The nucleophilic addition of alpha-metallated 1,3-dioxanes to planar chiral cationic eta3-allylmolybdenum complexes. Synthesis of (2E,5S,6R,7E)-6-methyl-8-phenylocta-2,7-dienoic acid methyl ester, a key component of the Cryptophycins.

Article abstract of DOI:10.1039/b400242c

Two adjacent stereogenic centres and a pendant alkene were constructed via nucleophilic addition of a 1,3-dioxan-4-ylcopper(I) reagent to a cationic eta3-allylmolybdenum complex as part of a synthesis of (2E,5S,6R,7E)-6-methyl-8-phenylocta-2,7-dienoic acid, a key component of the Cryptophycins. Oxidative addition of Mo(CO)(4)(THF)(2) to allyl benzoates provides an efficient synthesis of eta3-allylmolybdenum(dicarbonyl) complexes.

Full text of DOI:10.1039/b400242c

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The nucleophilic addition of ꢀ-metallated 1,3-dioxanes to planar
chiral cationic ꢁ3-allylmolybdenum complexes. Synthesis of
(2E,5S,6R,7E )-6-methyl-8-phenylocta-2,7-dienoic acid methyl
ester, a key component of the Cryptophycins
John Cooksey,a Andrew Gunn,a Philip J. Kocienski,*a Alexander Kuhl,b Sukhjinder Uppal,a
John A. Christopherb,c and Richard Bellc
a Department of Chemistry, Leeds University, Leeds, LS2 9JT, UK
b Department of Chemistry, Glasgow University, Glasgow, G12 8QQ, UK
c GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
Received 9th January 2004, Accepted 6th April 2004
First published as an Advance Article on the web 25th May 2004
Two adjacent stereogenic centres and a pendant alkene were constructed via nucleophilic addition of a 1,3-dioxan-
4-ylcopper() reagent to a cationic η3-allylmolybdenum complex as part of a synthesis of (2E,5S,6R,7E)-6-methyl-8-
phenylocta-2,7-dienoic acid, a key component of the Cryptophycins. Oxidative addition of Mo(CO)4(THF)2 to allyl
benzoates provides an efficient synthesis of η3-allylmolybdenum(dicarbonyl) complexes.
Introduction
We recently showed that the nucleophilic addition of tetra-
hydropyran-2-ylcopper() reagents to planar chiral η3-allyl-
molybdenum complexes offers a powerful method for the
stereoselective appendage of a chain to an oxacyclic ring.1 The
method, illustrated in Scheme 1 for the synthesis of C-glyco-
sides,2 entails the construction of two adjacent stereogenic
centres with a pendant alkene. The high level of stereocontrol
is a consequence of the reaction of the organocopper() nucleo-
phile with retention of configuration and preferential attack at
the allyl ligand anti to the molybdenum.3 The one burr under
the saddle is the issue of regioselectivity: a combination of
steric and electronic factors governs the site of attack. In the
case of complex 2, the steric effect predominates (≥15 : 1).4
Scheme 2
Results and discussion
Synthesis of the cationic ꢁ3-allylmolybdenum complex 7
The first practical and general synthesis of cationic η3-allyl-
Scheme 1
molybdenum complexes (Scheme 3) was reported in 1988 by
Faller and Linebarrier13,14 who showed that the scalemic allylic
We now show that 1,3-dioxan-4-ylcopper() reagents are
acetate 9 derived from Sharpless kinetic resolution of the corre-
effective nucleophilic partners in the reaction providing a
sponding allylic alcohol, underwent oxidative addition of the
method for the stereoselective appendage of 1,3-diol chains.5
15
complex Mo(CO)3(MeCN)3 with retention of configuration
The strategy is exemplified for the synthesis of the methyl ester
to give the neutral complex 10 after reaction with lithium
(5) of (2E,5S,6R,7E)-6-methyl-8-phenylocta-2,7-dienoic acid,
cyclopentadienide. Activation of the planar chiral neutral
a key component of the Cryptophycins (Scheme 2).6–10 The
Cryptophycins are cyclodepsipeptides with pronounced anti-
tumour activity owing to their inhibition of tubulin poly-
merisation.11,12 Our synthesis of 5 is a vehicle for exploring the
effect of a conjugating substituent on the regioselectivity of
nucleophilic addition to η3-allylmolybdenum complex 7 using
the α-metallated dioxane 8 as the nucleophile leading to the
dioxane derivative 6 which fixes the anti stereochemistry
between C5 and C6 in the target.
Scheme 3
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1719

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complex with nitrosonium tetrafluoroborate gave the cationic
complex 2 as a mixture of diastereoisomers owing to the
stereorandom nature of the ligand exchange.
of Mo species was observed in time dependent ratio which
included Mo(CO)5(THF) and cis-Mo(CO)4(THF)2. A clearer
picture emerged when Mo(CO)6 was heated in degassed THF
(0.08 M) for 22 h in the absence of pyridine and the reaction
was followed by 95Mo NMR and IR spectroscopy (Scheme 5). A
compound with a signal at Ϫ1291 ppm with infrared absorp-
tions at 2077, 1941 and 1893 cmϪ1 was rapidly formed which we
ascribed to Mo(CO)5(THF). This signal gradually disappeared
The Faller protocol was substantially modified for the
synthesis of the complex 7 (Scheme 4). Easy and efficient
kinetic resolution of the racemic allylic alcohol (RS)-11 was
accomplished using Novozyme 435, a recombinant immobil-
ised B-component lipase from Candida antarctica, and vinyl
acetate, to give (S)-11 and the acetate ester (R)-12 in 45% and
46% yield respectively.16,17 The enantiomeric ratio of the allylic
alcohol (S)-11 was assayed at 97 : 3 by NMR spectroscopic
analysis of the corresponding (R)-acetoxyphenylacetic ester 13.
Initial attempts to perform oxidative addition on the acetate
ester of (S)-11 using Mo(CO)3(MeCN)3 were disappointing.
The reaction was very slow in refluxing acetonitrile, requiring
five days to go to completion, and the isolated yield of the
neutral complex 15 was 35% at best after ligand exchange with
lithium cyclopentadienide. A parallel study established that the
rate of oxidative addition depended on the ester leaving group,
with benzoate giving the optimum yield and rate.18 When
benzoate (S)-14 was treated with Me(CO)3(MeCN)3 in reflux-
ing acetonitrile, the reaction was complete in just 28 h and
the yield of the isolated neutral complex 15 improved to 76%.
and was replaced by a major signal at Ϫ927 ppm with ∆ω1/2
=
120 Hz (in THF) due to cis-Mo(CO)4(THF)2 and a minor com-
ponent (ca. 4%) with a signal at Ϫ750 ppm, ∆ω1/2 = 65 Hz and
IR absorptions at 1919 and 1781 cmϪ1 which we ascribed to
fac-Mo(CO)3(THF)3.22 The stereochemistry of cis-Mo(CO)4-
(THF)2 was assigned from the infrared signals at 2021, 1939,
1893 and 1834 cmϪ1 and its rapid and quantitative transform-
ation to cis-Mo(CO)4(PPh3)2 on addition of two equivalents of
PPh3.23,24 cis-Mo(CO)4(THF)2 was stable in THF, in the absence
of light and oxygen, and could be precipitated from pentane at
Ϫ100 ЊC as a yellow solid but it was too labile to be isolated and
characterised by X-ray crystallography.
A further improvement attended the oxidative addition of
19,20
Mo(CO)4(Py)2
to the benzoate ester (S)-14 in refluxing
THF: the reaction was complete in 18 h and the yield of the
neutral complex 15 climbed to 88%. The neutral complex
15 was obtained as fine yellow needles (mp 85–88 ЊC) after
recrystallisation from ether–pentane but 95Mo NMR spectro-
scopic analysis revealed the presence of exo and endo isomers
(exo : endo = 13 : 1) that were easily distinguished by the large
difference in chemical shifts.21 Finally, ligand exchange with
nitrosonium tetrafluoroborate in acetonitrile at 0 ЊC gave
initially two isomeric cationic complexes 7 (ca. 1 : 1) owing
to the stereorandom introduction of central chirality at molyb-
denum. Although the cationic complex 7 could be isolated as
a solid by precipitation, it was usually generated and used in
solution without purification.
Scheme 5
A mixture of benzoate (S)-14 and Mo(CO)4(THF)2 was
refluxed in THF for 14 h whereupon TLC analysis indicated
complete consumption of the benzoate. On addition of LiCp,
the neutral complex 15 was obtained in 88% yield.25 Hence the
THF complex reacted slightly faster than its pyridine analogue
though the yield in this case was identical. In order to explore
the scope and synthetic advantages of the novel Mo(CO)4-
(THF)2 complex, we prepared a series of η3-allylmolybdenum
complexes 17a–h from allylic benzoates 16a–h using Mo(CO)4-
(Py)2 (Procedure A) and Mo(CO)4(THF)2 (Procedure B) under
identical conditions. The data presented in Table 1 shows that
the Mo(CO)4(THF)2 reagent gave faster reactions though the
yields were only marginally better (4–12%). TLC analysis of
the progress of the reaction also indicated that the Mo(CO)4-
(THF)2 reagent gave cleaner reactions, especially in the
synthesis of trisubstituted systems such as 17e and 17f.
Synthesis of the 1,3-dioxan-4-ylcopper(I) reagent 8
We planned to generate the key 1,3-dioxan-4-ylcopper()
reagent by transmetallation of the corresponding stannane to
its lithium derivative followed by a second transmetallation to
the copper reagent using a Cu() salt. The isopropylidene
protected 1,3-dioxan-4-ylstannane 25 (Scheme 6) was our initial
choice of stereodefined tin precursor because a six-step syn-
thesis from dimethyl (S)-malate had been reported.26 We were
unable to implement the published procedure or any of its
subsequent renditions27–29 but a reliable variation was eventu-
ally found and is summarised in Scheme 6. The sequence began
with the selective reduction of dimethyl (S)-malate with BH3ؒ
Scheme 4
The dramatic improvement in speed and yield observed with
Mo(CO)4(Py)2 and the allyl benzoate begged the question as to
whether further improvements could be wrested from ligand
substitutions on the molybdenum reagent. Mo(CO)4(Py)2 was
easily synthesised by refluxing Mo(CO)6 in THF for 12 h in the
presence of 2 equivalents of pyridine.19 When the reaction
was followed by 95Mo NMR spectroscopy, a complex mixture
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1720

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Table 1 The oxidative addition of Mo(CO)2(Py)2 and Mo(CO)4(THF)2 to allylic benzoates
Procedure A
Procedure B
16
R1
R2
R3
R4
Time
Yield 17
Time
Yield 17
a
b
c
d
e
f
H
H
H
Me
Me
Me
H
H
Me
H
H
Me
H
H
H
Me
CO2Et
Me
Me
iPr
CO2Et
H
H
Me
H
H
Me
H
Me
12 h
20 h
56 h
72 h
59 h
82 h
—
86%
82%
58%
70%
80%
50%
—
9 h
16 h
44 h
16 h
44 h
68 h
96 h
24 h
86%
85%
65%
82%
86%
58%
95%
88%
g
h
Me
H
Me
—
—
attempts to exploit precedent32 by using thiophenol and BF3ؒ
OEt2 in dichloromethane at a variety of temperatures and times
invariably returned the S,S-acetal 24 as the sole product. Use of
PhSSiMe3 in place of thiophenol gave trace amounts of 23a,b
at Ϫ78 ЊC using BF3ؒOEt2 as promoter but the combination of
PhSSiMe3 and ZnCl2 at Ϫ60 ЊC in dichloromethane gave the
desired O,S-acetals 23a,b (a : b = 1 : 3) in 81% yield after only
5 min. Finally, the best results were obtained by simply treating
22 with thiophenol in the presence of 4 mol% ZnCl2 at Ϫ30 ЊC
for 5 min whereupon 23a,b was obtained in 87% yield (a : b =
9 : 1) with only a trace of 24 being formed by TLC. The
diastereoisomeric acetals 23a,b were separable by column
chromatography and their relative stereochemistry was easily
determined by the characteristic signals for the acetal methyl
groups in the 13C NMR spectra. The syn-isomer 23a revealed
signals at 30.1 and 20.9 ppm in accord with the expected chair
conformation whereas the anti-diastereoisomer 23b gave
corresponding signals at 28.1 and 24.6 ppm indicative of the
expected twist-boat conformation.33
The reductive lithiation34 of the mixture of O,S-acetals 23a,b
using lithium di-tert-butylbiphenylide (LDBB)35,36 in THF at
Ϫ78 ЊC followed by quenching the reaction mixture with excess
chlorotributylstannane gave the known26 1,3-dioxan-4-yl-
stannane 26 as a single diastereoisomer. The stereoconvergent
formation of a single stannane from the mixture of O,S-acetals
is a consequence of the radical anomeric effect37–39 stabilising
the conformation of the SOMO in 25. Rapid donation of a
second electron from the LDBB gave the axial organolithium,
which is configurationally stable at low temperature,28,29 and
thence the axial stannane on transmetallation.
