Planar chiral (η6-arene)tricarbonylchromium complexes derived from mandelic acid

Article abstract of DOI:10.1016/S0022-328X(02)01399-2

The enantiomers of mandelic acid have each been converted into 1,3-dioxolan-4-one derivatives. Formation of the planar chiral η⁶-arene)tricarbonylchromium complexes has enabled an investigation of their potential to promote discrimination betwe

Full text of DOI:10.1016/S0022-328X(02)01399-2

Journal of Organometallic Chemistry 654 (2002) 140ꢀ149
/
www.elsevier.com/locate/jorganchem
Planar chiral (h6-arene)tricarbonylchromium complexes derived from
mandelic acid
Paul D. Woodgate *, Amir Ashoorzadeh, Ali Hosseini, Clifton E.F. Rickard, Lee-
Kei Yang
Department of Chemistry, The University of Auckland, Private Bag 92019, Auckland, New Zealand
Received 30 January 2002; accepted 13 March 2002
Abstract
The enantiomers of mandelic acid have each been converted into 1,3-dioxolan-4-one derivatives. Formation of the planar chiral
(h6-arene)tricarbonylchromium complexes has enabled an investigation of their potential to promote discrimination between the
diastereotopic ortho and/or meta arene hydrogens during lithiationꢀ
/
silylation. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Tricarbonylchromium; Mandelic acid; Planar chiral
1. Introduction
compounds, which possess significant potential as chiral
building blocks in synthesis [22]. In continuation of our
studies of the stereoselective functionalisation of (h6-
(h6-Arene)tricarbonylchromium complexes of aro-
matic ligands which are substituted unsymmetrically at
either the ortho or meta positions are not superimpo-
sable on their mirror image. This stereochemical feature,
known as planar chirality [1], has been exploited in
recent years as a key element in enantioselective
arene)Cr(CO)3 complexes [23ꢀ26], we report here the
/
results of work aimed at utilising the readily available
enantiomers of mandelic acid (2-hydroxy-2-phenylacetic
acid) as an internal chiral auxiliary, potentially leading
to chiral 2-hydroxyarylacetaldehydes.
syntheses [2ꢀ8] of bioactive compounds. There are two
/
general approaches to the synthesis of planar chiral (h6-
arene)Cr(CO)3 complexes. In one approach a non-
racemic base is used as an external chiral reagent to
deprotonate selectively one of the enantiotopic ortho (or
meta) hydrogens of the prochiral complex; subsequent
addition of an electrophile can lead to significant
enantiomeric excess in the functionalised aromatic
2. Results and discussion
Most of the chiral auxiliaries reported to be effective
in promoting directed metallation contain oxygen and/
or nitrogen functionalities such as tertiary amines,
ethers, oxazolidines, aminals, or acetals (1,3-dioxo-
lanes). We decided to investigate the extension of this
set to 1,3-dioxolan-4-ones, since the carbonyl group in
this lactone-acetal could, after reduction and protection,
act as an additional locus to influence the diastereos-
electivity of the arene deprotonation step. The fact that
both enantiomers of mandelic acid are commercially
available made it an attractive precursor to the dioxo-
lanone, which was reduced to a lactol and the alcohol
protected as its TBDMS ether. The phenyl ring was then
converted into its Cr(CO)3 h6 complex, and the
complex [9ꢀ12]. An alternative method relies on the
/
attachment of a chiral auxiliary to the arene ring prior to
complexation. An additional stereochemical element,
planar chirality, is then created by intramolecular
chelation of an achiral base, which ideally leads to
abstraction of only one of the diastereotopic ortho (or
meta) hydrogens [13ꢀ21]. These studies commonly refer
/
to complexes of either benzaldehyde or acetophenone
derivatives. 2-Hydroxy aldehydes are a related class of
* Corresponding author. Fax: ꢁ
/
64-9-3737422.
E-mail address: p.woodgate@auckland.ac.nz (P.D. Woodgate).
lithiationꢀsilylation sequence was studied.
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 3 9 9 - 2

P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
141
Reaction of (R)-mandelic acid (1) with cyclohexanone
in 1,4-dioxane with a catalytic amount of concentrated
H2SO4 at room temperature for 30 min afforded (R)-3-
phenyl-1,4-dioxaspiro[4.5]decan-2-one (2) (Scheme 1).
The crude product was recrystallised from hexanes to
give white crystals of the 1,4-dioxolan-2-one 2 in 90%
o[4.5]decan-2-ol (6) (100%; contains 8% of the cis
isomer).
Prior to h6-Cr(CO)3 complexation of the phenyl ring
the alcohol group was protected as a TBDMS ether.
Triethylamine (4.4 M equivalents) and a catalytic
amount of DMAP were added to a solution of the
yield. The pseudomolecular ion at m/z 233 [Mꢁ
H]ꢁ in
/
(2S,3R)-lactol
5
in dichloromethane, and then
TBDMSCl (4.4 M equivalents) was added slowly at
0 8C. After 46 h at room temperature, workup and flash
chromatography followed by recrystallisation gave
(2R,3R)-2-t -butyl(dimethyl)[(3-phenyl-1,4-dioxaspiro-
the mass spectrum, together with carbonyl signals at
1808 cmꢂ1 in the IR spectrum and 171.5 ppm in the
13C-NMR spectrum, confirmed formation of the lac-
tone, [a]2D0
ꢂ86.48 (c 1.02, dichloromethane). Similarly,
/
[4.5]decan-2-yl)oxy]silane (7) (66%), [a]D20
dichloromethane). The presence of signals at 1089 and
839 cmꢂ1 due to Siꢀ
OꢀC and SiꢀC stretching vibra-
tions in the IR spectrum, and in the mass spectrum at m/
z 348, 291, and 188 corresponding to [Mꢁ+], [Mꢂ
tBu]ꢁ, and [MꢂHCO2SiMe2tBu]ꢁ, confirm protection
of the lactol. The trans ꢀcis mixture (24:1) of TBDMS
ꢁ
/
468 (c 1.02,
S-mandelic acid (3) gave the S-lactone 4 (88%), [a]D20
ꢁ
/
81.68 (c 1.01, dichloromethane).
/
/
/
The next step involved reduction of the lactone to a
lactol (formally equivalent to an a-hydroxy aldehyde). A
solution of (R)-3-phenyl-1,4-dioxaspiro[4.5]decan-2-one
/
/
(2) in toluene, was treated with Dibal-H ꢂ78 8C, and
/
/
after 30 min aqueous HCl was added slowly. Workup
and filtration of the crude material through a short pad
of silica gel gave (2S,3R)-3-phenyl-1,4-dioxaspir-
o[4.5]decan-2-ol (5) (81%). The presence of a broad
OH band at 3392 cmꢂ1 in the IR spectrum, together
with a signal for the molecular ion at m/z 234 in the
mass spectrum, confirmed that reduction had been
ethers recovered from chromatography was highly
soluble in both polar and non-polar solvents. Hexanes,
pentane, petroleum spirits or benzene were used for
recrystallisation, but in all cases the resulting crystals
were of only moderate quality for determination of the
structure by X-ray analysis (Fig. 1). Although the values
1
of the R indices for all data (R1ꢃ
/
0.1321, wR2ꢃ/0.1795)
achieved. In the H-NMR spectrum, the signals in the
and the final R indices (R1ꢃ0.0724, wR2ꢃ
/
/0.1593) were
region 4.97ꢀ5.52 ppm due to H2 and H3 were used to
/
relatively large, there is no doubt of the relative
stereochemistry (trans) and therefore of the absolute
stereochemistry of the major chiral non-racemic diaster-
eoisomer 7.
estimate the ratio of diastereoisomers as 84:16 in favour
of 2S,3R (trans). Similar reduction of the S-lactone 4
with Dibal-H gave (2R,3S)-3-phenyl-1,4-dioxaspir-
The enantiomer (2S,3S)-2-t-butyl(dimethyl)[(3-phen-
yl-1,4-dioxaspiro[4.5]decan-2-yl)oxy]silane (8) was pre-
pared similarly from lactols 6. Chromatography
afforded only the trans diastereoisomer 8 (65%), [a]D20
ꢂ
/
46.18 (c 1.02, dichloromethane).
