Investigations into the C-deuteriation of silyl enol ethers derived from aryl alkyl ketones

Article abstract of DOI:10.1002/jlcr.1088

Results are reported on the regioselective C-deuteriation of a series of silyl enol ethers derived from aryl alkyl ketones using deuterium (D ₂) gas as the deuterium source and palladium-on-barium sulfate as the mediator. These results highlight the numerous reaction pathways and different product types available from simple deuteriation of substituted enol precursors. Copyright

Full text of DOI:10.1002/jlcr.1088

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS
J Label Compd Radiopharm 2006; 49: 757–771.
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jlcr.1088
Research Article
Investigations into the C-deuteriation of silyl enol
ethers derived from aryl alkyl ketones
Svitlana Buksha1, Gregory S. Coumbarides1, Marco Dingjan2,
Jason Eames2,*, Michael J. Suggate1 and Neluka Weerasooriya1
1 Department of Chemistry, Queen Mary, University of London, Mile End Road,
London E1 4NS, UK
2 Department of Chemistry, University of Hull, Cottingham Road, Kingston upon Hull,
HU6 7RX, UK
Summary
Results are reported on the regioselective C-deuteriation of a series of silyl enol ethers
derived from aryl alkyl ketones using deuterium (D2) gas as the deuterium source and
palladium-on-barium sulfate as the mediator. These results highlight the numerous
reaction pathways and different product types available from simple deuteriation of
substituted enol precursors. Copyright # 2006 John Wiley & Sons, Ltd.
Received 18 April 2006; Revised 5 May 2006; Accepted 5 May 2006
Key Words: alkyl aryl ketones; deuteriation; hydrogenation; palladium; reduction;
silyl enol ethers and silyl ethers
Introduction
The use of deuterium (D2) gas as a D-source in the presence of a suitable metal
catalyst has been shown to be a reliable method for selective deuterium
incorporation.1 By far, the most common approach has utilized reduction
(through deuteriation) of carbon-carbon double bonds.2 However, for
p-activated enol equivalents, such as silyl enol ethers3a and enol esters,3b
these processes are much less documented.
Within this area, Nakai has reported4 the enantio- and regioselective
protonation of silyl enol ether 1 using a combination of chiral catalyst
{PdCl2[(R)-BINAP] 3 and AgOTf, in the presence of molecular hydrogen to
give enantiomerically enriched 2-methyl-tetralone (R)-2 in 83% with 79%
*Correspondence to: Dr Jason Eames, Department of Chemistry, University of Hull, Cottingham Road,
Kingston upon Hull, HU6 7RX, UK. E-mail: j.eames@hull.ac.uk
Copyright # 2006 John Wiley & Sons, Ltd.

758
S. BUKSHA ET AL.
PPh2
PPh2
H
H
O
OSiMe3
Me
(R )-3
H
Me
{PdCl2[(R)-BINAP]}-3 (5% mol)
AgOTf (5% mol), i-Pr2NH
DMF/H2O
(R)-2; 79% e.e.; 83%
1
O
D
Me
{PdCl2[(R)-BINAP]}-3 (5% mol)
AgOTf (5% mol), i-Pr2NH
DMF/D2O
(R)-[D1]-2; (80% D); 80% e.e.; 79%
Scheme 1.
H
O
O
O
OCH2Ph
Me
N
H
5
H
OH
H
H
Me
H2, Pd
(R)-2; 56% e.e.; 58%
4
Scheme 2.
enantiomeric excess (Scheme 1).4 By comparison, deuteriation of silyl enol
ether 1 using D2O as the deuterium source gave the expected 2-deuterio-2-
methyltetralone (R)-[D1]-2 in similar yield and enantiomeric excess, but with
low deuterium incorporation (80%) (Scheme 1). This particular reaction
pathway can also be achieved through hydrogenation of a related enol
precursor, such as enol benzyl carbonate 4, using palladium-on-charcoal in the
presence of a chiral b-amino acid like 5, to give the enantiomerically enriched
2-methyl-tetralone (R)-2 in 58% yield with 56% enantiomeric excess (Scheme
2).5
We have recently become interested in these processes primarily as an
indirect method for the resolution of a-substituted aryl alkyl ketones.6,y
During our studies,7 we have discovered that related enol acetates, like 6, can
be reduced (using H2 and Pd-on-BaSO4) to give acetate syn-7, with high levels
of diastereoselectivity, and oxidized to give the related 2-methylnaphthoxy
acetate 8 in 82 and 18% yields, respectively (Scheme 3).7 Whereas, comparable
y For additional information see Eames et al. 8
Copyright # 2006 John Wiley & Sons, Ltd.
