Ruthenium(II) π-alkyne and vinylidene complexes derived from glycoynitols: New precursors for water-soluble unsaturated carbenes

Article abstract of DOI:10.1021/om034299g

A new class of precursors for water-soluble unsaturated carbenes was synthesized by reaction of [Cp*RuCl(PMe₃)₂] with a terminal alkyne and a propargyl alcohol, each bearing a polyhydroxylated lateral chain derived from D-xylose. In the reaction with the terminal glycoynitol, the presence of a pair of noninterconverting π-alkyne intermediates of [Cp*Ru-(PMe₃)₂]⁺ species was observed for the first time and the kinetics of isomerization to the same vinylidene species measured by NMR experiments.

Full text of DOI:10.1021/om034299g

2020
Organometallics 2004, 23, 2020-2026
Ru th en iu m (II) π-Alk yn e a n d Vin ylid en e Com p lexes
Der ived fr om Glycoyn itols: New P r ecu r sor s for
Wa ter -Solu ble Un sa tu r a ted Ca r ben es
Chiara Ciardi,†,‡ Gianna Reginato,*,‡ Luca Gonsalvi,‡ Isaac de los Rios,§
Antonio Romerosa,† and Maurizio Peruzzini*,‡
AÄ rea de Quı´mica Inorga´nica, Facultad de Ciencias Experimentales, Universidad de Almer´ıa,
04071 Almerı´a, Spain, Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti
Organometallici (ICCOM-CNR), Via Madonna del Piano, 50019 Sesto Fiorentino (Firenze),
Italy, and Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica
Inorganica, Facultad de Ciencias, Universidad de Cadiz, Campus Rio San Pedro,
11500 Puerto Real (Cadiz), Spain
Received November 14, 2003
A new class of precursors for water-soluble unsaturated carbenes was synthesized by
reaction of [Cp*RuCl(PMe3)2] with a terminal alkyne and a propargyl alcohol, each bearing
a polyhydroxylated lateral chain derived from D-xylose. In the reaction with the terminal
glycoynitol, the presence of a pair of noninterconverting π-alkyne intermediates of [Cp*Ru-
(PMe3)2]+ species was observed for the first time and the kinetics of isomerization to the
same vinylidene species measured by NMR experiments.
In tr od u ction
the most useful and versatile reagents for organic
synthesis and homogeneous catalysis.4 Although a great
number of transition metal unsaturated carbenes have
been synthesized, examples of water-soluble vinylidenes
and allenylidenes are, to the best of our knowledge,
limited to the two ruthenium(II) derivatives, [RuCl2-
{CdC(H)Ph}(TPPMS)2]Na2 and [{RuCl(µ-Cl)(CdCd
CPh2)(TPPMS)2}2]Na4, where TPPMS is the sulfonated
phosphine Ph2P{2-OS(O)2C6H4}-}.5 Hydrosoluble vi-
nylidenes may find application as water-soluble cata-
lysts, hence allowing the extension of the existing
Transition metal unsaturated carbenes have become
an active and important area of research in organome-
tallic chemistry during the last two decades.1 In par-
ticular, vinylidenes1,2 and allenylidenes,1,3 which are the
simplest members of this class of compounds, are among
Dedicated to Prof. J ose´ Vicente on the occasion of his 60th
birthday.
* Corresponding authors. E-mail:
mperuzzini@iccom.cnr.it.
gianna.reginato@unifi.it;
† Universidad de Almer´ıa.
‡ Istituto di Chimica dei Composti Organometallici (ICCOM-CNR).
§ Universidad de Cadiz.
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10.1021/om034299g CCC: $27.50 © 2004 American Chemical Society
Publication on Web 03/23/2004

Ru(II) π-Alkyne and Vinylidene Complexes
Organometallics, Vol. 23, No. 9, 2004 2021
differently protected sugars.11 The two-carbon chain
elongation was obtained by reaction of 3 with ethynyl-
magnesium chloride creating a new asymmetric center,
thus affording compound 5 as a mixture of diastereo-
isomers in a ratio S/R = 1.27 (5a ,b), which was not
resolved at this stage of the work.12
Sch em e 1
Syn th esis a n d Ch a r a cter iza tion of Ru (II) Ca r -
ben e Com p lexes of Glycoyn itols. The organometallic
chemistry of the polyhydroxyalkynes synthesized as
above was explored using the known ruthenium(II)
complex 1, which conjugates high-stability and well-
documented reactivity in both stoichiometric13a and
catalytic processes.13b Puerta and co-workers13 as well
as other authors14 have demonstrated that the reactivity
of these complexes with terminal alkynes involves the
π-bonding coordination of the alkyne to the metal center
followed by tautomerization into the vinylidene deriva-
tive. The latter process may follow two different path-
ways, namely, (a) the alkyne may oxidatively add to give
a Ru(IV) hydride-akynyl complex from which the vi-
nylidene forms by a concerted 1,3[H] shift from the
metal center to the â-carbon of the alkynyl ligand, or
(b) via a concerted 1,2[H] shift from the R-carbon to the
â-carbon atom without the intermediacy of the oxidative
addition step.13c,14 The former mechanism has been
observed for Rh and Ir,15 Co,16 and Ru.13 In a recent
study addressing the reactivity of [Cp*RuCl(PEt3)2] with
acetylene in methanol, the three isomeric species
π-alkyne, hydride(alkynyl), and vinylidene have been
isolated and characterized by X-ray analysis.17 In the
case of 1, the presence of the sterically less demanding
trimethylphosphine, with basicity comparable to PEt3,
makes the metal center similarly suited to stabilize
organometallic alkyne derivatives. In fact, according to
our expectations, 1 reacts with 4 in methanol in the
presence of NaBPh4 to afford the π-alkyne complex
[Cp*Ru(PMe3)2(η2-HCtCR)]BPh4 [R ) (2,2,2′,2′-tetra-
methyl-[4(S),4′(S)]bi[[1,3]dioxolanyl]-5(R)-yl)] (6) as a
microcrystalline pale yellow solid. Complex 6 is mod-
erately air stable as a solid, but slowly decomposes in
chloroform solution unless an inert atmosphere is pro-
vided. It has been characterized by elemental analysis
and IR and multinuclear NMR spectroscopy. The IR
spectrum displays one medium-intensity absorption
band at 1828 cm-1 due to ν(CtC) stretching of a di-
hapto-coordinated π-alkyne ligand. The NMR spectra
metathesis protocols to the water phase, for the syn-
thesis of drugs and other bioactive compounds related
to natural products.6
Hereby we report the synthesis of terminal alkynes
and propargylic alcohols bearing a polyhydroxylated
lateral chain which can be easily derived from simple
carbohydrates. The reactions of these glycoynitols with
[Cp*RuCl(PMe3)2] (1) to give the corresponding com-
plexes incorporating π-alkyne and vinylidenes bearing
the polar lateral chain are also described, together with
the first tests on the reactivity of these carbenes toward
nucleophiles.