Preparation of {[(2R,3R)-(1,2,3,4,5,6-h)-2-t-butyl(di-
methyl)-(3-phenyl-1,4-dioxaspiro[4.5]decan-2-yl)oxy]si-
lane}tricarbonylchromium (9) was achieved by
thermolysis of (2R,3R)-2-t-butyl(dimethyl)[(3-phenyl-
1,4-dioxaspiro[4.5]decan-2-yl)oxy]silane
(7)
with
Scheme 1.
Fig. 1. The atomic arrangement in (2R,3R)-7.

142
P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ149
/
Cr(CO)6 in 1,4-dioxane for 48 h. Flash chromatography
gave the h6 complex 9 as a single isomer (trans; 58%),
signals at m/z 556, 472, 73, and 52 corresponding to
[Mꢁ+] (C26H4052CrO6Si2), [Mꢂ3CO]ꢁ, (Si?Me3)ꢁ, and
Crꢁ confirmed that lithiationꢀ
silylation of the chiral
/
[a]2D0
ꢁ
/
39.88 (c 1.06, dichloromethane). Attempted
/
recrystallisation of the yellow viscous oil using a range
of non-polar solvents and applying different methods
was not successful. The presence of absorptions due to
carbonyl ligands in the IR spectrum at 1971 and 1893
cmꢂ1 and in the 13C-NMR spectrum at 232.35 ppm,
and of peaks in the mass spectrum at m/z 484, 428, 400,
non-racemic complex 9 had taken place. The structures
of the trimethylsilylarene regioisomers were established
by NMR experiments (COSY, long range COSY,
HSQC, and HSQC-TOCSY) to be one meta diastereoi-
somer (39%), the other meta diastereoisomer (42%), and
the para diastereoisomer (19%). That is, the meta ꢀpara
/
and 52 corresponding to [Mꢁ+], [Mꢂ
/
2CO]ꢁ, [Mꢂ
/
ratio is ca. 4:1; there was no evidence for either ortho-
silylated isomer.
3CO]ꢁ and Crꢁ, confirmed that h6 complexation had
1
occurred. Furthermore, in both the H- and 13C-NMR
Decomplexation of the mixture of three silylated
products by exposure of a solution in CDCl3 to oxygen
and daylight gave [(2R,3R)-(1,2,3,4,5,6-h)-2-t-butyl(di-
methyl)-(3-(3z-(trimethylsilyl)phenyl)-1,4-dioxaspiro-
[4.5]decan-2-yl)oxy]silane (13) as a mixture of two
spectra the signals (Table 1) due to the arene ring in
complex 9 were shifted upfield relative to those of the
free ligand (trans 7). Moreover, the NMR spectra both
indicated that only one isomer was present.
Thermolysis of (2S,3S)-2-t-butyl(dimethyl)[(3-phen-
yl-1,4-dioxaspiro[4.5]decan-2-yl)-oxy]silane (8) with
Cr(CO)6 followed by purification using flash chromato-
graphy also afforded a single (trans) isomer (69%). The
1H-, 13C-NMR, mass, and IR spectra of {[(2S,3S)-
(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-phenyl-1,4-dioxa-
spiro[4.5]decan-2-yl)oxy]silane}tricarbonylchromium
(10) were identical with those of enantiomer 9. As
regioisomers. The absence of both Cꢁ
/
O absorptions
due to carbonyl ligands in the IR spectrum, the presence
of signals in the mass spectrum at m/z 420 [Mꢁ
,
+
C23H40O3Si2] and 73 (Si?Me3)ꢁ, and the loss of the
yellow colour all indicated detachment of the h6-
Cr(CO)3 moiety. This decomplexation was carried out
to allow better resolution of the 1H- and 13C-NMR data
to enable definitive assignment of structure to the
regioisomers. A series of COSY, long-range COSY,
HSQC, and HSQC-TOCSY NMR experiments were
carried out in CDCl3, and then in C6D6, and the data
were interpreted in detail for the hydrogen and carbon
atoms of 13. The signals due to the arene ring hydrogen
and carbon atoms of the meta and para trimethylsily-
lated isomers are included in Table 2. As expected,
decomplexation produced only one meta-SiMe3 com-
pound [as opposed to two meta diastereoisomers in the
h6-(arene)Cr(CO)3 complex], as well as the para-SiMe3
expected, the value of the optical rotation of 10 {/
[a]2D0
ꢂ
/
37.78 (c 1.04, dichloromethane)} was comparable with
that of 9 but of opposite sign. Again, however,
recrystallisation of complex 10 could not be achieved
from a range of non-polar solvents.
With each pure enantiomeric h6-Cr(CO)3 complex 9
and 10 available, the influence of the mandelic acid-
derived auxiliary in potentially promoting distinction
chemically between the diastereotopic ortho and/or
meta arene hydrogens was investigated. Thus,
{[(2R,3R)-(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-phenyl-
1,4-dioxaspiro[4.5]decan-2-yl)oxy]silane}tricarbonyl-
isomer. The meta ꢀpara ratio was 84:16.
/
Deprotonation-electrophile/quenching of (2S,3S)-2-
t-butyl(dimethyl)[(3-phenyl-1,4-dioxaspiro[4.5]decan-2-
yl)oxy]silane (10) was carried out in THF under the
same experimental conditions as for the (2R,3R)
enantiomer 9. Flash chromatography gave the silylated
product 12 (78%) as a mixture of diastereoisomers.
Again, the structures of these isomers were assigned by
detailed interpretation of COSY, long range HSQC and
HSQC-TOCSY NMR experiments. They were one meta
diastereoisomer (42%), the other meta diastereoisomer
(40%) and the para diastereoisomer (18%). Table 3
chromium (9) was stirred in THF and cooled to ꢂ
78 8C. BuLi (2.3 M equivalents in hexanes) was injected
and the solution was stirred at ꢂ78 8C for 2.5 h.
/
/
Chlorotrimethylsilane (2.3 M equivalents) was added,
the mixture was stirred for 2.5 h, and then allowed to
warm to room temperature overnight. Workup and
flash chromatography gave a mixture of three regioi-
somers of {[(2R,3R)-(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-
(3-(3z-trimethylsilyl)phenyl)-1,4-dioxaspiro[4.5]decan-2-
yl)oxy]silane}tricarbonylchromium (11) in 50% yield as
a yellow oil. The presence in the mass spectrum of
1
includes H- and 13C-NMR data for the arene ring of
Table 1
1H- and 13C-NMR data for trans ligand 7 and trans complex 9
Arene H
dH Ligand 7 (ppm)
7.27ꢀ7.37 (m)
dH Complex 9 (ppm)
5.30ꢀ5.44 (m)
Arene C
dC Ligand 7 (ppm)
dC Complex 9 (ppm)
H12, H16
H13, H15 and H14
/
/
C12, C16
C14, C15
C13
125.95
127.83
128.46
139.18
90.31, 90.63
91.63
92.10
C11
108.92

P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
143
Table 2
Selected 1H- and 13C-NMR data (C6D6) for decomplexed ArSiMe3 regioisomers 13
Hydrogen dH meta (84%) (ppm) (J, Hz)
dH para (16%) (ppm) (J, Hz)
Carbons dC meta (84%) (ppm)
dC para (16%) (ppm)
Si?Me3
Hm
0.231 (s)
7.26 (t, 7.4)
Absent
0.189 (s)
Si?Me3
C16
C15
C12
C14
C11
C13
ꢂ
/
1.12
Weak
125.73
133.89
7.48 (d, 7.6)
7.48 (d, 7.6)
7.55 (d, 7.6)
Absent
126.53
128.22
131.15
133.21
139.09
140.63
/
Hm?
/
/
Ho?/
7.40 (d, 7.3)
7.59 (d, 7.6)
7.76 (s)
125.73
141.41
Hp
Ho
7.55 (d)
Not detected
133.89
each meta isomer (the para isomer was identified by the
singlet due to Si?Me3 at 0.294 ppm).