It was our original intention to use the 1,3-dioxan-4-yl-
copper() reagent 30 (Scheme 7) as the nucleophilic partner in
our synthesis of Cryptophycin 4. Rychnovsky had shown that
the lithium reagent 27, derived from transmetallation of the
stannane 26 with BuLi, reacted with the terminal oxirane 28
in the presence of BF3ؒOEt2 to give the alkylation product 29
as a single diastereoisomer (62%) with clean retention of
configuration.26 However, a model study of the key alkylation
reaction discovered an unexpected stereochemical problem.
When the lithium reagent 27 was converted to its copper()
derivative 30 at Ϫ78 ЊC and then added to a solution of the
simple cationic η3-allylmolybdenum complex 31 in acetonitrile
at Ϫ90 ЊC, the adducts 32a,b were obtained as a mixture of
separable diastereoisomers in 48% overall yield from 26.
Scheme 6
SMe2 as described by Moriwake30 to give the 1,2-diol 18 in 89%
yield. The terminal hydroxyl was selectively protected as the
triisopropylsilyl (TIPS) ether 19 and the methyl ester was
hydrolysed to give carboxylic acid 20. The hydroxyl and carb-
oxyl groups were protected as the 1,3-dioxan-4-one derivative
21 in 94% yield on treatment of 20 with 2-methoxypropene
in the presence of pyridinium p-toluenesulfonate (PPTS).
Reduction of the dioxanone to the lactol with DiBAL-H
at Ϫ78 ЊC followed immediately by in situ acetylation with
acetic anhydride in the presence of DMAP gave the (4S,6S)-
acetoxydioxane 22 in 84% yield as a single isomer. The high
stereoselectivity in the reduction-acetylation sequence was
precedented in similar transformations on dioxanones reported
by Rychnovsky.31,32
The formation of a significant proportion of the inversion
product 32a did not bode well for the Cryptophycin synthesis
and it was the first example in our programme in which
stereochemistry had been compromised in the addition of an
α-heteroalkylcopper() nucleophile to a cationic η3-allylmolyb-
The conversion of the acetoxydioxane 22 to the O,S-acetal
23a,b was the most vexatious step in the sequence. Initial
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1721

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Table 2 NOE data for dioxanes 33a,b and 34
δ (ppm)
Multiplicity, 3J (Hz)
NOE
H2
H4
H6
H2
H4
H6
H2
H4
H6
5.81
5.15
4.26
5.73
4.59
4.17–4.12
5.84
4.35
4.18
s
16%
—
H6
33a
33b
34
apparent d, 6.4
dddd, 10.7, 6.9, 5.2, 2.4
s
13.7, 2.3
m
s
10%
13%
14%
10%
16%
—
H2
H4
H2
H5
H6
apparent q, 6.9
dddd, 11.0, 2.5, 5.9, 5.9
10%
H2
Scheme 7
the temperature at ≤ Ϫ78 ЊC. A solution of the freshly
prepared cationic complex 7 in acetonitrile, generated by
adding nitrosonium tetrafluoroborate to the neutral complex
15 at 0 ЊC, was added in one portion to the copper reagent and
after 1 h, aqueous workup was followed by oxidative decom-
plexation (O2, CHCl3). Column chromatography returned
an inseparable mixture of regioisomeric olefins 6 and 35 in
71% yield whose relative proportion (1.2 : 1) was determined by
integration of the alkene signals at 6.51 (d) and 6.26 (dd) ppm
attributed to 6 and a multiplet at 5.64–5.50 attributed to
35 (Scheme 9). A further pair of inseparable regioisomeric
olefins (ca. 1 : 1) were also obtained in < 5% yield which were
tentatively assigned structures 36 and 37. Evidence for the
stereochemistry in 36 derived from the signal for C4H with a
denum complex. We surmised that the origin of the problem lay
in the repulsive 1,3-diaxial interaction between the Cu atom
and the axial isopropylidene methyl group in 30. To test
this hypothesis, the isopropylidene group was transacetalised
in 89% yield to the separable benzylidene acetals 33a,b (a : b =
7 : 1) by treatment of 26 with benzaldehyde dimethylacetal
in the presence of p-toluenesulfonic acid (Scheme 8). Equi-
libration of the minor diastereoisomer 33b under the same
reaction conditions returned a mixture of 33a : 33b in the ratio
11 : 1. The stereochemistry of the diastereoisomers was
deduced from 1H NMR spectroscopic data summarised in
Table 2. The major diastereoisomer 33a was identified by the
strong NOE interactions between C2H and C4H whilst the
minor diastereoisomer 33b displayed a strong NOE interaction
between C2H and C6H in accord with the twist-boat conform-
ation depicted.
3
large J coupling (11 Hz) with the axial proton at C5, and
strong NOE interactions between the protons at C2, C4 and C6
indicative of their axial relationship.
Scheme 8
Our suspicion that the configurational stability of the
copper() reagent 30 was a consequence of steric destabilisation
was lent some credence when the 1,3-dioxan-4-ylcopper()
reagent 8 prepared from 33a was treated with cationic complex
31 (Scheme 8). The adduct 34 was obtained as a single
diastereoisomer in 51% yield after oxidative decomplexation.
However, in the next section we will show that reagent 8 does
not preserve its stereochemical integrity in its reactions with
cationic complexes.
Scheme 9
Hydrolysis of the triisopropylsilyl and benzylidene acetal
protecting groups from the mixture of 6 and 35 gave triols 38
and 39 which could be separated, albeit with some difficulty,
by column chromatography (Scheme 10). Sodium periodate
oxidation of triol 38 revealed a β-hydroxy aldehyde which
Union of fragments 7 and 8 and completion of the synthesis
Stannane 33a was converted to the 1,3-dioxan-4-ylcopper()
reagent 8 on an 8.5 mmol scale whilst carefully maintaining
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1722

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underwent a Wadsworth–Horner–Emmons olefination using
trimethylphosphonoacetate and tetramethylguanidine in THF
at low temperature to give ester 5 in 83% overall yield from 38
as a single isomer.40 Comparison of spectroscopic data for 5
with those reported by Moore and Tius41 together with the
conversion of 5 to Cryptophycin 4 confirmed the structure and
stereochemistry of the target.5
dioxan-4-ylcopper() reagents are effective nucleophilic partners
that form adducts rapidly and stereoselectively with cationic
η3-allylmolybdenum complexes.43
Experimental
Organic extracts were dried using magnesium sulfate (MgSO4)
unless otherwise specified, and were concentrated using a rotary
evaporator. Diethyl ether and tetrahydrofuran were freshly
distilled from sodium benzophenone ketyl under nitrogen prior
to use. Eluants used in the purification of the Mo complexes
were degassed by sparging with dry nitrogen for 20–30 minutes
before use. CuBrؒSMe2 was prepared by the procedure of
Taylor44 and purified by recrystallisation before use. Commer-
cial n-butyllithium was titrated against 1,3-diphenylacetone-
p-tosylhydrazone prior to use.45
Specific optical rotations ([α]D) were measured at ambient
temperature (21 3 ЊC) on an Optical Activity polAAr 2000
polarimeter using a 5 mL cell with a 1 dm path length or a
0.5 mL cell with a 0.05 dm path length. Infra-red (IR) spectro-
scopic details are reported as vmax in cmϪ1, followed by an inten-
sity descriptor: s = strong, m = medium, br = broad; weak
1
absorptions are not recorded. H and 13C NMR spectra were
recorded in CDCl3, C6D6 or CD3CN solution in 5 mm diameter
tubes, and the chemical shift in ppm is quoted relative to the
residual signals of chloroform (δH 7.27, δC 77.2), benzene (δH
7.27, δC 128.4) or acetonitrile (δH 2.00, δC 117.7) unless specified
otherwise. Coupling constants (J) are reported in Hz. 1H NMR
signal assignments are based on COSY and HMQC corre-
lations. 13C NMR signal assignments are based on DEPT and
C–H correlation experiments. 95Mo NMR (13 MHz) spectra
were recorded on a Bruker WP200SY spectrometer and were
referenced externally to Na2[MoO4].46,47 Low and high reso-
lution mass spectra were run on a JEOL MStation JMS-700
spectrometer. Ion mass/charge (m/z) ratios are reported as
values in atomic mass units followed, in parenthesis, by the
peak intensity relative to the base peak (100%). GCMS was
performed on the above spectrometer, using a Chrompack
WCOT Fused Silica column (25 m × 0.25 mm, CP-SIL
8CB-MS stationary phase), initial temperature and heating
rates are specified for individual cases.
Scheme 10
The formation of the diastereoisomers 36 and 37 in the key
addition step was a minor vexation compared with the lack
of regioselectivity in the formation of 6 and 35. The contrast
with the good steric discrimination between the methyl and
isopropyl termini observed in complex 21,2 suggests that the
methyl and phenyl groups have similar steric requirements in
complex 7 thereby allowing the electronic directing effect of the
nitrosyl ligand to predominate.4,13 Tangential evidence for
this argument was gleaned by following the ligand exchange
1
reaction (15 to 7) by H NMR spectroscopy in CD3CN: two
major endo isomers (the kinetic products)21,42 were observed in
the ratio 1.2 : 1, paralleling the observed ratio of olefin products
following alkylation. Upon standing in CD3CN solution for
24 h, the two endo isomers isomerised to a mixture of four
compounds, presumably two pairs of exo and endo isomers, in
the ratio 2.3 : 2 : 1 : 1.2, as estimated from the intensities of
cyclopentadienyl singlets at 5.69, 6.11, 6.22, and 6.02 ppm
respectively.
(2S,3E )-4-Phenylbut-3-en-2-ol (11) and (1R,2E )-acetic acid
1-methyl-3-phenylallyl ester (12)
A suspension of Novozyme 435 (66 mg), crushed activated 4 Å
molecular sieves (330 mg), (RS)-11 (660 mg, 4.45 mmol) and
vinyl acetate (10.3 mL, 111 mmol) in pentane (20 mL) was
shaken gently at rt for 10 h. 1H NMR spectroscopy of the crude
reaction mixture indicated ≥ 50% conversion. After filtration
and concentration in vacuo, the residue was purified by column
Conclusions
chromatography (SiO2, ether : hexanes = 2 : 8
4 : 6) to give
The synthesis of (2E,5S,6R,7E)-6-methyl-8-phenylocta-
2,7-dienoic acid (5) with the correct relative and absolute
stereochemistry at C5 and C6 proved that (a) the key coupling
step had occurred anti to the molybdenum in 7; (b) the nucleo-
phile 8 added predominantly with retention of configuration;
and (c) the oxidative addition of Mo(CO)4(THF)2 to allylic
benzoates occurred with clean retention. The complete reten-
tion of stereochemistry in the addition of 1,3-dioxan-4-yl-
copper() reagent 8 to the simple cationic complex 31 and the
formation of epimeric adducts from the addition of 8 and 30 to
cationic complexes 7 and 31 respectively shows that erosion in
the stereochemical integrity of the nucleophile, though a rare
event, may be influenced by the structure of the cationic
complex, and by adverse steric interactions in the nucleophile.
Mo(CO)4(THF)2 has been developed as an easily prepared and
highly reactive reagent for the formation of η3-allylmolyb-
denum complexes from allylic benzoates, including trisub-
stituted systems which have hitherto been inaccessible by
conventional reagents. Finally, we have established that 1,3-
acetate (R)-12 (390 mg, 2.05 mmol, 46%) as a colourless oil, and
alcohol (S)-11 (300 mg, 2.02 mmol, 45%) as a colourless oil
which solidified upon standing. Alcohol (S)-11 gave mp
29–30 ЊC (hexanes–dichloromethane); lit.48 mp 31–33 ЊC; [α]D
=
Ϫ34.1 (c 2.34, CHCl3); lit.49 [α]D (enantiomer) = ϩ34.2 (c 1.77,
CHCl3). H and 13C NMR spectroscopic data were in accord-
1
ance with literature data.50,51 The enantiomeric ratio for alcohol
11 was estimated as 97 : 3 via formation of the corresponding
(R)-acetoxyphenylacetic ester 13 by an analogous procedure to
that detailed above.