J Label Compd Radiopharm. 2006; 49: 757–771
DOI: 10.1002/jlcr

INVESTIGATIONS INTO THE C-DEUTERIATION OF SILYL ENOL ETHERS
OAc
759
OAc
OAc
H
H2
Me
H
Me
Me
Pd-on-BaSO4
toluene
6
8; 18%
syn-7; 82%
OAc
OAc
D
OAc
OAc
H
D2
Me
Me
Me
D
Me
Pd-on-BaSO4
D
toluene
6
syn-[D2]-7
syn-[D1]-7
8; 20%
80%
C(1) ([D]:[H] = 77:23)
C(2) ([D]:[H] = 95:5)
Scheme 3.
deuteriation of enol acetate 6 using D2 in the presence of Pd-on-BaSO4 gave
the required D-labelled acetate syn-[D2]-7 with good levels of D-incorporation,
and the unlabelled 2-methylnaphthoxy acetate 8 (Scheme 3).7 These relative
pathways appear to be uninfluenced by the presence of deuterium as both
products syn-[D2]-7 and 8 were formed in similar amounts (Scheme 3).
However, from this preliminary study it was evident that the structural nature
of the enol derivative itself influenced the reaction pathway and product
distribution.7
We now report our study into the regioselective C-deuteriation of silyl enol
ethers derived from aryl alkyl ketones. We comment on factors that influence
the product distribution and discuss the role these play for efficient
regioselective C-deuteriation.
Results and discussion
For this study, we were required to synthesize a series of structurally related
silyl enol ethers 1, 10, 12, 14, 16 and 18 (Scheme 4). These silyl enol ethers were
synthesised in good yield by treatment of the parent aryl alkyl ketones 2, 9, 11,
13, 15 and 17 with lithium diisopropylamide (LDA) in THF at ꢀ788C,
followed by the addition of trimethylsilyl chloride to the corresponding
lithium enolate (Scheme 4).8 With these compounds in hand, we first probed
the hydrogenation of silyl enol ether 1 using palladium-on-barium sulphate as
the mediator. Addition of silyl enol ether 1 to a stirred solution of palladium-
on-barium sulphate in toluene under a hydrogen (H2) atmosphere at room
temperature, gave the diastereoisomerically pure9,z syn-silyl ether 19 and
2-methyl tetralone 2 in 61 and 35% yields, respectively (Scheme 5). It is
z The relative stereochemistry has been determined by a 400 MHz NOESY spectrum.
Copyright # 2006 John Wiley & Sons, Ltd.
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DOI: 10.1002/jlcr

760
S. BUKSHA ET AL.
1. LDA
1. LDA
Yield
74%
Ketone
Silyl Enol Ether
Yield
Ketone
Silyl Enol Ether
OSiMe3
2. Me3SiCl
2. Me3SiCl
O
O
OSiMe3
Me
Me
84%
2
18
OSiMe3
13
148
O
O
OSiMe3
79%
89%
9
108
OSiMe3
15
168
O
O
Me3SiO
78%
69%
OMe
OMe
11
12
17
188
Scheme 4.
OSiMe3
O
OSiMe3
Me
H
H2
Me
Me
Pd-on-BaSO4
H
H
toluene
2; 35%
syn-19; 61%
1
OSiMe3
O
OSiMe3
Me
D/H
D2
Me
Me
D
Pd-on-BaSO4
D
toluene
syn-[D2]-19; 76%
2; 10%
1
C(1) ([D]:[H] = 82:18)
C(2) ([D]:[H] = 95:5)
([D]:[H] = 98:2)
Scheme 5.
particularly interesting to note, dehydrogenation of silyl enol ether 1 (to give
the corresponding 2-trimethylsilyl-2-methylnaphthyl ether) does not occur.
However, reduction of its activated enol precursor (to give silyl ether syn-19)
appears to be more efficient than the corresponding desilylation (to give
Copyright # 2006 John Wiley & Sons, Ltd.