Decomplexation of the silylated product 12 gave
[(2S,3S)-(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-(3z-tri-
methylsilyl)phenyl)-1,4-dioxaspiro[4.5]decan-2-yl)oxy]si-
lane (14) as a mixture of a single meta isomer (86%) and
the para isomer (14%). The structures of the silylated
free ligands were again confirmed by COSY, long range
HSQC and HSQC-TOCSY NMR experiments, and also
by mass and IR spectroscopy. The results were similar
to those from decomplexation of the mixture 13.
The preparation of racemic trans 2-t-butyl(di-
methyl)[(3-phenyl-1,4-dioxaspiro[4.5]decan-2-yl)oxy]si-
lane was carried out in parallel during the present work.
The derived racemic complex 9/10 was able to be
crystallised, and single crystal X-ray analysis showed
the conformation of its h6-Cr(CO)3 tripod to be nearly
syn-eclipsed (Fig. 2). Although the h6-Cr(CO)3 com-
plexes of the analogous chiral non-racemic ligands 7 and
8 could not be crystallised, and therefore X-ray analyses
of either stereoisomer 9 or 10 could not be carried out, it
is assumed that for both enantiomers the syn-eclipsed
conformer is also preferred in the solid state.
Fig. 2. The atomic arrangement in rac-trans-{[(1,2,3,4,5,6-h)-2-t-
butyl(dimethyl)-(3-phenyl-1,4-dioxaspiro[4.5]decan-2-yl)oxy]silane}tri-
carbonylchromium (9/10).
a different conformation in the tricarbonylchromium
complex of the parent lactone, (R)-3-phenyl-1,4-dioxa-
spiro[4.5]decane-2-one (2) was converted into its h6-
(arene) complex 15. Indeed, X-ray analysis of a single
In the above work the lactone carbonyl group had
been reduced and then the lactol protected as the
TBDMS ether deliberately, in order to avoid competing
deprotonation of the benzylic proton H5 during reaction
of the h6-(arene)Cr(CO)3 complexes with BuLi. As
expected, lithiation of the complexed arene ring in the
lactol derivatives 9 and 10 occurred in good overall
yield. Unfortunately, however, quenching of the result-
ing carbanions did not lead to any discrimination
between the diastereotopic meta arene hydrogen atoms.
Since it was likely that the Cr(CO)3 tripod would prefer
crystal of (R)-15 (Fig. 3) indicated a preferred near-anti
staggered conformation for the h6-(arene)Cr(CO)3 moi-
Table 3
Selected 1H- and 13C-NMR data for h6-Cr(CO)3 meta-Si?Me3 regioisomers 12
Hydrogen dH meta (42%) (ppm) (J, Hz)
dH meta (40%) (ppm) (J, Hz)
Carbons dC meta (42%) (ppm)
dC meta (40%) (ppm)
Si?Me3
Hm
Ho
0.256 (s)
5.13 (t, 6.4)
5.50 (s)
0.297 (s)
Si?Me3
C16
C15
ꢂ
/
1.21
Weak
89.63
93.95
98.10
99.29
5.17 (t, 6.4)
Not detected
5.39 (d, 6.3)
5.63 (d, 7.6)
89.12
92.67
96.94
98.67
Hp
5.43 (d, 6.4)
5.65 (bd, 6.8)
C12
C14
/
Ho?/

144
P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ149
/
2.2. X-ray crystal structures of (2R,3R)-7, rac-trans-
(9/10) and (R)-15
Data were collected on a Siemens SMART area
detector diffractometer using 0.38 frames and profile
fitting. Lorentz, polarisation and absorption corrections
[28] were applied and equivalent reflections averaged.
Unit cell parameters were obtained by least-squares fit
to all data with I ꢀ10s(I). The structures were solved
/
by direct methods [29] and refined by full matrix least-
squares on F2 [30]. Hydrogen atoms were placed
geometrically and refined with a riding model, including
free rotation for methyl groups, with thermal parameter
20% (50% for methyl groups) greater than Uiso of the
carrier atom. All non-hydrogen atoms were refined with
anisotropic thermal parameters. The t-butyldimethylsi-
lyl group for 7 has large thermal vibration elipsoids.
This is presumably indicative of some disorder in these
atoms. The anisotropic thermal parameters have been
allowed to take up this disorder. Crystal data and
refinement parameters are given in Table 4 and the
Fig. 3. The atomic arrangement in (R)-15.
ety. In this structure one of the carbon monoxide ligands
points towards O4, indicating the possibility of an
electrostatic interaction between these two units.
Furthermore, the X-ray analysis confirmed that the
absolute configuration at C3 had not been changed via
enolisation during exposure to the acid necessary for
formation of the 1,4-dioxolan-2-one. Complex 15 was
not investigated further, however, since treatment with
BuLi would result in loss of the stereogenic centre
incorporated from the enantiopure mandelic acids.
structures are shown in Figs. 1ꢀ3.
/
3. Experimental
Structures were assigned using HRMS (D5
/
5 ppm)
for the molecular formula, in combination with com-
1
2.1. Summary
plete assignment of the H- and 13C-NMR spectra and
selected infrared data.
The regioselectivity of deprotonation of a complexed
arene ring can often be related to the orientation of the
tricarbonylchromium tripod [27]. An anti eclipsed con-
formation (as for electron withdrawing or bulky sub-
stituents) commonly directs attack of the base to the
ortho (and para) position(s) while a syn eclipsed
conformation, like that shown in Fig. 2, directs depro-
tonation to the meta position(s). This regioselection
reflects a further decrease in the electron density around
3.1. (R)-3-Phenyl-1,4-dioxaspiro[4.5]decan-2-one (2)
and (S)-3-phenyl-1,4-dioxaspiro[4.5]decan-2-one (4)
(R)-Mandelic acid (1) (5 g, 32.89 mmol) was stirred in
dry 1,4-dioxane (14.4 ml), cyclohexanone (6.9 ml, 66.67
mmol) was added, and the reaction mixture was stirred
for 10 min. Sulphuric acid (1.7 ml, 18 mol lꢂ1) was
added dropwise and the reaction mixture was left to stir
for 30 min. A solution of NaOH (90 ml, 0.6 mol lꢂ1) in
water was added. A white precipitate formed which was
the aromatic Cꢀ/H bond by the very electropositive
carbon of a CO ligand, which eclipses it. Bulky
substituents also prevent ortho deprotonation due to a
steric effect. Therefore, the experimental result that
meta-silylation of 9 and 10 dominated (to the exclusion
of ortho silylation) is in agreement with the regiochem-
ical outcome expected from both electronic and steric
considerations. Unfortunately, the fact that both meta-
silylated diastereoisomers were formed, and in equal
amounts, in THF means that the planar chirality present
in complexes 9 and 10 has not been translated into
chemical discrimination between the diastereotopic
meta hydrogens. Presumably, this is because the stereo-
genic centre C3 present in the chiral auxiliary is too
remote from the meta sites to exert any influence via
selective intramolecular chelation of the BuLi during
deprotonation.
extracted into CH2Cl2 (3ꢄ/40 ml). The extract was
washed with aq. NaHCO3 (3ꢄ
/
40 ml) and brine (3ꢄ40
/
ml), and dried (MgSO4). The solvents were removed in
vacuo and the crude product was recrystallised from
hexanes to afford (R)-3-phenyl-1,4-dioxaspiro[4.5]de-
can-2-one (2) (6.88 g, 90%) as white needles, m.p.
