Synthesis and applications to catalysis of novel cyclopentadienone iron tricarbonyl complexes

Article abstract of DOI:10.1039/c7dt03250a

A series of cyclopentadienone iron tricarbonyl complexes with diverse structures were prepared, in each case using the intramolecular cyclisation of a diyne as a key step. The complexes were generated as enantiomerically enriched through (i) asymmetric synthesis of a C2-symmetric diol following a reported protocol, (ii) resolution of enantiomerically-enriched diastereoisomers formed from a chiral alcohol and (iii) kinetic resolution of a racemic ketone-containing iron tricarbonyl complex. The approaches underline the diversity of the synthetic routes which can be employed in the synthesis of homochiral cyclopentadienone iron tricarbonyl complexes. Although the complexes proved to be effective as catalysts for the reduction of ketones, the alcohol products were formed in low ees (not exceeding ca. 35%), highlighting the challenging nature of asymmetric catalysis using complexes of this type.

Full text of DOI:10.1039/c7dt03250a

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Synthesis and applications to catalysis of novel
cyclopentadienone iron tricarbonyl complexes†
Cite this: DOI: 10.1039/c7dt03250a
Alessandro Del Grosso, Alexander E. Chamberlain, Guy J. Clarkson and
Martin Wills
*
A series of cyclopentadienone iron tricarbonyl complexes with diverse structures were prepared, in each
case using the intramolecular cyclisation of a diyne as a key step. The complexes were generated as enan-
tiomerically enriched through (i) asymmetric synthesis of a C2-symmetric diol following a reported proto-
col, (ii) resolution of enantiomerically-enriched diastereoisomers formed from a chiral alcohol and
(iii) kinetic resolution of a racemic ketone-containing iron tricarbonyl complex. The approaches underline
Received 1st September 2017,
Accepted 8th November 2017
the diversity of the synthetic routes which can be employed in the synthesis of homochiral cyclopentadie-
none iron tricarbonyl complexes. Although the complexes proved to be effective as catalysts for the
reduction of ketones, the alcohol products were formed in low ees (not exceeding ca. 35%), highlighting
the challenging nature of asymmetric catalysis using complexes of this type.
DOI: 10.1039/c7dt03250a
rsc.li/dalton
Introduction
Cyclopentadienone iron tricarbonyl complexes 1 have recently
found a significant number of applications in the catalysis of a
1
–3
4
number of organic transformations, notably hydrogenation
5
and transfer hydrogenation, and formation of C–N bonds via
reductive amination and ‘hydrogen borrowing’ reactions.
6
7
The hydrogen transfer is believed to proceed via formation of
the hydride 2 and 16-electron species 3, with the hydride trans-
8
fer itself through the transition state also illustrated in Fig. 1.
A number of derivatives of this class of catalyst have been Fig. 1 Iron tricarbonyl cyclopentadienone structures.
reported, for example 4–11, and some of these have been
applied in enantioselective catalysis of ketone and imine
9
reduction reactions. In other examples, non-chiral cyclopenta-
dienone iron tricarbonyl complexes have been used in con-
junction with an asymmetric reagent, such as a phosphonic
acid, in the catalysis of asymmetric reduction reactions
diverse structures, and efficient routes to their formation.
Whilst the complexes are competent pre-catalysts for asym-
metric reactions, the induced enantioselectivities remain low,
reflecting the challenge of achieving high enantioselectivities
with this class of complex.
1
0
(Fig. 2).
In a recent study, we described an efficient route to the syn-
thesis of catalysts such as 12, through the reaction of iron pen-
tacarbonyl with the derivatives of a C2-symmetric diol 13
Results and discussion
1
1
(Scheme 1).
Herein we describe the synthesis and applications of a In the first extension of our studies, we sought to determine
series of cyclopentadienone iron tricarbonyl complexes with what effect an electron-donating group on the side chains of
the catalyst might have. Towards this end we prepared the pyri-
1
2
dine-containing complex 14, from diol 15 and via the di-
alkyne precursor 16, following the route illustrated in
Scheme 2a. Treatment of 14 with slightly more than 1 equi-
valent of trimethylamine N-oxide (TMAO) resulted in for-
mation of a new species which appears to match the structure
17 in which one CO group was replaced by the pyridine in an
Department of Chemistry, The University of Warwick, Coventry, CV4 7AL, UK.
E-mail: m.wills@warwick.ac.uk
1
13
†
Electronic supplementary information (ESI) available: H and C NMR spectra,
1
3
GC examples. X-ray data. Chiral HPLC of the ligands prior to complexation.
CCDC 1567218–1567222. For ESI and crystallographic data in CIF or other elec-
tronic format see DOI: 10.1039/c7dt03250a
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Fig. 2 Reported asymmetric and non-asymmetric catalysts based on iron tricarbonyl cyclopentadienone structures.
Table 1 Hydrogenation of acetophenone using complexes 14, 17
and 18
Scheme 1 Previously-reported asymmetric iron complexes derived
from C2-symmetric diols.
Entry
Catalyst
Activator/%
Solvent
Conv./%
1
2
3
4
5
6
7
8
9
14
14
14
17
17
17
18
18
18
18
18
K
K
2
CO
CO
3
(3%)
(2%)
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
2
O
17.3
18.6
37.1
15.4
36.3
30.3
70.9
51.2
99.8
99.7
99.8
2
3
TMAO (1%)
CO (5%)
K
2
3
TMAO (1%)
TMAO (2%)
—
2 3
K CO (5%)
TMAO (1%)
TMAO (2%)
TMAO (3%)
1
1
0
1
Table 2 Asymmetric transfer hydrogenation of acetophenone using
complexes 14, 17 and 18
Alcohol/%
Conv./% (ee/%)
Formate/%
(ee/%)
Scheme 2 Synthesis of pyridine-containing complexes.
Entry Catalyst Activator/%
1
2
3
4
5
14
14
17
17
18
—
73.7
TMAO (10%) 99.7
99.9
63.1 (2.4 R) 10.6 (2.6 R)
90.8 (2 R) 8.9 (2.8 R)
85.5 (4.2 R) 14.4 (3 R)
87.8 (3.4 R) 11.8 (3 R)
45.4 (3.4 R) 12.7 (5.2 R)
—
intramolecular reaction. The addition of triphenylphosphine
TMAO (10%) 99.9
TMAO (10%) 58.1
a
to the cyclic complex 17 led to formation of a new product
3
1
a
with a peak at δ 57.57 in the P NMR which is indicative of
the formation of an iron triphenylphosphine complex. In
addition, a further complex, 18, containing a quinoline, was
prepared from the dialkyne 19 (Scheme 2b). Complexes 14, 17
Hetereogenous reaction (catalyst is not soluble).
and 18 proved to be effective catalysts for the reduction of or TMAO as an activating agent resulted in the highest conver-
ketones, with selected results shown in Table 1 for hydrogen- sions. In common with previous results, the addition of tri-
ation and Table 2 for transfer hydrogenation (full results are in phenylphosphine served to inhibit the reaction (see ESI†). The
the ESI†).
similarity between the results obtained with 14 and 17 suggest
In the hydrogenation reactions, catalysts 14 and 17 gave that they are reacting through a common intermediate, i.e. the
products in low conversions, although the addition of K CO
formation (possibly reversible) of 17 from 14 upon treatment
2
3
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with TMAO. The quinoline-derived complex 18 gave improved rings was completed (Scheme 3) following a route based on
conversions compared to the pyridine-containing complexes, the method previously reported, using the reaction of the
although the addition of TMAO was again essential for lithium salt of alkyne 20 with bis-Weinreb reagent 21, to give
optimal activation, and an excess of TMAO did not reduce the diketone 22, followed by ATH catalysed by tethered Ru(II)
conversions. In all cases the ees were low however and no complex 23, to the corresponding diol 24 in high ee. Both
higher than ca. 7–8% (full results for these and other tests are enantiomers, and the racemic standard (for HPLC analysis)
given in the ESI†).
were prepared for comparison, although the (S,S)-configur-
In the attempted asymmetric transfer hydrogenations ation products 24 were converted to catalysts for evaluation.
ATH), using a formic acid/triethylamine 5 : 2 azeotrope (FA/ Conversion of diol 24 to the dibenzyl derivative 25 was
(
TEA) mixture as both reducing agent and solvent, the pyridine- achieved efficiently. Both the diol and its two derivatives were
containing complex 14 required the addition of TMAO to give treated at 130 °C for 24 h with three equivalents of Fe(CO) to
5
optimal results however the cyclic complex 17 proved to be just form the required complexes 26 and 27 respectively. In each
as active with or without the addition of TMAO. This suggests case, a stable complex was formed and fully characterised,
that 17 may represent an ‘activated’ version of 14, with revers- including by X-ray crystallography (Fig. 3).
ible coordination of the pyridine acting to free a coordination
The X-ray crystallographic analysis of 26 and 27 (Fig. 3) con-
site for hydride delivery and subsequent hydrogen transfer. firmed the expected structures of the complexes, however there
The quinoline complex 18 gave poor conversion even with the was no obvious transfer of chirality to the o-OMe aromatic
addition of TMAO, however it appeared to not be soluble in rings. This flexibility may be responsible for the lack of selecti-
the reaction mixture. Again the ees were low in all cases vity in the subsequent reductions in which the catalysts were
(
between 2–4% only).
Previously reported catalysts 12, and those illustrated in
tested.
In the hydrogenation tests (Table 3; further results are
Scheme 2, contain unsubstituted phenyl rings adjacent to the listed in the ESI†), we focussed initially on the diol complex
central CvO of the cyclopentadienone, therefore we sought to 26. Again it was found that activation was required for best
see if an improvement could be made by the introduction of results, with full conversions being generated using TMAO.
an ortho-substituent to these rings, since the extra steric hin- Previously, and in initial tests, a combination of IPA and water
drance has the potential to further influence the asymmetry of was used as solvent, as this had been found to give good
the reduction reactions. The synthesis of a series of com- results. A series of alternative solvents were tested however
pounds containing ortho-methoxy groups on the aromatic these gave, with the exception of THF, inferior results in terms
of conversion, and no significant change to the ee. Reactions
at slightly lower temperatures (60 °C and 40 °C) resulted in
lower conversions, and the reduction of a series of acetophe-
none derivatives were also tested. In these tests, ortho-chloroa-
cetophenone gave a product in lower conversion than the less
hindered or electron-rich ketones. The dibenzyloxy-substituted
catalyst 27 was also effective although slightly more active in
2
THF than isopropanol/water (IPA/H O), and gave a product in
up to 21% ee, which was higher than the average for the diol.
This indicates that the extra steric hindrance created by the
combined ring and ortho-aromatic substrates had a small posi-
tive effect on the selectivity (Table 4).
In the case of the ATH reactions, again the conversions
were improved by the use of an activator at 80 °C, the ees of
acetophenone reduction, however, were improved to 25–30%.
Scheme 3 Synthesis of ortho-methoxy substituted complexes.
Fig. 3 X-ray crystallographic structures of complexes 26 and 27.
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Table 3 Hydrogenation of ketones using complexes 26 and 27
Entry
Catalyst
Substrate
Activator/%
Solvent/other changes
Conv./%
ee/%
10 (R)
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
26
26
26
26
26
26
26
26
26 60 °C
26 40 °C
26
26
26
26
27
27
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
PhCOMe
2-(OMe)C
4-(OMe)C
—
IPA/H
IPA/H
IPA/H
IPA
2
O
2
O
2
O
54.4
19.5
99.8
89.3
57.2
98.1
85.9
98.6
87.5
21.8
>99
91.6
56.8
96.6
77.8
100
K
2
CO
3
(5%)
9.2 (R)
9.4 (R)
3.6 (R)
7.4 (R)
2.2 (R)
0.2 (R)
9.4 (R)
9.0 (R)
12.0 (R)
8.6 (S)
6.0 (R)
3.6 (R)
10.2 (S)
21.0 (R)
16.0 (R)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
TMAO (1%)
2
H O
Toluene
Chlorobenzene
THF
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
THF
2
O
2
O
2
O
2
O
2
O
2
O
2
O
1
1
1
1
1
1
1
6
H
H
4
COMe
COMe
6
4
2-ClC
4-ClC
6
H
H
4
COMe
COMe
6
4
PhCOMe
PhCOMe
Table 4 Asymmetric transfer hydrogenation of acetophenone using complexes 26 and 27
Entry
Catalyst
Activator/%
Conv./%
Alcohol/% (ee/%)
Formate/% (ee/%)
1
2
26
26
—
54.9
99.6
25.7
51.5
87.8
93.3
46.8 (28.4 R)
87.2 (30.2 R)
25.2 (35.2 R)
49.9 (34.4 R)
81.9 (34.6 R)
89.4 (28.0 R)
8.2 (25 R)
12.3 (28 R)
0.5 (n/a)
1.6 (n/a)
5.9 (n/a)
TMAO (10%)
TMAO (10%)
TMAO (10%)
TMAO (10%)
TMAO (10%)
a
3
26 30 °C 24 h
26 30 °C 48 h
26 30 °C 72 h
27
a
4
a
5
6
10.6 (29.3 R)
a
Followed over time and at lower temp. of 30 °C.
A reaction was followed over time at a lower temperature of ca. successful, approach, we prepared the tetrahedropyran (THP)-
0 °C, and in this case the ee improved to ca. 35%, although protected diketone 28 using alkyne 29, and subsequently the
3
the reaction required 3 days to reach ca. 82%. In this case, as diol 30 through the sequence shown in Scheme 4.
was the case for all reductions using FA/TEA, some formate Unfortunately the cyclisation of this diol failed to give a clean
was also formed, presumably through formylation of the product. However the hydrolysis of the THP groups gave the
initial alcohol product, although the ee of the formate was tetrol 31 which was either di- or tetrabenzylated to give 32 and
similar to that of the alcohol. In previous work, we have estab- 33 respectively. Both dialkynes were cyclised with Fe(CO) in
5
lished that the alcohol and formate products in these reactions good yield to form complexes 34 and 35. Reaction of the di-
1
1
are of the same configuration. The result with the dibenzyl- benzyl intermediate 32 with t-butyldimethylsilyl chloride (TBSCl)
substituted complex 27 was comparable to that for the diol resulted in formation of 36 which was cyclised successfully but
catalyst 26, indicating that the increase of steric bulk had little in low isolated yield to 37. Peaks corresponding to the product
1
effect on the reaction enantioselectivity.
in the H NMR spectrum of 37 were very broad, however the
In order to improve the enantioselectivity, we sought to mass spectrum indicated formation of the desired complex.
place a larger group on the ortho position of the aromatic rings The application of complexes 34, 35 and 37 to the reduction
adjacent to the CvO of the cyclopentadienone and towards of acetophenone was tested, through both hydrogenation with
this end we prepared the acetylene reagent precursor o(OBn) hydrogen gas and ATH. Further results are given in the ESI.†
C
6
H
4
CCH (OBn = OCH
was very problematic with deprotonation at the benzylic CH
resulting in the formation of side products. In an alternative, of ca. 23% ee consistently. The dibenzyl 34 (i.e. containing
2
Ph), however the subsequent reaction In the pressure hydrogenation of acetophenone (Table 5) the
2
tetrabenzyl complex 35 required activation but gave a product
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Scheme 4 Synthesis of benzyloxy-substituted complexes via OTHP intermediate 30.