J Label Compd Radiopharm. 2006; 49: 757–771
DOI: 10.1002/jlcr

INVESTIGATIONS INTO THE C-DEUTERIATION OF SILYL ENOL ETHERS
761
2-methyltetralone 2) (Scheme 5). We next probed the deuteriation of silyl enol
ether 1 under our standard conditions (D2, Pd-on-BaSO4), which gave the
deuteriated syn-diastereoisomeric silyl ether [D2]-19 and 2-deuterio-2-methyl-
tetralone [D1]-2 in 76% and 10% yields, respectively. From this study, it is
apparent that near perfect isotopic incorporation had occured at the C(2)
positions in both silyl ether syn-[D2]-19 and 2-deuterio-2-methyl-tetralone
[D1]-2, whereas, only moderate D-incorporation ([D]:[H] = 82:18) had
occurred at the C(1) position for syn-[D2]-19 (Scheme 5). Under these
conditions, competitive desilylation and deuteriation of 1 appears to be less
favourable than analogous hydrogenation (Scheme 5).
With this information in hand, we next probed the structural nature (ring
size and substitution pattern) of the tetralone framework (in 1) by studying the
hydrogenation and deuteriation of silyl enol ethers 10, 12, 14, 16 and 18 to
determine which components were necessary for efficient deuteriation
(Schemes 6 and 7). Under our standard conditions, these silyl enol ethers
10, 12, 14, 16 and 18 behaved similarly to the original silyl enol ether 1 (derived
from tetralone 2) leading to unlabelled silyl ethers 19-24 and deuteriated silyl
ethers [D2]-19–24 in good yields, respectively (Schemes 6 and 7). The
stereochemical outcome for these deuteriations (and related hydrogenations)
appear to be syn-stereoselective leading to the formation of single diaster-
1
eoisomeric adducts by H NMR spectroscopy (Scheme 7). The levels of
H2
H2
Silyl Enol
Ether
Silyl Enol
Ether
Silyl Ether
Yield
61%a
Silyl Ether
Yield
Pd-on-BaSO4
Pd-on-BaSO4
OSiMe3
Me
OSiMe3
H
OSiMe3
OSiMe3
Me
50%
H
18
19
OSiMe3
148
22
OSiMe3
OSiMe3
OSiMe3
H
79%c
65%b
Me
H
108
OSiMe3
20
OSiMe3
168
23
Me3SiO
Me3SiO
70%
77%
OMe
12
OMe
21
188
24
a2; 35%; b9; 11%; c15; 12%
Scheme 6.
Copyright # 2006 John Wiley & Sons, Ltd.
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DOI: 10.1002/jlcr

762
S. BUKSHA ET AL.
D2
D2
Silyl Enol
Ether
Silyl Enol
Ether
Silyl Ether Yield
OSiMe3
Yield
50%
Silyl Ether
OSiMe3
Pd-on-BaSO4
Pd-on-BaSO4
OSiMe3
Me
OSiMe3
H/D
H/D
Me
76%a
D
D
18
148
[D2]-19:[D1]-19
C(1) ([D]:[H] = 82:18)
C(2) ([D]:[H] = 95:5)
[D2]-22:[D1]-22
C(1) ([D]:[H] = 92:8)
C(2) ([D]:[H] = 95:5)
OSiMe3
OSiMe3
OSiMe3
OSiMe3
H/D
H/D
D
60%b
Me
D
63%
108
168
[D2]-20:[D1]-20
C(1) ([D]:[H] = 50:50)
C(2) ([D]:[H] = 95:5)
[D2]-23:[D1]-23
C(1) ([D]:[H] = 75:25)
C(2) ([D]:[H] = 95:5)
OSiMe3
Me3SiO
Me3SiO
H/D
OSiMe3
D
H/D
D
79%
51%
OMe
12
OMe
188
[D2]-24:[D1]-24
C(1) ([D]:[H] = 87:13)
C(2) ([D]:[H] = 95:5)
[D2]-21:[D1]-21
C(1) ([D]:[H] = 81:19)
C(2) ([D]:[H] = 95:5)
a[D1]-2; 10% [(D):(H)] = 98:2; b[D1]-15; 25% [(D):(H)] = 75:25
Scheme 7.