Resu lts a n d Discu ssion
Syn th esis of Glycoyn itol Liga n d s. The synthetic
potential of metal carbenes has been widely investigated
by Do¨tz et al., to develop nonconventional routes to
C-glycosides and oligosaccharides.7 Although some ru-
thenium vinylidenes and allenylidenes derived from
polyhydroxyalkynes have been described and applied to
the total synthesis of natural compounds,8 these species
have not been as yet investigated in depth. In our study,
naturally occurring D-xylose was chosen as starting
material to obtain the corresponding terminal alkyne
and propargylic alcohol through standard transforma-
tions. The starting material was initially protected on
the aldehyde group as dithioacetal9 and then trans-
formed into the diacetonide (2) before being deprotected
to afford, with high yield, pure (2,2,2′,2′-tetramethyl-
[4(S),4′(S)]bi[[1,3]dioxolanyl]-5(R)-yl)carbaldehyde (3)
(Scheme 1).
Compound 3 could be used without further purifica-
tion as suitable starting material to obtain both inytoles
(2,2,2′,2′-tetramethyl-[4(S),4′(S)]bi[[1,3]dioxolanyl]-5(R)-
yl)ethyne (4) and (2,2,2′,2′-tetramethyl-[4(S),4′(S)]bi-
[[1,3]dioxolanyl]-5(R)-yl)propynol (5) with one- and two-
carbon chain elongation, respectively (Scheme 2) as
diasteromerically pure compounds.
The single-carbon homologation required the use of
dimethyl-1-diazo-2-oxopropylphosphonate,10 affording
very efficiently the target molecule in high yield and
purity via a one-pot reaction, as recently described for
(11) Thie´ry, J .-C.; Fre´chou, C.; Demailly, G. Tetrahedron Lett. 2000,
41, 6337.
(12) Neither diastereoselective synthesis of 5 nor resolution of the
mixture of anomers was attempted, as the further utilization of this
ligand in allenylidene synthesis would have resulted in loss of the
chiral information.
(6) Maynard, H. D.; Okada, S. Y.; Grubbs, R. H. J . Am. Chem. Soc.
2001, 123, 1275. (b) Watson, K. J .; Anderson, D. R.; Nguyen, S. T.
Macromolecules 2001, 34, 3507. (c) Biagini, S. C. G.; Davies, R. G.;
Gibson, V. C.; Giles, M. R.; Marshall, E. L.; North, M. Polymer 2001,
42, 6669.
(7) For recent reviews see: (a) Do¨tz, K. H.; Ehlenz, R. Chem. Eur.
J . 1997, 3, 175. (b) Do¨tz, K. H.; J akel, C.; Haase, W.-C. J . Organomet.
Chem. 2001, 119, 617. (c) Haase, W.-C.; Nieger, M.; Do¨tz, K. H. J .
Organomet. Chem. 2003, and references therein.
(8) Trost, B. M.; Toste, F. D.; Pinkerton, A. B. Chem. Rev. 2001,
101, 2067.
(9) Arroyo-Go´mez, Y.; Lo´pez-Sastre, J . A.; Rodr´ıguez-Amo, J . F.;
Santos-Garc´ıa, M.; Sanz-Tejedor, M. A. Tetrahedron: Asymmetry 1999,
10, 973. (b) Dondoni, A.; Marra, A.; Massi A. J . Org. Chem. 1997, 62,
6261.
(13) de los Rios, I.; J imenez-Tenorio, M.; Puerta, M. C.; Valerga, P.
J . Chem. Soc., Chem. Commun. 1995, 1757. (b) de los Rios, I.; J imenez-
Tenorio, M.; Puerta, M. C.; Valerga, P. J . Am. Chem. Soc. 1997, 19
529. (c) Bustelo, E.; J imenez-Tenorio, M.; Puerta, M. C.; Valerga, P.
Organometallics 1999, 18, 950. (f) Bustelo, E.; J imenez-Tenorio, M.;
Puerta, M. C.; Valerga, P. Organometallics 1999, 18, 4563.
(14) Lomprey, J . R.; Selegue, J . P. J . Am. Chem. Soc. 1992, 114,
5518. (b) Bullock, R. M. J . Chem. Soc., Chem. Commun. 1989, 165.
(15) See for example: (a) Wolf, J .; Werner, H.; Serhadli, O.; Ziegler,
M. L. Angew. Chem., Int. Ed. 1983, 22, 414. (b) Werner, H.; Ho¨hn, A.
J . Organomet. Chem. 1984, 272, 105. (c) Garcia-Alonso, F. J .; Ho¨hn,
A.; Wolf, J .; Otto, H.; Werner, H. Angew. Chem., Int. Ed. 1985, 24,
406. (d) Dziallas, M.; Werner, H. J . Chem. Soc., Chem. Commun. 1987,
852.
(16) Bianchini, C.; Peruzzini, M.; Vacca, A.; Zanobini, F. Organo-
metallics 1991, 10, 3697.
(17) Bustelo, E.; Carbo´, J . J .; Lledo´s, A.; Mereiter, K.; Puerta, M.
C.; Valerga, P. J . Am. Chem. Soc. 2003, 125, 3311.
(10) Meffre, P.; Hermann, S.; Durand, P., Reginato, G.; Riu, A.
Tetrahedron 2002, 58, 5159. (b) Eymery, F.; Iorga, B.; Savignac P.
Synthesis 2000, 185.

2022 Organometallics, Vol. 23, No. 9, 2004
Ciardi et al.
Sch em e 2
show that 6 exists in acetone-d6 solution as a 69:31
mixture of two isomers. The 31P{1H} NMR spectrum
indicates that both isomers exhibit an AB spin system,
suggesting the nonequivalence of the two PMe3 ligands.