107ꢀ
[Mꢁ
ppm)). nmax (KBr) 3060 (Cꢀ
1808 (CꢂO), 1456 (CꢂC), 946 (Cꢀ
1.45ꢀ1.96 (m, 10H, C6H10), 5.38 (s, 1H, H3), 7.35ꢀ
/
109 8C. [a]2D0
H]ꢁ 233.1181. C14H17O3 requires 233.1178 (ꢂ
H, aromatic), 2941 (CꢀH),
Oꢀ
C) cmꢂ1. dH
7.49
ꢂ
/
86.48 (c 1.02, CH2Cl2). (Found:
/
/1.3
/
/
/
/
/
/
/
/
(m, 5H, H12, H16, H13, H15, H14) ppm. dC 22.99
(CH2, C8), 23.07 (CH2, C7), 24.46 (CH2, C9), 35.75
(CH2, C6), 36.74 (CH2, C10), 75.46 (CH, C3), 111.79 (C,
C5), 126.36 (CH, C12, C16), 128.68 (CH, C13, C15),

P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
145
Table 4
X-ray data collection and processing parameters
(2R,3R)-7
20H32O3Si
rac-trans-(9/10)
(R)-15
Formula
Molecular weight
Temperature (K)
C
C23H32O5Si
484.58
150
C17H16CrO6
368.30
150
348.55
150
˚
Wavelength (A)
0.71073
Tetragonal
P43
0.71073
Orthorhombic
Pbcn
0.71073
Orthorhombic
P212121
Crystal system
Space group
Unit cell dimensions
˚
a (A)
11.1754(4)
11.1754(4)
16.4808(8)
2058.28(14)
4
31.4744(11)
13.4151(5)
11.7832(4)
4975.2(3)
8
5.9191(1)
14.0193(2)
19.0677(1)
1582.27(4)
4
˚
b (A)
˚
c (A)
3
V (A )
˚
Z
Dcalc (g cmꢂ3
m (mmꢂ1
F(000)
)
1.125
0.13
760
1.294
0.54
2048
1.546
0.75
760
)
Crystal size (mm)
2u Range (8)
Reflections collected
Independent reflections
A (min/max)
0.48ꢄ
/
0.12ꢄ
/
0.08
0.42ꢄ
/
0.26ꢄ
/
0.15
0.55ꢄ
1.8ꢀ26.3
9619
3200 [Rint
0.682, 0.928
0.01989, wR2ꢃ
0.0213, wR2ꢃ0.0515
1.052
0.16, ꢂ
/
0.16ꢄ
/
0.10
1.8ꢀ25.0
/
1.6ꢀ26.7
/
/
10 920
3609 [Rint
0.941, 0.989
27 642
5276 [Rint
ꢃ/
0.0927]
ꢃ/0.0223]
ꢃ/0.0173]
0.804, 0.923
0.0317, wR2ꢃ
0.0402, wR2ꢃ
1.057
0.29, ꢂ
R1 (observed data)
R1 (all data)
Goodness-of-fit on F2
0.0724, wR2ꢃ
0.1321, wR2ꢃ
/
0.1593
0.1795
/
0.0826
0.0887
/
0.0507
/
/
/
0.730
ꢂ3
˚
Difference map (min/max) (e A
)
ꢁ
/
0.37, ꢂ
/
0.35
ꢁ/
/0.44
ꢁ/
/0.30
1=2
/
/
Rꢃa ½½Fo½ꢂ½Fc½½=a ½Fo½; wR2 ꢃfa [w(F 2o ꢂF c2)2]=a [w(F o2)2]g
:
128.86 (CH, C14), 134.73 (C, C11), 171.50 (Cꢂ
/
O, C2)
EtOAc (3ꢄ8 ml). The extract was passed through a
/
ppm.
Similarly, (S)-mandelic acid (3) gave (S)-3-phenyl-
1,4-dioxaspiro[4.5]decan-2-one (4) (88%) as white nee-
short pad of silica gel and the solvent was removed
under reduced pressure to provide (2S,3R)-3-phenyl-
1,4-dioxaspiro[4.5]decan-2-ol (5) (0.82 g, 81%) as col-
107 8C (hexanes). [a]D20
ꢁ
/
81.68 (c 1.01,
H]ꢁ 233.11769. C14H17O3 re-
H,
ourless crystals, m.p. 73ꢀ
234.1257. C14H18O3 requires 234.1256 (ꢂ
nmax (KBr) 3392 (OꢀH), 3064 (CꢀH, aromatic), 2935
(CꢀH), 1450 (CꢂC), 942 (CꢀOꢀ
C) cmꢂ1. dH for major
isomer (trans, 84% by H-NMR) 1.41ꢀ1.95 (m, 10H,
C6H10), 3.53 (d, b, Jꢃ4.0 Hz, 1H, OH), 4.97 (d, Jꢃ3.7
Hz, 1H, H3), 5.28 (t, Jꢃ3.8 Hz, 1H, H2), 7.15ꢀ7.39 (m,
/
76 8C. (Found: [Mꢁ
]
+
dles, m.p. 105ꢀ
CH2Cl2). (Found: [Mꢁ
quires 233.11777 (0.3 ppm)). nmax (KBr) 3054 (Cꢀ
aromatic), 2945 (CꢀH), 1785 (CꢂO), 1451 (CꢂC), 945
(CꢀOꢀ 1.96 (m, 10H, C6H10), 5.38 (s,
C) cmꢂ1. dH 1.45ꢀ
1H, H3), 7.35ꢀ7.49 (m, 5H, H12, H16, H13, H15, H14)
/
/
/0.6 ppm)).
/
/
/
/
/
/
/
/
/
/
1
/
/
/
/
/
/
/
ppm. dC 22.98 (CH2, C8), 23.08 (CH2, C7), 24.44 (CH2,
C9), 35.73 (CH2, C6), 36.73 (CH2, C10), 75.44 (CH, C3),
111.77 (C, C5), 126.34 (CH, C12, C16), 128.66 (CH,
C13, C15), 128.84 (CH, C14), 134.73 (C, C11), 171.48
/
/
5H, H12, H16, H13, H15, H14) ppm. dC for major trans
isomer 23.72 (CH2, C8), 23.82 (CH2, C7), 25.07 (CH2,
C9), 36.24 (CH2, C6), 37.08 (CH2, C10), 84.18 (CH, C3),
101.71 (CH, C2), 111.94 (C, C5), 126.13 (CH, C12,
C16), 128.08 (CH, C13, C15), 128.50 (CH, C14), 138.44
(Cꢂ/O, C2) ppm.
1
(C, C11) ppm. dH for minor isomer (cis, 16% by H-
3.2. (2S,3R)-3-Phenyl-1,4-dioxaspiro[4.5]decan-2-ol
(5) and (2R,3S)-3-phenyl-1,4-dioxaspiro[4.5]decan-2-
ol (6)
NMR) 5.16 (d, Jꢃ
/
3.7 Hz, 1H, H3), 5.52 (dd, Jꢃ
/3.8
Hz, J?ꢃ6.6 Hz, 1H, H2) ppm. dC for minor cis isomer
/
23.06 (CH2, C7), 24.44 (CH2, C9), 35.30 (CH2, C6),
38.46 (CH2, C10), 81.08 (CH, C3), 95.39 (CH, C2),
126.83 (CH, C12, C16), 128.19 (CH, C13, C15), 129.01
(CH, C14) ppm.
A solution of (R)-3-phenyl-1,4-dioxaspiro[4.5]decan-
2-one (2) (1 g, 4.31 mmol) in dry C6H5CH3 (10.8 ml) was
stirred and cooled in a dry-ice bath (ꢂ78 8C) under an
/
atmosphere of nitrogen. DIBAL-H (7.2 ml, 1 mol lꢂ1
solution in C6H5CH3, 7.2 mmol) was added. The
mixture was stirred at the same temperature for 30
min, and then HCl (7.2 ml, 1 mol lꢂ1) was added very
slowly. The solution was left to stir at room temperature
(r.t.) for another 30 min, and then was extracted into
Similarly,
(S)-3-phenyl-1,4-dioxaspiro[4.5]decan-2-
one (4) afforded (2R,3S)-3-phenyl-1,4-dioxaspir-
o[4.5]decan-2-ol (6) (100%) as colourless crystals, m.p.