deuterium incorporation were characteristically higher in the C(2) position
than the neighbouring C(1) position (Scheme 7). From this study, it is evident
that the indenyl skeleton in 14 promoted efficient deuteriation at both C(1) and
C(2) positions {[D]:[H] = 92:8 at C(1) and 95:5 at C(2), respectively} (Scheme
7). By comparison, the homologues tetralenyl and benzocycloheptenyl
skeletons (in 10 and 18) gave lower levels of deuteriation at their C(1)
positions ([D]:[H] = 50:50 for 20 and 87:13 for 24, respectively). Through
probing the substitution pattern of these silyl enol ethers, we have found that
the more substituted indenyl skeleton (in 16) lowered the level of regioselective
C(1) deuteriation ([D]:[H] = 75:25). For the analogous tetralenyl skeleton,
increased substitution at C(2) appears to promote more regioselective C(1)
deuteriation {[D]:[H] = 82:18 at C(1) for [D2]-19 and 50:50 at C(1) for [D2]-20,
respectively}. Whereas, by increasing the nucleophilicity of the aryl ring of the
silyl enol ether through the use of a methyoxytetralenyl skeleton (in 12)
increased the levels of deuteriation to 81:19 ([D]:[H]) for [D2]-21.
Copyright # 2006 John Wiley & Sons, Ltd.
J Label Compd Radiopharm. 2006; 49: 757–771
DOI: 10.1002/jlcr

INVESTIGATIONS INTO THE C-DEUTERIATION OF SILYL ENOL ETHERS
763
OAc
Me
6
(i)
OAc
OSiMe3
D/H
D/H
(ii) 24 h
Me
D
D2
D
D
Pd-on-BaSO4
OSiMe3
in toluene
(iii)
[D2]-22; 27%d
[D2]-7; 30%c
14
C(1) ([D]:[H] = 72:28)
C(2) ([D]:[H] = 95:5)
C(1) ([D]:[H] = 76:24)
C(2) ([D]:[H] = 95:5)
(iv) 24 h
crecovered 6 in 21%; drecovered 14 in 22%
OSiMe3
14
(i)
OAc
D/H
OSiMe3
D/H
Me
(ii) 24 h
D2
D
D
D
Pd-on-BaSO4
OAc
in toluene
(iii)
Me
[D2]-22; 28%a
[D2]-7; 32%b
6
C(1) ([D]:[H] = 92:8)
C(2) ([D]:[H] = 95:5)
C(1) ([D]:[H] = 93:7)
C(2) ([D]:[H] = 95:5)
(iv) 24 h
arecovered 14 in 35%; brecovered 6 in 24%
Scheme 8.
However, the role of the palladium catalyst was found to be important for
the outcome of these deuteriations (Scheme 8). Attempts at pre-activating the
palladium catalyst by pre-reduction of the enol acetate 6 (using palladium-on-
barium sulphate) to give [D2]-7; [D]:[H]=76:24 (30% yield), followed by
sequential deuteriation of silyl enol ether 14 gave the required silyl ether [D2]-
22 with reduced deuterium incorporation at its C(2)-position {[D]:[H] = 72:28
(27% yield)}. By comparison, using silyl enol ether 14 as the suicide alkene,
followed by deuteriation of enol acetate 6, gave the silyl ether [D2]-22 {C(2)
position [D]:[H] = 92:8 (28% yield)} and acetate [D2]-7 {C(2) position [D]:[H]
= 93:7 (32% yield)} with much better levels of deuterium incorporation
(Scheme 8). For the silyl enol ether 14, the levels of deuterium incorporation
were unsurprising due to the propensity of enol acetate 6 to oxidize (thought
the loss of hydrogen) to form the unlabelled 2-methylnaphthoxy acetate 8
under these reaction conditions (as shown in Scheme 3). By comparison, the
levels of deuterium incorporation for acetate [D2]-7 increased from [D]:[H] =
77:23 to 93:7 through using the silyl enol ether 14 as a suicide alkene (Scheme
8). Clearly, the structural nature of the ‘active’-catalyst appears to be very
important on the outcome and the levels of deuterium incorporation.
Copyright # 2006 John Wiley & Sons, Ltd.
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DOI: 10.1002/jlcr

764
S. BUKSHA ET AL.
From this study it is apparent that the reaction pathway for hydrogenation
(or deuteriation) of a seemingly simple enol equivalent is non-trivial. We
have shown that hydrogenation of silyl enol ether 1 and enol acetate 67
under our standard conditions (Pd-on-BaSO4) can lead to the corresponding
reduced silyl ether syn-19 and acetate syn-7,7 respectively (Schemes 3
and 5). Preferential formation of the parent ketone, tetralone 2, although
enantiomerically enriched can be achieved by analogous hydrogenation of
related carbonate 4 (via the intermediate enol(ate) 25 through palladium
mediated hydrogenation in the presence of 5),5 and by protonation of the
silyl enol ether 1 (using (R)-3, Pd(II)Cl2, AgOTf in DMF and H2O)4 (Schemes
1 and 2).