The major isomer 6a displays two doublets at 4.16 and
7.56 ppm, while the other isomer 6b shows two doublets
Sch em e 3
1
centered at 6.62 and 5.35 ppm, respectively. In the H
NMR spectrum, the signals corresponding to the skel-
eton of the sugar moiety are doubled, in agreement with
the existence of a pair of isomers. In particular two
doublets of doublets at 5.34 and 5.23 ppm corresponding
to 6a and 6b, respectively, are assigned to the terminal
alkyne proton resonance, HCtCR. 1H{31P} NMR ex-
periments indicate that only one of the PMe3 phospho-
rus atoms is coupled with this proton, as the other
smaller coupling is due to coupling with the nearest
proton of the sugar moiety. A reliable 13C NMR analysis
could not be run because of the rapid tautomerization
of both π-alkyne rotamers into the unique vinylidene
complex [Cp*Ru(PMe3)2{dCdC(H)R}]BPh4 [R ) 2,2,2′,2′-
tetramethyl-[4(S),4′(S)]bi[[1,3]dioxolanyl]-5(R)-yl)] (7) in
acetone and DMSO (see below).
Isomers 6a and 6b do not interconvert into each other,
as their ratio does not change with the temperature in
a series of 31P{1H} NMR spectra run at variable tem-
peratures between -60 and 20 °C. Also, no exchange
peaks due to the phosphorus atoms of the two AB sys-
tems were detected by a 2D 31P{1H} exchange spectros-
copy experiment.14,18
The existence of a pair of noninterconverting isomers
for the π-alkyne derivative 6 can be attributed to the
presence of a pair of rotationally distinct isomers. The
two π-alkyne rotamers, which to the best of our knowl-
edge have no precedent in the rich organoalkyne chem-
istry of [Cp*Ru(PR3)2]+ complexes, are likely to be
separated by a significant rotational barrier, which is
not crossed at room temperature. The bulkiness of the
alkyne sugar substituent is probably responsible for
hampering the rotation about the ruthenium-π-alkyne
bond. From a theoretical analysis on the model com-
pound [CpMn(CO)2(π-HCtCH)], Hoffmann and Silves-
tre suggested that the favored orientation of the CtC
triple bond is almost parallel to the symmetry plane of
the CpMn(CO)2 moiety.19 In contrast, X-ray analysis on
the real compounds [Cp*Ru(PR3)2(η2-HCtCH)]BPh4 (R
) Me,14a Et17) confirmed a rotational orientation, al-
though largely distorted, closer to an orthogonal dispo-
sition. Whatever the real orientation in the pair of
rotamers of 6 may be, the steric hindrance between the
bulky alkyne substituent and the methyl groups on the
cyclopentadienyl ring in 6 may well account for a high
rotational barrier, which does not allow the two rota-
mers to equilibrate up to 20 °C.20
Mech a n istic Stu d ies a n d Kin etics. To evaluate the
rotational barrier separating the two rotamers in 6, we
ran a series of 31P{1H} NMR spectra in DMSO increas-
ing the temperature above 80 °C. Under these condi-
tions, the two AB spin systems experienced a modest
drift of their chemical shifts, approaching each other
without merging in a unique signal, in line with the
behavior shown by π-alkyne CpRu complexes featuring
terminal alkynes.21 At high temperature, the two com-
pounds tautomerize into the vinylidene complex [Cp*Ru-
(PMe3)2{dCdC(H)R}]BPh4 (7). The presence of a unique
vinylidene derivative for 6 indirectly supports our
hypothesis concerning the existence of a pair of nonin-
terconverting rotamers separated by a large rotational
barrier. One-pot reaction of 1 with 4 in refluxing
tetrahydrofuran directly gives the vinylidene 7 after 1
h heating. The reaction is complete at room temperature
in 6 h to yield a yellowish-orange solution from which
yellowish-orange microcrystals of 7 are obtained after
workup, as shown in Scheme 3.
The kinetics of the isomerization of the π-alkyne
complexes 6 into the vinylidene 7 was studied by
31P{1H} NMR, monitoring the reaction progress at
different temperatures with data collected over 3 half-
lives or more. The data were acquired following the rate
of decrease of the two AB systems of the π-alkyne
complexes and were consistent with a first-order process
for both rotamers. The rate constants were comparable
(T ) 298 K, k1 ) 5.0 × 10-5 M-1 s-1 for the major
isomer, 5.3 × 10-5 M-1 s-1 for the minor isomer),
although the superimposition of the NMR signals
increases the error of the measurements. The activation
(20) A mixture of noninterconverting exo and endo isomers was
found for the η2-alkyne niobocene complexes [Nb(η5-C5H4SiMe3)(η2-
HCtCR)(CO)]. A computational study indicated a high rotational
barrier of 20.9 kcal mol-1. Garc´ıa-Yebra, C.; Lo´pez-Mardomingo, C.;
Fajardo, M.; Antin˜olo, A.; Otero, A.; Rodriguez, A.; Vallat, A.; Lucas,
D.; Mygnier, Y.; Carbo´, J . J .; Lledos, A.; Bo, C. Organometallics 2000,
19, 1749.
(18) Urtel, K.; Frick, A.; Huttner, G.; Zsolnai, L.; Kircher, P.; Rutsch,
P.; Kaifer, E.; J acobi, A. Eur. J . Inorg. Chem. 2000, 33.
(19) Silvestre, J .; Hoffmann, R. Helv. Chim. Acta 1985, 68, 1461.
(21) de los Rios, I.; Tenorio, M. J .; Puerta, M. C.; Valerga, P. J . Am.
Chem. Soc. 1997, 119, 6529.

Ru(II) π-Alkyne and Vinylidene Complexes
Organometallics, Vol. 23, No. 9, 2004 2023
Ta ble 1. Ra te Con sta n ts for Isom er iza tion
Rea ction of 6a ,b to 7
T/K
105 kiso-a/s-1
ln(kiso-a/T) 105 kiso-b/s-1
ln(kiso-b /T)
293
299
311
317
323
3.0
5.0
20.0
22.0
40.0
-16.09
-15.60
-14.25
-14.18
-13.60
3.0
5.3
16.0
20.0
40.0
-16.09
-15.55
-14.48
-14.28
-13.60
Sch em e 4
F igu r e 1. 13C{1H} NMR resonance of the CR carbon of the
vinylidene 8 showing the existence of two diastereomers
(3:2 ratio).
the observed multiplicity due to coupling with the two
PMe3 ligands.
1
The reaction was also monitored by 31P{1H} and H
NMR in a separate experiment using MeOH-d4 as
solvent. Quantitative deuteration of the vinylidene at
Câ was observed as a consequence of the acidic nature
of the MdCdC(H) proton25 and results in the appear-
ance of a non-binomial triplet (1:1:1 intensity pattern)
at δ 106.3 in the 13C{1H} NMR spectrum due to coupling
with the deuterium label. Remarkably, a single π-alkyne
intermediate existing as a couple of anomers (9a ,b in
3:2 ratio) is formed, in contrast with what is observed
for the reaction of 1 with 4, in which two separate
rotamers were identified. The free rotation about the
metal-alkyne bond responsible for this behavior may
arise from the presence of the propargylic carbon in 5,
allowing for a decrease of the steric hindrance with
respect to 4.