78ꢀ
234.1256 (0.7 ppm)). nmax (KBr) 3364 (Oꢀ
H, aromatic), 2934 (CꢀH), 1450 (CꢂC), 947 (Cꢀ
/
80 8C. (Found: [Mꢁ+] 234.1254. C14H18O3 requires
/
H), 3067 (Cꢀ
/
/
/
/
OꢀC)
/

146
P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
1
cmꢂ1. dH for major isomer (trans, 92% by H-NMR)
1.40ꢀ1.95 (m, 10H, C6H10), 3.58 (d, b, Jꢃ4.0 Hz, 1H,
OH), 4.97 (d, Jꢃ3.8 Hz, 1H, H3), 5.29 (t, Jꢃ3.9 Hz,
1H, H2), 7.25ꢀ7.42 (m, 5H, H12, H16, H13, H15, H14)
Similarly, (2R,3S)-3-phenyl-1,4-dioxaspiro[4.5]decan-
2-ol (6) gave (2S,3S)-2-t-butyl(dimethyl)[(3-phenyl-1,4-
dioxaspiro[4.5]decan-2-yl)oxy]silane (8) (65%), as milky
/
/
/
/
/
crystals m.p. 64ꢀ
(Found: [Mꢁ+] 348.2122. C20H32O3Si requires 348.2121
(ꢂ0.4 ppm)). nmax (KBr) 3052 (CꢀH, aromatic), 2936
(CꢀH), 1450 (CꢂC), 1089 (SiꢀOꢀC), 942 (CꢀOꢀC), 840
(Siꢀ CH3), 0.097 (s, 3H,
C) cmꢂ1. dH 0.056 (s, 3H, Siꢀ
SiꢀCH3), 0.899 (s, 9H, SiꢀCꢀ(CH3)3), 1.40ꢀ1.94 (m,
10H, C6H10), 4.95 (d, Jꢃ3.3 Hz, 1H, H3), 5.20 (d, Jꢃ
3.3 Hz, 1H, H2), 7.27ꢀ7.37 (m, 5H, H12, H16, H13,
H15, H14) ppm. dC ꢂ5.17 (CH3, SiꢀCH3), ꢂ4.29 (CH3,
SiꢀCH3), 17.83 (C, SiꢀCꢀ(CH3)3), 23.80 (CH2, C8),
23.95 (CH2, C7), 25.27 (CH2, C9), 25.61 (CH3, SiꢀCꢀ
/
66 8C. [a]2D0
ꢂ
/
46.18 (c 1.02, CH2Cl2).
ppm. dC for major isomer 23.71 (CH2, C8), 23.81 (CH2,
C7), 25.06 (CH2, C9), 36.24 (CH2, C6), 37.08 (CH2,
C10), 84.17 (CH, C3), 101.70 (CH, C2), 111.94 (C, C5),
126.12 (CH, C12, C16), 128.08 (CH, C13, C15), 128.49
(CH, C14), 138.41 (C, C11) ppm. dH for minor isomer
/
/
/
/
/
/
/
/
/
/
/
/
/
/
(cis, 8% by 1H-NMR) 5.16 (d, Jꢃ
(dd, Jꢃ3.8 Hz, J?ꢃ6.6 Hz, 1H, H2) ppm. dC for minor
isomer 35.29 (CH2, C6), 38.45 (CH2, C10), 81.08 (CH,
/
3.8 Hz, 1H, H3), 5.51
/
/
/
/
/
/
/
/
C3), 95.38 (CH, C2), 126.83 (CH, C12, C16) ppm.
/
/
/
/
/
3.3. (2R,3R)-2-t-Butyl(dimethyl)[(3-phenyl-1,4-
dioxaspiro[4.5]decan-2-yl)oxy]silane (7) and (2S,3S)-
2-t-Butyl(dimethyl)[(3-phenyl-1,4-
(CH3)3), 36.20 (CH2, C6), 37.16 (CH2, C10), 85.83 (CH,
C3), 102.41 (CH, C2), 111.77 (C, C5), 125.95 (CH, C12,
C16), 127.83 (CH, C14), 128.45 (CH, C13, C15), 139.19
(C, C11) ppm.
dioxaspiro[4.5]decan-2-yl)oxy]silane (8)
To a stirred solution of (2S,3R)-3-phenyl-1,4-dioxas-
piro[4.5]decan-2-ol (5) (0.8 g, 3.42 mmol), Et3N (1 ml,
6.84 mmol) and DMAP (75.2 mg, 0.62 mmol) in dry
CH2Cl2 (30 ml) was added slowly a solution of t-
butylchlorodimethylsilane (2.27 g, 15 mmol) in dry
CH2Cl2 (7.5 ml) at 0 8C and under an atmosphere of
nitrogen. The mixture was stirred for 2 h at the same
temperature, and then stirred at r.t. for 48 h. A deep red
solution resulted. The solution was washed with HCl
3.4. {[(2R,3R)-(1,2,3,4,5,6-h)-2-t-Butyl(dimethyl)-(3-
phenyl-1,4-dioxaspiro[4.5]decan-2-
yl)oxy]silane}tricarbonylchromium (9)
Cr(CO)6 (0.19 g, 0.863 mmol) was added to a solution
of (2R,3R)-2-t-butyl(dimethyl)[(3-phenyl-1,4-dioxaspir-
o[4.5]decan-2-yl)oxy]silane (7) (0.244 g, 0.701 mmol) in
dry 1,4-dioxane (10 ml) and the mixture was degassed by
(18.8 ml, 1 mol lꢂ1), saturated aq. NaHCO3 (3ꢄ
and brine (3ꢄ20 ml), and dried (MgSO4). It was then
filtered through a short pad of silica gel and concen-
trated to provide a yellow oil. HexanesꢀEtOAc (2 ml,
90:1) was added to dilute the syrupy residue and the
solution was then adsorbed onto silica gel (1 g). Flash
/20 ml)
freezeꢀ
/
pumpꢀ
/
thaw cycling (three times). It was then
140 8C) with
/
heated under reflux (sand bath, 130ꢀ
/
stirring for 48 h, during which time nitrogen was bled
slowly through a bubbler. The crude product was passed
through a Celite pad and the solvent was removed from
the filtrate in vacuo. Flash chromatography using
/
chromatography on silica gel with hexanesꢀ
(99:1, 95:1, 90:1) gave (2R,3R)-2-t-butyl(dimethyl)[(3-
phenyl-1,4-dioxaspiro[4.5]decan-2-yl)oxy]silane (7)
(0.783 g, 66%) as milky crystals, m.p. 63ꢀ
65 8C. [a]2D0
468 (c 1.02, CH2Cl2). (Found: [Mꢁ+] 348.2120.