Acetate (R)-12 gave [α]D = ϩ143.1 (c 3.38, CHCl3); lit.52 [α]D =
1
ϩ151.1 (c 5.27, CHCl3). H NMR and IR spectroscopic data
were in accordance with literature data.53 13C NMR (100 MHz,
CDCl3): δ = 170.5 (COMe), 136.5 (C, Ph), 131.7 (CH, Ph), 129.0
(CH, Ph), 128.7 (2CH, Ph), 128.0 (CH, Ph), 126.7 (2CH, Ph),
71.1 (C1H), 21.5 (COMe), 20.5 (C1-Me). The enantiomeric
ratio for acetate (R)-12 was estimated as 96 : 4 by cleavage of
the acetate (10 wt% K2CO3, MeOH, rt, 15 h) and formation
of the corresponding (R)-acetoxyphenylacetic ester.
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
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(R)-Acetoxyphenylacetic acid (1S )-1-methyl-3-phenylallyl ester
[(R,S )-13]
13C NMR (100 MHz, CDCl3): δ = 165.9 (COPh), 136.5 (C),
133.0 (CH), 131.8 (CH), 131.1 (CH), 129.7 (2CH), 129.0 (CH),
128.7 (2CH), 128.5 (2CH), 128.0 (CH), 126.7 (2CH), 71.7 (CH),
20.6 (CH3).
To a solution of alcohol (S)-11 (41 mg, 0.28 mmol), (R)-
acetoxyphenylacetic acid (59 mg, 0.30 mmol) and DMAP
(2 mg, 0.01 mmol) in CH2Cl2 (10 mL) at 0 ЊC under N2 was
added DCC (86 mg, 0.41 mmol). The mixture was stirred at
0 ЊC for 10 min and at rt for 50 min before filtering through
Celite and washing with Et2O. After drying, filtration and
concentration in vacuo, the residue was purified by column
chromatography (SiO2, ether : hexanes = 3 : 7) to give the title
compound (76 mg, 0.23 mmol, 84%) as a colourless oil. The
diastereoisomeric ratio at C1 was estimated as 97 : 3 via inte-
syn-syn-Dicarbonyl(ꢁ5-cyclopentadienyl)-[(1,2,3-ꢁ)-(1R,2S,3S )-
1-phenyl-2-but-2-en-1-yl]molybdenum (15)
Procedure A. To a solution of Mo(CO)6 (512 mg, 1.94 mmol)
in degassed THF (25 mL) under N2 was added pyridine (0.31
mL, 3.88 mmol) and the solution brought to reflux. After
refluxing for 12 h, a solution of benzoate (S)-14 (465 mg, 1.84
mmol) in degassed THF (1.5 mL) was added dropwise via
syringe to the red-orange solution, which was refluxed for a
further 18 h before cooling to rt over 1 h. Freshly prepared
LiCp (7.1 mL of a 0.29 M solution in THF was added and
the dark red-brown solution stirred at rt under N2 for 1 h. The
solution was transferred via syringe to a round-bottomed flask
and concentrated in vacuo to a volume of approximately 10 mL,
before purification by column chromatography (Al2O3, degassed
hexanes–Et2O, 2 : 1, under N2) and concentration in vacuo. The
title compound was obtained as a fine yellow crystalline solid
(597 mg, 1.71 mmol, 88%).
1
gration of the C3H signals in the H NMR spectrum: δ = 6.56
(d, J = 16.0, (1S)-diastereoisomer), δ = 6.26 (d, J = 16.0, (1R)-
diastereoisomer), with reference to a sample prepared from
(RS)-11.
[α]D = Ϫ107.7 (c 2.32, CHCl3).
IR (film): ν = 1755 s cmϪ1.
1H NMR (400 MHz, CDCl3 referenced to added TMS):
δ = 7.50–7.19 (10H, m, Ph), 6.58 (1H, d, J = 16.0 Hz, PhCH ),
6.16 (1H, dd, J = 16.0, 6.4 Hz, PhCH᎐CH ), 5.95 (1H, s,
᎐
CHOAc), 5.55 (1H, ddq, J = 6.4, 1.1, 6.5 Hz, CHCH3), 2.17
(3H, s, OAc), 1.27 (3H, d, J = 6.5 Hz, CHCH3).
13C NMR (100 MHz, CDCl ): δ = 170.3 (C᎐O), 168.2 (C᎐O),
Procedure B. A solution of Mo(CO)6 (0.804 g, 3.04 mol) in
degassed THF (25 mL) was heated to reflux under N2 where-
upon benzoate (S)-14 (0.732 g, 2.9 mmol) in degassed THF (2
mL) was added dropwise via syringe. After addition was com-
plete the mixture was refluxed for a further 12 h. The mixture
was allowed to cool to rt and a freshly prepared solution of
LiCp (0.3 M, 10 mL) was added. After stirring at rt for 1 h,
workup as described above gave the title complex (0.939 g,
2.9 mmol, 93%).
᎐
᎐
3
136.3 (C, Ph), 134.0 (C, Ph), 131.9 (CH), 129.2 (CH or Ph),
128.8 (2CH, Ph), 128.6 (2CH, Ph), 128.0 (2CH), 127.7 (2CH,
Ph), 126.7 (2CH, Ph), 74.8 (CHOAc), 72.6 (CH), 20.8
(CH3CO), 20.0 (CH3CH).
ϩ
ϩ
ؒ
LRMS (EI mode): m/z = 324.2 [M , 2%], 264.2 (7), 131.1
(100), 118.1 (40), 107.1 (32), 91.1 (20), 43.0 (17).
ϩ
ϩ
ؒ
HRMS (EI mode): found M , 324.1359. C20H20O4 requires
M, 324.1362.
Neutral complex 15 was generally used without further
purification, but for analytical purposes it could be purified by
recrystallisation from pentane to give fine yellow needles:
mp 85–88 ЊC; [α]D = ϩ8.0 (c 0.67, CHCl3).
(R)-Acetoxyphenylacetic acid (1R)-1-methyl-3-phenylallyl ester
[(R,R)-13]
IR (KBr): ν = 1917 s, 1839 s cmϪ1.
[α]D = Ϫ2.6 (c 1.40, CHCl3).
IR (film): ν = 1763 s, 1743 s cmϪ1.
1H NMR (400 MHz, CDCl3 referenced to added TMS):
δ = 7.30–7.19 (3H, m, Ph), 7.12–7.08 (2H, m, Ph), 5.10 (5H, s,
Cp), 4.88 (1H, t, J = 9.6 Hz, PhCH–CH–CH), 2.35 (1H, d, J =
10.0 Hz, PhCH–CH–CH), 1.86 (3H, d, J = 6.0 Hz, CHCH3),
1.78–1.73 (1H, m, PhCH–CH–CH ).
1H NMR (400 MHz, CDCl3 referenced to added TMS):
δ = 7.49–7.18 (10H, Ph), 6.26 (1H, d, J = 16.0 Hz, PhCH ), 5.98
(1H, dd, J = 16.0, 6.2 Hz, PhCH᎐CH ), 5.95 (1H, s, CHOAc),
᎐
5.55 (1H, ddq, J = 6.4, 1.2, 6.2 Hz, CHCH3), 2.19 (3H, s, OAc),
1.42 (3H, d, J = 6.4 Hz, CHCH3).
13C NMR (100 MHz, CDCl3): δ = 239.7 (CO), 239.6 (CO),
142.1 (C, Ph), 128.6 (2CH, Ph), 125.9 (CH, Ph), 125.1 (2CH,
Ph), 93.9 (5CH, Cp), 68.5 (PhCH–CH–CH), 58.8 (PhCH–CH–
CH), 58.4 (PhCH–CH–CH), 21.2 (CH3).
13C NMR (100 MHz, CDCl ): δ = 170.5 (C᎐O), 168.2 (C᎐O),
᎐
᎐
3
136.3 (C), 134.0 (C), 131.4 (CH), 129.4 (CH), 128.9 (2CH),
128.6 (3CH), 128.0 (3CH), 127.9 (CH), 126.6 (CH), 74.8
(CHOAc), 72.4 (CH–O), 20.9 (CH3CO), 20.4 (CH3CH).
LRMS (CIϩ mode, NH3): m/z = 342.1 [(M ϩ NH4)ϩ, 14%],
212.1 (14), 131.1 (100).
95Mo NMR (13 MHz, THF): δexo = Ϫ1617, δendo = Ϫ1412.
exo : endo = 13 : 1.
98
ϩ
ؒ
LRMS (EI mode): m/z = 350.2 [(M( Mo)) , 25%], 322.2
98
ϩ
ؒ
[(M( Mo)-CO) , 20], 292.2 (100).
Found: C, 58.60; H, 4.69. C17H16O2Mo requires C, 58.63; H,
4.63%.
(1S,2E )-Benzoic acid 1-methyl-3-phenylallyl ester [(S )-14]
To a solution of alcohol (S)-11 (3.82 g, 25.8 mmol) and 4-di-
methylaminopyridine (10 mg) in CH2Cl2 (30 mL) at rt under N2
was added benzoyl chloride (3.3 mL, 28.4 mmol) and triethyl-
amine (4.0 mL, 28.4 mmol). The solution was stirred at rt for 18
h before the addition of HCl (2 M, 30 mL). The phases were
separated and the aqueous phase extracted with CH2Cl2 (3 × 30
mL). The combined organic phases were washed with brine
(50 mL), dried, filtered and concentrated in vacuo. The pale
yellow solid residue was purified by recrystallisation from
hexanes to give the title compound (5.89 g, 23.3 mmol, 90%) as
a white solid: mp = 79–80 ЊC; [α]D = ϩ1.46 (c 7.56, CDCl3); lit.49
[α]D = ϩ0.42 (c 8.16 CHCl3).
syn-syn-Carbonyl-(nitrosyl)-(ꢁ5-cyclopentadienyl)-[(1,2,3-ꢁ)-
(1R,2S,3S )-1-phenyl-2-but-2-en-1-yl]molybdenum tetrafluoro-
borate (7)
Cationic complex 15 was routinely prepared in a minimum
volume (ca. 2–3 mL mmolϪ1) of freshly distilled MeCN at 0 ЊC
under N2 by the addition of NOBF4 (1.1 eq.) and transferred
directly via cannula to a solution of the nucleophile. However,
for characterisation purposes the title compound was prepared
on a 3.4 mmol scale and transferred to Et2O (200 mL) at 0 ЊC
under N2 to yield a light-brown solid after cooling to Ϫ60 ЊC
for 15 min. Cationic complex 7 (518 mg, 1.20 mmol, 36%) was
isolated by filtration under an atmosphere of N2: IR (solution
in CD3CN): ν = 2080 s, 1720 s cmϪ1. Complex 7 was initially
isolated as a mixture of two major isomers (presumably a pair
of endo isomers), in the approximate ratio 1.2 : 1. On standing
at rt for 24 h, a mixture of four isomers was obtained in a ratio
IR (KBr): ν = 1709 s cmϪ1.
1H NMR (400 MHz, CDCl3 referenced to added TMS):
δ = 8.10–8.06 (2H, m, Ph), 7.55–7.21 (8H, m, Ph), 6.69 (1H, d,
J = 16.0 Hz, PhCH ), 6.30 (1H, dd, J = 16.0, 6.6 Hz, PhCH᎐
᎐
CH ), 5.79 (1H, ddq, J = 6.5, 1.1, 6.5 Hz, CHCH3), 1.54 (3H, d,
J = 6.5 Hz, CHCH3).
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1724

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of approximately 2.3 : 2 : 1 : 1.2, as estimated by the
integrations of Cp singlets at 5.69, 6.11, 6.22 and 6.02 ppm
respectively.
5.82 (1H, dq, J = 8.2, 6.7 Hz, C4H), 4.14 (2H, q, J = 7.2 Hz,
OCH2CH3), 1.91 (3H, d, J = 1.1 Hz, C2CH3), 1.4 (3H, d, J = 6.4
Hz, C5H3), 1.23 (3H, t, J = 7.2 Hz, OCH2CH3).
13C NMR (75 MHz, CDCl3): δ = 168.1 (C), 166.2 (C), 139.9
(CH), 133.5 (CH), 130.6 (C), 130.1 (CH), 130.0 (2CH), 128.8
(2CH), 68.7 (CH), 61.3 (CH2), 20.2 (CH3), 14.6 (CH3), 13.3
(CH3).