Rea ctivity of Ru (II)-Glycovin ylid en es w ith Nu -
cleop h iles. The reactivity of the vinylidene complex 7
was preliminary evaluated by filling some NMR tube
tests with selected nucleophilic reagents such as water
and ammonia in order to verify whether the presence
of a bulky substituent on the Câ carbon has an influence
on the known reactivity of these unsaturated carbenes
toward nucleophiles and electrophiles.1b,26 Reaction with
ammonia is straightforward and results in the forma-
tion of the sugar-functionalized aminocarbene [Cp*Ru-
(PMe3)2{dC(NH2)CH2R}]BPh4 (10) as expected.27 The
reaction with water takes place only upon heating a
solution of 7 in DMSO-d6 containing D2O at 80 °C for
12 h (Scheme 5), yielding the known [Cp*Ru(PMe3)2-
(CO)]BPh4 carbonyl derivative (11),28 together with 1
equiv of the methylated sugar, deriving from the regio-
selective addition of H2O across the CRdCâ vinylidene
bond.25 Although the addition of ammonia and water
to ruthenium vinylidenes is a well-understood reaction,
they can be used for synthetic purposes to functionalize
a protected sugar as described.
enthalpy of the process was calculated as approximately
15.8 kcal mol-1 for the major of the two isomers and
15.2 kcal mol-1 for the minor one. The closeness of the
values, also in accordance with data reported in the
literature for analogous processes,13b,22 agrees with the
existence in solution of two rotational π-alkyne isomers
which transform, with the same mechanism and same
rate law, into a unique vinylidene species. Kinetic data
are summarized in Table 1 below.
Encouraged by the outcome of the reaction of 1 with
4, which resulted in the synthesis of the first unsatur-
ated polyhydroxyvinylidene Ru(II) complex, we decided
to study the reaction of 1 with alkynol 5 to verify
whether a related allenylidene might be accessible via
the well-known Selegue’s protocol.23 The mechanism
involves the initial π-coordination of the alkyne, followed
by metal-assisted tautomerization to a hydroxyvi-
nylidene species, which, in most cases, gives spontane-
ous intramolecular dehydration to afford the correspond-
ing allenylidene complex.23
In the case of the reaction of 1 with 5 in MeOH, no
allenylidene complex was observed,24 instead stopping
at the corresponding hydroxyvinylidene complex [Cp*Ru-
(PMe3)2{dCdC(H)CH(OH)R}]BPh4 (8), present as a
mixture of diastereoisomers (8a ,b in 3:2 ratio) deriving
from the diastereoisomeric excess generated for 5
through the synthetic pathway described above. The
pair of anomers in 8 is stable to spontaneous dehydra-
tion, as observed by heating the solution close to the
boiling point of methanol (Scheme 4). The final product
8 can be recognized by 13C NMR, where a pair of triplets
near 344 ppm is observed (Figure 1). These triplets are
attributable to the R-carbon atoms of the hydroxyvi-
nylidene ligands in the diastereomeric mixture of 8, with
Con clu sion s. In this study, a new class of precursors
for water-soluble unsaturated carbenes was synthesized
by reaction of [Cp*RuCl(PMe3)2] with a terminal alkyne
and propargylic alcohol bearing a fully protected poly-
(25) Bianchini, C.; Casares, J . A.; Peruzzini, M.; Romerosa, A.;
Zanobini, F. J . Am. Chem. Soc. 1996, 118, 4585.
(26) Carvalho, M. F. N. N.; Henderson, R. A.; Pombeiro, A. J . L.;
Richards, R. L. J . Chem. Soc., Chem. Commun. 1989, 431.
(27) Bianchini, C.; Peruzzini, M.; Masi, D.; Romerosa, A.; Zanobini,
F. Organometallics 1999, 18, 2376.
(22) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J . Chem.
Soc., Dalton Trans. 1982, 2203. (b) Werner, H. Angew. Chem., Int. Ed.
1991, 700.
(23) Selegue, J . P. Organometallics 1982, 1, 217.
(24) de los Rios, I.; Tenorio, M. J .; Puerta, M. C.; Valerga, P. J .
Organomet. Chem. 1997, 549, 221.
(28) Tilley, T. D.; Grubbs, R. H.; Bercaw, J . Organometallics 1984,
3, 274.

2024 Organometallics, Vol. 23, No. 9, 2004
Ciardi et al.
Sch em e 5
0.8 mL). After 15 min, acetone (40 mL) was added, and the
final solution was stirred at room temperature overnight. The
resulting solution was neutralized with NH4OH (28% solution),
concentrated to a small volume, and then dissolved in H2O
(10 mL) and ethyl acetate (5 mL). The aqueous layer was
washed three times with ethyl acetate (5 mL each), and the
combined organic phases were dried over dry Na2SO4. The
solvent was then removed in vacuo, and the crude was purified
by flash chromatography using a 1:2 ethyl acetate/light
petroleum mixture as eluent. Yield: 3.3 g, 73%. Spectroscopic
data were in agreement with those previously reported.9b 1H
NMR, δ (CDCl3, 200 MHz): 4.37-4.28 (2H, m, SCH, CH2CH),
4.16-3.88 (4H, m, CH2, CH2CHCH, CH2CHCHCH), 2.83-2.55
(4H, m, 2 × SCH2), 1.46 (3H, s, CH3), 1.42 (6H, bs, 2 × CH3),
1.36 (3H, s, CH3), 1.26 (3H, t, 3J ) 7.4 Hz, SCH2CH3), 1.23
hydroxylated lateral chain derived from the synthetic
elaboration of D-xylose. The reaction proceeds via for-
mation of a pair of noninterconverting π-alkyne inter-
mediates, which were observed for the first time with
[Cp*Ru(PR3)2]+ species. Work is in progress to obtain
selective deprotection of the diacetonide groups, yielding
the water-soluble carbene derivatives in the free form,
and to better investigate the scope of the metal-
mediated sugar functionalizations.
Exp er im en ta l Section
Ma ter ia ls a n d In str u m en ts. All reactions and manipula-
tions involving organometallic syntheses were routinely per-
formed under a dry nitrogen atmosphere using standard
Schlenk techniques. Tetrahydrofuran (THF) was freshly dis-
tilled over LiAlH4 and purged with nitrogen prior to use.
Methanol was purified by distillation over CaH2 before use.