Table 5 Hydrogenation of acetophenone using complexes 34, 35 and
Table 6 Asymmetric transfer hydrogenation of acetophenone using
complexes 34, 35 and 37
3
7
Entry
Catalyst
Activator/%
Solvent
Conv./%
ee/%
Alcohol/%
Conv./% (ee/%)
Formate/%
(ee/%)
Entry Catalyst Activator/%
1
2
3
4
5
6
7
8
9
0
1
2
3
35
35
35
34
34
34
35
35
35
35
35
35
37
—
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
2
O
2
O
2
O
2
O
2
O
2
O
4.8
25.2 (R)
23.2 (R)
23 (R)
3.4 (R)
5.2 (R)
K
2
CO
3
(5%)
>99
>99
>99
12
>99
>99
54.2
91.6
>99
87.6
98.8
85.2%
1
2
3
35
34
37
TMAO (10%) 55.7
TMAO (10%) 96.2
TMAO (10%) 98.6
47.9 (35.6 R) 7.8 (35.8 R)
88.3 (25.8 R) 7.9 (26.4 R)
91.1 (34.2 R) 8.5 (32.6 R)
TMAO (1%)
—
K
2
CO
3
(5%)
TMAO (1%)
1% TMAO
1% TMAO
1% TMAO
1% TMAO
1% TMAO
1% TMAO
TMAO 1%
3.2 (R)
EtOAc
Toluene
THF
IPA
Neat
24.5 (R)
16.2 (R)
25.2 (R)
19.2 (R)
18.8 (R)
Further extension of the range of complexes for investi-
gation was achieved through the asymmetric synthesis of com-
plexes containing a single chiral centre and non-identical
1
1
1
1
tBuOH
19.6 (R) groups flanking the central CvO of the cyclone. This concept
2
IPA/H O
12 (R)
of planar chirality has been applied before in similar reduc-
9
c,14
tions
however the opportunity was taken to explore new
routes to the synthesis of Fe cyclone catalysts (Scheme 5).
hydroxyl groups in the ring fused to the cyclopentadienone)
worked without activation and indeed were less active in the
1
1
presence of K CO ; a trend we have noticed before. Further
2
3
solvents were tested (Table 5 and ESI†) and of these, EtOAc,
THF, IPA and tBuOH gave good but not improved results. A
reaction at 60 °C gave a lower conversion with no improvement
to the ee. A similar result was obtained using complex 37. In
ATH reactions (Table 6) the ee (26%) generated by the dibenzy-
loxy complex 34 was not as high as the 36% ee achieved using
the tetra OBn complex 35 however in both cases the reactions
in FA/TEA gave a higher ee than the hydrogenation reaction
with the same substrate. Although not fully purified, the bis-
OTBS-substituted complex 37 gave a product of ca. 34% ee in a
preliminary ATH test. Once again, the formate side-product
was of similar ee to the alcohol in each case.
Scheme 5 Synthesis of diastereoisomeric complexes 40 and 41.
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Fig. 4 X-ray crystallographic structures of complexes 40 and 41 respectively.
Addition of phenylacetylide anion to TMSCCCH CH CHO fol-
2
2
lowed by oxidation gave ketone 38 which was subsequently
reduced to 39 in 94–95% ee using ATH with both enantiomers
of tethered catalyst 23. Cyclisation of 39 gave a mixture of two
diastereomeric complexes 40 and 41 which were readily
resolved by flash chromatography on silica gel and character-
ised by X-ray crystallography to confirm the relative stereo-
chemistry in each isomer (Fig. 4). These create compounds
with planar chirality about the centre CvO of the cyclone
group.
Scheme 6 Synthesis of enantiomerically-enriched complexes via
a
In the reduction tests on acetophenone, both hydrogen- dynamic kinetic resolution.
ation and transfer hydrogenation (Table 7), the diastereoiso-
meric complexes 40 and 41 gave alcohols of opposite configur-
ation, indicating that the planar symmetry of the molecule could be separated by chromatography on silica gel
created the primary directing effect. However the enantio- (Scheme 6). The X-ray crystallographic structure of alcohol 45
selectivity was very low in all cases. Once again, for the hydro- was also obtained (Fig. 5), in order to confirm the endo
genation reaction, activation was required, with TMAO giving relationship of the alcohol to the iron centre, as would be
the best results.
anticipated from the expected addition of hydride to the face
unit due to steric
final class of asymmetric catalyst (Scheme 6); we prepared the hindrance.
bistrimethylsilyl (bisTMS) complex 42 (previously prepared by
Although TMS groups flank both sides of the central ketone
Pearson et al.), in racemic form from aldehyde 43 via ketone in this case, the asymmetric complexes provide the opportu-
4. Asymmetric reduction, following a precedent set by pre- nity to gauge the effect of distant chiral centres on any asym-
vious work in our group, with tethered catalyst 23, led to pre- metric induction. Both new catalysts were also tested in asym-
ferential reduction of one enantiomer of racemic 42 to leave metric reductions of acetophenone (Table 8) but gave only
enriched ketone 42 and alcohol 45, both in high ee, which moderate results, although it was reassuring to see the oppo-
A kinetic resolution approach was also used to prepare a of the ketone away from the Fe(CO)
3
1
5
2
c
4
1
5
Table 7 Asymmetric hydrogenation (entries 1–6) and ATH (entries 7 and 8) of acetophenone using complexes 40 and 41
Entry
Catalyst
Activator/%
Solvent
Conv./%
ee/%
1
2
3
4
5
6
40
40
40
41
41
41
—
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
2
O
2
O
2
O
2
O
2
O
2
O
4
68
99.7
11.9
82.3
99.8
5 (R)
K
2
CO
3
(5%)
7.4 (R)
6.2 (R)
11.4 (S)
11.6 (S)
12.2 (S)
TMAO (1%)
—
K
2
3
CO (5%)
TMAO (1%)
Entry
Catalyst
Activator/%
Solvent
Alcohol/% (ee/%)
Formate/% (ee/%)
7
8
40
41
TMAO (10%)
TMAO (10%)
FA/TEA
FA/TEA
91.1 (3.8 R)
88.4 (5.8 S)
8.1 (4 R)
9.9 (5.6 S)
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Fig. 5 Solid state structure of (−)-45 with atom labels and thermal ellip-
soids at 50% probability level.
site sense of induction between 42 and 45 in the asymmetric
hydrogenation reactions, as would be predicted on the basis of
planar chirality control. Although in reality they are too low to Fig. 6 (a) Hydrides formed from complexes 34, 35, 37, 40 and 41
indicate any significant directing effect.
respectively. (b) Likely modes of hydride transfer from complexes 46–50
based on literature precedents. (c) Transition state control model for
asymmetric hydride transfer from 46–48 to each face of the ketone
substrate (the ovals representing positions of the tilted aromatic rings)
Although the measured enantiomeric excesses are low,
some trends emerge from the data which suggest that the
steric bulk and substitution on the groups flanking the central
indicating
their
diastereomeric
nature
and
potential
for
CvO bond influence the process of asymmetric induction. enantiodifferentiation.
Hydrides 46–50 (Fig. 6a), formed through activation of 34, 35,
3
7, 40 and 41 respectively, are representative of those that
would be formed from the iron tricarbonyl precursors. defined and this leads in turn to improved differentiation of
Assuming that the proposed concerted mechanism for hydride the faces of the ketone in the reduction step.
transfer (illustrated in Fig. 6b for each complex) is operating,
In the case of 49 and 50, the complexes have a pseudo-
then our working model for 46–48 is that the tilt of the aro- planar chirality and in this case a similar differentiation of the
matic rings is influenced by the alkoxy groups on the 4-carbon faces of the ketone substrate can operate (not illustrated) due
backbone and this creates a chiral environment in the region to the difference in the steric bulk of the substituents either
where hydride transfer takes place (Fig. 6c). In turn this is side of the central CvO bond. This would be likely to dis-
likely to create a difference in the steric hindrance of one face favour approach from one face over the other sufficiently to
of the ketone to the complex relative to the other face, and has generate an enantioselectivity, and would account for the
in turn the potential to differentiate between addition of the reversal in enantioselectivity from 49 to 50.
hydride to the Re or Si face of the ketone substrate. The ees of
However the limited enantioselectivity may be the result of
the reduction products are generally higher using catalysts the significant distance from the groups flanking the central
with larger alkoxy groups on the 4-C backbone, which may CvO of the cyclopentadienone ring from the ketone substitu-
suggest that the ‘tilt’ of the aromatic rings is slightly better- ents in the proposed reduction model. Until this distance can
Table 8 Asymmetric hydrogenation (entries 1–6) and ATH (entry 7) of acetophenone using catalysts 42 and 45
Entry
Catalyst
Activator/%
Solvent
Conv./%
ee/%
1
2
3
4
5
6
45
45
45
42
42
42
—
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
IPA/H
2
O
2
O
2
O
2
O
2
O
2
O
13.7
99.4
99.6
>99
9.6
6.8 (S)
9.4 (S)
4.2 (S)
3.8 (R)
2.6 (R)
0.4 (R)
2 3
K CO (5%)
TMAO (10%)
—
K
2
CO
3
(5%)
TMAO (1%)
>99
Entry
7
Catalyst
42
Activator (%)
TMAO (10%)
Solvent
FA/TEA
Alcohol/% (ee/%)
3.9 (3.8 ee R)
Formate/% (ee/%)
24.2 (4 ee R)
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be closed, or the mechanism better understood, progress diol 15 (812 mg, 2.80 mmol) and 2-(bromomethyl)pyridine
towards high enantioselectivities with this class of catalyst will hydrobromide (1.56 g, 6.17 mmol) was dissolved/suspended in
3
remain challenging. The improved ees obtained using the ATH anhydrous THF (80 cm ). The mixture was cooled at 0 °C and
process also cannot be directly explained with the model in NaH (60% in mineral oil, 447 mg, 11.2 mmol) was added in
3
Fig. 6c, and suggest the operation of an additional directing small portions. After 19 hours, H O (100 cm ) was added drop-
2
effect by the solvent.
wise and the mixture was stirred 10 minutes. Then THF
In conclusion, we have completed the synthesis of a range of was removed and the product was extracted with DCM
3
enantiomerically-enriched cyclopentadienone iron tricarbonyl (3 × 100 cm ). The reunited organic layers were washed with
3
complexes through a range of diverse approaches, thus opening brine (50 cm ) and dried over MgSO
4
. The volatiles were
up routes to a range of valuable derivatives for testing as removed and the product was purified by flash chromato-
reduction and oxidation catalysts. Larger functional groups flank- graphy on silica gel (eluent: petroleum ether/EtOAc = 1 : 1 to
ing the central CvO bond in the catalyst appear to give improved petroleum ether/EtOAc = 1 : 4) to give 2,2′-((((3S,6S)-1,8-di-
enantioselectivities in reductions, however even the best enantio- phenylocta-1,7-diyne-3,6-diyl)bis(oxy))bis(methylene))dipyridine 16
meric excesses were relatively modest. Whilst the synthesis of the (1.27 g, 2.69 mmol, yield: 96%) as colourless solid.
2
5
3
iron-based catalysts was successful, the results indicate that sig- M.p. 64.2–66.4 °C. [α] −88.6 (c 0.50, CHCl ). IR(neat) 3058,
D
nificant work remains to be carried out in order to translate our 2966, 2931, 2893, 2868, 2836, 2220, 1591, 1571, 1489, 1476,
understanding of the mechanism to the synthesis of a highly 1457, 1441, 1388, 1343, 1329, 1299, 1242. δH (500 MHz,
enantioselective catalyst for the target applications. This remains CDCl
3
), 8.56 (2H, d, J = 4.9 Hz, PyH), 7.68 (2H, td, J = 7.7, 1.7
Hz, PyH), 7.51 (2H, d, J = 7.8 Hz, PyH), 7.40–7.46 (4H, m, ArH),
.23–7.34 (6H, m, ArH), 7.18 (2H, dd, J = 6.9, 5.3 Hz, PyH), 5.02
2H, d, J = 13.3 Hz, PyCHH), 4.74 (2H, d, J = 13.3 Hz, PyCHH),
.49–4.61 (2H, m, CHOR), 2.11–2.32 (4H, m, CH ).
the subject of ongoing studies in our group.
7
(
4
2
δ
C
Experimental section
General experimental methods
(
(
125 MHz, CDCl ), 158.4 (C), 148.9 (CH), 136.6 (CH), 131.8
CH), 128.4 (CH), 128.2 (CH), 122.5 (C), 122.3 (CH), 121.5 (CH),
3
8
7.4 (C), 86.5 (C), 71.5 (CH
2
), 69.8 (CH), 31.6 (CH
2
). m/z (ESI)
All solvents and reagents were degassed before use and all reac-
tions were carried out under a nitrogen atmosphere. Reactions
were monitored by TLC using aluminium backed silica gel
plates, visualized using UV 254 nm and phosphomolybdic acid
or potassium permanganate. Flash column chromatography
was carried out routinely on silica gel. Reagents and solvents
were used as received from commercial sources unless other-
wise stated. The synthesis of iron complexes was carried out in
ACE 15 Ml 150 psi pressure tested pressure tubes and heated in
aluminium heating blocks. Pressure hydrogenation reactions
+
+
[M + H] , 473.2; [M + Na] , 495.2. HRMS (ESI-Q-TOF) m/z: [M +
+
28 2 2
Na] calcd for C32H N O Na 495.2043; found 495.204.
Tricarbonyl-((4S,7S)-1,3-diphenyl-4,7-bis(pyridin-2-
ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one) iron 14.
1
were carried out in a Parr pressure vessel. H NMR spectra were
This compound is novel. In an ACE pressure tube under a
nitrogen atmosphere 2,2′-((((3S,6S)-1,8-diphenylocta-1,7-diyne-
recorded on a Bruker DPX (400 or 500 MHz) spectrometer.