1H NMR (360 MHz, CD3CN) data for the initial (endo)
isomers: δ = 7.54–7.35 (10H, m, Ph), 6.11 (5H, s, Cp), 5.69 (5H,
s, Cp), 6.23–5.93 (2H, m, PhCH–CH–CH), 5.28 (1H, d, J = 11.7
Hz, PhCH–CH–CH), 5.20 (1H, d, J = 13.4 Hz, PhCH–CH–
CH), 3.95 (1H, dq, J = 12.9, 6.2 Hz, PhCH–CH–CH ), 3.76 (1H,
dq, J = 12.3, 6.2 Hz, PhCH–CH–CH ), 2.47 (3H, d, J = 5.9 Hz,
CHCH3), 2.30 (3H, d, J = 6.3 Hz, CHCH3); partial data for the
exo-isomers: δ = 6.22 (5H, s, Cp), 6.02 (5H, s, Cp), 4.77 (1H, d,
J = 13.8 Hz, PhCH–CH–CH), 4.51–4.44 (2H, m, PhCH–CH–
CH ), 4.40 (1H, d, J = 13.0 Hz, PhCH–CH–CH), 2.42 (3H, d,
J = 6.4 Hz, CHCH3). Signals for C2H and the second C4H
doublet obscured by major isomer peaks at 6.23–5.93 ppm and
2.30 ppm respectively.
LRMS (FAB mode): m/z = 263 [(Mϩ ϩ H), 12%], 141 (100),
105 (51), 77 (7).
HRMS (ES mode): Found (Mϩ ϩ H), 263.1280. C15H18O4 ϩ
H) requires M, 263.1283.
Dicarbonyl(ꢁ5-cyclopentadienyl)-(ꢁ3-propenyl)-molybdenum
(17a)
Complex 17a, prepared from benzoate 16a56,57 in 86% yield by
procedure A (10.8 mmol scale) and 86% yield by procedure
B (5.5 mmol scale), was obtained as yellow needles: mp 136–
139 ЊC (Et2O–pentane); lit.58 mp 135–138 ЊC (Et2O–heptane).
1H NMR spectroscopy indicated that 17a was a mixture of
exo and endo isomers (3.3 : 1) in good agreement with literature
13C NMR (100 MHz, CD3CN, equilibrium mixture of four
isomers): δ = 214.9 (C), 213.9 (C), 211.0 (C), 209.5 (C), 136.8
(C), 135.8 (C), 135.4 (C), 134.0 (C), 131.4 (2CH), 130.7 (2CH),
130.0 (2CH), 129.8 (2CH), 129.7 (2CH), 129.5 (2CH), 129.4
(2CH), 128.0 (2CH), 127.7 (2CH), 127.6 (2CH), 106.7 (CH),
106.5 (CH), 104.2 (CH), 103.3 (5CH), 102.5 (5CH), 102.4
(5CH), 101.8 (5CH), 101.0 (CH), 94.6 (CH), 93.4 (CH), 92.3
(CH), 88.0 (CH), 83.3 (CH), 80.6 (CH), 76.8 (CH), 74.6 (CH),
21.1 (CH3), 19.6 (CH3), 18.9 (CH3), 18.2 (CH3).
data.21,58 95Mo NMR (13 MHz, THF): δexo = Ϫ1856, δendo
Ϫ1648.21
=
Dicarbonyl(ꢁ5-cyclopentadienyl)-(ꢁ3-2-methylallyl)-molybdenum
(17b)
95Mo NMR (13 MHz, MeCN): δ = Ϫ1293, Ϫ1339, Ϫ1383
ppm, in the approximate ratio 1 : 2.5 : 4, with approximate line
widths of 210 Hz, 206 Hz, 290 Hz respectively.
Complex 17b, prepared from benzoate 16b59 in 82% yield by
procedure A (3.3 mmol scale) and 85% yield by procedure B
(4.6 mmol scale), was obtained as a yellow solid: mp 76–78 ЊC
(Et2O–pentane); lit.60 mp 79–81 ЊC. The IR, 1H NMR and 95Mo
NMR spectroscopic data agreed with those reported by Faller
and co-workers.21,60
ϩ
ؒ
HRMS (FAB mode, nitrobenzyl alcohol matrix): found M ,
98
ϩ
ؒ
352.0235. C16H16O2N Mo requires M, 352.0238. Found M ,
350.0246. C16H16O2N96Mo requires M, 350.0235.
13C NMR (75 MHz, CDCl3): δ = 105.4 (C), 90.5 (5CH, Cp),
38.6 (2CH2), 23.6 (CH3).
Benzoic acid 1,2-dimethyl-2-butenyl ester (16e)
To a solution of 1,2-dimethyl-2-butenol (1.46 g, 14.6 mmol) in
CH2Cl2 (60 mL) at 0 ЊC was added DMAP (0.1 g, 0.73 mmol),
NEt3 (3.1 mL, 21.9 mmol) and benzoyl chloride (1.9 mL,
16 mmol). The cooling bath was removed and the reaction
mixture allowed to stir at ambient temperature for 12 h where-
upon the excess benzoyl chloride was destroyed by the addition
of 3-dimethylaminopropylamine (1 mL). The reaction mixture
was washed with HCl (1 M, 2 × 45 mL) and NaHCO3 (1 M,
2 × 45 mL). The organic layer was dried (MgSO4) and concen-
trated in vacuo. The residue was purified by column chromato-
graphy (SiO2, Et2O : hexanes = 1 : 4) to give the title compound
(1.82 g, 8.9 mmol, 61%) as a colourless oil.
Dicarbonyl-(ꢁ5-cyclopentadienyl)-(2,3,4-ꢁ-2-methyl-3-butenyl)-
molybdenum (17c)
Complex 17c, prepared from benzoate 16c61 in 58% yield by
procedure A (2.1 mmol scale) and 65% yield by procedure B
(3.2 mmol scale), was obtained as a yellow solid: mp 61–63 ЊC
1
(Et2O–pentane); lit.60 mp 65–69 ЊC (Et2O–hexane). The IR, H
NMR and 95Mo NMR spectroscopic data agreed with those
reported by Faller and co-workers.21,60
13C NMR (75 MHz, CDCl3): δ = 92.2 (5CH, Cp), 81.5 (C2),
68.6 (C3H), 31.1 (C4H2), 30.8 (CH3), 14.4 (CH3).
IR (film): ν = 1720 s cmϪ1.
syn,syn-Dicarbonyl-(ꢁ5-cyclopentadienyl)-[2,3,4-ꢁ-(2R,3S,4S )-
1-ethoxy-1-oxopent-2-enyl]molybdenum (17d)
1H NMR (300 MHz, CDCl3): δ = 8.04–8.08 (2H, m, o-ArH),
7.53–7.58 (1H, m, p-ArH), 7.41–7.47 (2H, m, m-ArH), 5.64
(1H, qq, J = 6.7, 0.3 Hz, C3H), 5.52 (1H, q, J = 6.5 Hz, C1H),
1.72 (3H, s, C2CH3), 1.63 (3H, d, J = 6.5 Hz, C4H3), 1.43 (3H,
d, J = 6.5 Hz, C1CH3).
Complex 17d, prepared from benzoate 16d in 70% yield by
procedure A (3.2 mmol scale) and 82% yield by procedure
B (0.3 mmol scale), was obtained as an air-sensitive viscous
13C NMR (75 MHz, CDCl3): δ = 166.2 (CO), 135.5 (C2),
133.1 (CH), 131.3 (C), 129.7 (2CH), 128.7 (2CH), 122.1 (C3H),
76.1 (C1H), 19.6 (C1CH3), 13.5 (C2CH3), 12.1 (C4H3).
Found: C, 76.41; H, 7.88. C13H16O2 requires C, 76.44; H,
7.90%.
1
yellow-orange oil. The H and 13C NMR spectroscopic data
agreed with those reported.62
Dicarbonyl-(ꢁ5-cyclopentadienyl)-(2,3,4-ꢁ-3-methyl-3-pentenyl)-
molybdenum (17e)
The title complex 17e, prepared from benzoate 16e in 80% yield
by procedure A (1.7 mmol scale) and 85% yield by procedure B
(3.7 mmol scale), was obtained as a yellow solid: mp 136–
137 ЊC (Et2O–pentane).
(4S,2E )-2-Methyl-4-(benzoyloxy)-pent-2-enoic acid ethyl ester
(16h)
Benzoate 16h, prepared from (4S,2E)-ethyl-4-hydroxy-2-meth-
ylpent-2-enoate54,55 (0.18 g, 1.2 mmol) in 84% yield by the
procedure described for 16e, was isolated as a colourless oil
after purification by column chromatography (SiO2, hexanes :
Et2O = 10 : 1).
IR (film): ν = 1930 s, 1850 s cmϪ1.
1H NMR (300 MHz, CDCl3): δ = 4.75 (5H, s, CpH), 2.21
(2H, q, J = 6.0 Hz, C2H and C4H), 2.02 (6H, d, J = 6.0 Hz,
C1H3 and C5H3), 1.82 (3H, s, C3H3).
[α]D = 74.9 (c 0.91, CHCl3).
13C NMR (75 MHz, CDCl3): δ = 105.7 (C3), 91.0 (5CH, Cp),
51.8 (C2H and C4H), 16.8 (2CH3), 13.3 (CH3).
IR (film): ν = 1717 s, 1659 m cmϪ1.
1H NMR (300 MHz, CDCl3): δ = 7.98 (2H, dd, J = 8.5, 1.3
Hz, o-ArH), 7.48 (1H, td, J = 7.2, 1.2 Hz, p-ArH), 7.35 (2H, t,
J = 7.2 Hz, m-ArH), 6.66 (1H, dd, J = 8.6 Hz, 1.4 Hz, C3H),
95Mo NMR (13 MHz, CDCl3): δ = Ϫ1487.
ϩ
HRMS (EIϩ mode): found M , 300.2010. C12H14O2Mo
ؒ
requires M, 300.2088.
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1725

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Dicarbonyl-(ꢁ5-cyclopentadienyl)-(2,3,4-ꢁ-2-methyl-3-pentenyl)-
molybdenum (17f)
was purified by column chromatography (SiO2, ethyl acetate :
hexanes = 1 : 9) to give the title compound (18.5 g, 63.6 mmol,
71%) as a colourless oil.
Complex 17f, prepared from benzoate 16f63 in 50% yield by
procedure A (1.4 mmol scale) and 58% yield by procedure B
(1.7 mmol scale), was obtained as a dark yellow oil.
IR (film): ν = 1931 s, 1848 s cmϪ1.
[α]D = Ϫ7.2 (c 1.06, CHCl3).
IR (film): ν = 3481 br m, 2944 s, 2867 s, 1736 s cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 4.11 (1H, ddq, J = 7.6, 5.8,
4.8 Hz, C3H), 3.72 (1H, dd, J = 9.8, 4.9 Hz, C4HAHB),
3.71 (3H, s, CO2Me), 2.91 (1H, d, J = 4.8 Hz, OH), 3.66 (1H,
dd, J = 9.8, 5.8 Hz, C4HAHB), 2.58 (1H, dd, J = 16.0, 4.8 Hz,
C2HAHB), 2.52 (1H, dd, J = 16.0, 7.6 Hz, C2HAHB), 1.06 (18H,
d, J = 5.6 Hz, SiCHMe2), 1.15–1.04 (3H, m, SiCHMe2.
13C NMR (100 MHz, CDCl3): δ = 172.7 (C1), 68.8
(C3H), 66.6 (C4H2), 51.9 (CO2Me), 38.0 (C2H2), 18.1 (6CH3,
SiCHMe2), 12.0 (3CH, SiCHMe2).
1H NMR (300 MHz, CDCl3): δ = 5.26 (5H, s, CpH), 4.05
(1H, d, J = 9.8 Hz, C3H), 1.93 (1H, m, C4H), 1.78 (3H, d,
J = 6.3 Hz, C5H3), 1.74 (3H, s, C1H3), 0.99 (3H, s, CH3).
13C NMR (75 MHz, CDCl3): δ = 93.4 (5CH, Cp), 72.5 (C3H),
72.3 (C2), 55.7 (C4H), 31.2 (C2-Me), 23.1 (C1H3), 21.6 (C5H3).
The sample deteriorated before the weak and broad carbonyl
signals could be recorded.
95Mo NMR (13 MHz, CDCl3): δ = Ϫ1654.
LRMS (CI mode, isobutane): m/z = 291.2 [(M ϩ H)ϩ, 100%],
247.1 (15).
Found: C, 57.81; H, 10.37. C14H30O4Si requires: C, 57.89; H,
10.41%.
ϩ
HRMS (EIϩ mode): found M , 300.2010. C12H14O2Mo
ؒ
requires M, 300.2088.
Dicarbonyl-(ꢁ5-(cyclopentadienyl)-(1,2,3-ꢁ-2,4-dimethyl-2-pent-
enyl)-molybdenum (17g)
(3S )-3-Hydroxy-4-(triisopropylsilyloxy)butyric acid (20)
Complex 17g, prepared from benzoate 16g64 in 95% yield
(2.15 mmol scale) by procedure B, was obtained as a yellow oil.
IR (film): ν = 1941 s, 1866 s cmϪ1.