The complex [Cp*RuCl(PMe3)2] (1) was prepared according to
the procedure reported in the literature.28 Diazophosphonate
was prepared as reported.10a All other reagents and chemicals
were commercial grade products from Fluka and Aldrich and
used as received without further purification except where
noted. Solid complexes were collected on sintered glass-frits
and washed with light petroleum ether (bp 40-60 °C) before
being dried via a stream of nitrogen. Reactions were monitored
by TLC plates using Merck Kieselgel silica gel 60 F 254 plates
(0.25 nm). Flash chromatography was performed using 400-
300 mesh, ICN silica 32-63, ICN Biomedicals, 60 Å. Deuterated
chloroform, acetone, and benzene for NMR measurements
3
(3H, t, J ) 7.4 Hz, SCH2CH3). 13C{1H} NMR, δ (CDCl3, 50.4
MHz): 109.8 (OCO), 109.3 (OCO), 80.0 (CH), 78.5 (CH), 75.1
(CH), 65.7 (CH2), 52.8 (CHS), 27.2, 27.0, 26.0, 25.4, 25.1, 24.7
(4 CH3 + 2 CH2), 14.2, 14.1 (2 × CH2CH3). MS, m/z (%): 217
(6, M+ - H - 2 SCHdCH2); 143 (73, M+ - 2 SCHdCH2 - CH
- 4 CH3); 135 (100, M+ - CH2CHOCO(CH3)2 - CHCHOCO-
(CH3)2), 101 (50, 143 - CHCHOCO(CH3)), 59 (135 - SCHd
CH2-CH).
(b) Syn th esis of (2,2,2′,2′-Tetr a m eth yl-[4(S),4′(S)]bi-
[[1,3]d ioxola n yl]-5(R)-yl)ca r ba ld eh yd e (3). Compound 2
(1.5 g, 4.6 mmol) was dissolved in acetone (16 mL) and H2O
(1.5 mL) and reacted with HgO (2.3 g, 10.5 mmol) and HgCl2
(2.3 g, 8.3 mmol). The mixture was heated to 55 °C and stirred
at this temperature for 3.5 h. After cooling to room tempera-
ture the slurry was filtered through a Celite pad and the
filtrate concentrated to dryness. The crude was taken with
dichloromethane (3 × 10 mL) and filtered again through Celite.
The organic layers were washed with a 1 M solution of KI and
then dried on dry Na2SO4. Removal of the solvent under
vacuum gave 0.87 g of aldehyde 3 as an almost pure solid (yield
77%), which was used for the following step without further
1
(Aldrich) were dried over molecular sieves (4 Å). H, 13C{1H},
and 31P{1H} NMR spectra were recorded on Bruker AC200,
Varian VXR300, or Bruker AVANCE DRX 500 spectrometers
operating at 200.13, 299.94, or 500.13 MHz (1H), 50.32, 75.42,
or 125.80 MHz (13C), and 81.01, 121.42, or 202.45 MHz (31P),
respectively. Peak positions are relative to tetramethylsilane
and were calibrated against the residual solvent resonance (1H)
or the deuterated solvent multiplet (13C). 31P NMR chemical
shifts were measured relative to external 85% H3PO4, with
downfield values taken as positive. 13C-DEPT-135 experiments
were run on a Bruker AC200 spectrometer. Infrared spectra
were recorded as Nujol mulls in a Perkin-Elmer 1600 series
FT-IR spectrometer between NaCl plates. Elemental analyses
(C, H, N) were performed using a Carlo Erba model 1106
elemental analyzer. Mass spectra were recorded using a
Hewlett-Packard 5790 carrying a capillar column OV 101, 30
m, or QMD 1000 Carlo Erba connected to a Mega 5160 gas
chromatograph equipped with an SE 54 column, 30 m. In both
cases the ionization potential was 70 eV.
1
3
purification. H NMR, δ (CDCl3, 200 MHz): 9.75 (1H, d, J )
1.6 Hz, CHO), 4.25-4.18 (2H, m, CH2), 4.13-4.00 (2H, m,
CHCHO + CH2CH), 3.84 (1H, dd, 3J ) 8.4 Hz, 3J ) 6.6 Hz,
CH2CHCH), 1.46 (3H, s, CH3), 1.41 (3H, s, CH3), 1.38 (3H, s,
CH3), 1.35 (3H, s, CH3). 13C{1H} NMR, δ (CDCl3, 50.4 MHz):
201.0 (CHO), 111.8 (C(CH3)2), 110.0 (C(CH3)2), 81.3 (CH), 77.1
(CH), 75.5 (CH), 65.3 (CH2), 26.6 (CH3), 26.2 (CH3), 26.0 (CH3),
25.2 (CH3). MS, m/z (%): 215 (16, M+ - CH3), 201 (3, M+
-
CHO), 172 (1, 201 - CH2), 157 (3, 172 - CH3), 143 (50, 157 -
CH2), 101 (78, 201 - CHCHOCO(CH3)).
(c) Syn th esis of (2,2,2′,2′-Tetr a m eth yl-[4(S),4′(S)]bi-
[[1,3]d ioxola n yl]-5(R)-yl)eth yn e (4). Compound 3 (0.75 g,
3.2 mmol) was dissolved in dry methanol (25 mL) under
nitrogen and reacted with dimethyl(2-oxo-propyl)diazophos-
phonate (0.63 g, 3.2 mmol) and K2CO3 (0.90 g, 6.5 mmol) at 0
°C for 6 h, then for an additional 4 h at room temperature.
The solvent was then removed under reduced pressure,
avoiding heating to afford a crude solid, which was dissolved
(a ) Syn th esis of 5(R)-Bis(eth ylsu lfa n ylm eth yl)-2,2,2′,2′-
tetr a m eth yl-[4(S),4′(S)]bi[[1,3]d ioxola n yl] (2). d-Xylose
(2.0 g, 13.3 mmol) was reacted at room temperature with
CH3CH2SH (2.9 mL, 40.0 mmol) and concentrated HCl (37%,

Ru(II) π-Alkyne and Vinylidene Complexes
Organometallics, Vol. 23, No. 9, 2004 2025
in a 1:1 mixture of water and ethyl acetate (20 mL). The
organic layer was separated, washed with brine, and then
dried over Na2SO4. Removal of the solvent under reduced
) 9.2 Hz, P(CH3)3). Anal. Calcd for C52H71BO4P2Ru: C, 66.87;
H, 7.66. Found: C, 67.20; H, 7.57.