Chemical shifts are reported in δ units, parts per million relative
to 7.26 ppm for chloroform and 0.00 ppm for TMS. Mass
spectra for analysis of synthetic products were recorded on a
Bruker Esquire 2000 or a Bruker MicroTOF mass spectrometer.
IR spectra were recorded on a PerkinElmer Spectrum One FT-IR
Golden Gate instrument. Melting points were recorded on a
Stuart Scientific SMP 1 instrument and are uncorrected.
3,6-diyl)bis(oxy))bis(methylene))dipyridine
16 (500 mg,
3
1.06 mmol) was dissolved in anhydrous toluene (5 cm ) pre-
viously degassed by freeze–pump–thaw cycles. Fe(CO)
5
3
(
0.79 cm , 5.86 mmol) was added, the pressure tube was
sealed and the mixture was heated at 130 °C. After 24 hours
the mixture was cooled to room temperature and the pressure
tube was carefully opened into the fumehood to release CO
pressure. Then the mixture was diluted with EtOAc (15 cm )
and filtered through a Celite plug washing through with EtOAc
2
,2′-((((3S,6S)-1,8-Diphenylocta-1,7-diyne-3,6-diyl)bis(oxy))bis
3
(methylene))dipyridine 16.
3
(
100 cm ). The volatiles were removed and the product was
purified by flash chromatography on silica gel (eluent: EtOAc
to EtOAc/MeOH = 9/1) to give tricarbonyl-((4S,7S)-1,3-diphenyl-
4,7-bis(pyridin-2-ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one)
iron 14 (485 mg, 0.76 mmol, yield: 72%) as an orange solid.
2
5
M.p. 55.6 °C dec. [α] +82.3 (c 0.52, CHCl
3
). IR(neat) 3056,
D
3
1
013, 2931, 2864, 2062, 1983, 1633, 1590, 1571, 1499, 1475,
435, 1388, 1362, 1329 cm− . δ
1
(500 MHz, CDCl ), 8.53 (1 H,
H 3
This compound is novel. In an round bottom flask under a dq, J = 4.9, 0.8 Hz, PyH), 8.47 (1 H, dq, J = 4.9, 0.6 Hz, PyH),
nitrogen atmosphere (3S,6S)-1,8-diphenylocta-1,7-diyne-3,6- 7.78–7.83 (2 H, m, ArH), 7.71–7.77 (2 H, m, ArH), 7.58 (1 H, td,
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J = 7.7, 1.7 Hz, PyH), 7.51 (1 H, td, J = 7.7, 1.7 Hz, PyH), 71.5 (C), 70.7, 69.3 (CH
2
), 69.1 (CH), 27.5 (CH
2
), 23.9 (CH
2
).
+
+
7
.27–7.42 (6 H, m, ArH), 7.18 (1 H, ddd, J = 7.3, 5.0, 0.8 Hz, m/z (ESI) [M + H] , 613.1; [M + Na] , 635.1. HRMS (ESI-Q-TOF)
+
2 5
PyH), 7.14 (1 H, ddd, J = 7.3, 5.0, 0.8 Hz, PyH), 7.03 (1 H, d, J = m/z: [M + H] calcd for C35H29FeN O 613.1421; found
7
3
.8 Hz, PyH), 6.71 (1 H, d, J = 7.8 Hz, PyH), 4.82 (1 H, t, J = 613.1427.
.2 Hz, CHOR), 4.73 (1 H, d, J = 12.1 Hz, PyCHH), 4.60 (1 H, d, 2,2′-((((3S,6S)-1,8-Diphenylocta-1,7-diyne-3,6-diyl)bis(oxy))bis
J = 12.1 Hz, PyCHH), 4.57 (1 H, d, J = 12.1 Hz, PyCHH), 4.52 (methylene))diquinoline 19.
1 H, t, J = 3.3 Hz, CHOR), 4.28 (1 H, d, J = 12.1 Hz, PyCHH),
(
2
.14–2.35 (3 H, m, CH ), 2.03–2.12 (1 H, m, CH ). δ (125 MHz,
2 2 C
3
CDCl ), 208.16 (C), 170.08 (C), 157.18 (C), 156.91 (C), 148.93
(
(
(
CH), 148.80 (CH), 136.60 (CH), 136.50 (CH), 131.23 (C), 131.06
C), 130.08 (CH), 129.71 (CH), 128.38 (CH), 128.34 (CH), 128.02
CH), 122.62 (CH), 122.52 (CH), 122.25 (CH), 121.69 (CH),
1
00.15 (C), 100.08 (C), 83.28 (C), 81.69 (C), 72.82 (CH
2
), 72.62
(
(
CH ), 70.80 (CH), 68.74 (CH), 22.09 (CH ), 21.98 (CH ). m/z
2
2
2
+
+
ESI) [M + H] , 641.1; [M + Na] , 663.1. HRMS (ESI-Q-TOF) m/z:
+
[M
+
Na] calcd for
63.1191.
Dicarbonyl-((4S,7S)-1,3-diphenyl-4,7-bis(pyridin-2-
ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one) iron 17.
36 2 6
C H28FeN O Na 663.1190; found
6
This compound is novel. In an round bottom flask under a
nitrogen atmosphere (3S,6S)-1,8-diphenylocta-1,7-diyne-3,6-
diol 15 (1.00 g, 3.44 mmol) was dissolved in anhydrous DMF
3
(
40 cm ). The mixture was cooled at 0 °C and NaH (60% in
This compound is novel. In an round bottom flask under a mineral oil, 826 mg, 20.65 mmol) was added in small por-
nitrogen atmosphere, tricarbonyl-((4S,7S)-1,3-diphenyl-4,7-bis tions. Then and 2-(chloromethyl)quinoline hydrochloride
(
pyridin-2-ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one) Iron (1.56 g, 7.94 mmol) was added in small portions and the
1
4 (500 mg, 0.78 mmol) was dissolved in anhydrous DCM reaction mixture was warmed at room temperature. After
3
3
3
(20 cm ). Then trimethylamine N-oxide (77 mg, 1.10 mmol) 24 hours, NH
4
Cl aqueous (30 cm ) and H
2
O (50 cm ) were
3
was added and the reaction mixture was stirred for 1 hour and added. The product was extracted with 3 × 150 cm and the
the volatiles were removed. The product was purified by flash reunited organic layers were washed with 3 × 100 cm of
3
chromatography on silica gel (eluent: hexane/EtOAc = 3 : 7 to
: 4) to give dicarbonyl-((4S,7S)-1,3-diphenyl-4,7-bis(pyridin-2- fied by flash chromatography on silica gel (eluent: pentane/
ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one) iron 17 (386 mg, EtOAc = 9 : 1 to 3 : 7) to give 2,2′-((((3S,6S)-1,8-diphenylocta-
2
H O. The volatiles were removed and the product was puri-
1
0
.63 mmol, yield: 81%) as orange solid. M.p. 150 °C dec. 1,7-diyne-3,6-diyl)bis(oxy))bis(methylene))diquinoline
19
2
5
−3
[α] +985.3 (c 6.8 × 10 , CHCl ). IR 3095, 3077, 3052, (1.52 g, 2.65 mmol, yield: 77%) as brown solid which was
(neat)
D
3
2
1
988, 2952, 2910, 1992, 1934, 1617, 1597, 1571, 1497, 1477, enough pure by NMR to be used without further purifi-
447, 1437, 1393, 1367, 1314, 1242 cm−1
cation. A sample for full characterisation was purified by
δH (500 MHz, CDCl ), 8.62 (1H, d, J = 5.0 Hz, PyH), 8.40 (1H, double crystallisation from hot hexane giving a white solid.
.
3
2
5
d, J = 4.3 Hz, PyH), 7.82–7.88 (2H, m, ArH), 7.48–7.58 (3H, m, M.p. 98.4–99.6 °C. [α] −148.0 (c 0.66, CHCl
3
). IR(neat) 3056,
× ArH and 1× PyH), 7.45 (1H, dd, J = 7.7, 1.7 Hz, PyH), 2961, 2937, 2868, 2228, 1735, 1709, 1616, 1596, 1561, 1503,
.20–7.32 (3H, m, ArH), 7.18 (1H, d, J = 6.9 Hz, PyH), 7.07 (1H, 1490, 1444, 1425, 1384, 1335, 1313, 1254, 1228, 1206.
(500 MHz, CDCl ), 8.13 (2H, d, J = 8.5 Hz, ArH), 8.05 (2H,
ddd, J = 7.3, 6.0, 1.4 Hz, PyH), 6.55 (1H, d, J = 7.8 Hz, PyH), d, J = 8.5 Hz, ArH), 7.78 (2H, d, J = 8.1 Hz, ArH), 7.64–7.73
.65 (1H, d, J = 13.0 Hz, PyCHH), 5.32 (1H, d, J = 4.4 Hz, (4H, m, ArH), 7.48–7.54 (2H, m, ArH), 7.38–7.44 (4H, m,
D
2
7
dd, J = 6.7, 5.2 Hz, PyH), 6.95–7.02 (3H, m, ArH), 6.76 (1H,
δ
H
3
5
CHOR), 4.71–4.79 (2H, m, 1× PyCHH and 1× CHOR), 4.42 (1H, ArH), 7.24–7.33 (6H, m, ArH), 5.17 (2H, d, J = 13.3 Hz,
d, J = 12.0 Hz, PyCHH), 3.93 (1H, d, J = 12.0 Hz, PyCHH), 2.65 ArCHH), 4.92 (2H, d, J = 13.3 Hz, ArCHH), 4.57–4.68 (2H, m,
(
1H, tt, J = 14.4, 3.0 Hz CHH), 2.54 (1H, tdd, J = 14.4, 5.6, 3.5 CHOR), 2.18–2.36 (4H, m, CH ). δ (125 MHz, CDCl ), 159.1
2 C 3
Hz CHH), 2.43 (1H, dq, J = 14.4, 3.0 Hz, CHH), 2.22–2.31 (1H, (C), 147.4 (C), 136.6 (CH), 131.8 (CH), 129.5 (CH), 128.9
m, CHH). δ (125 MHz, CDCl ), 217.0 (C), 211.6 (C), 168.7 (C), (CH), 128.4 (CH), 128.2 (CH), 127.6 (CH), 127.5 (C), 126.2
62.3 (C), 159.7 (CH), 157.5 (C), 148.5 (CH), 138.1 (CH), 136.4 (CH), 122.5 (C), 119.6 (CH), 87.5 (C), 86.7 (C), 72.2 (CH ),
C
3
1
2
+
+
2
(CH), 133.5 (C), 132.0 (C), 129.4 (CH), 128.3 (CH), 128.0 (CH), 70.0 (CH), 31.7 (CH ). m/z (ESI) [M + H] , 573.2; [M + Na] ,
+
1
1
27.7 (CH), 127.2 (CH), 126.0 (CH), 125.5 (CH), 124.6 (CH), 595.2. HRMS (ESI-Q-TOF) m/z: [M
22.3 (CH), 121.8 (CH), 99.4 (C), 82.7 (C), 81.7 (C), 73.1 (CH2), C40H33N O N 573.2537; found 573.2537.
+
H] calcd for
2
2
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3
Tricarbonyl-(4S,7S)-1,3-diphenyl-4,7-bis(quinolin-2-
ylmethoxy)-4,5,6,7-tetrahydro-2H-inden-2-one iron 18.
3.86 mmol) was dissolved in anhydrous THF (10 cm ). The
mixture was cooled at −78 °C and n-butyllithium (2.5 M in
hexanes, 1.55 cm , 3.88 mmol) was added dropwise. The
3
mixture was warmed to room temperature and stirred at this
temperature for 1 hour. Then the mixture was cooled to 0 °C
1
and transferred via cannula dropwise to a flask containing N ,
4
1
4
N -dimethoxy-N ,N -dimethylsuccinamide
1
21
(359
mg,
3
.76 mmol) dissolved/suspended in THF (15 cm ) at −78 °C.
After 5 minutes the mixture was warmed at room temperature
and stirred at this temperature for 90 minutes. Then the
This compound is novel. In an ACE pressure tube under a mixture was cooled to −40 °C and saturated NaHCO
aqueous
3
3
nitrogen atmosphere 2,2′-((((3S,6S)-1,8-diphenylocta-1,7-diyne- solution (10 cm ) was added. The mixture was warmed to
3
3
0
2
,6-diyl)bis(oxy))bis(methylene))diquinoline 19 (400 mg, room temperature and H O (30 cm ) was added. The product
3
3
.70 mmol) was dissolved in anhydrous toluene (5 cm ) pre- was extracted with DCM (3 × 50 cm ) and the reunited organic
3
viously degassed by freeze–pump–thaw cycles. Fe(CO)
(
5
layers were washed with brine (50 cm ) and dried over Na
0.47 cm , 3.49 mmol) was added, the pressure tube was The volatiles were removed and the product was purified by
2 4
SO .
3
sealed and the mixture was heated at 130 °C. After 22 hours filtration through a silica plug washing with DCM to give
the mixture was cooled to room temperature and the pressure 1,8-bis(2-methoxyphenyl)octa-1,7-diyne-3,6-dione 22 (458 mg,
tube was carefully opened into the fumehood to release CO 1.32 mmol, yield: 80%) as colourless solid.
3
pressure. Then the mixture was diluted with EtOAc (15 cm )
M.p. 128.8–130.1 °C. IR(neat) 2983, 2948, 2919, 2840, 2183,
and filtered through a Celite plug washing through with EtOAc 1656, 1593, 1569, 1488, 1460, 1427, 1402, 1314, 1282, 1252,
3
−1
(
100 cm ). The volatiles were removed and the product was 1216 cm . δ
purified by flash chromatography on silica gel (eluent: ArH), 7.39–7.46 (2H, m, ArH), 6.85–6.99 (4H, m, ArH), 3.90 (6H,
pentane/EtOAc = 1 : 1 to 3 : 7) to give tricarbonyl-(4S,7S)-1,3- s, CH ), 3.15 (4H, s, CH ). δ (125 MHz, CDCl ), 185.4 (C),
diphenyl-4,7-bis(quinolin-2-ylmethoxy)-4,5,6,7-tetrahydro-2H- 161.6 (C), 135.0 (CH), 132.6 (CH), 120.6 (CH), 110.8 (CH), 109.0
inden-2-one iron 18 (244 mg, 0.33 mmol, 47%) as yellow/ (C), 91.5 (C), 89.1 (C), 55.8 (CH ), 39.2 (CH ). m/z (ESI)
). [M + Na] 369.0. HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for
IR(neat) 3056, 2930, 2862, 2064, 2011, 1988, 1733, 1633, 1599,
Na 369.1097; found 369.1094.
(3S,6S)-1,8-Bis(2-methoxyphenyl)octa-1,7-diyne-3,6-diol 24.