To a solution of ester 19 (38.6 g, 133 mmol) in MeOH (600 mL)
was added 10% aqueous potassium carbonate solution (270
mL) and the mixture refluxed for 1.5 h. After cooling to rt, the
mixture was acidified to pH 2 with 2 M HCl. After extraction
with Et2O (2 × 250 mL) and washing with brine (200 mL), the
organic phase was dried, filtered, and concentrated in vacuo.
The residue was purified by column chromatography (SiO2,
1H NMR (300 MHz, C6D6): δ = 4.58 (5H, s, CpH), 2.55 (1H,
s, C1Htrans), 2.40–2.25 (1H, m, C4H), 2.11 (1H, d, J = 9.7 Hz,
C3H), 1.67 (3H, s, C2Me), 1.27 (1H, s, C1Hcis), 1.06–1.01 (6H,
m, C4Me2).
13C NMR (75 MHz, C6D6): δ = 242.8 (CO), 242.3 (CO), 103.2
(C2), 91.1 (5CH, Cp), 71.4 (C3H), 36.6 (C1H2), 30.2 (C4H),
25.9 (CH3), 25.2 (CH3), 19.3 (CH3).
Satisfactory HRMS (electrospray) or microanalytical data
could not be obtained for 17g.
ethyl acetate : hexanes = 2 : 8
1 : 1) to give the title compound
(27.1 g, 98 mmol, 74%) as a colourless oil.
[α]D = Ϫ7.2 (c 0.83, CHCl3).
IR (film): ν = 3460 br, 1713 s cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 6.50 (1H, br s, OH),
4.17–4.07 (1H, m, C3H), 3.73 (1H, dd, J = 9.8, 4.9 Hz,
C4HAHB), 3.68 (1H, dd, J = 9.8, 5.7 Hz, C4HAHB), 2.63 (1H,
dd, J = 16.2, 4.6 Hz, C2HAHB), 2.56 (1H, dd, J = 16.2, 7.9 Hz,
C2HAHB), 1.05 (18H, d, J = 5.7 Hz, SiCHMe2), 1.15–1.05 (3H,
m, SiCHMe2).
Dicarbonyl-(ꢁ5-cyclopentadienyl)-(2,3,4-ꢁ-2-methyl-1-ethoxy-1-
oxopent-2-enyl)molybdenum (17h)
Complex 17g, prepared from benzoate 16g in 88% yield
(0.76 mmol scale) by procedure B, was obtained as a yellow-
orange oil:
13C NMR (100 MHz, CDCl3): δ = 177.6 (C1), 68.7 (C3H),
66.4 (C4H2), 38.1 (C2H2), 18.0 (6CH3, SiCHMe2), 12.0 (3CH,
SiCHMe2).
[α]D = ϩ41.3 (c 0.21, CHCl3).
IR (film): ν = 1949 s, 1868 s, 1693 s cmϪ1.
LRMS (CI mode, isobutane): m/z = 277 [(M ϩ H)ϩ, 100%],
259 (14), 233 (23), 173 (19).
1H NMR (300 MHz, CDCl3): δ = 4.97 (1H, d, J = 10.7 Hz,
C3H), 4.73 (5H, s, CpH), 4.07 (1H, dq, J = 10.75, 7.2 Hz,
CHAHBCH3), 3.96 (1H, dq, J = 10.75, 7.2 Hz, CHAHBCH3),
2.34 (1H, dq, J = 10.7, 6.3 Hz, C4H), 1.51 (3H, d, J = 6.3 Hz,
C5H3), 1.18 (3H, s, C2CH3), 1.02 (3H, t, J = 7.1 Hz,
OCH2CH3).
Found: C, 56.22; H, 10.03. C13H28O4Si requires: C, 56.48; H,
10.21%.
(6S )-6-[(Triisopropylsilyloxy)methyl]-2,2-dimethyl-1,3-dioxan-
4-one (21)
13C NMR (300 MHz, CDCl3): δ = 238.1 (CO), 237.7 (CO),
173.5 (CO), 93.2 (5CH, Cp), 73.4 (C4H), 62.9 (C2), 59.6 (C3H),
58.9 (CH2), 19.5 (C2CH3), 15.9 (C5H3), 13.8 (CH3).
To a solution of acid 20 (7.45 g, 27.0 mmol) and 2-methoxy-
propene (3.10 mL, 32.3 mmol) in CH2Cl2 (250 mL) at rt
under N2 was added pyridinium p-toluenesulfonate (339 mg,
1.35 mmol). The clear solution was stirred at rt for 3 h before
concentration in vacuo. The residue was purified by column
chromatography (SiO2, ether : hexanes = 4 : 6) to give the title
compound (7.15 g, 22.6 mmol, 84%) as a clear oil: [α]D = Ϫ38.4
(c 1.10, CHCl3). Further elution yielded acid 20 (730 mg, 2.64
mmol, 10%).
ϩ
ؒ
LRMS (EI mode): m/z = 360.2 (M , 8%), 332.2 (M Ϫ CO,
20), 304.2 (M Ϫ 2CO, 37), 228.1 (100)
(3S )-3,4-Dihydroxybutyric acid methyl ester (18)
Diol 18, prepared in 89% yield on an 89 mmol scale by the
method of Moriwake and co-workers, gave [α]D = Ϫ23.2 (c 1.22,
CHCl3); lit. [α]D = Ϫ24.6 (c 1.00, CHCl3).30,65 1H and 13C NMR
spectroscopic data were in accordance with literature data.65
IR (film): ν = 2945 s, 2864 s, 1746 s cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 4.20 (1H, tt, J = 7.1, 4.8 Hz,
C6H), 3.81 (1H, dd, J = 10.4, 4.8 Hz, CHAHBOTIPS), 3.74 (1H,
dd, J = 10.4, 4.8 Hz, CHAHBOTIPS), 2.59 (2H, apparent d,
J = 7.1 Hz, C5H2), 1.59 and 1.57 (3H each, s, CMe2), 1.05 (18H,
d, J = 5.2 Hz, SiCHMe2), 1.14–1.03 (3H, m, SiCHMe2).
13C NMR (100 MHz, CDCl3): δ = 168.1 (C4), 106.1 (C2), 68.7
(C6H), 65.6 (CH2OTIPS), 31.8 (C5H2), 29.1 (CH3), 25.0 (CH3),
18.0 (6CH3, SiCHMe2), 12.0 (3CH, SiCHMe2).
(3S )-3-Hydroxy-4-(triisopropylsilyloxy)butyric acid methyl ester
(19)
To a solution of diol 18 (12.0 g, 89.3 mmol) and imidazole
(12.2 g, 178.6 mmol) in N,N-dimethylformamide (100 mL) at
0 ЊC under N2 was added triisopropylsilyl chloride (20.1 mL,
93.8 mmol). The solution was stirred at rt for 30 h and then
poured into hexanes (250 mL) and H2O (75 mL). The phases
were separated and the organic phase washed with H2O (2 × 50
mL), dried, filtered and concentrated in vacuo. The residue
LRMS (CI mode, isobutane): m/z = 317.3 [(M ϩ H)ϩ, 100%],
259.2 (16).
Found: C, 60.71; H, 10.07. C16H32O4Si requires: C, 60.72;
H, 10.19%.
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1726

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(4S,6S )-4-Acetoxy-2,2-dimethyl-6-(triisopropylsilyloxymethyl)-
1,3-dioxane (22)
Spectroscopic data for thioether 23b: (Rf = 0.85, Et2O :
PhMe = 2 : 98)
[α]D = ϩ85.0 (c 0.22, CHCl3).
To a solution of dioxanone 21 (19.1 g, 60.4 mmol) in CH2Cl2
(180 mL) at Ϫ78 ЊC under N2 was added neat DIBAL-H
(11.3 mL, 63.4 mmol) dropwise. After stirring Ϫ78 ЊC for 1 h,
pyridine (14.6 mL, 181 mmol), 4-dimethylaminopyridine
(8.11 g, 66.4 mmol) in CH2Cl2 (50 mL) and acetic anhydride
(22.8 mL, 241 mmol) were added and the clear solution stirred
at Ϫ78 ЊC for a further 1.5 h before the addition of aqueous
NH4Cl (100 mL) and aqueous sodium potassium tartrate
(100 mL). The solution was allowed to warm to rt with vigorous
stirring over 1 h. The phases were separated, and the aqueous
phase extracted with CH2Cl2 (3 × 100 mL). The combined
organic phases were washed with ice-cold 1 M NaHSO4 (3 ×
100 mL), aqueous NaHCO3 (2 × 100 mL) and brine (100 mL),
dried, filtered and concentrated in vacuo to yield the crude
product as a colourless oil. The residue was purified by column
chromatography (SiO2, ether : hexanes = 1 : 9) to give the
title compound (18.3 g, 50.7 mmol, 84%) as a clear oil.
13C NMR spectroscopy indicated that acetate 22 was a single
diastereoisomer, identified as the syn-1,3-diol acetonide isomer
by reference to the shifts of the acetonide methyl signals, and to
the coupling constants of C4H.66,67
IR (film): ν = 2942 s, 2859 s, 1461 m, 1382 m, 1137 m, 1114 m,
873 m, 688 m cmϪ1.
1H NMR (360 MHz, CDCl3): δ = 7.52–7.47 (2H, m, Ph),
7.33–7.22 (3H, m, Ph), 5.50 (1H, t, J = 5.8 Hz, C4H), 4.17 (1H,
ddt, J = 10.2, 4.7, 5.5 Hz, C6H), 3.80 (1H, dd, J = 10.2, 5.5 Hz,
CHAHBOTIPS), 3.64 (1H, dd, J = 10.2, 5.7 Hz, CHAHBOTIPS),
2.08 (1H, ddd, J = 13.5, 10.1, 6.0 Hz, C5HAHB), 1.99 (1H, ddd,
J = 13.5, 5.7, 4.7 Hz, C5HAHB), 1.61 and 1.38 (3H each, s,
CMe2), 1.14–1.04 (3H, m, SiCHMe2), 1.07 (18H, d, J = 4.5 Hz,
SiCHMe2).
13C NMR (90 MHz, CDCl3): δ = 135.6 (C, Ph), 131.0 (2CH,
Ph), 129.0 (2CH, Ph), 127.1 (CH, Ph), 101.1 (C2), 78.6 (C4H or
C6H), 67.8 (C4H or C6H), 66.5 (CH2OTIPS), 34.0 (C5H2), 28.1
(CMe2), 24.6 (CMe2), 18.1 (6CH3, SiCHMe2), 12.1 (3CH,
SiCHMe2).
LRMS (FABϩ mode): m/z = 433.4 [(M ϩ Na)ϩ, 22%], 335.4
(14), 301.4 (47), 243.3 (82), 173.2 (100), 157.2 (73), 115.3 (43).
HRMS (FABϩ mode, PEG): found [M ϩ Na]ϩ, 433.2210.
C22H38O3SSiNa requires 433.2209.
Compound 23a (Rf = 0.78, Et2O : PhMe = 2:98) has been
described previously, with only the following 13C NMR data
reported: δ = 30.0 (Me), 19.9 (Me) ppm.66
[α]D = Ϫ5.1 (c 1.26, CHCl3).
IR (film): ν = 1757 s cmϪ1.
[α]D = Ϫ54.2 (c 0.36, CHCl3).
1H NMR (400 MHz, CDCl3): δ = 6.18 (1H, dd J = 10.0, 3.0
Hz, C4H), 4.01 (1H, dddd, J = 11.7, 6.3, 4.8, 2.5 Hz, C6H), 3.81
(1H, dd, J = 9.8, 5.0 Hz, CHAHBOTIPS), 3.61 (1H, dd, J = 9.6,
6.4 Hz, CHAHBOTIPS), 2.11 (3H, s, COMe), 1.96 (1H, dt,
J = 12.4, 2.8 Hz, C5HAHB), 1.56–1.43 (1H, m, C5HAHB), 1.52
and 1.44 (3H each, s, CMe2), 1.13–1.01 (3H, m, SiCHMe2), 1.05
(18H, d, J = 4.8 Hz, SiCHMe2).
IR (film): ν = 2938 s, 2859 s, 1138 m, 1117 m, 955 m, 881 m,
689 m cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 7.50–7.48 (2H, m, Ph),
7.32–7.23 (3H, m, Ph), 5.31 (1H, dd, J = 12.0, 2.5 Hz, C4H),
4.02 (1H, dddd, J = 11.3, 6.4, 4.9, 2.4 Hz, C6H), 3.76 (1H, dd,
J = 9.8, 4.9 Hz, CHAHBOTIPS), 3.54 (1H, dd, J = 9.8, 6.4 Hz,
CHAHBOTIPS), 1.98 (1H, dt, J = 12.9, 12.5 Hz, C5HAHB),
1.61–1.52 (1H, m, C5HAHB), 1.55 and 1.52 (3H each, s, CMe2),
1.12–1.04 (3H, m, SiCHMe2), 1.04 (18H, d, J = 4.5 Hz,
SiCHMe2).