(f) Syn th esis of [Cp *Ru (P Me3)2{dCdC(H)R}]BP h 4 [R
) (2,2,2′,2′-t et r a m et h yl-[4(S),4′(S)]b i[[1,3]d ioxola n yl]-
5(R)-yl)] (7). Meth od A. Compound 6 (0.4 g, 0.41 mmol;
mixture of isomers) was dissolved in 20 mL of acetone and
stirred at room temperature for 12 h. After this time a 3:1
mixture of ethanol and light petroleum ether was added to
precipitate the vinylidene complex 7. The yellowish-orange
solid was filtered and dried under nitrogen. Yield: 55%.
Meth od B. A solution of 4 (0.10 g 0.44 mmol) in 1.0 mL of
CHCl3 was added to a THF solution of 1 (0.19 g, 0.4 mmol)
containing NaBPh4 (0.34 mg, 1.00 mmol). The resulting yellow-
orange solution was brought to reflux and stirred for 1 h. After
this time, the yellow solution was concentrated almost to
dryness. Addition of a 2:1 light petroleum ether/ethanol
mixture (13 mL) gave [Cp*Ru(PMe3)2{dCdC(H)R}]BPh4 (7)
as a yellow microcrystalline solid. Yield: 0.20 mg (50%). IR
pressure afforded 0.61 g of pure 3 as a solid. Yield: 83%; [R]26
D
-15.95 [c 0.1, CHCl3]. 1H NMR, δ (CDCl3, 200 MHz): 4.48 (1H,
dd, 3J ) 7.6 Hz, 4J ) 2.2 Hz, CHCtCH), 4.22 (1H, td, 3J ) 7.6
3
3
3
Hz, J ) 5.2 Hz, CHCH2), 4.11 (1H, dd, J ) 7.6 Hz, J ) 5.2
Hz, CHCHCtCH), 4.07 (1H, dd, 3J ) 8.4 Hz, 2J ) 6.6 Hz, CH2),
3.93 (1H, dd, 3J ) 8.4 Hz, 2J ) 6.6 Hz, CH2), 2.56 (1H, d, 4J )
2.2 Hz, CtCH), 1.50 (3H, s, CH3), 1.46 (3H, s, CH3), 1.44 (3H,
s, CH3), 1.39 (3H, s, CH3). 13C{1H} NMR, δ (CDCl3, 50.4
MHz): 111.8 (C(CH3)2), 110.7 (C(CH3)2), 81.0 (CtCH), 82.6,
75.7, 67.4 (CH2CH + CH2CHCH + CCtCH + tCH), 66.0
(CH2), 27.3 (CH3), 26.9 (CH3), 26.7 (CH3), 26.0 (CH3). MS, m/z
(%): 211 (100, M - CH3), 101 (75, M+ - CHCHOCO(CH3)2Ct
CH). Anal. Calcd for C12H18O4: C, 63.70; H, 8.02. Found: C,
64.20; H, 8.22.
(d ) Syn th esis of (2,2,2′,2′-Tetr a m eth yl-[4(S),4′(S)]bi-
[[1,3]d ioxola n yl]-5(R)-yl)p r op yn ol (5). To a solution of 3
(1.0 g, 4.34 mmol) in ca. 22 mL of THF was added dropwise
17 mL of a 0.5 M THF solution of CHtCMgCl through a
dropping funnel. The mixture was stirred at room temperature
for 4 h before being diluted with diethyl ether (10 mL), water
(10 mL), and ammonium buffer (10 mL). The aqueous layers
were separated and extracted with ether, and the combined
organic phases washed with brine and dried over Na2SO4. The
solvent was removed under reduced pressure and the crude
compound purified by flash chromatography (eluent dichlo-
romethane/diethyl ether, 1:1) to a mixture of diastomers in
the ratio S/R = 1.27 (5a ,b). Yield: 43%. 1H NMR, δ (C6D6,
500 MHz): 5a , 4.44 (1H, m, CHOH), 4.42 (1H, dd, 3J ) 2.2
(Nujol, cm-1): 1642 ν(CdC), 610 ν(B-C) cm-1 31P{1H} NMR,
.
δ (acetone-d6, 202.46 MHz): 4.51, 3.66 (AB system, 2J AB ) 38.9
1
Hz, PMe3). H NMR, δ (acetone-d6, 500 MHz): 4.80 (1H, dd,
3J ) 9.2 Hz, 3J ) 8.4 Hz, CdCHCH), 4.45 (1H, dt, 3J ) 9.2
4
3
3
Hz, J HP ) 2.1 Hz, CdCH), 4.25 (1H, ddd, J ) 2.4 Hz, J )
3
2
3
6.8 Hz, J ) 7.7 Hz, CH2CH), 4.11 (1H, dd, J ) 8.0 Hz, J )
2
3
6.8 Hz, CHH), 3.93 (1H, t, J ) J ) 7.9 Hz, CHH), 3.56 (1H,
3
3
4
dd, J ) 2.3 Hz, J ) 8.4 Hz, CH2CHCH), 1.97 (15H, t, J HP
)
2
1.3 Hz, C5(CH3)5), 1.67 (9H, d, J HP ) 9.8 Hz, P(CH3)3), 1.66
2
(9H, d, J HP ) 9.8 Hz, P(CH3)3), 1.38 (6H, s, OC(CH3)2), 1.36
(6H, s, OC(CH3)2). 13C{1H} NMR, δ (acetone-d6, 125.80 MHz):
2
344.05 (t, J CP ) 15.5 Hz, RudC), 109.48 (s, C(CH3)2), 108.58
(s, C(CH3)2), 105.33 (s, CdCH), 103.57 (s, C5(CH3)5), 81.82 (s,
CH2CHCH), 73.62 (s, CH2CHCH), 70.22 (s, CdCHCH), 66.07
(s, CH2), 27.16, 26.46, 25.91 (s, C(CH3)2 + C(CH3)(CH3)), 25.86
3
3
3
Hz, J ) 4.9 Hz, CHCHOH), 4.26 (1H, ddd, J ) 2.4 Hz, J )
3
3
3
6.8 Hz, J ) 7.7 Hz, CH2CH), 4.15 (1H, dd, J ) 2.4 Hz, J )
7.6 Hz, CH2CHCH), 4.06 (1H, t, J ) 7.9 Hz, CH2), 3.86 (1H,
dd, 3J ) 6.8 Hz, 2J ) 8.1 Hz, CH2), 2.09 (1H, s, OH), 2.08 (1H,
d, CtCH), 1.54 (3H, s, CH3), 1.51 (3H, s, CH3), 1.46 (3H, s,
CH3), 1.45 (3H, s, CH3); 5b, 4.43 (1H, m, CHOH), 4.39 (1H, t,
1
(s, C(CH3)(CH3)), 20.30 (d, J CP ) 33.6 Hz, P(CH3)3), 20.25 (d
1J CP ) 33.5 Hz, P(CH3)3). Anal. Calcd for C52H71BO4P2Ru: C,
66.87; H, 7.66. Found: C, 66.76; H, 7.59.