In conclusion, we have shown that regioselective C-deuteriation of a silyl
enol ether (e.g. 14) can occur efficiently to give the corresponding dideuteriated
silyl ether (e.g. [D2]-22) in good yield. The overall levels of deuterium
incorporation were found to be highly dependent on the structural and
electronic nature of the parent silyl enol ether used; an indenyl skeleton gave
higher levels of incorporation than larger tetralenyl and benzocycloheptenyl
homologues. For all cases so far studied, the levels of D-incorporation
were characteristically near perfect at the C(2) position but moderate at
the neighbouring C(1) position. We are currently investigating the
mechanistic outcome of these reactions and this study will be reported in
due course.
Experimental
General
All solvents were distilled before use. Tetrahydrofuran (THF) was freshly
distilled from sodium and triphenylmethane was used as the indicator. All
reactions were carried out under nitrogen using oven-dried glassware. Flash
column chromatography was carried out using Merck Kieselgel 60 (230–400
mesh). Thin layer chromatography (TLC) was carried out on commercially
available pre-coated plates (Merck Kieselgel 60F254 silica). Proton and carbon
NMR spectra were recorded on a JEOL EX 270, and Bruker AM 250, AMX
400 and AM 600 Fourier transform spectrometers (using an internal
deuterium lock). Chemical shifts are quoted in parts per million downfield
from tetramethylsilane. Carbon NMR spectra were recorded with broad
proton decoupling. Infrared spectra were recorded on a Shimadzu 8300 FTIR
spectrometer and mass spectra were recorded on a Kratos 50MSTC
spectrometer using a DS503 data system for high-resolution analysis.
Deuterium gas (99.8% atom D)(ISOTEC INC) was purchased from Aldrich
Chemical Company (cat no. 36,186-0).
Copyright # 2006 John Wiley & Sons, Ltd.
J Label Compd Radiopharm. 2006; 49: 757–771
DOI: 10.1002/jlcr

INVESTIGATIONS INTO THE C-DEUTERIATION OF SILYL ENOL ETHERS
765
1-Trimethylsilyloxy-5-methoxy-tetral-1-ene 12
Using the same method as the silyl enol ether 1, 5-methoxy-tetralone 11 (1.0 g,
5.7 mmol), LDA (formed by addition of n-BuLi (2.48 ml, 2.5 M in hexane,
6.2 mmol) to diisopropylamine (0.58 g, 0.79 ml, 5.7 mmol)] in THF (10 ml) and
trimethylsilyl chloride (0.62 g, 0.72 ml, 5.7 mmol) gave, after column chroma-
tography on silica gel eluting with light petroleum (b.p. 40-60 8C)-diethyl ether
(9:1) 1-trimethylsilyloxy-5-methoxy-tetral-1-ene 12 (0.97 g, 69%) as a colour-
less oil; RF [light petroleum (b.p. 40-608C)-diethyl ether (9:1)] 0.75; vmax(film)/
cmꢀ1 1640 (C ¼¼ C); dH(270 MHz, CDCl3) 7.17ꢀ7.06 (2 H, m, 2 ꢁ CH; Ar),
6.79 (1 H, dd, J 7.9 and 1.2, CH; Ar), 5.17 (1 H, t, J 4.7, CH2), 3.81 (3 H, s,
CH3), 2.75 (2 H, t, J 7.9, CH2), 2.31-2.27 (2 H, m, CH2) and 0.20 (9 H, s,
3 ꢁ CH3; Si(CH3)3); dC(100 MHz, CDCl3) 155.5 (COCH3; Ar), 147.6
(OC ¼¼ C), 140.4 (i-C; Ar), 134.4 (i-C; Ar), 126.0, 114.6 and 109.8 (3 ꢁ CH;
Ar), 105.3 (OC ¼¼ C), 55.3 (OCH3), 21.4 and 19.9 (2 ꢁ CH2), and 0.2
(3 ꢁ CH3; (CH3)3Si); m/z 176.1 (100%, MH+}SiMe3).