C20H32O3Si requires 348.2121 (0.2 ppm)). nmax (KBr)
3065 (CꢀH, aromatic), 2934 (CꢀH), 1449 (CꢂC), 1089
(SiꢀOꢀC), 943 (CꢀOꢀC), 839 (Siꢀ
C) cmꢂ1. dH for
major isomer (trans, 96% by H-NMR) 0.057 (s, 3H,
SiꢀCH3), 0.098 (s, 3H, SiꢀCH3), 0.899 (s, 9H, SiꢀCꢀ
(CH3)3), 1.40ꢀ1.94 (m, 10H, C6H10), 4.95 (d, Jꢃ3.2 Hz,
1H, H3), 5.20 (d, Jꢃ3.2 Hz, 1H, H2), 7.30ꢀ7.37 (m,
5H, H12, H16, H13, H15, H14) ppm. dC for major
isomer ꢂ5.19 (CH3, SiꢀCH3), ꢂ4.31 (CH3, SiꢀCH3),
17.81 (C, SiꢀCꢀ(CH3)3), 23.78 (CH2, C8), 23.93 (CH2,
C7), 25.25 (CH2, C9), 25.60 (CH3, SiꢀCꢀ(CH3)3), 36.18
/
EtOAc
hexanesꢀEtOAc (95:5, 90:10) gave {[(2R,3R)-
/
(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-phenyl-1,4-dioxas-
piro[4.5]decan-2-yl)oxy]silane}tricarbonylchromium (9)
/
(0.197 g, 58%), [a]D20
ꢁ
/
39.88 (c 1.06, CH2Cl2). (Found:
[Mꢁ+] 484.1372. C23H3252CrO6Si requires 484.1373 (0.2
ppm)). nmax 3053 (CꢀH, aromatic), 2936 (CꢀH), 1971
(CꢁO), 1893 (CꢁO), 1450 (CꢂC), 1089 (SiꢀOꢀC), 941
(CꢀOꢀC), 840 (Siꢀ CH3),
C) cmꢂ1. dH 0.121 (s, 3H, Siꢀ
0.135 (s, 3H, SiꢀCH3), 0.904 (s, 9H, SiꢀCꢀ(CH3)3),
1.42ꢀ1.85 (m, 10H, C6H10), 4.58 (d, Jꢃ3.0 Hz, 1H,
H3), 5.23 (d, Jꢃ3.0 Hz, 1H, H2), 5.30ꢀ5.44 (m, 5H,
H12, H16, H13, H15, H14) ppm. dC
5.21 (CH3, Siꢀ
CH3), ꢂ4.21 (CH3, SiꢀCH3), 17.78 (C, SiꢀCꢀ(CH3)3),
23.70 (CH2, C8), 23.82 (CH2, C7), 25.11 (CH2, C9),
25.59 (CH3, SiꢀCꢀ(CH3)3), 36.15 (CH2, C6), 37.02
ꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
1
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ꢂ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
(CH2, C10), 83.67 (CH, C3), 90.31 and 90.63 (CH,
C12, C16), 91.63 (CH, C14 and C13 or C15), 92.10 (CH,
C15 or C13), 102.05 (CH, C2), 108.92 (C, C11), 112.63
(CH2, C6), 37.14 (CH2, C10), 85.81 (CH, C3), 102.39
(CH, C2), 111.75 (C, C5), 125.93 (CH, C12, C16),
127.82 (CH, C14), 128.44 (CH, C13, C15), 139.17 (C,
(C, C5), 232.35 (C, Cꢁ
428 (5, [Mꢂ2CO]), 400 (72, [Mꢂ
C6H10O), 287 (50, (302ꢂCH3)), 245 (100, 302ꢂ
(30, Crꢁ).
/
O) ppm. m/z 484 (14, [Mꢁ+]),
3CO]), 302 (5, 400ꢂ
tBu), 52
1
C11) ppm. dH for minor isomer (cis, 4% by H-NMR)
/
/
/
5.03 (d, Jꢃ
/
3.4 Hz, 1H, H3), 5.41 (d, Jꢃ/3.7 Hz, 1H,
/
/
H2) ppm.

P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
147
3.5. {[(2S,3S)-(1,2,3,4,5,6-h)-2-t-Butyl(dimethyl)-(3-
phenyl-1,4-dioxaspiro[4.5]decan-2-
yl)oxy]silane}tricarbonylchromium (10)
dC for one major isomer 89.12 (CH, C16), 92.66 (CH,
C15), 96.94 (CH, C12), 98.67 (CH, C14) ppm. dH for
1
other major isomer (meta, 42% by H-NMR) 0.137 (s,
3H, Siꢀ
(CH3)3), 0.909 (s, 9H, Siꢀ
10H, C6H10), 4.58 (d, Jꢃ2.6 Hz, 1H, H3), 5.49 (s, 1H,
Ho), 5.65 (d, b, Jꢃ5.5 Hz, 2H, Ho?; Hp) ppm. dC for
other major isomer ꢂ5.21 (CH3, SiꢀCH3), ꢂ4.24 (CH3,
SiꢀCH3), ꢂ1.22 (CH3, Si?ꢀ(CH3)3), 17.74 (C, SiꢀCꢀ
(CH3)3), 23.81 (CH2, C8), 23.95 (CH2, C7), 25.12
(CH3)3), 36.06 (CH2,
/
CH3), 0.160 (s, 3H, Siꢀ
/
CH3), 0.287 (s, 9H, Si?ꢀ
/
Reaction of Cr(CO)6 (0.34 g, 1.55 mmol) with
(2S,3S) - 2 - t - butyl(dimethyl)[(3-phenyl-1,4-dioxaspiro-
[4.5]decan-2-yl)oxy]silane (8) (0.42 g, 1.21 mmol) in dry
1,4-dioxane (17 ml) as above gave {[(2S,3S)-(1,2,3,4,5,6-
h)-2-t-butyl(dimethyl)-(3-phenyl-1,4-dioxaspiro[4.5]de-
/
Cꢀ
/
(CH3)3), 1.42ꢀ1.87 (m,
/
/
/
/
/
/
/
/
/
/
/
can-2-yl)oxy]silane}tricarbonylchromium (10) (0.403 g,
69%), [a]2D0
ꢂ
/
37.78 (c 1.04, CH2Cl2). (Found: [Mꢁ
]
(CH2, C9), 25.60 (CH3, Siꢀ
/
Cꢀ
/
+
484.1371. C23H3252CrO6Si requires 484.1373 (0.5 ppm)).
nmax 3054 (CꢀH, aromatic), 2936 (CꢀH), 1971 (CꢁO),
1891 (CꢁO), 1450 (CꢂC), 1092 (SiꢀOꢀC), 942 (CꢀOꢀ
C), 840 (Siꢀ CH3), 0.132
C) cmꢂ1. dH 0.126 (s, 3H, Siꢀ
(s, 3H, SiꢀCH3), 0.905 (s, 9H, SiꢀCꢀ(CH3)3), 1.42ꢀ1.83
(m, 10H, C6H10), 4.58 (d, Jꢃ3.0 Hz, 1H, H3), 5.23 (d,
Jꢃ3.0 Hz, 1H, H2), 5.32ꢀ5.42 (m, 5H, H12, H16, H13,
H15, H14) ppm. dC ꢂ5.21 (CH3, SiꢀCH3), ꢂ4.21 (CH3,
SiꢀCH3), 17.77 (C, SiꢀCꢀ(CH3)3), 23.70 (CH2, C8),
23.82 (CH2, C7), 25.11 (CH2, C9), 25.59 (CH3, SiꢀCꢀ
C6), 37.02 (CH2, C10), 83.67 (CH, C3), 98.09 (CH,
C12), 99.29 (CH, C14), 102.38 (CH, C2), 112.41 (C, C5),
/
/
/
/
/
/
/
/
/
232.74 (C, Cꢁ
/
O) ppm. dH for minor isomer (para, 19%
by H-NMR) 0.094 (s, 3H, SiꢀCH3), 0.127 (s, 3H, Siꢀ
CH3), 0.362 (s, 9H, Si?ꢀ(CH3)3), 4.64 (d, Jꢃ3.1 Hz, 1H,
H3) ppm.
1
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
3.7. Deprotonationꢀsilylation of {[(2S,3S)-
/
/
/
/
(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-phenyl-1,4-
/
/
dioxaspiro[4.5]decan-2-
yl)oxy]silane}tricarbonylchromium (10)
(CH3)3), 36.15 (CH2, C6), 37.02 (CH2, C10), 83.67 (CH,
C3), 90.31 (CH, C12, C16), 91.62 (CH, C13, C15), 92.10
(CH, C14), 102.06 (CH, C2), 108.94 (C, C11), 112.62 (C,
Reaction of {[(2S,3S)-(1,2,3,4,5,6-h)-2-t-butyl(di-
methyl)-(3-phenyl-1,4-dioxaspiro-[4.5]decan-2-yl)-
oxy]silane}tricarbonylchromium (10) (0.1 g, 0.207
mmol) in dry THF with BuLi (0.21 ml, 2.2 mol lꢂ1 in
hexanes, 0.462 mmol) and then chlorotrimethylsilane
(0.06 ml, 0.469 mmol) gave {[(2S,3S)-(1,2,3,4,5,6-h)-2-
t-butyl(dimethyl)-(3-(3z-trimethyl-silyl)phenyl)-1,4-di-
C5), 232.36 (C, Cꢁ/O) ppm.