H 3
(500 MHz, CDCl ), 7.52 (2H, dd, J = 7.5, 1.2 Hz,
3
2
C
3
3
2
orange solid. M.p. 74.7 °C dec. [α]2 +23.0 (c 0.10, CHCl
5
D
+
+
3
22 18 4
C H O
565, 1501, 1442, 1427, 1364, 1311, 1218, 1070 cm−
.
1
1
δH (500 MHz, CDCl ), 7.91–8.07 (4H, m, ArH), 7.75–7.82 (6H,
3
m, ArH), 7.63–7.75 (2H, m, ArH), 7.49–7.58 (2H, m, ArH),
7
.27–7.39 (6H, m, ArH), 7.08 (1H, d, J = 8.4 Hz, ArH), 6.75 (1H,
d, J = 8.4 Hz, ArH), 4.85–4.95 (2H, m, 1× CHOR and 1×
ArCHH), 4.76 (2H, dd, J = 15.2, 12.1 Hz, ArCHH), 4.60–4.65
(1H, m, CHOR), 4.47 (1H, d, J = 12.1 Hz, ArCHH), 2.18–2.40
(
3H, m, CH ), 2.08–2.15 (1H, m, CH ); δ (125 MHz, CDCl3),
2
2
C
2
1
08.2 (C), 170.1 (C), 157.7 (C), 157.4 (C), 147.3 (C), 147.2 (C),
36.6 (CH), 136.5 (CH), 131.2 (C), 131.1 (C), 130.2 (CH), 129.64 This compound is novel. In an round bottom flask under a
(
(
(
CH), 129.57 (CH), 129.0 (CH), 128.9 (CH), 128.44 (CH), 128.40 nitrogen atmosphere 1,8-bis(2-methoxyphenyl)octa-1,7-diyne-
CH), 128.1 (CH), 127.6 (CH), 127.53 (C), 127.50 (C), 126.5 3,6-dione 22 (450 mg, 1.30 mmol) was dissolved in anhydrous
3
CH), 126.4 (CH), 120.1 (CH), 119.5 (CH), 100.2 (C), 100.0 (C), DCM (1.5 cm ). [(S,S)-Teth-TsDpen-RuCl] 23 (8 mg,
8
(
[
3.5 (C), 81.6 (C), 73.4 (CH ), 73.3 (CH ), 71.0 (CH), 69.0 0.013 mmol) and an azeotropic mixture of formic acid/triethyl-
2 2
+
3
CH), 22.2 (CH ), 22.1 (CH ). m/z (ESI) [M + H] , 741.2; amine (5 : 2 mixture, 1.5 cm ) were added. After 26 hours, satu-
2 2
+
+
3
3
M + Na] , 763.2. HRMS (ESI-Q-TOF) m/z: [M + H] calcd for rated NaHCO aqueous solution (5 cm ) and H O (5 cm ) were
3
2
C H FeN O 741.1683; found 741.1670.
added and the mixture was stirred 30 minutes. The product
4
4
33
2 6
3
1
,8-Bis(2-methoxyphenyl)octa-1,7-diyne-3,6-dione 22.
was extracted with DCM (3 × 20 cm ). The reunited organic
3
layers were washed with brine (15 cm ) and dried over Na SO .
2
4
The volatiles were removed and the product was purified by
flash chromatography on silica gel (eluent: petroleum ether/
EtOAc = 7 : 3 to 3 : 7) to give (3S,6S)-1,8-bis(2-methoxyphenyl)
octa-1,7-diyne-3,6-diol 24 (438 mg, 1.25 mmol, yield: 96%, dr =
98.3 : 1.7, >99% ee) as colourless solid. The enantiomeric and
diastereomeric excess were determined by HPLC analysis with
a ChiralPak IB column: 0.46 cm × 25 cm, mobile phase
This compound is novel. In a round bottom flask under a EtOAc : hexane 3 : 2, flow rate 1 mL min− , temperature 30 °C,
1
3
nitrogen atmosphere 1-ethynyl-2-methoxybenzene 20 (0.5 cm , UV detection at λ = 254 nm; tR = 6.4 min (R,R), tR = 11.8 min
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(
(
2
1
7
R,S), t
c 0.62, CHCl ). IR
R
= 22.9 min (S,S). M.p. 113.3–114.8 °C. [α]25 −16.8 and the mixture was stirred 30 minutes. The product was
D
3
3489, 3070, 3021, 2968, 2948, 2892, extracted with DCM (3 × 10 cm ). The reunited organic layers
3
(neat)
3
867, 2838, 2226, 1596, 1574, 1488, 1428, 1406, 1346, 1316, were washed with brine (10 cm ) and dried over Mg
2
SO
), 7.40 (2H, dd, J = volatiles were removed and the product was purified by fil-
.6, 1.6 Hz, ArH), 7.29 (2H, ddd, J = 8.4, 7.5, 1.7 Hz, ArH), 6.90 tration through a silica plug washing with EtOAc to give 1,8-bis
4
. The
−
1
H 3
257, 1232, 1205 cm . δ (500 MHz, CDCl
(
(
2H, dd, J = 7.5, 0.8 Hz, ArH), 6.87 (2H, d, J = 8.4 Hz, ArH), 4.83 (2-methoxyphenyl)octa-1,7-diyne-3,6-diol
24
(46
(500 MHz,
mg,
2H, q, J = 4.7 Hz, CHOH), 3.88 (6H, s, CH
3
), 2.64 (2H, d, J = 0.13 mmol, yield: 90.9%) as light brown solid. δ
H
5
.6 Hz, OH), 2.06–2.24 (4H, m, CH2).
(125 MHz, CDCl ), 160.0 (C), 133.6 (CH), 129.9 (CH), 6.84–6.92 (8H, m, ArH), 4.82 (1.7H, br. s., CHOH), 4.76 (2.3H,
20.4 (CH), 111.7 (C), 110.6 (CH), 94.0 (C), 81.5 (C), 62.6 (CH), br. s., CHOH), 3.88 (12H, d, J = 5.2 Hz, CH ), 3.03 (2H, d, J =
5.7 (CH ), 33.4 (CH ). m/z (ESI) [M + Na] 373.1. HRMS 5.5 Hz, OH), 2.69 (2H, d, J = 2.7 Hz, OH), 2.06–2.25 (8H, m,
CDCl ), 7.37–7.42 (4H, m, ArH), 7.26–7.32 (4H, m, ArH),
3
δ
C
3
1
5
3
+
3
2
+
(
ESI-Q-TOF) m/z: [M + Na] calcd for C22
found 373.1403.
3R,6R)-1,8-Bis(2-methoxyphenyl)octa-1,7-diyne-3,6-diol 24.
22 4 2 C 3
H O Na 373.1410; CH ). δ (125 MHz, CDCl ), 160.05 (C), 160.03 (C), 133.6 (CH),
133.5 (CH), 129.9 (CH), 120.45 (CH), 120.42 (CH), 111.7 (C),
110.6 (CH), 94.1 (C), 94.0 (C), 81.6 (C), 81.4 (C), 62.8 (CH), 62.6
(
(
3 3 2 2
CH), 55.72 (CH ), 55.69 (CH ), 33.9 (CH ), 33.3 (CH ).
Tricarbonyl-(4S,7S)-4,7-dihydroxy-1,3-bis(2-methoxyphenyl)-
,5,6,7-tetrahydro-2H-inden-2-one iron 26.
4
This compound is novel. In an round bottom flask under a
nitrogen atmosphere 1,8-bis(2-methoxyphenyl)octa-1,7-diyne-
3
,6-dione 22 (100 mg, 0.29 mmol) was dissolved in anhydrous This compound is novel. In an ACE pressure tube under a
3
DCM (1.0 cm ). [(R,R)-Teth-TsDpen-RuCl] 23 (1.8 mg, nitrogen atmosphere (3S,6S)-1,8-bis(2-methoxyphenyl)octa-1,7-
.0029 mmol) and an azeotropic mixture of formic acid/tri- diyne-3,6-diol 24 (190 mg, 0.54 mmol) was dissolved/sus-
0
3
3
ethylamine (5 : 2 mixture, 0.5 cm ) were added. After 26 hours pended in anhydrous toluene (5 cm ) previously degassed by
saturated NaHCO aqueous solution (5 cm ) and H O (5 cm ) freeze–pump–thaw cycles. Fe(CO) (0.37 cm , 2.74 mmol) was
3
3
3
3
2
5
were added and the mixture was stirred 30 minutes. The added, the pressure tube was sealed and the mixture was
3
product was extracted with DCM (3 × 20 cm ). The reunited heated at 130 °C for 24 hours. After the mixture was cooled to
3
organic layers were washed with brine (15 cm ) and dried over room temperature and the pressure tube was carefully opened
2 4
Na SO . The volatiles were removed and the product was puri- into the fumehood to release CO pressure. Then the mixture
3
fied by flash chromatography on silica gel (eluent: petroleum was diluted with EtOAc (15 cm ) and filtered through a Celite
3
ether/EtOAc = 7 : 3 to 3 : 7) to give (3R,6R)-1,8-bis(2-methoxy- plug washing through with EtOAc (100 cm ). The volatiles were
phenyl)octa-1,7-diyne-3,6-diol 24 (78 mg, 0.22 mmol, yield: removed and the product was purified by flash chromato-
7
7%, dr = 98.1 : 1.9, >99% ee) as colourless solid. The enantio- graphy on silica gel (eluent: pentane/EtOAc = 7 : 3 to 1 : 4) to
meric and diastereomeric excess were determined by HPLC give
tricarbonyl-(4S,7S)-4,7-dihydroxy-1,3-bis(2-methoxyphe-
analysis with a ChiralPak IB column: 0.46 cm × 25 cm, mobile nyl)-4,5,6,7-tetrahydro-2H-inden-2-one iron 26 (193 mg,
−
1
phase EtOAc : hexane 3 : 2, flow rate 1 mL min , temperature 0.37 mmol, yield: 69%) as yellow solid. M.p. 183.0–184.0 °C.
2
5
3
0 °C, UV detection at λ = 254 nm; t = 6.4 min (R,R), tR
=
[α] −88.8 (c 0.49, CHCl ). IR
3367 (broad), 3077, 3008,
(neat)
R
D
3
2
5
1
1.8 min (R,S), t
R
= 22.9 min (S,S). [α] +16.6 (c 0.46, CHCl
3
).
2936, 2856, 2837, 2071, 2027, 1979, 1737, 1625, 1600, 1497,
D
1
1
,8-Bis(2-methoxyphenyl)octa-1,7-diyne-3,6-diol 24.
1466, 1435, 1388, 1310, 1278, 1244 cm− . δH (500 MHz, CDCl3),
7
.69 (1H, dd, J = 7.6, 1.0 Hz, ArH), 7.43 (1H, dd, J = 7.5, 1.2 Hz,
ArH), 7.33–7.41 (2H, m, ArH), 6.95–7.10 (4H, m, ArH),
.91–5.00 (1H, m, CHOH), 4.76–4.83 (1H, m, CHOH), 3.904
3H, s, CH ), 3.895 (3H, s, CH ), 2.80 (1H, d, J = 1.4 Hz, OH),
4
(
3
3
2
.42 (1H, d, J = 3.2 Hz, OH), 2.22–2.35 (2H, m, CH
(125 MHz, CDCl
08.5 (C), 169.1 (C), 157.0 (C), 156.5 (C), 134.4 (CH), 133.1
2
), 1.75–1.88
(
1H, m, CHH), 1.56–1.71 (1H, m, CHH). δ
C
3
),
2
(
CH), 130.3 (CH), 130.2 (CH), 121.7 (CH), 121.2 (CH), 119.98
This compound is novel. In an round bottom flask under a (C), 118.96 (C), 111.8 (CH), 111.6 (CH), 105.1 (C), 104.5 (C),
nitrogen atmosphere 1,8-bis(2-methoxyphenyl)octa-1,7-diyne- 80.1 (C), 79.1 (C), 63.7 (CH), 63.5 (CH), 55.7 (CH ), 55.5 (CH ),
3
3
+
+
3
1
,6-dione 22 (50 mg, 0.14 mmol) was dissolved in DCM/MeOH 28.5 (CH
2
), 28.3 (CH
2
). m/z (ESI) [M + H] 519.0; [M + Na]
3
+
: 1 (2 cm ). NaBH
4
(14 mg, 0.37 mmol) was added and the 540.9. HRMS (ESI-Q-TOF) m/z: [M
+
Na] calcd for
3
reaction was stirred for 2 hours. Then H O (10 cm ) was added C H FeO Na 541.0556; found 541.0558.
2
26 22
8
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2
,2′-((3S,6S)-3,6-Bis(benzyloxy)octa-1,7-diyne-1,8-diyl)bis
was cooled to room temperature and the pressure tube was
carefully opened into the fumehood to release CO pressure.
(
methoxybenzene) 25.
3
Then the mixture was diluted with EtOAc (15 cm ) and filtered
3
through a Celite plug washing through with EtOAc (100 cm ).
The volatiles were removed and the product was purified by
flash chromatography on silica gel (eluent: hexane to hexane/
EtOAc = 1 : 1) to give tricarbonyl-(4S,7S)-4,7-bis(benzyloxy)-1,3-
bis(2-methoxyphenyl)-4,5,6,7-tetrahydro-2-2H-inden-2-one iron
2
7 (85 mg, 0.12 mmol, yield: 20%) as yellow solid. M.
2
5
p. 148.0–149.0 °C. [α] −123.4 (c 0.23, CHCl
3
). IR(neat) 3059,
D
3
1
029, 2996, 2930, 2900, 2834, 2061, 2008, 1987, 1632, 1586,
562, 1484, 1456, 1421, 1344, 1312, 1239 cm−
(500 MHz, CDCl ), 7.93 (1H, d, J = 5.2 Hz, ArH),
.27–7.39 (3H, m, ArH), 7.09–7.22 (6H, m, ArH), 6.95–7.07 (2H,
1
.
δ
H
3
7
This compound is novel. In an round bottom flask under a
nitrogen atmosphere (3S,6S)-1,8-bis(2-methoxyphenyl)octa-1,7-
diyne-3,6-diol 24 (383 mg, 1.09 mmol) was dissolved in anhy-
m, ArH), 6.84–6.94 (2H, m, ArH), 6.69 (4H, d, J = 7.2 Hz, ArH),
.70–4.77 (1H, m, CHOR), 4.62–4.69 (1H, m, CHOR), 4.43 (1H,
d, J = 11.0 Hz, CHH), 4.34 (1H, d, J = 10.5 Hz, CHH), 4.22 (1H,
d, J = 11.0 Hz, CHH), 4.07 (1H, d, J = 10.5 Hz, CHH), 3.84 (3H,
4
3
drous THF (10 cm ) and NaH (60% in mineral oil, 109 mg,
2
.72 mmol) was added in small portions. After 30 minutes,
s, CH
.83–1.95 (1H, m, CHH), 1.65–1.77 (1H, m, CHH).