13C NMR (100 MHz, CDCl3): δ = 169.6 (COMe), 100.7 (C2),
89.6 (C4H), 69.5 (CH2OTIPS), 66.8 (C6H), 33.1 (C5H2), 29.8
(3, CMe2), 21.4 (3, COMe), 20.9 (3, CMe2), 18.1 (6CH3,
SiCHMe2), 12.1 (3CH, SiCHMe2).
13C NMR (100 MHz, CDCl3): δ = 134.3 (C, Ph), 131.4 (2CH,
1, Ph), 129.0 (2CH, 1, Ph), 127.3 (CH, Ph), 100.3 (C2), 77.7
(C4H or C6H), 70.5 (C4H or C6H), 66.9 (CH2OTIPS), 34.0
(C5H2), 30.1 (CMe2), 20.0 (CMe2), 18.1 (6CH3, SiCHMe2), 12.1
(3CH, SiCHMe2).
LRMS (CI mode, NH3): m/z = 378.3 [(M ϩ NH4)ϩ, 67%],
318.3 (100), 301.2 (92).
Found: C, 59.95; H, 9.88. C18H36O5Si requires: C, 59.96; H,
10.06%.
LRMS (CI mode, NH3): m/z = 428.2 [(M ϩ NH4)ϩ, 34%],
370.2 (39), 318.2 (69), 301.2 (100), 283.2 (81), 260.2 (31), 151.1
(39).
(4R,6S )-2,2-Dimethyl-4-phenylsulfanyl-6-(triisopropylsilyloxy-
methyl)-1,3-dioxane (23b) and (4S,6S )-2,2-dimethyl-4-phenyl-
sulfanyl-6-(triisopropylsilyloxymethyl)-1,3-dioxane (23a)
HRMS (CIϩ mode, isobutane): found [M ϩ H]ϩ, 411.2389.
C22H39O3SSi requires 411.2389.
To a solution of acetate 22 (9.90 g, 27.5 mmol) in CH2Cl2
(110 mL) at Ϫ70 ЊC under N2 was added phenylthiotrimethyl-
silane (5.5 mL, 28.8 mmol) and ZnCl2 (0.82 mL of a 1.0 M
solution in ether, 0.82 mmol) dropwise. The light brown
solution was stirred at Ϫ70 ЊC for 17 h before addition of 1 M
NaOH (50 mL) and warming to rt. The phases were separated,
and the aqueous phase extracted with CH2Cl2 (3 × 50 mL).
The combined organic phases were washed with 1 M NaOH
(50 mL) and brine (50 mL), dried, filtered and concentrated
in vacuo. The residue was purified by column chromatography
Found (mixture of isomers): C, 64.36; H, 9.41. C22H38O3SSi
requires: C, 64.34; H, 9.33%.
4,4-Bis-phenylsulfanyl-1-(triisopropylsilyloxy)butan-2-ol (24)
The title compound was obtained in an initial attempt to
synthesise thioethers 23b and 23a by the following procedure:
a solution of acetate 22 (57 mg, 0.16 mmol) and thiophenol
(0.03 mL, 0.32 mmol) in CH2Cl2 (5 mL) was cooled to Ϫ78 ЊC
under N2 and BF3ؒOEt2 (0.02 mL, 0.19 mmol) was added
dropwise. After stirring at Ϫ78 ЊC for 1 h, NaOH (1 M, 2 mL)
was added, the mixture was warmed to rt and the phases
were separated. The aqueous phase was extracted with CH2Cl2
(3 × 10 mL), and the combined organic phases washed with
NaOH (1 M, 2 × 10 mL), brine (10 mL), dried, filtered and
concentrated in vacuo. The residue was purified by column
chromatography (SiO2, Et2O : hexanes = 1 : 9) to give the title
compound (55 mg, 0.12 mmol, 75%) as a colourless oil.
[α]D = Ϫ8.1 (c 0.42, CHCl3).
(SiO2, ether : hexanes = 2 : 98
4 : 96) to give a mixture of the
title compounds (9.74 g, 23.7 mmol, 86%) as a clear oil. 1H and
13C NMR spectroscopy indicated a ratio of 23b : 23a of
approximately 7 : 3.66,67 For analytical purposes, a sample of
isomers 23b and 23a was separated by careful column
chromatography.
Alternative procedure: ZnCl2 (1.9 mL of a 1.0 M solution in
ether, 1.9 mmol) was added dropwise to a solution of acetate
22 (17.4 g, 48.4 mmol) and thiophenol (5.2 mL, 50.8 mmol) in
CH2Cl2 (240 mL) at Ϫ30 ЊC under N2. After stirring for 15 min
at Ϫ30 ЊC NaOH (1 M, 100 mL) was added and the mixture
allowed to warm to rt. Workup and purification as above
yielded a mixture of the title compounds (17.3 g, 42.1 mmol) as
IR (film): ν = 2943 s, 2866 s, 1582 m, 1477 m, 1464 m, 1117 m,
882 m, 791 m cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 7.53–7.50 (2H, m, Ph),
7.46–7.43 (2H, m, Ph), 7.33–7.23 (6H, m, Ph), 4.74 (1H, dd,
J = 10.5, 4.1 Hz, H4), 4.16–4.11 (1H, m, H2), 3.70 (1H, dd,
1
a colourless oil. H and 13C NMR spectroscopy indicated a
ratio of 23b : 23a of approximately 1 : 9.66,67
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1727

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J = 9.8, 3.7 Hz, C1HAHB), 3.50 (1H, dd, J = 9.8, 6.4 Hz,
C1HAHB), 2.50 (1H, d, J = 4.8 Hz, OH), 2.09 (1H, ddd, J = 14.2,
9.9, 4.1 Hz, C3HAHB), 1.79 (1H, ddd, J = 14.2, 10.5, 3.1 Hz,
C3HAHB), 1.07–0.99 (3H, m, SiCHMe2), 1.03 (18H, d, J = 4.8
Hz, SiCHMe2).
reaction temperature below Ϫ80 ЊC. The orange solution was
stirred at Ϫ78 ЊC for 30 min before cooling to Ϫ90 ЊC and
dropwise addition of a solution of complex 31 (which had been
freshly prepared from neutral complex 17a (91 mg, 0.35 mmol)
and NOBF4 (45 mg, 0.39 mmol) in MeCN (4 mL), 0 ЊC, 20
min). The brown solution was allowed to warm to Ϫ78 ЊC over
30 min before addition of aqueous NH3 (5 mL), aqueous
NH4Cl (10 mL) and Et2O (25 mL) and removal of the cooling
bath. After warming to room temperature, the mixture was
filtered through Celite, rinsing with Et2O (3 × 25 mL). The
phases were separated, the aqueous phase was extracted with
Et2O (3 × 25 mL) and the combined organic phases were
washed with brine (50 mL), dried, filtered and concentrated in
vacuo. The crude products were dissolved in analytical grade
chloroform (50 mL), and stirred at rt with a stream of O2
bubbling through the solution for 17 h. The solvent was
removed in vacuo and the residue purified by column chromato-
graphy (SiO2, Et2O : hexanes = 2 : 98) to give the title compound
(53 mg, 0.15 mmol, 48%) as a colourless oil. 1H NMR spectro-
scopy indicated that olefin 32a,b was present as a mixture of
epimers (inseparable by column chromatography) at the C4
position. The major isomer was determined to be the (6S)-
13C NMR (100 MHz, CDCl3): δ = 134.3 (C, Ph), 134.0 (C,
Ph), 133.0 (2CH, Ph), 132.7 (2CH, Ph), 129.1 (4CH, Ph), 127.9
(CH, Ph), 127.8 (CH, Ph), 69.5 (C2H), 67.3 (C1H2), 54.8
(C4H), 39.6 (C3H2), 18.1 (6CH3, SiCHMe2), 12.0 (3CH,
SiCHMe2).
LRMS (CI mode, NH3): m/z = 480.0 [(M ϩ NH4)ϩ, 3%],
370.1 (23), 335.1 (100), 174.1 (9).
(4R,6S )-2,2-Dimethyl-4-tributylstannyl-6-triisopropylsilyloxy-
methyl-1,3-dioxane (26)
Lithium 4,4Ј-di-tert-butylbiphenylide (LDBB) was prepared by
a modification to the method of Freeman and Hutchinson:36
a
mixture of Li (3.24 g, 467 mmol), 4,4Ј-di-tert-butylbiphenyl
(12.5 g, 46.7 mmol) and THF (160 mL) was stirred at 0 ЊC for
48 h under a static Ar atmosphere. The LDBB solution was
added dropwise to a solution of sulfides 23a and 23b (4.42 g,
10.8 mmol) in THF (120 mL) at Ϫ78 ЊC and the resulting dark
blue solution stirred at Ϫ78 ЊC for 10 min before the addition of
Bu3SnCl (3.3 mL, 11.3 mmol) dropwise. After stirring for 10
min, H2O (100 mL) and Et2O (100 mL) were added and the cold
bath removed. The phases were separated and the aqueous
phase was extracted with Et2O (3 × 50 mL). The combined
organic phases washed with NaOH (0.5 M, 3 × 50 mL), dried,
filtered and concentrated in vacuo. The residue was purified by
epimer by the large (3J 11.6) coupling of H6 to H5 (C6D6). 13
C
NMR spectroscopic data confirmed the assignment, acetonide
methyl carbon shifts at 30.2 and 20.0 ppm being indicative
of the stereochemistry.66,67 The minor (6R)-isomer exhibited
acetonide methyl carbon shifts at 25.2 ppm (2C, 3). The ratio
1
of equatorial : axial isomers was estimated from H NMR
spectroscopy (CDCl3) comparing the integration of signals at:
3.79–3.72 (2 overlapping dd, 1 each from (6R)- and (6S)-
isomers) and 3.63 (1H, dd, (6R)-isomer).
column chromatography (SiO2, hexanes
ether : hexanes =
1 : 99) to give the title compound (4.96 g, 8.38 mmol, 81%) as a
colourless oil. 13C NMR spectroscopy indicated the presence
of a single isomer, identified as the expected trans-disubstituted
1,3-dioxane by reference to the chemical shifts of the acetonide
methyl signals.66,67 Compound 26 has been previously described,
with only the following 13C NMR spectroscopic data reported:
δ = 24.7 (Me), 24.5 (Me) ppm.66
[α]D = Ϫ12.8 (c 1.06, CHCl3).
IR (film): ν = 2943 s, 2866 s, 1642 w, 1464 m, 1379 m, 1261 m,
1200 m, 1172 m, 1114 s, 994 m, 883 m cmϪ1.
1
(6S)-isomer only H NMR (400 MHz, C6D6): δ = 5.90–5.80
(1H, m, CH᎐CH2), 5.06–5.01 (2H, m, CH᎐CH2), 3.88 (1H, ddt,
᎐
᎐
J = 11.6, 2.5, 5.5 Hz, C4H), 3.80 (1H, dd, J = 9.7, 5.2 Hz,
CH2OTIPS), 3.69 (1H, ddt, J = 11.6, 2.4, 6.0 Hz, C6H), 3.57
(1H, dd, J = 9.7, 2.2 Hz, CH2OTIPS), 2.34–2.27 (1H, m,
[α]D = Ϫ17.2 (c 1.02, CHCl3).
IR (film): ν = 2949 s, 2928 s, 2870 s, 1465 m, 1382 m, 1225 m,
CHAHBCH᎐CH2), 2.14–2.07 (1H, m, CHAHBCH᎐CH2), 1.50
᎐
᎐
1143 m, 1101 m, 1002 m, 878 m, 692 m cmϪ1.
(3H, s, MeACMeB), 1.45 (1H, dt, J = 12.8, 2.6 Hz, C5HAHB),
1.30 (3H, s, MeACMeB), 1.26–1.17 (1H, m, C5HAHB), 1.11
(18H, d, J = 2.8 Hz, SiCHMe2), 1.15–1.08 (3H, m, SiCHMe2).
(6S)-isomer (major) 13C NMR (100 MHz, CDCl3): δ = 134.4
1H NMR (400 MHz, CDCl3): δ = 4.20 (1H, dd, J = 11.3, 6.3
Hz, C4H), 3.90 (1H, dq, J = 8.8, 5.9 Hz, C6H), 3.75 (1H, dd,
J = 10.0, 5.8 Hz, CHAHBOTIPS), 3.62 (1H, dd, J = 10.0, 5.8 Hz,
CHAHBOTIPS), 2.11 (1H, dt, J = 5.9, 12.1 Hz, C5HAHB), 1.69
(1H, ddd, J = 12.7, 8.9, 6.2 Hz, C5HAHB), 1.58–1.46 (6H, m,
SnCH2CH2CH2Me), 1.36–1.26 (6H, m, SnCH2CH2CH2Me),
1.32 and 1.29 (3H each, s, CMe2), 1.13–1.05 (3H, m, SiCHMe2),
1.07 (18H, d, J = 4.4 Hz, SiCHMe2), 0.93–0.84 (15H, m,
SnCH2CH2CH2Me).