3.6. Deprotonationꢀ/silylation of {[(2R,3R)-
(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-phenyl-1,4-
dioxaspiro[4.5]decan-2-
yl)oxy]silane}tricarbonylchromium (9)
oxaspiro[4.5]-decan-2-yl)oxy]silane}tricarbonylchro-
+
{[(2R,3R)-(1,2,3,4,5,6-h)-2-t-Butyl(dimethyl)-(3-
phenyl-1,4-dioxaspiro[4.5]decan-2-yl)-oxy]silane}tricar-
bonylchromium (9) (0.15 g, 0.31 mmol) was stirred in
mium (12) as a yellow oil (90 mg, 78%). (Found: [Mꢁ
]
556.1771. C26H4052CrO6Si2 requires 556.1769 (ꢂ
ppm)). nmax 3054 (CꢀH, aromatic), 2936 (CꢀH), 1968
(CꢁO), 1893 (CꢁO), 1450 (CꢂC), 1090 (SiꢀOꢀC), 943
(CꢀOꢀC), 839 (Siꢀ
C) cmꢂ1. dH for one major isomer
(meta, 42% by H-NMR) 0.065 (s, 3H, SiꢀCH3), 0.104
(s, 3H, SiꢀCH3), 0.256 (s, 9H, Si?ꢀ(CH3)3), 0.903 (s, 9H,
SiꢀCꢀ(CH3)3), 1.42ꢀ1.91 (m, 10H, C6H10), 4.53 (d, Jꢃ
3.2 Hz, 1H, H3), 5.13 (t, Jꢃ6.4 Hz, 1H, Hm), 5.21 (d, b,
1H, H2), 5.43 (d, Jꢃ6.4 Hz, 1H, Hp), 5.50 (s, 1H, Ho),
5.65 (d, b, Jꢃ6.8 Hz, 1H, Ho?) ppm. dC for one major
isomer ꢂ5.21 (CH3, SiꢀCH3), ꢂ4.17 (CH3, SiꢀCH3),
1.21 (CH3, Si?ꢀ(CH3)3), 17.74 (C, SiꢀCꢀ(CH3)3),
23.83 (CH2, C8), 23.97 (CH2, C7), 25.12 (CH2, C9),
(CH3)3), 36.07 (CH2, C6), 37.02
/0.5
/
/
dry THF (10 ml) and cooled to ꢂ
/
78 8C under an
/
/
/
/
/
atmosphere of nitrogen for 30 min. Butyllithium (0.31
ml, 2.2 mol lꢂ1 in hexanes, 0.682 mmol) was injected
/
/
/
1
/
and the solution was stirred at ꢂ
/
78 8C for 2.5 h.
/
/
Chlorotrimethylsilane (0.09 ml, 0.704 mmol, freshly
distilled from CaH2) was injected into the mixture,
which was stirred at the same temperature for 2.5 h and
then allowed to warm to r.t. over 30 min. The solvent
was evaporated under reduced pressure and the residue
was taken up in EtOAc (20 ml) and filtered through
Celite. Evaporation of the solvent under vacuum gave
/
/
/
/
/
/
/
/
/
/
/
ꢂ
/
/
/
/
an orange syrup. Flash chromatography using hexanesꢀ
/
25.61 (CH3, Siꢀ
/
Cꢀ
/
EtOAc (20:1) gave {[(2R,3R)-(1,2,3,4,5,6-h)-2-t-bu-
(CH2, C10), 83.67 (CH, C3), 89.12 (CH, C16), 92.67
(CH, C15), 96.94 (CH, C12), 98.67 (CH, C14), 102.38
tyl(dimethyl)-(3-(3z-trimethylsilyl)phenyl)-1,4-dioxas-
piro[4.5]decan-2-yl)oxy]silane}tricarbonylchromium
(CH, C2), 112.41 (C, C5), 232.74 (C, Cꢁ
/
O) ppm. dH for
other major isomer (meta, 40% by H-NMR) 0.146 (s,
3H, SiꢀCH3), 0.169 (s, 3H, SiꢀCH3), 0.297 (s, 9H, Si?ꢀ
(CH3)3), 0.917 (s, 9H, SiꢀCꢀ(CH3)3), 4.59 (d, Jꢃ2.8
Hz, 1H, H3), 5.17 (t, Jꢃ6.4 Hz, 1H, Hm), 5.31 (d, b,
1H, H2), 5.39 (d, Jꢃ6.3 Hz, 1H, Hp), 5.63 (d, Jꢃ7.6
1
(11) as a yellow oil, (87 mg, 50%). (Found: [Mꢁ
]
+
556.1767. C26H4052CrO6Si2 requires 556.1769 (0.3
ppm)). nmax 3054 (CꢀH, aromatic), 2936 (CꢀH), 1968
(CꢁO), 1892 (CꢁO), 1450 (CꢂC), 1090 (SiꢀOꢀC), 943
(CꢀOꢀC), 840 (Siꢀ
C) cmꢂ1. dH for one major isomer
(meta, 39% by H-NMR) 0.055 (s, 3H, SiꢀCH3), 0.247
(s, 9H, Si?ꢀ(CH3)3), 4.53 (d, Jꢃ3.3 Hz, 1H, H3) ppm.
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
1
/
Hz, 1H, Ho) ppm. dC for other major isomer 89.63 (CH,
C16), 93.95 (CH, C15), 98.10 (CH, C12), 99.29 (CH,
/
/

148
P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ149
/
C14) ppm. dH for minor isomer (para, 18% by 1H-
NMR) 0.127 (s, 3H, SiꢀCH3), 0.136 (s, 3H, SiꢀCH3),
0.294 (s, 9H, Si?ꢀ(CH3)3), 0.925 (s, 9H, SiꢀCꢀ(CH3)3),
4.63 (d, Jꢃ2.4 Hz, 1H, H3), 5.25 (d, Jꢃ3.1 Hz, 1H,
H2) ppm.
for 48 h to give [(2S,3S)-(1,2,3,4,5,6-h)-2-t-butyl(di-
/
/
methyl)-(3-(3z-trimethylsilyl)phenyl)-1,4-dioxaspiro-
+
/
/
/
[4.5]decan-2-yl)oxy]silane
(14).
(Found:
[Mꢁ
]
/
/
420.2513. C23H40O3Si2 requires 420.2516 (0.7 ppm)).
nmax (CDCl3) 2929 (CꢀH), 1095 (SiꢀOꢀC), 839 (SiꢀC)
cmꢂ1. dH for major isomer (meta, 86% by H-NMR)
0.065 (s, 3H, SiꢀCH3), 0.105 (s, 3H, SiꢀCH3), 0.257 (s,
9H, Si?ꢀ(CH3)3), 0.904 (s, 9H, SiꢀCꢀ(CH3)3), 1.42ꢀ1.92
(m, 10H, C6H10), 4.97 (d, Jꢃ3.2 Hz, 1H, H3), 5.20 (d,
Jꢃ3.2 Hz, 1H, H2), 7.26ꢀ7.37 (m, 2H, Ho?; Hm), 7.44
(d, Jꢃ6.8 Hz, 1H, Hp), 7.49 (s, 1H, Ho) ppm. dC for
major isomer ꢂ5.16 (CH3, SiꢀCH3), ꢂ4.28 (CH3, Siꢀ
CH3), ꢂ1.17 (CH3, Si?ꢀ(CH3)3), 17.75 (C, SiꢀC ꢀ
(CH3)3), 23.80 (CH2, C8), 23.94 (CH2, C7), 25.27
(CH3)3), 36.22 (CH2,
/
/
/
/
1
3.8. Decomplexation of {[(2R,3R)-(1,2,3,4,5,6-h)-2-t-
butyl(dimethyl)-(3-(3z-(trimethyl silyl)phenyl)-1,4-
dioxaspiro[4.5]decan-2-yl)oxy]silane}-
/
/
/
/
/
/
/
tricarbonylchromium (11)
/
/
/
CDCl3 (2 ml) was added to {[(2R,3R)-(1,2,3,4,5,6-h)-
2-t-butyl(dimethyl)-(3-(3z-(trimethylsilyl)phenyl)-1,4-di-
oxaspiro[4.5]decan-2-yl)oxy]silane}tricarbonylchro-
mium (11) (87 mg, 0.156 mmol) and the solution was
exposed to air for 10 min. It was then capped and
exposed to laboratory light for 48 h. The solution turned
cloudy green and was filtered through cotton wool; a
colourless solution resulted. Removal of the solvent
/
/
/
/
/
/
/
/
(CH2, C9), 25.61 (CH3, Siꢀ
/
Cꢀ
/
C6), 37.16 (CH2, C10), 85.91 (CH, C3), 102.42 (CH,
C2), 112.25 (C, C5), 126.16 (CH, C16), 127.85 (CH,
C15), 130.87 (CH, C12), 132.80 (CH, C14) ppm. dH for
1
minor isomer (para, 14% by H-NMR) 4.95 (d, Jꢃ
/3.0
gave
[(2R,3R)-(1,2,3,4,5,6-h)-2-t-butyl(dimethyl)-(3-
Hz, 1H, H3), 5.23 (d, Jꢃ3.1 Hz, 1H, H2) ppm.