(125 MHz, CDCl ), 209.0 (C), 157.4 (C), 156.5 (C), 137.3 (C),
3 3 2
), 3.79 (3H, br. s., CH ), 2.27–2.45 (2H, m, CH ),
3
benzyl bromide (0.29 cm , 2.44 mmol) and tetrabutyl-
1
ammonium iodide (158 mg, 0.43 mmol) were added. After
δ
C
3
3
2
4 hours, saturated aqueous NH
4
Cl solution (50 cm ) was
1
1
1
7
2
33.1 (CH), 129.4 (CH), 129.3 (CH), 128.2 (CH), 127.9 (CH),
27.68 (CH), 127.67 (CH), 127.63 (CH), 127.3 (CH), 120.5 (CH),
3
added and the product was extracted with DCM (3 × 50 cm ).
The reunited organic layers were washed with brine (50 cm )
3
19.88 (C), 119.83 (C), 110.9 (CH), 71.8 (CH
2
), 71.38 (CH
), 25.5 (CH
2
),
),
and dried over MgSO
product was purified by flash chromatography on silica gel
eluent: petroleum ether/EtOAc = 9 : 1) to give 2,2′-((3S,6S)-3,6-
bis(benzyloxy)octa-1,7-diyne-1,8-diyl)bis(methoxybenzene) 25
4
. The volatiles were removed and the
1.36 (CH), 70.3 (br., CH), 55.2 (CH ), 54.5 (CH
3
3
2
+
+
4.7 (CH ). m/z (ESI) [M + H] 699.0; [M + Na] 721.0.
HRMS (ESI-Q-TOF) m/z: [M + H] calcd for C40
2
(
+
H
35FeO
8
699.1676; found 699.1685.
3
0
(
511 mg, 0.96 mmol, 88%) as yellow oil. [α] −133.4 (c 0.515,
D
1,8-Bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-1,7-
diyne-3,6-dione 28.
CHCl ). IR
1
3062, 3029, 3004, 2961, 2934, 2836, 2224, 1596,
3
(neat)
575, 1547, 1492, 1454, 1434, 1333, 1291, 1261 cm−
1
.
δ
H
(500 MHz, CDCl
3
), 7.41 (6H, d, J = 7.5 Hz, ArH), 7.33 (4H, t,
J = 7.4 Hz, ArH), 7.24–7.30 (4H, m, ArH), 6.83–6.92 (4H, m,
ArH), 4.89 (2H, d, J = 11.7 Hz, PhCHH), 4.62 (2H, d, J =
1
1.7 Hz, PhCHH), 4.40–4.48 (2H, m, CHOR), 3.85 (6H, s, CH
3
),
2
.06–2.24 (4H, m, CH ). δ (125 MHz, CDCl ), 160.2 (C), 138.2
2
C
3
(
1
6
C), 133.5 (CH), 129.7 (CH), 128.3 (CH), 128.1 (CH), 127.5 (CH),
This compound is novel. In an round bottom flask under a
nitrogen atmosphere 2-(2-ethynylphenoxy)tetrahydro-2H-pyran
29 (6.76 g, 33.42 mmol) was dissolved in anhydrous THF
20.3 (CH), 112.0 (C), 110.6 (CH), 92.2 (C), 82.5 (C), 70.3 (CH
2
),
+
9.0 (CH), 55.6 (CH ), 31.7 (CH ). m/z (ESI) [M + Na] , 553.1.
3
2
+
HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for C36
53.2349; found 553.2344.
Tricarbonyl-(4S,7S)-4,7-bis(benzyloxy)-1,3-bis(2-methoxyphe-
nyl)-4,5,6,7-tetrahydro-2-2H-inden-2-one iron 27.
H
34
O
4
Na
3
(
100 cm ). The mixture was cooled at −78 °C and n-butyl-
5
3
lithium (2.5 M in hexanes, 14 cm , 35.00 mmol) was added
dropwise over a period of 15 minutes. The mixture was
warmed to −40 °C and stirred at this temperature for
3
0 minutes. Then the mixture was transferred via cannula
1
4
1
4
dropwise to a flask containing N ,N -dimethoxy-N ,N -di-
methylsuccinamide 21 (3.1 g, 15.18 mmol) dissolved/sus-
pended in THF (80 cm ) at −78 °C. After 5 minutes the
3
mixture was warmed at 0 °C and stirred at this temperature for
3
0 minutes. Then the mixture was cooled to −40 °C and satu-
3
This compound is novel. In an ACE pressure tube under a rated NaHCO3 aqueous solution (100 cm ) was added. The
nitrogen atmosphere 2,2′-((3S,6S)-3,6-bis(benzyloxy)octa-1,7- mixture was warmed to room temperature and H O (200 cm )
2
diyne-1,8-diyl)bis(methoxybenzene) 25 (323 mg, 0.61 mmol) was added. The product was extracted with DCM (3 × 500 cm )
was dissolved in anhydrous toluene (5 cm ) previously and the reunited organic layers were dried over Na SO . The
3
3
3
2
4
3
degassed by freeze–pump–thaw cycles. Fe(CO)
.04 mmol) was added, the pressure tube was sealed and the chromatography on silica gel (eluent: hexane/DCM = 1 : 1 to
mixture was heated at 130 °C for 18 hours. After the mixture DCM/EtOAc = 4 : 1) to give 1,8-bis(2-((tetrahydro-2H-pyran-2-yl)
5
(0.40 cm , volatiles were removed and the product was purified by flash
3
Dalton Trans.
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oxy)phenyl)octa-1,7-diyne-3,6-dione 28 (6.46 g, 13.27 mmol, This compound is novel. In an round bottom flask under a
yield: 87%) as a white solid. M.p. 127.6–129.4 °C. IR(neat) 2965, nitrogen atmosphere 1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy)
2
1
7
8
3
2
1
1
940, 2874, 2859, 2193, 1662, 1595, 1572, 1486, 1447, 1405, phenyl)octa-1,7-diyne-3,6-dione 28 (2.0 g, 4.11 mmol) was dis-
388, 1355, 1316, 1283, 1251, 1203 cm . δ (500 MHz, CDCl ), solved/suspended in anhydrous DCM (7 cm ). [(S,S)-Teth-
H 3
−
1
3
.52 (2H, dd, J = 7.6, 1.5 Hz), 7.35–7.43 (2H, m), 7.17 (2H, d, J = TsDpen-RuCl] 23 (26 mg, 0.042 mmol) and an azeotropic
3
.4 Hz), 6.98 (2H, td, J = 7.6, 0.6 Hz), 5.56 (2H, t, J = 2.7 Hz), mixture of formic acid/triethylamine (5 : 2 mixture, 5.0 cm )
.90 (2H, td, J = 11.1, 2.7 Hz), 3.56–3.66 (1H, m), 3.13 (4H, s), were added. After 22 hours saturated NaHCO
3
aqueous solu-
3
3
.03–2.15 (2H, m), 1.95–2.03 (2H, m), 1.84–1.93 (2H, m), tion (50 cm ) and H O (50 cm ) were added and the mixture
2
.59–1.76 (6H, m). δ
C 3
(125 MHz, CDCl ), 185.1 (C), 159.1 (C), was stirred 30 minutes. The product was extracted with DCM
3
34.7 (CH), 132.5 (CH), 121.5 (CH), 115.1 (CH), 110.1 (C), 96.4 (3 × 150 cm ). The reunited organic layers were washed with
3
(
(
CH), 91.4 (C), 89.1 (C), 61.8 (CH ), 39.2 (CH ), 30.1 (CH ), 25.1 brine (100 cm ) and dried over MgSO . The volatiles were
2 2 2 4
CH
+
2
), 18.2 (CH
2
). m/z (ESI) [M + Na] 509.2. HRMS (ESI-TOF) removed and the product was purified by flash chromato-
Na 509.1935; found 509.1928. graphy on silica gel (eluent: petroleum ether/EtOAc = 7 : 3 to
+
30 6
m/z: [M + Na] calcd for C30H O
1
,8-Bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-1,7-
1 : 1) to give (3S,6S)-1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy)
phenyl)octa-1,7-diyne-3,6-diol 30 (1.95 g, 3.99 mmol, yield:
diyne-3,6-diol 30.
96.7%, dr = 98.3 : 1.7, >99% ee) as a sticky colourless solid.
The enantiomeric and diastereomeric excess were determined
by HPLC analysis with a ChiralPak IB column: 0.46 cm ×
2
5 cm, mobile phase EtOAc : hexane 7 : 3, flow rate 1 mL
−
1
min , temperature 30 °C, UV detection at λ = 254 nm; tR
=
=
1
2
3
1
3.4 and 13.9 min (R,R), t
6.2, 28.3 and 30.2 min (S,S). [α] −0.58 (c 1.3, CHCl
R R
= 16.2, 16.6 and 17.2 min (R,S), t
2
5
3
). IR(neat)
D
400 (br), 2942, 2869, 2853, 2228, 1596, 1574, 1488 1445, 1389,
356, 1326, 1285, 1254, 1229, 1200, 1182 cm− . δ
1
(500 MHz,
H
This compound is novel. In an round bottom flask under a
nitrogen atmosphere 1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy)
CDCl
3
), 7.37 (2H, d, J = 7.6 Hz, ArH), 7.24 (2H, t, J = 8.3 Hz,
ArH), 7.10 (2H, d, J = 8.4 Hz, ArH), 6.92 (2H, t, J = 7.5 Hz, ArH),
5.50 (2H, br. s., CH), 4.78 (2H, br. s., CHOH), 3.85–4.02 (2H, m,
CHH), 3.50–3.65 (2H, m, CHH), 2.74 (2H, br. d, OH), 1.99–2.23
phenyl)octa-1,7-diyne-3,6-dione 28 (110 mg, 0.23 mmol) was
3
dissolved/suspended in DCM/MeOH (1 : 1, 3 cm ). NaBH
4
3
(
26 mg, 0.69 mg) was added. After 4 hours H O (10 cm ) was
2
(
6H, m, CH ), 1.90–1.99 (2H, m, CH ), 1.81–1.90 (2H, m, CH ),
2 2 2
added and the mixture was stirred 30 minutes. The product
3
2 C 3
1.50–1.73 (6H, m, CH ) δ (125 MHz, CDCl ), 157.5 (C), 133.25
was extracted with DCM (3 × 15 cm ). The volatiles were
(
(
CH), 133.23 (CH), 129.7 (CH), 121.4 (CH), 115.54 (CH), 115.50
CH), 113.07 (C), 113.05 (C), 96.7 (CH), 93.5 (C), 81.61 (C),
removed and the product was purified by flash chromato-
graphy on silica gel (eluent: hexane/EtOAc = 1 : 4 to 3 : 2) to
8
(
(
1.59 (C), 62.54 (CH
CH ), 25.1 (CH ), 18.5 (CH
ESI-Q-TOF) m/z: [M + Na] calcd for C H O Na 513.2248;
2
), 62.52 (CH), 61.9 (CH
2 2
), 33.3 (CH ), 30.2
give
diyne-3,6-diol 30 (83 mg, 0.17 mmol, yield: 74.8%) as sticky
colourless solid. δ (500 MHz, CDCl ), 7.37 (4H, d, J = 7.6 Hz,
ArH), 7.20–7.28 (4H, m, ArH), 7.10 (4H, d, J = 8.2 Hz, ArH), 6.92
4H, t, J = 7.6 Hz, ArH), 5.49 (4H, br. s., CH), 4.62–4.83 (4H, 2
1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-1,7-
+
2
2
2
). m/z (ESI) [M + Na] 513.1. HRMS
+
30
34 6
H
3
found 513.2254.
(
3R,6R)-1,8-Bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-
(
1,7-diyne-3,6-diol 30.
overlapping br. s. at 4.78 and 4.74, CHOH), 3.82–4.04 (4H, m,
CHH), 3.47–3.68 (4H, m, CHH), 2.62–2.85 (4H, m, OH),
1
.52–2.24 (32H, m, CH ). δC (125 MHz, CDCl ), 157.6 (C),
2 3
1
33.24 (CH), 133.21 (CH), 129.7 (CH), 121.48 (CH), 121.45
(
(
CH), 115.6 (CH), 115.52 (CH), 115.51 (CH), 113.10 (C), 113.07
C), 96.72 (CH), 96.68 (CH), 96.66 (CH), 93.56 (C), 93.46 (C),
8
2 2 2 2
1.6 (C), 62.70 (CH ), 62.68 (CH ), 62.55 (CH ), 62.54 (CH ),
6
2.96 (CH ), 61.94 (CH ), 33.80 (CH ), 33.77 (CH ), 33.74
2
2
2
2
(
CH ), 33.4 (CH ), 30.2 (CH ), 25.1 (CH ), 18.5 (CH ).
2 2 2 2 2
This compound is novel. In an round bottom flask under a
nitrogen atmosphere 1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy)
phenyl)octa-1,7-diyne-3,6-dione 28 (150 mg, 0.31 mmol) was
(3S,6S)-1,8-Bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-
1
,7-diyne-3,6-diol 30.
3
dissolved/suspended in anhydrous DCM (1.0 cm ). [(R,R)-Teth-
TsDpen-RuCl] 23 (1.9 mg, 0.003 mmol) and an azeotropic
3
mixture of formic acid/triethylamine (5 : 2 mixture, 0.5 cm )
were added. After 23 hours saturated NaHCO aqueous solu-
3
3
3
tion (5 cm ) and H
2
O (10 cm ) were added and the mixture
was stirred 30 minutes. The product was extracted with DCM
3
(
3 × 20 cm ). The reunited organic layers were washed with
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3
3
brine (20 cm ) and dried over MgSO
4
. The volatiles were 0.62 mmol) was dissolved in anhydrous DMF (2 cm ). Benzyl
3
removed and the product was purified by flash chromato- bromide (0.17 cm , 1.43 mmol) and anhydrous potassium car-
graphy on silica gel (eluent: petroleum ether/EtOAc = 7 : 3 to bonate (214 mg, 1.55 mmol) were added and the mixture was
1
: 1) to give (3R,6R)-1,8-bis(2-((tetrahydro-2H-pyran-2-yl)oxy) heated to 85 °C. After 17 hours, the mixture was cooled to
3
phenyl)octa-1,7-diyne-3,6-diol 31 (146 mg, 0.30 mmol, yield: room temperature and H O (15 cm ) was added. The product
2
3
9
6%, dr = 98.4 : 1.6, >99% ee) as a sticky colourless solid. The was extracted with DCM (20 cm ) and the organic layer was
3
3
2
enantiomeric and diastereomeric excess were determined by washed with H O (15 cm ) and brine (15 cm ). The volatiles
HPLC analysis with a ChiralPak IB column: 0.46 cm × 25 cm, were removed and the product was purified by flash chromato-
mobile phase EtOAc : hexane 7 : 3, flow rate 1 mL min− , temp- graphy on silica gel (eluent: hexane/EtOAc = 3 : 7 to 1 : 4) to
1
erature 30 °C, UV detection at λ = 254 nm; t
R
= 13.4 and give (3S,6S)-1,8-bis(2-(benzyloxy)phenyl)octa-1,7-diyne-3,6-diol
1
2
3.9 min (R,R), tR = 16.2, 16.6 and 17.2 min (R,S), t = 26.2, 32 (231 mg, 0.46 mmol, yield: 74%) as colourless solid.
