(d, J CP ) 5.2 Hz, C-1 or C-3), 75.41 (d, J CP ) 2.9 Hz, C-1 or
C-3), 93.27 (dd, 2J CP ) 22.4 Hz, 2J CP ) 22.4 Hz, Ru-CR), 97.81
(s, C-2), 109.88 and 112.30 (s, C-3a and C-7a), 114.76 (s, Câ),
123.76-149.57 (m, Ph, C-4, C-5, C-6, C-7, and CdC(CH3)2),
205.26 (s, CdO) ppm; ∆δ(C-3a,7a) ) -19.61. Anal. Calcd for
RuC70H62P2O (1082.28): C, 77.68; H, 5.77. Found: C, 77.64;
H, 5.68.
14.852(4)
15.413(2)
21.198(3)
99.909(14)
4780.1(16)
4
b, Å
c, Å
â, deg
V, Å3
Z
10 662(13)
8
F
calcd, Mg/m3
1.271
1.367
µ, mm-1
0.396
0.439
Syn th esis of th e σ-Alk yn yl Com p lex [Ru {CtCCP h 2-
(C10H15O)}(η5-C9H7)(P P h 3)2] (20). A solution of (R)-(+)-
pulegone (0.162 mL, 1 mmol) in 10 mL of THF was treated,
at -20 °C, with LDA (0.179 g, 1 mmol) for 30 min and then
transferred to a solution of 1 (1.076 g, 1 mmol) in 50 mL of
THF. The mixture was wamred to room temperature, and the
solvent was then removed in vacuo. The resulting solid residue
was dissolved in dichloromethane (ca. 5 mL) and transferred
to an Al2O3 (neutral; activity grade I) chromatography column.
Elution with a hexane/diethyl ether mixture (4/1) gave an
orange band from which complex 19 was isolated in 39% (0.422
g) yield. Further elution with diethyl ether gave a new orange
band from which the σ-alkynyl complex 20 was isolated after
solvent removal: yield 26% (0.281 g); IR (KBr, cm-1) ν 2077
F(000)
4280
2056
cryst size, mm
θ range, deg
limits (hkl)
0.37 × 0.30 × 0.27 0.54 × 0.39 × 0.10
1.18-30.58
-29 to +29;
-23 to +18;
-43 to +37
83 463/31 094
2.04-27.47
0-19; 0-19;
-27 to +27
no. of rflns collected/
unique
11 289/11 289
R(int)
0.0916
0.000
completeness to θmax, % 97.3
abs cor multiscan
max, Tmin 1.000, 0.651
99.4
ψ scans
T
0.902, 0.844
refinement method
no. of data/restraints
no. of params
full-matrix least squares on F2
31 094/98
1276
11 289/7
1196
(CtC), 1683 (CdO); 31P{1H} NMR (C6D6) δ 51.52 and 51.99
weighting params g1, g2 0.0605, 0.00
0.0455, 3.7799
1.018
0.0454
(d, J PP ) 33.8 Hz) ppm; 1H NMR (C6D6) δ 0.70 (d, 3H, J HH
)
)
2
goodness of fit on F2
R1 (I > 2σ(I))
0.988
0.0513
6.5 Hz, CHCH3), 1.26-1.54 (m, 4H, CH2), 1.86 (dd, 1H, J HH
14.2 Hz, J HH ) 11.4 Hz, CdOCH2CHCH3), 2.21 (m, 1H, Cd
OCH2CHCH3), 2.48 (dd, 1H, J HH ) 14.2 Hz, J HH ) 2.9 Hz, Cd
OCH2CHCH3), 2.97 (s, 3H, CH3), 3.32 (br, 2H, CH2), 4.68 and
4.76 (br, 1H each, H-1 and H-3), 5.37 (br, 1H, H-2), 6.46-7.46
(m, 44H, Ph, H-4, H-5, H-6 and H-7) ppm; 13C{1H} NMR (C6D6)
δ 22.63 and 24.06 (s, CH3), 29.34, 33.99, 47.68, and 52.53 (s,
CH2), 33.06 (s, CH), 52.22 (s, Cγ), 73.59 and 73.84 (s, C-1 and
wR2 (all data)
0.1440
0.1150
Flack param, est
Flack param, ref
∆Fmax, ∆Fmin, e/Å3
-0.02(3)
-0.01(4)
0.00(3)
0.00(9)
1.177, -1.062
0.587, -0.601
The function minimized was in both cases [∑w(Fo - Fc2)2/
∑w(Fo2)2]1/2, w ) 1/[σ2(Fo2) + (g1P)2 + (g2P)], where P ) (Max (Fo2,0)
+ 2Fc2)/3.
a
2
2
2
C-3), 96.79 (s, C-2), 96.81 (dd, J CP ) 22.5 Hz, J CP ) 22.5 Hz,
Ru-CR), 110.98, and 111.29 (s, C-3a and C-7a), 117.84 (s, Câ),
124.93, 125.17, 126.14, and 126.47 (s, C-4, C-5, C-6, and C-7),
127.48-150.89 (m, Ph and CdC(CH3)2), 204.19 (s, CdO)
ppm; ∆δ(C-3a,7a) ) -19.56. Anal. Calcd for RuC70H62P2O
(1082.28): C, 77.68; H, 5.77. Found: C, 77.21; H, 5.83.