1-Trimethylsilyloxy-2-methyl-tetralane Syn-19 and 2-methyl-tetralone 2
Hydrogen gas (500 ml) was gradually added to a stirred solution of
1-trimethylsilyloxy-2-methyl-tetral-1-ene 18 (0.2 g, 0.86 mmol) and Pd-on-BaSO4
(40 mg, 5% on BaSO4 unreduced) in toluene (3 ml). The resulting solution was
stirred for 48 h. A solution of ethyl acetate (5 ml) was added, and the mixture
was filtered and evaporated under reduced pressure. The residue was purified
by flush column chromatography on silica gel eluting with light petroleum
(b.p. 40–608C)-diethyl ether (9:1) to give diastereoisomerically pure [see
footnote z] 1-trimethylsilyloxy-2-methyl-tetralane syn-19 (0.12 g, 61%) as a
colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (19:1)] 0.5;
vmax(film)/cmꢀ1 1600 (Ar) and 1034 (C–O); dH (270 MHz, CDCl3) 7.29-7.25
(1 H, m, CH; Ar), 7.16–7.13 (3 H, m, 3 ꢁ CH; Ar), 4.68 (1 H, d, J 3.5, CHO),
2.90–2.82 (1 H, m, CHAHB), 2.76–2.71 (1 H, m, CHAHB), 1.90–1.80 (1 H, m,
CHCH3), 1.71–1.67 (2 H, m, CH2), 0.99 (3 H, d, J 6.5, CH3) and 0.15 (9 H, s,
3 ꢁ CH3; (CH3)3Si); dC (100 MHz, CDCl3) 141.2 (iꢀC; Ar), 135.7 (iꢀC; Ar),
128.7, 128.1, 126.3 and 125.4 (4 ꢁ CH; Ar), 71.8 (CHOSi), 33.6 (CHCH3), 27.5
and 26.4 (2 ꢁ CH2), 16.6 (CH3) and 0.2 (3 ꢁ CH3; (CH3)3Si); m/z 235.1 (100%,
MH+); and 2-methyl-tetralone 2 (48 mg, 35%) as a colourless oil; RF [(light
petroleum (b.p. 40–608C)-diethyl ether) (19:1)] 0.25; vmax(NaCl)/cmꢀ1 1683
(C ¼¼ O); dH(270 MHz, CDCl3) 8.05 (1 H, d, J 7.3 Hz, CH; Ar), 7.45 (1 H, t, J
7.3 Hz, CH; Ar), 7.29 (1 H, t, J 7.3 Hz, CH; Ar), 7.20 (1 H, d, J 7.3 Hz, CH;
Ar), 2.98 (2 H, d quintet, J 7.0 and 5.5, CH2), 2.57 (1 H, m, CH), 2.12 (1 H, m,
CH), 1.87 (1 H, d quintet, J 7.0 and 4.4, CH) and 1.26 (3 H, d, J 6.8, CH3);
dC(100 MHz, CDCl3) 201.0 (C ¼¼ O), 144.4 and 133.2 (2 ꢁ iꢀC; Ar), 132.5,
Copyright # 2006 John Wiley & Sons, Ltd.
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766
S. BUKSHA ET AL.
128.9, 127.5 and 126.7 (4 ꢁ CH; Ar), 42.8, 31.5 and 29.0 (3 ꢁ CH2) and 15.5
(CH3) (Found M+ 160.0882, C11H12O requires M+ 160.0882).