8.3 and 30.2 min (S,S). H and C NMR were identical to the M.p. 122.3–123.5 °C. [α]D −15.5 (c 0.10, CH CN). IR(neat) 3257
3
R
1
13
27
reported data for (3S,6S)-1,8-bis(2-((tetrahydro-2H-pyran-2-yl) (broad), 3078, 3033, 2951, 2900, 2859, 1599, 1575, 1494, 1444,
2
7
−1
oxy)phenyl)octa-1,7-diyne-3,6-diol. [α] +0.58 (c 1.8, CHCl3).
(
1414, 1377, 1312, 1290, 1281, 1264, 1241 cm . δH (500 MHz,
CD CN), 7.48 (4H, d, J = 7.6 Hz, ArH), 7.36 (6H, ddd, J = 7.6,
D
3S,6S)-1,8-Bis(2-hydroxyphenyl)octa-1,7-diyne-3,6-diol 31.
3
4
8
.7, 3.1 Hz, ArH), 7.23–7.32 (4H, m, ArH), 7.01 (2H, d, J =
.2 Hz, ArH), 6.91 (2H, td, J = 7.5, 0.9 Hz, ArH), 5.13 (4H, s,
PhCH
.91–1.95 (4H, m, CH
C), 134.4 (CH), 130.9 (CH), 129.5 (CH), 128.8 (CH), 128.3 (CH),
2
), 4.56–4.64 (2H, m, CHOR), 3.49 (2H, d, J = 5.5 Hz, OH),
1
2
). δ (125 MHz, CD CN), 160.1 (C), 138.2
C
3
(
1
6
21.9 (CH), 114.0 (CH), 113.6 (C), 96.0 (C), 81.3 (C), 71.0 (CH
2
),
+
+
2.7 (CH), 34.6 (CH
2
). m/z (ESI) [M + Na] 525.2; [M + K] 541.2.
+
HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for C H O Na
34
30 4
5
25.2036; found 525.2045.
Tricarbonyl-(4S,7S)-1,3-bis(2-(benzyloxy)phenyl)-4,7-dihy-
droxy-4,5,6,7-tetrahydro-2H-inden-2-one iron 34.
This compound is novel. In an round bottom flask (3S,6S)-1,8-
bis(2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)octa-1,7-diyne-3,6-
diol 30 (1.55 g, 3.17 mmol) was dissolved in a mixture of DCM/
3
EtOH (1 : 3, 25 cm ) and pyridinium p-toluenesulfonate
(107 mg, 0.43 mmol) was added. The mixture was stirred for
1
9 hours and the volatiles were removed. The product was pur-
ified by flash chromatography on silica gel (eluent: hexane/
EtOAc = 3 : 2 to EtOAc) to give (3S,6S)-1,8-bis(2-hydroxyphenyl)
octa-1,7-diyne-3,6-diol 31 (859 g, 2.66 mmol, yield: 84%) as col-
2
7
This compound is novel. In an ACE pressure tube under a
nitrogen atmosphere (3S,6S)-1,8-bis(2-(benzyloxy)phenyl)-octa-
1,7-diyne-3,6-diol 32 (200 mg, 0.40 mmol) was dissolved/sus-
ourless solid. [α]D +15.2 (c 0.9, CH OH). M.p. 144.0–145.6 °C.
3
IR(neat) 3419 (br.), 3145 (br.), 2225, 1604, 1585, 1502, 1450,
−
1
1
391, 1365, 1324, 1288, 1258 cm . δ
H 6
(500 MHz, DMSO-d ),
3
pended in anhydrous toluene (3 cm ) previously degassed by
9
.79 (2H, s, OH), 7.24 (2H, dd, J = 7.6, 1.5 Hz, ArH), 7.12–7.18
3
freeze–pump–thaw cycles. Fe(CO)
5
(0.27 cm , 2.00 mmol) was
(2H, m, ArH), 6.86 (2H, d, J = 8.2 Hz, ArH), 6.75 (2H, t, J =
added, the pressure tube was sealed and the mixture was
heated at 130 °C for 22 hours. After the mixture was cooled to
room temperature and the pressure tube was carefully opened
into the fumehood to release CO pressure. Then the mixture
7
5
.5 Hz, ArH), 5.41 (2H, d, J = 5.5 Hz, OH), 4.50 (2H, d, J =
.3 Hz, CHOH), 1.73–1.92 (4H, m, CH ). δC (125 MHz, DMSO-
2
d6), 158.2 (C), 132.9 (CH), 129.6 (CH), 119.0 (CH), 115.4 (CH),
09.9 (C), 95.4 (C), 80.1 (C), 60.8 (CH), 33.8 (CH ). m/z (ESI)
1
2
3
+
+
was diluted with EtOAc (15 cm ) and filtered through a Celite
[M + Na] 345.1. HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for
3
plug washing through with EtOAc (100 cm ). The volatiles were
C H O Na 345.1097; found 345.1101.
2
0
18 4
removed and the product was purified by flash chromato-
graphy on silica gel (eluent: hexane/EtOAc = 1 : 4 to 1 : 1) to
(3S,6S)-1,8-Bis(2-(benzyloxy)phenyl)octa-1,7-diyne-3,6-diol 32.
give
tricarbonyl-(4S,7S)-1,3-bis(2-(benzyloxy)-phenyl)-4,7-di-
hydroxy-4,5,6,7-tetrahydro-2H-inden-2-one iron 34 (193 mg,
2
6
0
−
2
1
7
.29 mmol, yield: 72%) as yellow solid. M.p. 155 °C dec. [α]D
82.5 (c 0.19, CHCl ). IR(neat) 3370 (broad), 3062, 3034, 2958,
924, 2856, 2063, 2011, 1988, 1737, 1717, 1616, 1597, 1579,
3
494, 1450, 1373, 1297, 1278, 1226 cm− . δ
1
H
3
(500 MHz, CDCl ),
.16–7.40 (14H, m, ArH), 7.07 (2H, t, J = 7.5 Hz, ArH), 6.99 (1H,
d, J = 8.1 Hz, ArH), 6.90 (1H, d, J = 8.2 Hz, ArH), 5.00–5.15 (4H,
m, CH ), 4.76–4.83 (1H, m, CHOH), 4.59–4.65 (1H, m, CHOH),
In a round bottom flask under a nitrogen atmosphere (3S,6S)- 3.34 (1H, s, OH), 2.18–2.27 (1H, m, CHH), 2.09–2.18 (2H, m,
,8-bis(2-hydroxyphenyl)octa-1,7-diyne-3,6-diol 31 (200 mg, CHH and OH), 1.66–1.79 (1H, m, CHH), 1.50–1.63 (1H, m,
2
1
Dalton Trans.
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Paper
CHH). δ
C
(125 MHz, CDCl
3
), 208.2 (C), 170.8 (C), 156.51 (C), This compound is novel. In an ACE pressure tube under a
1
56.47 (C), 136.6 (C), 136.2 (C), 135.0 (CH), 134.4 (CH), 130.4 nitrogen atmosphere (3S,6S)-1,8-bis(2-(benzyloxy)phenyl)-octa-
(
1
1
CH), 130.2 (CH), 128.59 (CH), 128.52 (CH), 127.89 (CH), 1,7-diyne-3,6-diol 33 (1.00 g, 1.46 mmol) was dissolved/sus-
3
27.80 (CH), 127.2 (CH), 126.9 (CH), 122.5 (CH), 121.8 (CH), pended in anhydrous toluene (7 cm ) previously degassed by
3
20.1 (C), 119.9 (C), 114.8 (CH), 113.3 (CH), 106.5 (C), 105.1 freeze–pump–thaw cycles. Fe(CO)5 (1.0 cm , 7.42 mmol) was
(
6
2 2
C), 81.1 (C), 80.8 (C), 71.9 (CH ), 70.6 (CH ), 62.6 (CH), added, the pressure tube was sealed and the mixture was
+
2.4 (CH), 27.8 (CH
2
), 27.4 (CH
2
). m/z (ESI) [M + H] 671.1; heated at 130 °C for 23 hours. After the mixture was cooled to
+
[
M + Na] 693.1.
,2′-((3S,6S)-3,6-Bis(benzyloxy)octa-1,7-diyne-1,8-diyl)bis
(benzyloxy)benzene) 33.
room temperature and the pressure tube was carefully opened
2
into the fumehood to release CO pressure. Then the mixture
3
(
was diluted with EtOAc (15 cm ) and filtered through a Celite
3
plug washing through with EtOAc (100 cm ). The volatiles were
removed and the product was purified by flash chromato-
graphy on silica gel (eluent: hexane/EtOAc = 9 : 1 to 7 : 3) to
give tricarbonyl-(4S,7S)-4,7-bis(benzyloxy)-1,3-bis(2-(benzyloxy)
phenyl)-4,5,6,7-tetrahydro-2H-inden-2-one iron 35 (1.04 g,
1
.22 mmol, yield: 84%) as yellow solid. M.p. 65.4–67.0 °C.
2
1
[α] −90.1 (c 0.25, CHCl ). IR
3060, 3030, 2926, 2860,
(neat)
D
3
2
1
6
060, 1981, 1644, 1599, 1579, 1495, 1450, 1364, 1338, 1277,
224 cm− . δ
.84–7.42 (25H, m, ArH), 6.77 (1H, d, J = 8.2 Hz, ArH), 6.70
and CHOR),
and CHOR), 3.90–4.12 (2H, m, CH ),
nitrogen atmosphere (3S,6S)-1,8-bis(2-hydroxyphenyl)octa-1,7- 2.14 (1H, br. s., CHH), 1.97 (1H, br. s., CHH), 1.83 (1H, br. s.,
diyne-3,6-diol 31 (250 mg, 0.78 mmol) was dissolved in anhy- CHH), 1.59 (2H, br. s., CHH). δ (125 MHz, CDCl ), 208.8 (C),
drous THF (2 cm ). NaH (60% in mineral oil, 155 mg, 156.8 (C), 137.8 (C), 137.4 (C), 137.2 (C), 136.9 (C), 133.0 (CH),
1
H
3
(500 MHz, CDCl ), 7.59 (1H, br. s., ArH),
(
2H, d, J = 7.2 Hz, ArH), 4.66–5.33 (4H, m, CH
2
This compound is novel. In an round bottom flask under a 4.17–4.64 (4H, m, CH
2
2
C
3
3
3
3
.88 mmol) and benzyl bromide (0.46 cm , 3.87 mmol) were 129.6 (CH), 129.5 (CH), 128.4 (CH), 128.3 (CH), 128.1 (CH),
added and the mixture was heated at 50 °C. After 18 hours, the 127.95 (CH), 127.92 (CH), 127.87 (CH), 127.6 (CH), 127.34
mixture was cooled to room temperature and saturated NH Cl (CH), 127.29 (CH), 127.23 (CH), 126.68 (CH), 126.56 (CH),
O (10 cm ) were added. The 121.7 (br., CH), 120.4 (CH), 119.9 (C), 113.2 (CH), 112.8 (CH),
4
3
3
aqueous solution (5 cm ) and H
product was extracted with DCM (3 × 20 cm ) and the reunited 71.7 (CH ), 70.5 (CH
2
organic layers were dried over Na SO . The volatiles were 68.7 (CH), 24.0 (CH ), 23.5 (CH
2
3
2
), 71.4 (CH
2
2
), 70.4 (CH), 69.6 (br., CH
2
),
+
2
4
2
). m/z (ESI) [M + H] 851.2;
+
+
removed and the product was purified by flash chromato- [M + Na] 873.1. HRMS (ESI-Q-TOF) m/z: [M + H] calcd for
graphy on silica gel (eluent: hexane to hexane/EtOAc = 5 : 1) to 43FeO 851.2303; found 851.2302.
give 2,2′-((3S,6S)-3,6-bis(benzyloxy)octa-1,7-diyne-1,8-diyl)bis (5S,8S)-5,8-Bis((2-(benzyloxy)phenyl)ethynyl)-2,2,3,3,10,10,11,11-
(benzyloxy)benzene) 33 (256 mg, 0.37 mmol, yield: 48%) as octamethyl-4,9-dioxa-3,10-disiladodecane 36.
C
52
H
8
(
2
8
yellow oil. [α]D −127.3 (c 0.41, CHCl ). IR
3086, 3063,
(neat)
3
3
1
7
6
030, 2928, 2860, 1595, 1574, 1489, 1444, 1380, 1332, 1289,
261, 1227 cm− . δ
1
(500 MHz, CDCl ), 7.45 (4H, d, J = 7.6 Hz),
H 3
.40 (2H, d, J = 7.5 Hz), 7.21–7.33 (16H, m), 7.16–7.21 (2H, m),
.85–6.94 (4H, M), 5.12 (4H, s), 4.80 (2H, d, J = 11.9 Hz), 4.53
(2H, d, J = 11.9 Hz), 4.37 (2H, t, J = 5.5 Hz), 2.02–2.20 (4H, m).
δC (125 MHz, CDCl ), 159.4 (C), 138.1 (C), 136.8 (C), 133.6
3
(
(
CH), 129.6 (CH), 128.5 (CH), 128.2 (CH), 128.1 (CH), 127.8
CH), 127.5 (CH), 127.1 (CH), 120.7 (CH), 112.8 (C), 112.4 (CH),
9
2.3 (C), 82.5 (C), 70.34 (CH ), 70.30 (CH ), 68.8 (CH), 31.7
2 2
+
+
(CH
2
). m/z (ESI) [M + Na] 705.3; [M + K] 721.3. HRMS This compound is novel. In an round bottom flask under a
+
(ESI-TOF) m/z: [M + Na] calcd for C48
H
42
O
4
Na 705.2975; nitrogen atmosphere (3S,6S)-1,8-bis(2-benzyloxyphenyl)octa-
found 705.2976.