(CH᎐CH ), 117.2 (CH᎐CH ), 98.6 (CMe ), 70.2 (C4H), 68.7
᎐
᎐
2
2
2
(C6H), 67.4 (CH OTIPS), 41.1 (CH CH᎐CH ), 33.9 (C5H ),
᎐
2
2
2
2
30.2 (MeACMeB), 20.0 (MeACMeB), 18.1 (6CH3, SiCHMe2),
12.2 (3CH, SiCHMe2).
(6R)-isomer (minor) 13C NMR (100 MHz, CDCl3): δ = 134.7
(CH᎐CH ), 117.0 (CH᎐CH ), 100.3 (CMe ), 68.1 (C6H or
᎐
᎐
13C NMR (100 MHz, CDCl3): δ = 100.4 (C2), 68.1 (C6H),
66.7 (CH2OTIPS), 59.8 (C4H), 34.1 (C5H2), 29.3 (3CH2,
2
2
2
C4H), 66.7 (CH OTIPS), 66.5 (C6H or C4H), 40.4 (CH CH᎐
᎐
2
2
CH2), 34.4 (C5H2), 25.2 (2C, CMe2), 18.1 (6CH3, SiCHMe2),
12.2 (3CH, SiCHMe2).
2
3JC–Sn = 10.4, SnCH2CH2CH2Me), 27.8 (3CH2, JC–Sn = 25.2,
SnCH2CH2CH2Me), 24.9 (CMe2), 24.7 (CMe2), 18.1 (6CH3,
SiCHMe2), 13.9 (3CH3, SnCH2CH2CH2Me), 12.2 (3CH,
LRMS (CIϩ mode): m/z = 343.2 [(M ϩ H)ϩ, 5], 285.2 (100),
267.2 (26), 241.2 (20), 217.2 (7), 173.1 (13), 111.1 (32).
Found: C, 66.75; H, 11.09. C19H38O3Si requires: C, 66.61; H,
11.18%.
1
SiCHMe2), 8.8 (3CH2, JC–Sn = 161.0, 150.9, SnCH2CH2-
CH2Me).
ϩ
LRMS (EIϩ mode): m/z = 591.2 [M , 0.1%], 535.2 (19),
ؒ
477.2 (40), 291.1 (100), 243.2 (75), 157.1 (74), 115.0 (38).
Found: C, 56.90; H, 9.98. C28H60O3SiSn requires: C, 56.85; H,
10.22%.
(2R,4R,6S )-2-Phenyl-4-tributylstannanyl-6-triisopropylsilyl-
oxymethyl-1,3-dioxane (33a) and (2S,4R,6S )-2-phenyl-4-tri-
butylstannanyl-6-triisopropylsilyloxymethyl-1,3-dioxane (33b)
(4RS,6S )-4-Allyl-2,2-dimethyl-6-triisopropylsilyloxymethyl-1,3-
dioxane (32a,b)
To a solution of stannane 26 (4.32 g, 7.30 mmol), methanol
(0.9 mL, 21.9 mmol) and benzaldehyde dimethylacetal (5.5 mL,
36.5 mmol) in CH2Cl2 (120 mL) at rt under N2 was added
p-TsOH (69 mg, 0.37 mmol). The solution was stirred at rt for
7 h before concentration in vacuo. The residue was purified by
column chromatography (SiO2, Et2O : hexanes = 2 : 98) to give
the title compounds (4.17 g, 6.52 mmol, 89%) as a colourless
oil. 1H NMR spectroscopy indicated a mixture of 33a and 33b
BuLi (0.15 mL of a 2.29 M solution in hexanes, 0.35 mmol) was
added to a solution of stannane 26 (190 mg, 0.32 mmol) in
THF (20 mL) at Ϫ78 ЊC under N2. The solution was stirred at
Ϫ78 ЊC for 5 min and then cooled to Ϫ90 ЊC. A solution of
CuBrؒSMe2 (79 mg, 0.39 mmol) in diisopropyl sulfide (0.3 mL)
and THF (0.3 mL) was added via cannula maintaining the
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
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in the approximate ratio 7 : 1, based on the integration of C2H
singlets at 5.81 and 5.73 ppm respectively. Separation of
isomers was possible by careful column chromatography (SiO2,
PhMe : hexanes = 1 : 3). The major isomer was identified as the
(2R)-isomer 33a by NOE studies.
Data for the (2R)-isomer (33a): (Rf = 0.13, PhMe : hexanes =
1 : 3)
[α]D = ϩ20.6 (c 1.61, CHCl3).
large (12–16%) enhancements observed between C6H and
C2H, and no enhancement observed between C4H and C6H
when either position was irradiated.
[α]D = ϩ17.5 (c 0.59 CHCl3).
IR (film): ν = 2866 s, 1463 m, 1383 m, 1216 m, 1118 s, 1069 m,
1027 m, 995 s, 918 m, 883 s, 754 s, 697 m cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 7.51–7.48 (2H, m, Ph),
7.38–7.30 (3H, m, Ph), 5.88 (1H, ddt, J = 16.8, 10.0, 7.3 Hz,
IR (film): ν = 2922 s, 2860 s, 1460 m, 1107 m, 755 m, 687 m
CH᎐CH ), 5.84 (1H, s, C2H), 5.21–5.13 (2H, m, CH᎐CH ),
᎐ ᎐
2 2
cmϪ1.
4.35 (1H, m, apparent q, J = 6.9 Hz, C6H), 4.18 (1H, ddt,
J = 11.0, 2.5, 5.9 Hz, C4H), 3.93 (1H, dd, J = 9.9, 5.4 Hz,
CHAHBOTIPS), 3.69 (1H, dd, J = 9.9, 6.4 Hz, CHAHBOTIPS),
1H NMR (400 MHz, C6D6): δ = 7.93–7.90 (2H, m, Ph), 7.36–
7.22 (3H, m, Ph), 5.81 (1H, s, C2H), 5.15 (1H, apparent d,
J = 6.4 Hz, C4H), 4.26 (1H, dddd, J = 10.7, 6.9, 5.2, 2.4 Hz,
C6H), 4.18 (1H, dd, J = 9.7, 5.0 Hz, CHAHBOTIPS), 3.89 (1H,
dd, J = 9.7, 7.2 Hz, CHAHBOTIPS), 2.56 (1H, ddd, J = 13.3,
10.8, 6.4 Hz, C5HAHB), 2.07 (1H, br dd, J = 13.3, 1.4 Hz,
C5HAHB), 1.76–1.63 (6H, m, SnCH2CH2CH2Me), 1.49 (6H,
sextet, J = 7.3 Hz, SnCH2CH2CH2Me), 1.27–1.12 (12H, m,
SnCH2CH2CH2Me ϩ SiCHMe2), 1.22 (18H, d, J = 2.8 Hz,
SiCHMe2), 1.04 (6H, t, J = 7.2 Hz, SnCH2CH2CH2Me).
13C NMR (100 MHz, CDCl3): δ = 139.1 (C, Ph), 128.8 (CH,
Ph), 128.4 (2CH, Ph), 126.2 (2CH, Ph), 100.6 (C2H), 77.4
(C6H), 74.4 (C4H), 66.6 (CH2OTIPS), 33.9 (C5H2), 29.3
2.87 (1H, dt, J = 14.4, 7.3 Hz, CH H CH᎐CH ), 2.55 (1H, dt,
᎐
A
B
2
J = 14.4, 7.3 Hz, CH H CH᎐CH ), 2.00 (1H, ddd, J = 13.8,
᎐
A
B
2
11.2, 6.2 Hz, C5HAHB), 1.74 (1H, ddd, J = 13.5, 2.5, 1.3 Hz,
C5HAHB), 1.15–1.03 (3H, m, SiCHMe2), 1.08 (18H, d, J = 5.2
Hz, SiCHMe2).
13C NMR (100 MHz, CDCl3): δ = 139.1 (C, Ph), 134.7
(CH᎐CH ), 128.8 (CH, Ph), 128.3 (2CH, Ph), 126.3 (2CH, Ph),
᎐
2
117.6 (CH᎐CH ), 94.4 (CHPh), 73.2 (C4H), 72.3 (C6H), 66.9
᎐
2
(CH OTIPS), 35.6 (CH CH᎐CH ), 30.3 (C5H ), 18.2 (6CH ,
᎐
2
2
2
2
3
SiCHMe2), 12.1 (3CH, SiCHMe2).
LRMS (CIϩ mode): m/z = 391.1 [(M ϩ H)ϩ, 100], 347.1 (8),
285.1 (50), 261.1 (11), 241.1 (11), 111.1 (13), 107.1 (12).
Found: C, 70.65; H, 9.73. C23H38O3Si requires: C, 70.72; H,
9.81%.
(3CH2, 3JC–Sn = 10.2, SnCH2CH2CH2Me), 27.7 (3CH2, 2JC–Sn
=
27.8, SnCH2CH2CH2Me), 18.2 (6CH3, SiCHMe2), 13.8 (3CH3,
Sn(CH2)3Me), 12.1 (3CH, SiCHMe2), 10.3 (3CH2, 1JC–Sn 150.1,
143.6, SnCH2CH2CH2Me).
LRMS (CIϩ mode): m/z = 641.2 [(M ϩ H)ϩ, 35], 583.1 (100),
581.1 (76), 533.2 (32), 475.1 (18), 291.1 (44), 289.1 (34), 243.2
(22), 107.1 (86).
(2S,4S,6S )-4-[(1R,2E )-1-Methyl-3-phenyl-2-propenyl]-2-
phenyl-6-triisopropylsilyloxymethyl-1,3-dioxane (6) and
(2S,4S,6S )-4-[(1S,2E )-1-phenyl-2-butenyl]-2-phenyl-6-triiso-
propylsilyloxymethyl-1,3-dioxane (35)
Found: C, 60.17; H, 9.41. C32H60O3SiSn requires: C, 60.09; H,
9.46%.
Data for the (2S)-isomer (33b): (Rf = 0.22, PhMe : hexanes =
1 : 3).
[α]D = Ϫ2.14 (c 1.54, CHCl3).
n-BuLi (5.4 mL of a 1.7 M solution in hexanes) was added
dropwise to a solution of stannane 33a (5.40 g, 8.45 mmol) in
THF (150 mL) at Ϫ80 ЊC under N2. After the light-yellow solu-
tion was stirred at Ϫ80 ЊC for 1 h, a solution of CuBrؒSMe2
(2.08 g, 10.14 mmol) in di-iso-propylsulfide (7 mL) and THF
(8.5 mL) was added via cannula, maintaining the internal
solution temperature below Ϫ80 ЊC. The orange-brown solu-
tion was stirred at Ϫ80 ЊC for 1 h under N2 before the addition
IR (film): ν = 2960 s, 2864 s, 1460 s, 1380 m, 1114 m, 1073 m,
1018 m, 881 m, 798 m cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 7.46–7.44 (2H, m, Ph),
7.36–7.28 (3H, m, Ph), 5.73 (1H, s, C2H), 4.59 (1H, dd, J = 13.7,
2.3 Hz, C4H), 4.35 (1H, t, J = 9.0 Hz, CHAHBOTIPS), 4.17–
4.12 (1H, m, C6H), 4.01 (1H, dd, J = 9.5, 5.2 Hz, CHAHB-
OTIPS), 2.59 (1H, dt, J = 6.1, 13.8 Hz, C5HAHB), 1.85 (1H,
ddd, J = 13.8, 2.3, 1.1 Hz, C5HAHB), 1.61–1.51 (6H, m,
SnCH2CH2CH2Me), 1.31 (6H, sextet, J = 7.2 Hz, SnCH2CH2-
CH2Me), 1.18–1.08 (3H, m, SiCHMe2), 1.10 (18H, d, J = 5.2
Hz, SiCHMe2), 0.99–0.94 (6H, m, SnCH2CH2CH2Me), 0.90
(9H, t, J = 7.4 Hz, SnCH2CH2CH2Me).
of cationic complex
7 (freshly prepared: nitrosonium
tetrafluoroborate (1.28 g, 11.0 mmol) was added to a solution
of neutral complex 15 (3.53 g, 10.1 mmol, prepared by pro-
cedure A above) in MeCN (20 mL) at 0 ЊC and the yellow
solution stirred at 0 ЊC under N2 for 15 min) via cannula. The
light-brown solution was stirred at Ϫ80 ЊC for 1 h before the
addition of aqueous NH4Cl (40 mL) and aqueous NH3 (10 mL)
and removal of the cooling bath. After reaching room tem-
perature, the mixture was filtered through Celite, washing
thoroughly with Et2O (50 mL). The phases were separated, and
the aqueous phase extracted with Et2O (2 × 50 mL), and the
combined organic phases washed with brine (100 mL), dried,
filtered and concentrated in vacuo. The crude material was
dissolved in CHCl3 (250 mL) and stirred at rt for 17 h with a
stream of O2 bubbling through the brown solution. Removal of
solvent in vacuo yielded a dark brown oil which was purified by
column chromatography (SiO2, Et2O : hexanes = 2 : 98) to give a
mixture of the title compounds (2.90 g, 6.03 mmol, 71% from
13C NMR (100 MHz, CDCl3): δ = 140.0 (C, Ph), 128.5 (CH,
Ph), 128.2 (2CH, Ph), 126.2 (2CH, Ph), 97.9 (C2H), 73.1
(C4H), 68.1 (C6H), 61.8 (CH2OTIPS), 30.1 (C5H2), 29.3
(3CH2, 3JC–Sn = 10.2 Hz, SnCH2CH2CH2Me), 27.9 (3CH2, 2JC–Sn
= 26.8 Hz, SnCH2CH2CH2Me), 18.2 (6CH3, SiCHMe2), 13.9
(3CH3, Sn(CH2)3Me), 12.1 (3CH, SiCHMe2), 8.6 (3CH2, 1JC–Sn
= 160.6, 153.6 Hz, SnCH2CH2CH2Me).