1-Trimethylsilyloxy tetralane 20 and tetral-1-one 9
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-tetral-1-
ene 108 (0.78 g, 3.59 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4 unreduced),
hydrogen gas (500 ml) in toluene (10 ml) gave, after column chromatography
on silica gel eluting with light petroleum (b.p. 40-608C)-ether (9:1)
1-trimethylsilyloxy tetralane 20 (0.46 g, 65%) as a colourless oil; RF [light
petroleum (b.p. 40–608C)-ether (19:1)] 0.50; vmax(film)/cmꢀ1 1174 (CO); dH
(270 MHz, CDCl3) 7.42–7.40 (1 H, m, CH; Ar), 7.24–7.18 (2 H, m, 2 ꢁ CH;
Ar), 7.17–7.05 (1 H, m, CH; Ar), 4.67 (1 H, br s, CHO), 2.85–2.71 (2 H, m,
CH2), 2.01–1.93 (2 H, m, CH2), 1.89–1.78 (2 H, m, CH2) and 0.12 (9 H, s,
3 ꢁ CH3; (CH3)3Si); dC (100 MHz, CDCl3) 139.0 (iꢀC; Ar), 136.4 (iꢀC; Ar),
128.2, 127.5, 126.5 and 125.4 (4 ꢁ CH; Ar), 68.6 (CHO), 32.5, 28.7 and 19.2
(3 ꢁ CH2) and 0.0 (3 ꢁ CH3; (CH3)3Si); m/z 251.1 (100%, MH+); and tetral-1-
one 9 (58 mg, 11%). as a colourless oil; RF [light petroleum (b.p. 40–608C)-
ether (9:1)] 0.25; vmax(film)/cmꢀ1 1714 (C ¼¼ O); dH (270 MHz, CDCl3) 8.01
(1 H, d, J 7.5, CH; Ar), 7.45 (1 H, t, J 7.3, CH; Ar), 7.30–7.24 (2 H, m, 2 ꢁ CH;
Ar), 2.95 (2 H, t, J 6.8, CH2), 2.65 (2 H, t, J 6.8, CH2) and 2.13 (2 H, quintet, J
6.8, CH2); dC (100 MHz, CDCl3) 197.8 (C ¼¼ O), 144.4 (iꢀC; Ar), 133.2 (iꢀC;
Ar), 132.6, 128.7, 127.0 and 126.5 (4 ꢁ CH; Ar), 39.1, 29.6 and 23.0 (3 ꢁ CH2).
1-Trimethylsilyloxy-2-methyl-indanane 23 and 2-methyl-indan-1-one 15
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-2-methyl-
inden-1-ene 168 (0.19 g, 0.86 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), hydrogen gas (500 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p, 40-608C)-
diethyl ether (19:1) the 1-trimethylsilyloxy-2-methyl-indanane 23 (0.15 g. 79%)
as a colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (19:1)]
0.77; dH (270 MHz, CDCl3) 7.29–7.19 (4 H, m, 4 ꢁ CH; Ar), 5.05 (1 H, d, J 6.2,
CHO), 2.89 (1 H dd, J 15.3 and 6.9, CHAHB), 2.66 (1 H, dd, J 15.3 and 5.4,
CHAHB), 2.50–2.56 (1 H, m, CHCH3), 0.99 (3 H, d, J 6.9, CHCH3) and 0.18
(9 H, s, 3 ꢁ CH3; (CH3)3Si); dC (100 MHz, CDCl3) 142.4 (iꢀC; Ar), 140.5
(iꢀC; Ar), 127.3, 126.0, 124.6 and 124.1 (4 ꢁ CH; Ar), 77.0 (CHO), 38.1
(CHCH3), 37.6 and 13.7 (2 ꢁ CH2) and 0.7 (3 ꢁ CH3; (CH3)3Si); m/z 221.1
(100%, MH+) and 2-methyl-indan-1-one 15 (16 mg, 12%) as a colourless oil;
RF [light petroleum (b.p. 40–608C)-diethyl ether (19:1)] 0.44; dH (270 MHz,
CDCl3) 7.74 (1 H, d, J 7.6, CH; Ar), 7.54 (1 H, t, J 7.6, CH; Ar), 7.43 (1 H, d,
J 6.6, CH; Ar), 7.34 (1 H, t, J 7.6, CH; Ar), 3.37 (1 H, q, J 7.6, CHAHB),
2.75–2.68 (1 H, m, CHAHB), 2.69–2.63 (1 H, m, CHCH3) and 1.24 (3 H, d,
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J 7.2, CHCH3); dC (100 MHz, CDCl3) 209.6 (C ¼¼ O), 153.4 (iꢀC; Ar), 136.3
(iꢀC; Ar), 134.6, 127.3, 126.5 and 123.9 (4 ꢁ CH; Ar), 41.9 (CHCH3), 34.9
(CH2) and 16.2 (CHCH3); m/z 133 (100%, MH+}CH2).