Tricarbonyl-(4S,7S)-4,7-bis(benzyloxy)-1,3-bis(2-(benzyloxy)
phenyl)-4,5,6,7-tetrahydro-2H-inden-2-one iron 35.
1,7-diyne-3,6-diol 32 (500 mg, 0.99 mmol) was dissolved in
anhydrous DMF (10 cm ). Imidazole (339 mg, 4.98 mmol) and
3
tert-butylchlorodimethylsilane (375 mg, 2.49 mmol) were
3
added. After 20 hours, H
2
O (50 cm ) was added and the
3
product was extracted with EtOAc (200 cm ). The organic layer
was washed with brine (3 × 50 cm ) and dried over Na SO .
3
2
4
The volatiles were removed and the product was purified by
flash chromatography on silica gel (eluent: hexane to hexane/
EtOAc = 19 : 1) to give (5S,8S)-5,8-bis((2-(benzyloxy)phenyl)
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ethynyl)-2,2,3,3,10,10,11,11-octamethyl-4,9-dioxa-3,10-disilado-
5-(Trimethylsilyl)pent-4-ynal.
decane: 36 (718 mg, 0.98 mmol, yield: 99%) as colourless oil.
2
7
[
α] −23.2 (c 1.6, CHCl
3
). IR(neat) 3067, 3033, 2953, 2928, 2884,
D
2
1
7
6
855, 1596, 1574, 1490, 1471, 1444, 1407, 1380, 1360, 1338,
−
1
289, 1257, 1229 cm . δH (500 MHz, CD Cl), 7.43 (4H, d, J =
3
.5 Hz, ArH), 7.30–7.40 (6H, m, ArH), 7.15–7.26 (4H, m, ArH),
.82–6.90 (4H, m, ArH), 5.11 (4H, s, CH
2
OR), 4.59–4.72 (2H, m, In a round bottom flask, under nitrogen, oxalyl chloride (2 M
3
CHOR), 1.90–2.14 (4H, m, CH ), 0.90 (18H, d, J = 2.6 Hz, CH ), in DCM, 14.2 cm , 28.40 mmol) was diluted with DCM
2
3
3
0
3 C 3
.13 (12H, dd, J = 8.9, 2.5 Hz, CH ). δ (125 MHz, CDCl
), 159.2 (15 cm ). The solution was cooled to −78 °C and anhydrous
3
(
C), 136.9 (C), 133.6 (CH), 129.3 (CH), 128.4 (CH), 127.6 (CH), DMSO (4 cm , 56.31 mmol) was added dropwise. Then the
1
7
(
27.0 (CH), 120.6 (CH), 113.2 (C), 112.6 (CH), 95.1 (C), 80.6 (C), mixture was stirred for 30 minutes and a solution of 5-(tri-
3
0.2 (CH
), −5.0 (CH
HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for C H O Si Na 118.4 mmol) was added dropwise. The mixture was continued
2
), 63.4 (CH), 34.5 (CH
2 3
), 25.8 (CH
), 18.3 (C), −4.4 methylsilyl)pent-4-yn-1-ol (3.7 g, 23.7 mmol) in DCM (25 cm )
+
+
3
CH
3
3
). m/z (ESI) [M + Na] 753.4; [M + K] 769.3. was added dropwise. After 30 minutes Et
3
N (16.5 cm ,
+
4
6
58
4
2
7
53.3766; found 753.3759.
Tricarbonyl-(4S,7S)-1,3-bis(2-(benzyloxy)phenyl)-4,7-bis
(tert-butyldimethylsilyl)oxy)-4,5,6,7-tetrahydro-2H-inden-2-one (100 cm ) was added and the product was extracted with DCM
to stir at −78 °C for 1 hour then warmed to room temperature.
After 16 hours a saturated aqueous solution of NaHCO
3
3
(
3
iron 37.
(3 × 100 cm ). The reunited organic layers were washed with
3
2 4
brine (50 cm ) and dried over Na SO . The volatiles were
removed and the product was purified by flash chromato-
graphy on silica gel (eluent: petroleum ether to petroleum
ether/EtOAc = 9/1) to give 5-(trimethylsilyl)pent-4-ynal (2.69 g,
1
13
1
7.43 mmol, 74%) as yellow oil. H NMR and C NMR were
16
identical to the reported data;
δ
H
(500 MHz, CDCl
3
), 9.79
(
1H, s, OvCH), 2.64–2.70 (2H, m, CH ), 2.52–2.58 (2H, m,
2
CH ), 0.14 (9H, s, CH ). δ (125 MHz, CDCl ), 200.4 (CH), 104.7
2
3
C
3
(
C), 85.8 (CH), 42.5 (CH
2
), 13.1 (CH
2
3
), 0.0 (CH ).
1-Phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-ol 30.
This compound is novel. In an ACE pressure tube under a
nitrogen atmosphere (5S,8S)-5,8-bis((2-(benzyloxy)phenyl)
ethynyl)-2,2,3,3,10,10,11,11-octamethyl-4,9-dioxa-3,10-disilado-
decane 36 (500 mg, 0.68 mmol) was dissolved/suspended in
3
anhydrous toluene (5 cm ) previously degassed by freeze– In a Schlenk tube under a nitrogen atmosphere phenyl-
3
3
pump–thaw cycles. Fe(CO) (0.46 cm , 3.41 mmol) was added, acetylene (0.85 cm , 7.74 mmol) was dissolved in anhydrous
5
3
the pressure tube was sealed and the mixture was heated at THF (20 cm ). The mixture was cooled at −78 °C and n-butyl-
30 °C for 19 hours. After the mixture was cooled to room lithium (2.5 M in hexanes, 3.1 cm , 7.75 mmol) was added
3
1
temperature and the pressure tube was carefully opened into dropwise. The mixture was warmed to room temperature and
the fumehood to release CO pressure. Then the mixture was stirred at this temperature for 1 hour. Then the mixture was
3
diluted with EtOAc (15 cm ) and filtered through a Celite plug cooled to −78 °C and transferred via cannula dropwise to a
3
washing through with EtOAc (100 cm ). The volatiles were flask
containing
5-(trimethylsilyl)pent-4-ynal
(1.0
g,
3
removed and the product was purified by flash chromato- 6.48 mmol) dissolved in anhydrous THF (20 cm ) at −78 °C.
graphy on silica gel (eluent: hexane to hexane/EtOAc = 1 : 1) After 5 minutes the mixture was warmed at room temperature
3
to give tricarbonyl-(4S,7S)-1,3-bis(2-(benzyloxy)phenyl)-4,7-bis and stirred at this temperature for 3 hours. Then H O (50 cm )
2
(
(tert-butyldimethylsilyl)oxy)-4,5,6,7-tetrahydro-2H-inden-2-one
was added dropwise and the product was extracted with DCM
3
iron 37 (162 mg, 0.18 mmol, yield: 26%) as yellow solid. (3 × 50 cm ). The reunited organic layers were washed with
M.p. 92 °C dec. [α]D −192.3 (c 0.1, CHCl ). IR
2
1
3
2950, 2927, brine (50 cm ) and dried over Na SO . The volatiles were
2 4
3
(neat)
2
1
882, 2854, 2061, 2008, 1980, 1648, 1599, 1579, 1497, 1450, removed and the product was purified by flash chromato-
−
1
363, 1277, 1248 cm . δ
H 3
(500 MHz, CDCl , −50 °C), 7.75 graphy on silica gel (eluent: petroleum ether to petroleum
(0.5H, dd, J = 23.0, 7.5 Hz, ArH), 7.14–7.50 (10H, m, ArH), ether/EtOAc = 13/1) to give racemic 1-phenyl-7-(trimethylsilyl)
6
.72–7.13 (7H, m, ArH), 6.64 (1H, d, J = 8.6 Hz, ArH), 4.40–5.50 hepta-1,6-diyn-3-ol 39 (1.54 g, 6.00 mmol, 93%) as yellow oil.
1
13
17
(6H, m, CH
2
OR and CHOR), 1.32–2.37 (4H, m, CH
2
), 0.48–0.78
H NMR and CNMR were identical to the reported data.
(
18H, m, CH ), −0.35–0.05 (6H, m, CH ), −0.98–−0.60 (6H, m, δH (500 MHz, CDCl ), 7.40–7.47 (2H, m, ArH), 7.28–7.34 (3H,
3
3
3
+
+
3
CH ). m/z (ESI) [M + H] 899.2; [M + Na] 921.2. HRMS (ESI-Q- m, ArH), 4.76 (1H, q, J = 5.8 Hz, CHOH), 2.41–2.59 (2H, m,
+
TOF) m/z: [M + H] calcd for C50
99.3102.
H
59FeO
8
Si
2
899.3094; found CH
2
), 2.15 (1H, d, J = 5.3 Hz, CHOH), 2.02 (2H, q, J = 6.9 Hz,
8
CH ), 0.16 (9H, s, CH ). δ (125 MHz, CDCl ), 131.7 (CH), 128.5
2
3
C
3
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(
(
H
CH), 128.3 (CH), 122.4 (C), 106.1 (C), 89.2 (C), 85.6 (C), 85.3 1440, 1353, 1335, 1327, 1312, 1279, 1247. δ (500 MHz,
C), 62.0 (CH), 36.4 (CH ), 16.0 (CH ), 0.1 (CH ).
CDCl ), 7.40–7.47 (2H, m, ArH), 7.28–7.34 (3H, m, ArH), 4.76
2
2
3
3
1
-Phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-one 38.
(1H, q, J = 5.8 Hz, CHOH), 2.41–2.59 (2H, m, CH
2
), 2.15 (1H, d,
), 0.16 (9H, s,
CH ). δ (125 MHz, CDCl ), 131.7 (CH), 128.5 (CH), 128.3 (CH),
J = 5.3 Hz, CHOH), 2.02 (2H, q, J = 6.9 Hz, CH
2
3
C
3
1
(
22.4 (C), 106.1 (C), 89.2 (C), 85.6 (C), 85.3 (C), 62.0 (CH), 36.4
CH ), 16.0 (CH ), 0.1 (CH ).
R)-1-Phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-ol 30.
2
2
3
(
This compound is novel. In an round bottom flask under a
nitrogen atmosphere, racemic 1-phenyl-7-(trimethylsilyl)hepta-
1
,6-diyn-3-ol 39 (820 mg, 3.20 mmol) was dissolved in DCM
3
(20 cm ). Then PCC (1.38 g, 6.40 mmol) was added. After
2
4 hours the mixture was filtered through a Celite plug
3
washing through with DCM (30 cm ). The volatiles were
removed and the product was purified by flash chromato-
graphy on silica gel (eluent: petroleum ether to petroleum
ether/EtOAc = 49/1) to give 1-phenyl-7-(trimethylsilyl)hepta-1,6-
diyn-3-one 38 (504 mg, 1.98 mmol, yield: 62%) as pale yellow
In an round bottom flask under a nitrogen atmosphere
1
0
-phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-one 38 (100 mg,
.39 mmol) was dissolved in anhydrous DCM (0.3 cm ). [(R,R)-
3
Teth-TsDpen-RuCl] 23 (2.4 mg, 0.039 mmol) and an azeotropic
mixture of formic acid/triethylamine (5 : 2 mixture, 0.3 cm )
3
oil. IR(neat) 2972, 2959, 2935, 2925, 2896, 2201, 2177, 1671,
489, 1443, 1407, 1358, 1334, 1278, 1249, 1190 cm− . δ
1
1
H
3
were added. After 7 hours saturated NaHCO aqueous solution
3
3
(500 MHz, CDCl ), 7.56–7.61 (2H, m, ArH), 7.44–7.49 (1H, m,
3
(5 cm ) and H O (5 cm ) were added and the mixture was
2
ArH), 7.36–7.42 (2H, m, ArH), 2.89–2.96 (2H, m, CH
.59–2.67 (2H, m, CH ), 0.14 (9H, s, CH ). δ (125 MHz,
CDCl ), 185.4 (C), 133.1 (CH), 130.9 (CH), 128.6 (CH), 119.8
2
),
stirred 30 minutes. The product was extracted with DCM (3 ×
3
2
2
3
C
20 cm ). The reunited organic layers were dried over Na
2
SO
4
.
3
The volatiles were removed and the product was purified by
flash chromatography on silica gel (eluent: hexane to hexane/
EtOAc = 9 : 1) to give (R)-1-phenyl-7-(trimethylsilyl)hepta-1,6-
diyn-3-ol 39 (66 mg, 0.26 mmol, yield: 66%, 95% ee) as white
solid. The enantiomeric excess was determined by HPLC ana-
lysis with a ChiralPak OD column: 0.46 cm × 25 cm, mobile
(
(
C), 104.7 (C), 91.6 (C), 87.3 (C), 85.6 (C), 44.2 (CH
2
), 14.7
+
+
CH
HRMS (ESI-Q-TOF) m/z: [M + Na] calcd for C H OSiNa
2 3
), 0.0 (CH ). m/z (ESI) [M + H] 255.1; [M + Na] 277.1.
+
1
6
18
2
77.1019; found 277.1024.
S)-1-Phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-ol 39.
(
−
1
phase iso-propanol : hexane 9 : 1, flow rate 1 mL min , temp-
erature 30 °C, UV detection at λ = 254 nm; t = 6.5 min (R), t =
R
R
1
3.8 min (S).
1
13
17
H NMR and C NMR were identical to the reported data.
2
5
22
M.p. 34.6–36.0 °C. [α] −47.3 (c 0.45, CHCl ) (lit [α]D −36.3
D
3
(
c 0.88, CHCl
3
), 90% ee R).