LRMS (CIϩ mode): m/z = 641.0 [(M ϩ H)ϩ, 49%], 583.0
(100), 581.0 (75), 533.0 (31), 351.1 (42), 291.0 (69), 289.0 (53).
Found: C, 60.07; H, 9.36. C32H60O3SiSn requires: C, 60.09; H,
9.46%.
1
stannane 33a) as a pale yellow oil. H NMR spectroscopy
revealed a ratio of 6 : 35 of approximately 1.2 : 1 (in favour
of the desired isomer), estimated by integration of the vinylic
proton peaks at 6.51 and 6.28 ppm (6) and 5.64–5.50 ppm (35).
[α]D (1.2 : 1 mixture of 6 : 35) = ϩ23.3 (c 1.50, CHCl3).
IR (film) ν = 2942 s, 2866 s, 1462 m, 1117 s, 1069 m, 1028 m,
1014 m, 995 m, 882 m, 748 m, 696 s, 660 m cmϪ1.
(2S,4R,6S )-4-Allyl-2-phenyl-6-triisopropylsilyloxymethyl-1,3-
dioxane (34)
Olefin 34 was prepared in an analogous fashion to olefin 32 on a
scale of 0.25 mmol of stannane 33a and 0.28 mmol of neutral
complex 31. Purification by column chromatography (SiO2,
Et2O : hexanes = 3 : 97) gave the title compound (50 mg,
0.13 mmol, 51%) as a clear oil. 1H and 13C NMR spectroscopy
indicated the presence of a single isomer, identified as the (6S)-
isomer on the basis of the small (J = 6.9) coupling between C6H
and C5H. NOE experiments confirmed the assignment, with
1H NMR (400 MHz, CDCl3): δ = 7.53–7.17 (19H, m, Ph),
7.05–7.04 (1H, m, Ph), 6.51 [1H, d, J = 15.9 Hz, PhCH᎐CHR,
᎐
(6)], 6.28 [1H, dd, J = 15.9, 8.4 Hz, PhCH᎐CHR, (6)], 5.85 [1H,
᎐
s, CHPh, (6)], 5.76 [1H, s, CHPh, (35)], 5.64–5.50 [2H, m,
MeCH᎐CHR, (35)], 4.44 [1H, dd, J = 11.1, 5.0 Hz, (35)], 4.27–
᎐
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1729

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3.90 (6H, m), 3.72 [2H, ddd, J = 10.0, 6.6, 1.4 Hz, (6)], 3.19 (1H,
q, J = 8.3 Hz), 2.11 [1H, ddd, J = 13.5, 2.5, 1.5 Hz, (35)],
2.02–1.90 (3H, m), 1.66 [3H, dd, J = 5.6, 0.8 Hz, (35)], 1.13 [3H,
d, J = 6.4 Hz, Me (6)], 1.12–1.00 (42H, m, SiCHMe2).
Found: C, 71.27; H, 8.73. C14H20O3 requires: C, 71.16; H,
8.53%.
(2E,5S,6R,7E )-5-Hydroxy-6-methyl-8-phenylocta-2,7-dienoic
acid methyl ester (5)
13C NMR (100 MHz, CDCl3): δ = 141.9 (C, Ph), 139.1 (C,
Ph), 138.9 (C, Ph), 137.8 (C, Ph), 133.5 [PhCH᎐CHR (6)], 132.2
᎐
To a solution of triol 38 (125 mg, 0.53 mmol) in MeOH (15 mL)
and H2O (5 mL) at rt was added sodium periodate (170 mg,
0.79 mmol). The clear solution was stirred at rt for 1.5 h, after
which time a white precipitate was present. Methanol was
removed in vacuo and H2O (30 mL) and CH2Cl2 (20 mL) were
added. The phases were separated and the aqueous phase
extracted with CH2Cl2 (2 × 20 mL). The combined organic
phases were dried, filtered and concentrated in vacuo to afford a
crude aldehyde as a colourless oil (103 mg, 0.50 mmol). The
crude aldehyde was twice dissolved in PhMe (20 mL) and the
solvent evaporated. To a solution of the crude aldehyde in THF
(17 mL) was added trimethylphosphonoacetate (0.17 mL, 1.17
mmol) and the mixture cooled to Ϫ78 ЊC under N2 whereupon
N,N,NЈ,NЈ-tetramethylguanidine (0.15 mL, 1.17 mmol) in
THF (5 mL) was added dropwise over 2 min. The clear solution
was allowed to warm to rt over 16 h and stirred at rt for 42 h
before the addition of H2O (20 mL) and Et2O (20 mL). The
phases were separated and the aqueous phase was extracted
with Et2O (3 × 25 mL). The combined organic phases were
dried, filtered and concentrated in vacuo to afford a pale yellow
oil. The residue was purified by column chromatography (SiO2,
[CH᎐CH, (35)], 130.1 [PhCH᎐CHR (6)], 128.8 (2CH, Ph),
᎐
᎐
128.7 (2CH, Ph), 128.6 [CH, Ph or CH᎐CH, (35)], 128.4 [CH,
᎐
Ph or CH᎐CH, (35)], 128.3 (2CH, Ph), 128.2 (2CH, Ph), 128.1
᎐
(2CH, Ph), 127.9 [CH, Ph or CH᎐CH, (35)], 127.2 [CH, Ph or
᎐
CH᎐CH, (35)], 126.6 [CH, Ph or CH᎐CH, (35)], 126.3 (2CH,
᎐
᎐
Ph), 126.2 (2CH, Ph), 125.9 (2CH, Ph), 94.8 [CHPh (6)], 94.3
[CHPh, (35)], 76.6 (CH), 74.8 (CH), 73.3 (CH), 73.1 (CH), 66.8
(2CH ), 50.0 (CH), 37.6 [PhCH᎐CHCHMeR, (6)], 28.9 (CH ),
᎐
2
2
28.7 (CH2), 18.2 (14CH3, Me ϩ SiCHMe2), 12.2 (6CH,
SiCHMe2).
LRMS (CI mode, isobutane): m/z = 481 [(M ϩ H)ϩ, 17%],
393 (21), 375 (58), 351 (100), 307 (25), 245 (44).
Found: C, 74.86; H, 9.41. C30H44O3Si requires: C, 74.95; H,
9.22%.
(2R,4S,5R,6E )-5-Methyl-7-phenyl-hept-6-ene-1,2,4-triol (38)
and (2R,4S,5S,6E )-5-phenyl-oct-6-ene-1,2,4-triol (39)
To a solution of dioxanes 6 and 35 (6 : 35 = 1.2 : 1, 2.77 g, 5.76
mmol) in MeOH (100 mL) at rt was added p-toluenesulfonic
acid monohydrate (164 mg, 0.86 mmol). The pale yellow solu-
tion was stirred at rt for 1 d before solvent removal in vacuo. The
residue was purified by column chromatography (SiO2, EtOAc)
to give a mixture of the title compounds (861 mg, 3.64 mmol,
63%) as a pale yellow oil. Careful repetitive column chromato-
graphy allowed the separation of isomers. Triol 38, a viscous
oil, gave : [α]D = ϩ103.6 (c 1.10, MeOH).
Et2O : cyclohexane = 2 : 8
4 : 6) to give the title compound
(114 mg, 0.44 mmol, 83%) as a colourless oil. [α]D = ϩ71.7
(c 1.20, CHCl3); lit. [α]D = ϩ55.2 (c 0.31, CHCl3).41 Spectro-
scopic data were in accordance with literature data.41
Acknowledgements
IR (film): ν = 3465 br s, 2935 m, 2873 m, 1452 m, 1388 m,
1365 m, 1329 m, 1082 m, 992 m, 972 m cmϪ1.
We would like to thank the Deutsche Forschungsgemeinschaft,
the EPSRC, Merck Sharp & Dohme and GlaxoSmithKline for
financial support.
1H NMR (400 MHz, CDCl3): δ = 7.38–7.23 (5H, m, Ph), 6.49
(1H, d, J = 16.1 Hz, C7H), 6.12 (1H, dd, J = 16.1, 8.7 Hz, C6H),
4.05–3.99 (1H, m, C2H), 3.80–3.76 (1H, m, C4H), 3.67 (1H, dd,
J = 11.1, 3.6 Hz, C1HAHB), 3.54 (1H, dd, J = 11.1, 7.0 Hz,
C1HAHB), 2.41 (1H, br sextet, J = 7.3 Hz, C5H), 1.75 (1H, ddd,
J = 14.4, 8.7, 2.5 Hz, C3HAHB), 1.60 (1H, ddd, J = 14.4, 9.3, 3.5
Hz, C3HAHB), 1.12 (3H, d, J = 6.8 Hz, C5–Me).
References
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or C7H), 131.6 (C6H or C7H), 128.8 (2CH, Ph), 127.7 (CH,
Ph), 126.4 (2CH, Ph), 72.3 (C2H), 69.6 (C4H), 66.9 (C1H2),
44.2 (C5H), 36.4 (C3H2), 16.9 (C5–Me).
LRMS (CI mode, NH3): m/z = 254.2 [(M ϩ NH4)ϩ, 100%],
237.1 (28), 219.1 (22).
Found: C, 71.15; H, 8.70. C14H20O3 requires: C, 71.16; H,
8.53%.
Triol 39 solidified upon standing and was recrystallised from
Et2O to give fine white needles, mp 110–111 ЊC.
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IR (KBr): ν = 3397 br s, 1112 m, 1082 m, 1070 s, 1025 s, 963
m, 702 m cmϪ1.
1H NMR (400 MHz, CDCl3): δ = 7.53–7.30 (2H, m, Ph),
7.26–7.17 (3H, m, Ph), 5.65–5.53 (2H, m, C6H and C7H), 4.13
(1H, dt, J = 2.5, 8.8 Hz, C4H), 4.07–4.01 (1H, m, C2H), 3.65
(1H, dd, J = 11.1, 3.5 Hz, C1HAHB), 3.53 (1H, dd, J = 11.1, 7.0
Hz, C1HAHB), 3.30 (1H, t, J = 8.2 Hz, C5H), 2.94 (1H, br s,
OH), 2.18 (1H, br s, OH), 1.88 (1H, ddd, J = 14.5, 8.7, 2.6 Hz,
C3HAHB), 1.68 (3H, d, J = 5.0 Hz, C8H3), 1.63 (1H, br s, OH),
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13C NMR (100 MHz, CDCl3): δ = 141.4 (C, Ph), 130.8
(Ph, C6H or C7H), 129.2 (2CH, Ph), 128.5 (2CH, Ph), 128.4
(Ph, C6H or C7H), 127.2 (Ph, C6H or C7H), 72.1 (C4H),
69.7 (C2H), 67.1 (C1H2), 56.7 (C5H), 36.8 (C3H2), 18.3
(C8H3).
LRMS (CI mode, NH3): m/z = 254.2 [(M ϩ NH4)ϩ, 100%],
236.2 (30), 219.2 (8), 116.1 (12).
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1730

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44 R. J. K. Taylor, Organocopper Reagents, Oxford University Press,
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O r g . B i o m o l . C h e m . , 2 0 0 4 , 2, 1 7 1 9 – 1 7 3 1
1731