127.24-139.88 (m, Ph), 130.37 (s, dCCH3), 151.42 (s, )C-Cd
O), 201.53 (s, CdO) ppm; ∆δ(C-3a,7a) ) -20.15. Anal. Calcd
for RuC67H68P2O (1052.30): C, 76.47; H, 6.51. Found: C, 76.57;
H, 6.39.
X-r a y Diffr a ction . The crystal structures of complexes 11b
and 14 were analyzed by X-ray diffraction (data collection,
crystal, and refinement parameters are collected in Table 1),
and it quickly became clear that both structures were char-
acterized by severe pseudosymmetry. This arises because a
large portion of the molecule in each case is superimposable
on its mirror image, while only parts of the chiral ligand, at
the periphery of the molecule and representing roughly 12%
of the scattering power for 11b and 19% for 14, are not. In
both cases, the crystals have two molecules in the asymmetric
unit, and in each case the two molecules are in fact mirror
images of each other in all but the portion of the chiral ligand
distal to the innermost chiral carbon atom. For 11b, the space
group would be Pbca in the absence of the chiral moiety, but
this ligand has the same absolute configuration in both
molecules, giving an asymmetric unit that can be formally
described as consisting of a pair of diastereoisomers and
lowering the overall symmetry of the crystal to P212121. An
analogous situation holds for 14, which also has Z′ ) 2 (Z )
4) and would have space group P21/n if not for the chiral
fragment, which lowers the symmetry to P21. Again, a large
part of the scattering density forms a centric pattern, broken
only by the fixed stereochemistry of the outermost part of the
chiral ligand. As can be imagined, it was of utmost importance
in both cases to measure the diffraction data with care, and
especially so for the systematically weak data that would have
been systematic absences in Pbca but not P212121 or in P21/n
Syn th esis of th e σ-Alk yn yl Com p lex [Ru {CtCC(C9H16)-
(C10H15O)}(η5-C9H7)(P P h 3)2] (21). A solution of (R)-(+)-
pulegone (0.810 mL, 5 mmol) in 20 mL of THF was treated,
at -20 °C, with LDA (0.895 g, 5 mmol) for 30 min and then
transferred to a solution of 10 (1.046 g, 1 mmol) in 50 mL of
THF. The mixture was warmed to room temperature, and the
solvent was then removed in vacuo. The resulting solid residue
was dissolved in dichloromethane (ca. 5 mL) and transferred
to a silica gel chromatography column. Elution with a hexane/
diethyl ether mixture (5/1) gave a red band from which
complex 21 was isolated after solvent removal: yield 51%
(0.536 g); IR (KBr, cm-1) ν 2064 (CtC), 1706 (CdO); 31P{1H}
2
NMR (C6D6) δ 51.38 and 52.67 (d, J PP ) 33.9 Hz) ppm; 1H
(C6D6) δ 0.75 (d, 3H, J HH ) 6.3 Hz, CHCH3), 1.06, 1.19, 1.63,
and 2.83 (s, 3H each, CH3), 1.24 (m, 4H, CH2), 1.52, 1.74, and
2.69 (m, 2H each, CH2), 1.95 (m, 3H, CH2), 2.26 (m, 1H,
CHCH3), 2.46 (m, 1H, CH2), 3.27 (m, 1H, CH), 4.77 and 4.89
(br, 1H each, H-1 and H-3), 5.68 (br, 1H, H-2), 6.16 and 6.78
(m, 2H each, H-4, H-5, H-6, and H-7), 6.95-7.32 (m, 30H, Ph)
ppm; 13C{1H} NMR (C6D6) δ 19.40, 21.96, 22.29, 27.83, and
28.14 (s, CH3), 26.39, 28.43, 32.92, 34.59, 41.49, 43.39, and
51.11 (s, CH2), 31.04 and 52.53 (s, CH), 44.95 and 54.01 (s, C),
2
56.22 (s, Cγ), 73.35 and 73.85 (d, J CP ) 5.4 Hz, C-1 and C-3),
2
2
86.92 (dd, J CP ) 23.8 Hz, J CP ) 20.7 Hz, Ru-CR), 96.18
(s, C-2), 109.76 and 111.33 (s, C-3a and C-7a), 116.24 (s, Câ),
123.39, 124.22, 125.26, and 126.07 (s, C-4, C-5, C-6, and C-7),

3726 Organometallics, Vol. 21, No. 18, 2002
Cadierno et al.
but not P21. For 11b data were measured using a SMART
diffractometer,15 with scan times set so as to achieve acceptable
measurements of the weakest data. For 14, data were gathered
at T ) 150 K on a CAD-4 diffractometer16 using a variable
scan speed algorithm in which no datum was skipped because
of a poor showing on the preliminary scan. That is, the weakest
data were measured for the longest time.