(g) Syn th esis of [Cp *Ru (P Me3)2{dCdC(H)CH(OH)R}]-
BP h 4 [R ) (2,2,2′,2′-tetr a m eth yl-[4(S),4′(S)]bi[[1,3]d ioxo-
la n yl]-5(R)-yl)] (8). To a solution of 1 (0.20 g, 0.47 mmol) in
15 mL of MeOH were added 120 mg of 5 (ca. 0.47 mmol) and
160 mg of NaBPh4 (0.47 mmol). The solution was stirred at
room temperature for 3 h, then the slurry was filtered trough
Celite and the solution concentrated to dryness. The crude was
extracted with ethanol (ca. 5 mL). Addition of light petroleum
ether (15 mL) gave 8 as a brownish-orange solid. Yield: 250
mg (65%). Compound 8 is obtained as a 3:2 diastereoisomeric
mixture (8a ,b). IR (Nujol, cm-1): 3564 ν(O-H), 1651 ν(CdC),
3J ) 3.7 Hz, CHCHOH), 4.13 (1H, dd, J ) 2.4 Hz, J ) 8.2
3
3
3
3
3
Hz, CH2CHCH), 4.12 (1H, ddd, J ) 2.8 Hz, J ) 6.7 Hz, J )
8.2 Hz, CH2CH), 4.02 (1H, t, J ) 7.0 Hz, CH2), 3.83 (1H, dd,
3J ) 6.7 Hz, J ) 8.1 Hz, CH2), 2.32 (1H, d, OH), 2.10 (1H, d,
2
CtCH), 1.52 (3H, s, CH3), 1.48 (3H, s, CH3), 1.44 (3H, s, CH3),
1.40 (3H, s, CH3). 13C{1H} NMR, δ (C6D6 125.75 MHz): 5a ,
81.61 (CtCH), 79.22 (CH2CHCHCH), 77.22, 76.91 (2 ×
C(CH3)2), 76.67 (CH2CHCH), 75.24 (CH2CH), 74.55 (CtCH),
65.86 (CH2), 62.72 (CCtCH), 27.13 (CH3), 27.03 (CH3), 26.09
(CH3), 25.72 (CH3); 5b, 82.21 (CtCH), 79.46 (CH2CHCHCH),
77.55, 76.70 (2 × C(CH3)2), 76.44 (CH2CHCH), 74.57 (CH2CH),
74.07 (CtCH), 65.72 (CH2), 62.36 (CCtCH), 27.17 (CH3), 27.04
615 ν(B-C) cm-1
8a (60%), 5.87, 2.58 (AB system, J AB ) 39.0 Hz, PMe3); 8b
(40%), 6.45, 2.11 (AB system, 2J AB ) 39.0 Hz, PMe3). 1H NMR,
δ (acetone-d6, 400 MHz): 8a 4.77 (1H, m, RudCdCH-
.
31P{1H} NMR, δ (acetone-d6, 202.45 MHz):
2
(CH3), 25.99 (CH3), 25.52 (CH3). MS, m/z (%): 241 (4, M+
-
CH - H - H), 201 (2, M+ - CHOHCtCH), 101 (31, 201 -
CHCHOCO(CH3)2. Anal. Calcd for C13H20O5: C, 60.92; H, 7.87.
Found: C, 61.07; H, 8.01.
3
4
CH(OH)R), 4.52 (1H, dt, J HH ) 8.4 Hz, J HP ) 6 Hz, RudCd
CH), 3.8-4.1 (5H, m, CH2CHCH + CdC(H)CH), 1.88 (15H, t,
4J HP ) 1.2 Hz, (C5(CH3)5), 1.52 (9H, d, 2J HP ) 9.6 Hz, P(CH3)3),
(e) Syn th esis of [Cp *Ru (P Me3)2(η2-HCtCR)]BP h 4 [R )
(2,2,2′,2′-tetr a m eth yl-[4(S),4′(S)]bi[[1,3]d ioxola n yl]-5(R)-
yl)] (6). To a suspension of 1 (0.19 g, 0.40 mmol) and NaBPh4
(0.34 mg, 1.0 mmol) in 20 mL of methanol were added 1 mL
of CHCl3 and 0.1 g of 4 (0.44 mmol) under stirring. The mixture
was stirred at room temperature for 1 h to give a yellow
solution. Addition of light petroleum ether (30 mL) and ethanol
(10 mL) yielded [Cp*Ru(PMe3)2(π-HCtCR)]BPh4 (6) as a pale
yellow precipitate. Yield: 0.18 g (49%). IR (Nujol, cm-1): 1828
2
1.52 (9H, d, J HP ) 9.6 Hz, P(CH3)3), 1.42-1.45 (12H, s, 4 ×
OC(CH3)2); 8b 4.75 (1H, m, RudCdCH-CH(OH)R), 4.52
3
4
(1H, dt, J HH ) 8.6 Hz, J HP ) 6.1 Hz, RudCdCH), 3.8-4.1
(5H, m, CH2CHCH + CdC(H)CH), 1.87 (15H, t, J HP ) 1.2 Hz,
2
(C5(CH3)5), 1.51 (9H, d, J HP ) 9.6 Hz, P(CH3)3), 1.49 (9H, d,
2J HP ) 9.6 Hz, P(CH3)3), 1.42-1.45 (12H, m, 4 × OC(CH3)2).
13C{1H} NMR, δ (acetone-d6, 125.80 MHz): 8a 343.95 (t, J CP
2
3
)15.5 Hz, RudC), 109.60 (s, C(CH3)2), 109.45 (t, J CP ) 1.5
Hz, CdCH), 109.39 (s, C(CH3)2), 104.48 (t, J CP ) 1.5 Hz,
ν(CtC), 610 ν(B-C) cm-1
.