/
(3z-(trimethylsilyl)phenyl)-1,4-dioxaspiro[4.5]decan-2-
yl)oxy]silane (13). (Found: [Mꢁ+] 420.2513. C23H40-
O3Si2 requires 420.2516 (0.6 ppm)). nmax (CDCl3) 2934
3.10. Tricarbonyl{(R)-[(1,2,3,4,5,6-h)-3-phenyl-1,4-
dioxaspiro-[4.5]-decan-2-one]}chromium (15)
(Cꢀ
for major isomer (meta, 84% by 1H-NMR) 0.029 (s, 3H,
SiꢀCH3), 0.122 (s, 3H, SiꢀCH3), 0.231 (s, 9H, Si?ꢀ
(CH3)3), 0.960 (s, 9H, SiꢀCꢀ(CH3)3), 1.30ꢀ2.04 (m,
10H, C6H10), 5.20 (d, Jꢃ3.4 Hz, 1H, H3), 5.39 (d, Jꢃ
3.4 Hz, 1H, H2), 7.26 (t, Jꢃ7.4 Hz, 1H, Hm), 7.40 (d,
Jꢃ7.3 Hz, 1H, Ho?); 7.59 (d, Jꢃ7.6 Hz, 1H, Hp), 7.76
(s, 1H, Ho) ppm. dC (C6D6) for major isomer ꢂ5.09
(CH3, SiꢀCH3), ꢂ4.12 (CH3, SiꢀCH3), ꢂ1.12 (CH3,
Si?ꢀ(CH3)3), 18.09 (C, SiꢀC ꢀ(CH3)3), 24.25 (CH2, C8),
24.30 (CH2, C7), 25.61 (CH2, C9), 25.84 (CH3, SiꢀCꢀ
/
H), 1093 (Siꢀ
/
Oꢀ
/
C), 839 (Siꢀ
/
C) cmꢂ1. dH (C6D6)
A mixture of (R)-3-phenyl-1,4-dioxaspiro[4.5]decan-
2-one (2) (0.50 g, 2.16 mmol) and Cr(CO)6 (0.576 g, 2.62
mmol) in 1,4-dioxane (30 ml) was refluxed for 48 h.
/
/
/
/
/
/
/
/
Workup and flash column chromatography (C6H14ꢀ
/
/
EtOAc, 90:10) gave: (i) tricarbonyl{(R)-[(1,2,3,4,5,6-
h)-3-phenyl-1,4-dioxaspiro-[4.5]-decan-2-one]}chrom-
/
/
/
/
ium (15) as a yellow solid (0.556 g, 70%), m.p. 158ꢀ
160 8C. (Found: [Mꢁ
C17H1652CrO6, 368.0352 (1.0 ppm)). nmax (KBr); 3072
(CꢀH aromatic), 1977 (CꢁO), 1873 (CꢁO), 1782 (CꢂO),
1495 (CꢀC aromatic), 938 (CꢀOꢀ
C) cmꢂ1. dH (400
MHz) 1.457ꢀ1.532 (m, 2H, H8), 1.653ꢀ1.826 (m, 4H,
H7 and H9), 1.851ꢀ1.964 (m, 4H, H6 and H10), 5.036
(s, 1H, H3), 5.30ꢀ5.40 (m, 3H, 2ꢄ meta and 1 para H),
5.528 (d, Jꢃ6.4 Hz, 1H, ortho), 5.567 (d, Jꢃ6.4 Hz,
]
368.0348. Calc. for
+
/
/
/
/
/
/
/
/
/
/
/
/
/
(CH3)3), 36.67 (CH2, C6), 37.76 (CH2, C10), 86.26 (CH,
C3), 103.09 (CH, C2), 111.89 (C, C5), 126.53 (CH, C16),
128.22 (CH, C15), 131.15 (CH, C12), 133.21 (CH, C14),
139.09 (C, C11), 140.63 (C, C13) ppm. dH (C6D6) for
/
/
/
/
/
/
/
/
minor isomer (para, 16% by 1H-NMR) 0.009 (s, 3H, Siꢀ
CH3), 0.114 (s, 3H, SiꢀCH3), 0.189 (s, 9H, Si?ꢀ(CH3)3),
0.947 (s, 9H, SiꢀCꢀ(CH)3)3), 4.94 (d, Jꢃ3.2 Hz, 1H,
H3), 5.41 (d, Jꢃ3.4 Hz, 1H, H2), 7.48 (d, Jꢃ7.6 Hz,
1H, Ho), 7.55 (d, Jꢃ7.6 Hz, 1H, Hp) ppm. dC (C6D6)
/
/
/
/
/
1H, ortho) ppm. dC 22.9 (C7), 23.0 (C9), 24.3 (C8), 35.6
(C10), 36.4 (C6), 73.2 (C3), 88.8 (ortho), 90.7 (ortho),
91.3(meta), 91.6 (meta), 92.2 (para), 103.8 (ipso), 112.6
/
/
/
/
/
/
(C5), 169.5 (C2), 231.8 (Cꢁ
[Mꢁ+]), 340 (0.5, [Mꢂ
CO]), 312 (16, [Mꢂ
(80, [Mꢂ3CO]), 256 (5, [Mꢂ4CO]), 240 (12, 284ꢂ
C6H10O), 142 (46, PhCH52Crꢁ),
/
O) ppm. m/z 368 (11,
for minor isomer 125.73 (CH, C12, C16), 133.89 (CH,
C13, C15), 141.41 (C, C14) ppm.
/
/2CO]), 284
/
/
/
CO2), 186 (25, 284ꢂ
/
3.9. Decomplexation of {[(2S,3S)-(1,2,3,4,5,6-h)-2-t-
butyl(dimethyl)-(3-(3z-trimethyl silyl)phenyl)-1,4-
dioxaspiro[4.5]decan-2-
105 (2.0, PhCOꢁ), 91 (7, C7H7ꢁ); 77 (3, Phꢁ), 52 (100,
52Crꢁ); and (ii) the free ligand 2 (0.150 g, 30%).
yl)oxy]silane}tricarbonylchromium (12)
4. Supplementary material
CDCl3 (2 ml) was added to {[(2S,3S)-(1,2,3,4,5,6-h)-
2-t-butyl(dimethyl)-(3-(3z-(trimethylsilyl)phenyl)-1,4-di-
oxaspiro[4.5]decan-2-yl)oxy]silane}tricarbonylchro-
mium (12) (90 mg, 0.162 mmol). The solution was
exposed to air for 10 min and then to laboratory light
Crystallographic data for the structures reported in
this paper have been deposited with the Cambridge
Crystallographic Data Centre, CCDC nos. 177802ꢀ
/
177804 for compounds (2R,3R)-7, rac-trans-(9/10) and

P.D. Woodgate et al. / Journal of Organometallic Chemistry 654 (2002) 140ꢀ
/
149
149
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