In an round bottom flask under a nitrogen atmosphere
1
1
-phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-one 38 (476 mg,
.87 mmol) was dissolved in anhydrous DCM (1.3 cm ). [(S,S)- Compounds 40 and 41
3
Teth-TsDpen-RuCl] 23 (11.6 mg, 0.019 mmol) and an azeotro-
pic mixture of formic acid/triethylamine (5 : 2 mixture,
3
1
.3 cm ) were added. After 18 hours saturated NaHCO
3
3
3
aqueous solution (10 cm ) and H
2
O (10 cm ) were added and
the mixture was stirred 30 minutes. The product was extracted
3
with DCM (3 × 20 cm ). The reunited organic layers were dried These compound are novel. In an ACE pressure tube under a
over Na SO . The volatiles were removed and the product was nitrogen atmosphere (S)-1-phenyl-7-(trimethylsilyl)hepta-1,6-
2
4
purified by flash chromatography on silica gel (eluent: pet- diyn-3-ol 39 (300 mg, 1.16 mmol) was dissolved in anhydrous
3
roleum ether to petroleum ether/EtOAc = 9 : 1) to give (S)-1- toluene (6 cm ) previously degassed by freeze–pump–thaw
3
phenyl-7-(trimethylsilyl)hepta-1,6-diyn-3-ol 39 (426 mg, cycles. Fe(CO)
5
(0.79 cm , 5.86 mmol) was added, the pressure
1
.66 mmol, yield: 89%, 94% ee) as white solid. The enantio- tube was sealed and the mixture was heated at 130 °C for
meric excess was determined by HPLC analysis with a 24 hours. After the mixture was cooled to room temperature
ChiralPak OD column: 0.46 cm × 25 cm, mobile phase iso- and the pressure tube was carefully opened into the fumehood
−
1
propanol : hexane 9 : 1, flow rate 1 mL min , temperature to release CO pressure. Then the mixture was diluted with
3
3
1
0 °C, UV detection at λ = 254 nm; t = 6.5 min (R), tR
=
EtOAc (15 cm ) and filtered through a Celite plug washing
R
1
13
3
3.8 min (S). H NMR and CNMR were identical to the through with EtOAc (100 cm ). The volatiles were removed and
). the products were purified by flash chromatography on silica
IR(neat) 3288 (broad), 2957, 2897, 2865, 2228, 2169, 1598, 1489, gel (eluent: hexane to hexane/EtOAc = 13/1) to give first the
reported data. M.p. 34.8–36.4 °C. [α] 2D 5 +47.6 (c 0.45, CHCl
1
7
3
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+
less polar 40 (198 mg, yield: 40%) as a yellow solid and then TOF) m/z: [M + Na] calcd for C16
more polar 41 (136 mg, yield: 27%) as an orange solid. 275.1258.
1,7-Bis(trimethylsilyl)hepta-1,6-diyn-3-one 44.
H
18OSiNa 275.1258; found
3
0
3
Data for 40; m.p. 193 °C dec. [α] −204.6 (c 0.14, CHCl ).
D
IR(neat) 3336 (broad), 3060, 2954, 2900, 2059, 1981, 1632, 1586,
1
8
505, 1447, 1413, 1379, 1304, 1247 cm−1. δH (500 MHz, CDCl3),
.04 (2H, d, J = 7.9 Hz, ArH), 7.23–7.40 (3H, m, ArH), 5.33–5.44
(
(
1H, m, CHOH), 3.02 (1H, ddd, J = 16.4, 9.3, 7.5 Hz, CHH), 2.85
1H, br. S, OH), 2.51–2.62 (1H, m, CHH), 2.35–2.43 (1H, m,
CHH), 2.23–2.35 (1H, m, CHH), 0.34 (9H, s, CH
CDCl
), 208.1 (C), 177.0 (C), 131.7 (C), 128.7 (CH), 128.2 (CH), methylsilyl)hepta-1,6-diyn-3-ol (877 mg, 3.47 mmol) was dis-
27.93 (CH), 127.90 (CH), 115.5 (C), 105.3 (C), 80.1 (C), 71.9 solved DCM (20 cm ). Then PCC (1.12 g, 6.40 mmol) and mole-
CH), 69.9 (C), 36.5 (CH ), 25.4 (CH
). m/z (ESI) cular sieves were added. After 14 hours the mixture was filtered
3 C
). δ
(125 MHz, This compound is novel. In an round bottom flask 1,7-bis(tri-
3
3
1
(
2
2
), −0.7 (CH
3
+
+
3
[
[
M + H] 425.0; [M + Na] 446.9. HRMS (ESI-Q-TOF) m/z: through a Celite plug washing through with DCM (50 cm ).
+
M + Na] calcd for C H FeO SiNa 447.0322; found 447.0324.
The volatiles were removed and the product was purified by
). flash chromatography on silica gel (eluent: hexane/EtOAc =
3
20
20
5
2
D
9
Data for 41; m.p. 196 °C dec. [α] +155.6 (c 0.16, CHCl
IR(neat) 3369 (broad), 3076, 2959, 2923, 2898, 2853, 2071, 2025, 97/3) to give 1,7-bis(trimethylsilyl)hepta-1,6-diyn-3-one 44
978, 1590, 1505, 1453, 1414, 1376, 1309, 1248 cm−1. δH (771 mg, 3.08 mmol, 86%) as a colourless oil. IR(neat) 2960,
1
(
−
1
500 MHz, CDCl
m, ArH), 7.28 (1H, d, J = 7.2 Hz, ArH), 5.51 (1H, td, J = 7.8, 4.4 (500 MHz, CDCl
Hz, CHOH), 2.52–2.78 (4H, m, CH and OH), 1.83–1.95 (1H, m, CH ), 0.23 (9H, s, CH
), 208.1 (C), 175.8 185.4 (C), 133.1 (CH), 130.9 (CH), 128.6 (CH), 119.8 (C), 104.7
C), 131.2 (C), 129.0, 128.4, 128.0, 115.4 (C), 109.9 (C), 80.6 (C), (C), 91.6 (C), 87.3 (C), 85.6 (C), 44.2 (CH ), 14.7 (CH ), 0.0
). C NMR (126 MHz, chloroform-d) δ = 185.1 (C), 104.6
), 14.5 (CH ), 0.0
). m/z (ESI) [M + Na] 272.8. HRMS (ESI-Q-
3
), 7.93 (2H, d, J = 7.5 Hz, ArH), 7.30–738 (2H, 2901, 2178, 2149, 1680, 1409, 1355, 1333, 1250, 1224 cm . δ
), 2.77–2.83 (2H, m, CH ), 2.50–2.56 (2H, m,
), 0.12 (9H, s, CH ). δ (125 MHz, CDCl ),
H
3
2
2
2
3
3
C
3
3 C 3
CHH), 0.32 (9H, s, CH ). δ (125 MHz, CDCl
(
7
(
[
2
2
1
3
1.4 (CH), 67.5 (C), 35.7 (CH ), 24.7 (CH ), −0.7 (CH ). m/z (CH
3
2
+
2
3
+
ESI) [M + H] 425.0; [M + Na] 446.9. HRMS (ESI-Q-TOF) m/z: (C), 101.4 (C), 98.7 (C), 85.5 (C), 44.0 (CH
2
2
+
+
M + Na] calcd for C20
H
20FeO
5
SiNa 447.0322; found 447.0325.
(CH
TOF) m/z: [M + Na] calcd for C13
73.1111.
Tricarbonyl-4,6-bis(trimethylsilyl)-2,3-dihydropentalene-1,5-
dione iron 42.
3
), −0.8 (CH
3
+
1
,7-Bis(trimethylsilyl)hepta-1,6-diyn-3-ol.
2
H22OSi Na 273.1101; found
2
This compound is novel. In a Schlenk tube under a nitrogen
3
atmosphere phenylacetylene (0.67 cm , 4.74 mmol) was dis-
3
solved in anhydrous THF (10 cm ). The mixture was cooled at
3
−
78 °C and n-butyllithium (2.5 M in hexanes, 1.9 cm ,
4
.76 mmol) was added dropwise. The cooling bath was In an ACE pressure tube under a nitrogen 1,7-bis(trimethyl-
removed and stirred for 10 minutes. Then the mixture was silyl)hepta-1,6-diyn-3-one 44 (745 mg, 2.97 mmol) was dis-
3
cooled to −78 °C and transferred via cannula dropwise to a solved/suspended in anhydrous toluene (5 cm ) previously
3
flask containing 5-(trimethylsilyl)pent-4-ynal 43 (580 mg, degassed by freeze–pump–thaw cycles. Fe(CO)
3
5
(2.0 cm ,
3
.76 mmol) dissolved in anhydrous THF (20 cm ) at −78 °C. 14.83 mmol) was added, the pressure tube was sealed and the
After 5 minutes the mixture was warmed at room temperature mixture was heated at 130 °C for 20 hours. After the mixture
3
and stirred at this temperature for 3 hours. Then H
2
O (20 cm ) was cooled to room temperature and the pressure tube was
was added dropwise and the product was extracted with DCM carefully opened into the fumehood to release CO pressure.
3
3
(
3 × 25 cm ). The reunited organic layers were washed with Then the mixture was diluted with EtOAc (15 cm ) and filtered
3
3
2 4
brine (25 cm ) and dried over Na SO . The volatiles were through a Celite plug washing through with EtOAc (100 cm ).
removed and the product was purified by flash chromato- The volatiles were removed and the product was purified by
graphy on silica gel (eluent: hexane to hexane/Et O = 9/1) to flash chromatography on silica gel (eluent: petroleum ether to
2
give
1,7-bis(trimethylsilyl)hepta-1,6-diyn-3-ol
(877
mg, petroleum ether /EtOAc = 9 : 1) to give tricarbonyl-4,6-bis(tri-
3
2
.47 mmol, 91%) as colourless oil. IR(neat) 3346 (broad), 2956, methylsilyl)-2,3-dihydropentalene-1,5-dione iron 42 (789 mg,
−
1
1
13
900, 2857, 2175, 1444, 1408, 1331, 1249 cm . δH (500 MHz, 1.89 mmol, yield: 63%) as yellow solid. H NMR and CNMR
2
c
3
CDCl ), 4.51 (1H, q, J = 6.1 Hz, CHOH), 2.46 (1H, dt, J = 17.1, were identical to the reported data. M.p. 105.5 °C dec. IR(neat)
7
(
.5 Hz, CHH), 2.38 (1H, dt, J = 17.1 Hz, J = 6.9 Hz, CHH), 2.08 2958, 2900, 2071, 2016, 1994, 1717, 1626, 1446, 1426, 1404,
1H, d, J = 5.6 Hz, OH), 1.91 (2H, q, J = 6.9 Hz, CH ), 0.18 (9H, 1347, 1263, 1244, 1226, 1203 cm− . δH (500 MHz, CDCl ), 3.15
1
2
3
s, CH
3
), 0.15 (9H, s, CH
3
). δ
C
(125 MHz, CDCl
3
), 106.1 (C), (1H, dt, J = 17.2, 6.9 Hz, CHH), 3.02 (1H, dt, J = 17.4, 5.0 Hz,
), 15.9 (CH ), CHH), 2.78 (2H, dd, J = 6.9, 5.0 Hz, CH ), 0.34 (9H, s, CH ),
1
0
05.7 (C), 90.0 (C), 85.5 (C), 61.8 (CH), 36.2 (CH
.1 (CH ), −0.2 (CH ). m/z (ESI) [M + Na] 274.8. HRMS (ESI-Q- 0.32 (9H, s, CH ). δ (125 MHz, CDCl ), 206.8 (C), 204.5 (C),
2
2
2
3
+
3
3
3
C
3
Dalton Trans.
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83.4 (C), 129.8 (C), 98.0 (C), 78.9 (C), 77.3 (C), 76.8 (C), 67.4 min− , temperature 30 °C, UV detection at λ = 254 nm; t
1
1
R
=
(
C), 36.9 (CH ), 23.5 (CH ), −0.4 (CH ), −0.8 (CH ). 6.1 min (ketone), t = 7.0 min (ketone), t = 11.4 min (alcohol),
2
2
3
3
R
R
2
4
Tricarbonyl-4-hydroxy-1,3-bis(trimethylsilyl)-5,6-dihydropen-
t
R
= 14.3 min (alcohol). Alcohol (−)-45; [α] −37.1 (c 0.48,
D
2
4
talen-2(4H)-one iron 45.
D
3 3
CHCl ). Ketone (+)-42; [α] +98.2 (c 0.11, CHCl ).
The alcohols formed by reductions have been reported and
our procedures and characterisation followed the protocols
1
1,18
reported.
Conflicts of interest
In an round bottom flask tricarbonyl-4,6-bis(trimethylsilyl)-
There are no conflicts to declare.
2
,3-dihydropentalene-1,5-dione iron 42 (100 mg, 0.24 mmol)
3
was dissolved in EtOH (12 cm ) NaBH
4
(11.5 mg, 0.30 mmol)
was added and the reaction was stirred for 1 hours. Then H O
2
3
Acknowledgements
(1 cm ) was added and the mixture was stirred 30 minutes.
The volatiles were removed and the product was purified by
flash chromatography on silica gel (eluent: pentane/EtOAc =
We thank the EPSRC for generous financial support of this
work through a project grant to fund ADG (grant no. EP/
M006670/1) and Johnson Matthey Catalysis and Chiral
Technologies for a gift of TethTsDpenRuCl catalyst 23. The
X-ray diffraction instrument was obtained through the Science
City Project with support from the AWM and part funded by
the ERDF. Warwick University are thanked for support of
MChem student AEC.
1
9 : 1 to 9 : 1) to give tricarbonyl-4-hydroxy-1,3-bis(trimethyl-
silyl)-5,6-dihydropentalen-2(4H)-one iron 45 (75 mg,
1
13
0
.18 mmol, 75%) as a yellow solid. H NMR and C NMR were
identical to the reported data. M.p. 172.9–173.7 °C. [α] D2 5
88.8 (c 0.49, CHCl ). IR(neat) 3289 (broad), 2961, 2934, 2900,
064, 2013, 1975, 1583, 1453, 1406, 1380, 1356, 1312,
), 5.21 (1H, td, J = 7.6, 5.0 Hz,
), 2.51–2.60 (1H, m, CHH),
.24–2.34 (1H, m, CHOH), 1.72–1.83 (1H, m, CHH), 0.31 (9H,
2c
−
3
2
1
247 cm− . δ
1
(500 MHz, CDCl
H
3
CHOH), 2.60–2.69 (2H, m, CH
2
2
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3
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(
26 mg, 0.12 mmol) and an azeotropic mixture of formic acid/
3
triethylamine (5 : 2 mixture, 0.8 cm ) were added. After 7 hours
saturated NaHCO
(
The product was extracted with DCM (3 × 30 cm ). The
reunited organic layers were washed with brine (100 cm ) and
3
3
aqueous solution (10 cm ) and H
2
O
3
15 cm ) were added and the mixture was stirred 30 minutes.
3
3
2 4
dried over Na SO . The volatiles were removed and the product
was purified by flash chromatography on silica gel (eluent:
pentane to pentane/EtOAc = 9 : 1) to give alcohol (−)-45
(204 mg, 0.49 mmol, yield: 40.6%, 97.6% ee) as yellow solid
and ketone (+)-42 (175 mg, 0.42 mmol, yield: 35.0%, 88.2% ee)
as yellow solid. The enantiomeric excesses ere determined by
HPLC analysis with a ChiralPak IA column: 0.46 cm × 25 cm,
mobile phase iso-propanol : hexane 3 : 97, flow rate 1 mL
This journal is © The Royal Society of Chemistry 2017
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Dalton Trans.
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