31P{1H} NMR, δ (acetone-d6, 121.42
3
MHz): 6a (69%), 7.56, 4.16 (AB system, 2J AB ) 46.6 Hz, PMe3);
C5(CH3)5), 81.82 (s, CH2CHCH), 73.62 (s, CH2CHCH), 70.22
(s, CdCHCH), 66.07 (s, CH2), 27.45, 27.04, 26.19, 25.78 (s,
6b (31%), 6.62, 5.35 (AB system, J AB ) 46.6 Hz, PMe3). 1H
2
3
1
3
NMR, δ (acetone-d6, 300 MHz): 6a 5.34 (1H, dd, J HP ) 18.3,
C(CH3)2), 20.52 (dd, J CP ) 31.2 Hz, J CP ) 4.1 Hz P(CH3)3),
1 3
4J ) 1.8 Hz, CtCH), 4.90 (1H, dbs, 3J ) 9.0 Hz HCtCCH),
20.40 (dd, J CP ) 31.4 Hz, J CP ) 4.0 Hz P(CH3)3), 10.67 (s,
C5(CH3)5); 8b 13C{1H} NMR, δ (acetone-d6, 125.80 MHz):
344.05 (t, J CP )15.5 Hz, RudC), 109.27 (s, C(CH3)2), 109.17
(s, C(CH3)2), 108.58 (t, J CP ) 1.5 Hz, CdCH), 104.32 (t, J CP
) 1.5 Hz, C5(CH3)5), 81.82 (s, CH2CHCH), 73.62 (s, CH2CHCH),
4
1.76 (15H, t, J ) 1.2 Hz, J ) 1.8 Hz, (C5(CH3)5), 1.69 (9H, d,
2J HP ) 9.6 Hz, P(CH3)3); 6b 5.23 (1H, dd, 3J HP ) 19.8 Hz, 4J )
2
3
3
3
1.8 Hz, CtCH), 5.03 (1H, dbs, J ) 9.3 Hz, HCtCCH), 1.75
4
2
(15H, t, J ) 1.2 Hz, J ) 1.8 Hz, (C5(CH3)5), 1.58 (9H, d, J HP

2026 Organometallics, Vol. 23, No. 9, 2004
Ciardi et al.
70.22 (s, CdCHCH), 65.68 (s, CH2), 27.32, 27.16, 26.24, 25.70
(s, C(CH3)2), 20.53 (dd, 1J CP ) 31.4 Hz, 3J CP ) 4.3 Hz, P(CH3)3),
20.40 (dd, J CP ) 31.1 Hz, J CP ) 4.3 Hz, P(CH3)3), 10.69 (s,
C5(CH3)5). Anal. Calcd for C53H73BO5P2Ru: C, 66.04; H, 7.63.
Found: C, 66.19; H, 7.85.
tetramethyl-[4(S),4′(S)]bi[[1,3]dioxolanyl]-5(R)-yl)] (10) as the
only detectable species. 31P{1H} NMR, δ (acetone-d6, 81.01
MHz): 1.05, 0.18 (AB system, 2J AB ) 37.2 Hz, PMe3). 1H NMR,
δ (acetone-d6, 200.13 MHz): 9.15 (2H, bs, NH2), 1.76 (15H, t,
C5(CH3)5), 1.51 (6H, d, P(CH3)2), 1.48 (6H, d, P(CH3)2).
1
3
(h ) Rea ction of [Cp *Ru Cl(P Me3)2] (1) w ith 2,2,2′,2′-
Tet r a m et h yl-[4(S),4′(S)]b i[[1,3]d ioxola n yl]-5(R)-yl)p r o-
p yn ol (5). NMR Tu be Test. A solution of 1 (18.5 mg, 0.04
mmol) in MeOH-d4 (0.8 mL) was added to a 5 mm screw-cap
NMR tube containing 13.3 mg (0.05 mmol) of the glycoynitol
5 (1.3 equiv). After inserting the tube in the NMR spectrometer
kept at room temperature, a 31P{1H} NMR spectrum im-
mediately acquired showed the formation of both the π-alkyne
intermediate (two diasteroisomers, 9a and 9b in ca. 3:2 ratio)
and the hydroxyvinylidene [Cp*Ru(PMe3)2{dCdC(H)CH-
(OH)R}]Cl (two diasteroisomers, 8a and 8b in ca. 3:2 ratio).
On standing at room temperature, the complete transforma-
(j) Rea ction of [Cp *Ru (P Me3)2{dCdC(H)R}]BP h 4 [R )
(2,2,2′,2′-tetr a m eth yl-[4(S),4′(S)]bi[[1,3]d ioxola n yl]-5(R)-
yl)] w ith H2O. NMR Tu be Test. D2O (0.1 mL) was syringed
into 1.0 mL of a DMSO-d6 solution of 7 (35 mg, 0.04 mmol)
prepared in a NMR tube. The tube was vigorously shaken and
then inserted into the NMR spectrometer to be monitored by
31P{1H} NMR spectroscopy. No reaction was observed within
12 h. After this time the sample was heated to 80 °C in a
thermostated oil bath for 12 h and a new 31P{1H} NMR
spectrum acquired. A singlet at -0.10 ppm indicated the
presence of the carbonyl complex [Cp*Ru(PMe3)2(CO)]BPh4
(11). The solid collected from the NMR tube showed in the IR
tion of 9 into 8 took place in about 20 min. 31P{1H} NMR, δ
spectrum a ν(CO) stretching at 1952 cm-1
.
2
(MeOH-d4, 81.01 MHz): 9a , 6.45, 6.70 (AB system, J AB
)
328.6 Hz); 9b, 3.60, 2.86 (AB system, 2J AB ) 76.0 Hz); 8a , 5.63,
4.39 (AB system, J AB ) 46.5 Hz, PMe3); 8b, 4.19, 3.04 (AB
2
Ack n ow led gm en t. This work was supported by
INTAS (00-00179) and NATO (PST.CLG.978521). Thanks
are also due to EC through COST D17 and D29 Chem-
istry Actions (WGD17/0003/00 and WGD29/0009-003)
and RTN no. MRTN-CT-2003-503864 (AQUACHEM) for
promoting this scientific activity. I.d.l.R. thanks the
MCYT of Spain for a Ramon y Cajal Contract.
2
system, J AB ) 38.7 Hz, PMe3).
(i) Rea ction of [Cp *Ru (P Me3)2{dCdC(H)R}]BP h 4 [R )
(2,2,2′,2′-tetr a m eth yl-[4(S),4′(S)]bi[[1,3]d ioxola n yl]-5(R)-
yl)] w ith NH3. NMR Tu be Test. Gaseous NH3 was bubbled
throughout an acetone-d6 (0.8 mL) solution of 7 (35 mg, 0.04
mmol) prepared in a screw-cap 5 mm NMR tube. Monitoring
the reaction by 31P{1H} NMR spectroscopy showed the forma-
tion of [Cp*Ru(PMe3)2{dC(NH2)CH2R}]BPh4 [R ) 2,2,2′,2′-
OM034299G