For 11b, absorption corrections to the SMART data were
applied by the multiscan procedure using the program SAD-
ABS.17 For 14, absorption corrections18 were based on full or
partial ψ scans of 20 reflections with Eulerian-equivalent angle
ø distributed through the range -30.6 to +48.7°, so as to
maximize the solid volume covered by the set of incident and
scattered beams.
atoms. For this interstitial solvent, restraints were placed on
the 1,2- and 1,3-distances; similar restraints were placed on
the two disordered congeners. The anisotropic displacement
parameters of the atoms of the disordered solvent were also
restrained, to a rigid-bond model and to isotropic behavior.
For 11b, a restraint to isotropic behavior was placed on one
of the atoms of the indenyl ligand, C(7). Otherwise, all non-
hydrogen atoms of both structures were refined freely with
anisotropic displacement parameters.
The refined values of the Flack parameter21 were 0.00(3)
for 11b and 0.00(9) for 14, for the absolute structures reported.
For 11b, the anisotropic displacement parameters for the five-
membered ring of the chiral ligand showed elongation per-
pendicular to the best plane of the ring, which is symptomatic
of conformational disordersthis does not reflect on the deter-
mination of the absolute configurations of the chiral carbon
atoms. For 14, no signs of even the slightest conformational
disorder were observed for the five-membered rings of the
chiral ligands; it was observed that both independent mol-
ecules in the asymmetric unit have the same conformations
for this group. Both refinements were stable and convergent.
Both structures were solved by direct methods19 and devel-
oped and refined in the usual sequence of least-squares
refinements and difference Fourier maps.20 In each case the
uniform stereochemistry of the chiral groups was observed
with no ambiguity and with no special treatment to the
structural model (i.e., no constraints or restraints were needed
for these ligands). In both cases, hydrogen atoms were placed
at calculated positions and refined as riding atoms with
isotropic displacement parameters set to 1.2 times the equiva-
lent isotropic displacement parameters of their respective
parent atoms. For 14, in addition to the two molecules of the
complex, the asymmetric unit contains one formula unit of
n-pentane, disordered over two sites sharing one of the carbon
Ack n ow led gm en t. This work was supported by the
Ministerio de Ciencia y Tecnolog´ıa (MCyT) and the
Direccio´n General de Investigacio´n Cient´ıfica y Te´cnica
(DGICyT) of Spain (Projects BQU2000-0227 and PB98-
1593). S.C. thanks the Ministerio de Educacio´n y
Cultura (MEC) of Spain for the award of a Ph.D. grant.
(15) (a) Diffractometer control: SMART V5.624, copyright 1997-
2001, Bruker AXS, Inc. (b) Integration: SAINT+ V6.02, copyright
1997-1999, Bruker AXS, Inc.
(16) (a) Diffractometer control: CAD4/PC Version 2.0, copyright
1996, Nonius bv, Delft, The Netherlands. (b) Data reduction: XCAD4B
(K. Harms, 1996).
(17) SADABS: Area-Detector Absorption Correction, copyright 1996,
Siemens Industrial Automation, Inc., Madison, WI.
(18) SHELXTL release 5.05/VMS, copyright 1996, Siemens Analyti-
cal X-ray Instruments, Inc.
(19) SHELXS-97: Fortran program for crystal structure solution,
copyright 1997, George M. Sheldrick.
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal structure data for 11b and 14, including tables of atomic
parameters, anisotropic thermal parameters, and bond dis-
tances and bond angles, and Tables S1-S6, containing 31P-
{1H}, 1H, and 13C{1H} NMR spectroscopic data for compounds
3a ,b through 8a ,b. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM0202928
(20) SHELXL-97: A program for crystal structure refinement,
release 97-2, copyright 1997, George M. Sheldrick, University of
Go¨ttingen, Germany, 1997.
(21) (a) Flack, H. D. Acta Crystallogr., Sect. A 1983, 39, 876. (b)
Bernardinelli, G.; Flack, H. D. Acta Crystallogr., Sect. A 1985, 41, 500.