1-Trimethylsilyloxy-5-methoxytetralane 21
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-5-
methoxy-tetral-1-ene 12 (0.28 g, 1.12 mmol), Pd-on-BaSO4 (40 mg, 5% on
BaSO4 unreduced), hydrogen gas (500 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (9:1) the 1-trimethylsilyloxy-5-methoxytetralane 21 (0.22 g, 77%)
as a colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (9:1)] 0.9;
vmax(film)/cmꢀ1 1212 (C–O); dH (270 MHz, CDCl3) 7.14 (1 H, t, J 7.7, CH;
Ar), 6.95 (1 H, d, J 7.7, CH; Ar), 6.68 (1 H, d, J 7.7, CH; Ar), 4.77 (1 H, t, J 4.5,
COH), 3.76 (3 H, s, COCH3), 2.66–2.59 (2 H, m, CH2), 1.96–1.92 (2 H, m,
CH2), 1.79–1.72 (2 H, m, CH2) and 0.19 (9 H, s, 3 ꢁ CH3; Si(CH3)3); dC
(100 MHz, CDCl3) 156.5 (iꢀCO; Ar), 140.1 and 125.4 (2 ꢁ iꢀC; Ar), 125.1,
120.0 and 108.0 (3 ꢁ CH; Ar), 68.6 (CHO), 54.8 (COCH3), 31.8 (CH), 22.3 and
18.5 (2 ꢁ CH2) and 0.84 (3 ꢁ CH3; (CH3)3Si); m/z 251.1 (100%, MH+).
1-Trimethylsilyloxy-indanane 22
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-indanane
148 (0.2 g, 0.97 mmol) , Pd-on-BaSO4 (40 mg, 5% on BaSO4 unreduced),
hydrogen gas (500 ml) in toluene (2 ml) gave, after column chromatography on
silica gel eluting with light petroleum (b.p. 40–608C)-diethyl ether (9:1) the
1-trimethylsilyloxy-indanane 22 (0.10 g. 50%) as a colourless oil; RF [light
petroleum (b.p. 40–608C)-diethyl ether (9:1)] 0.86; vmax(film)/cmꢀ1 1108
(C–O); dH (270 MHz, CDCl3) 7.23–7.19 (4 H, m, 4 ꢁ CH; Ar), 5.23 (1 H, t, J
6.7, CHO), 2.98–2.95 (1 H, m, CHAHB), 2.79–2.73 (1 H, m, CHAHB), 2.40–
2.36 (1 H, m, CHAHB), 1.95–1.88 (1 H, m, CHAHB) and 0.20 (9 H, s, 3 ꢁ CH3;
(CH3)3Si); dC (100 MHz, CDCl3) 144.9 (iꢀC; Ar), 142.3 (iꢀC; Ar), 127.4,
126.2, 124.4 and 123.8 (4 ꢁ CH; Ar), 75.9 (CHO), 35.9 and 30.6 (CH2) and 0.2
(3 ꢁ CH3; (CH3)3Si); m/z 207.1 (100%, MH+).
1-Trimethylsilyloxybenzosuberane 24
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-
benzosuber-1-ene 188 (0.19 g, 0.8 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), hydrogen gas (500 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (19:1) the 1-trimethylsilyloxybenzosuberane 24 (0.13 g, 70%) as a
colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (19:1)] 0.9;
v
max(film)/cmꢀ1 2927 (C–H) and 1110 (C–O); dH (270 MHz, CDCl3) 7.40 (1 H,
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d, J 7.1, CH; Ar), 7.13–7.06 (3 H, m, 3 ꢁ CH; Ar), 4.84 (1 H, d, J 6.7, CHO),
2.91–2.86 (1 H, m, CHAHB), 2.72–2.68 (1 H, m, CHAHB), 2.08–1.96 (1 H, m,
CHCHD), 1.89–1.66 (4 H, m, 2 ꢁ CH2), 1.48–1.41 (1 H, m, CHCHD) and 0.08
(9 H, s, 3 ꢁ CH3; Si(CH3)3); dC (100 MHz, CDCl3) 144.8 (iꢀC; Ar), 140.5
(iꢀC; Ar), 129.1, 126.4, 125.8 and 125.2 (4 ꢁ CH; Ar), 74.2 (CHO), 37.8, 35.8,
27.9 and 27.7 (4 ꢁ CH2) and 0.3 (3 ꢁ CH3; (CH3)3Si); m/z 235.1 (100%,
MH+).
1-Trimethylsilyloxy-1,2-dideuterio-2-methyl-tetralane [D2]-syn-19 and 2-methyl-
2-deuterio-tetralone [D1]-2
Under the same conditions as the silyl ether syn-19, 1-trimethylsilyloxy-2-
methyl-tetral-1-ene 18 (0.2 g, 0.86 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), deuterium gas (500 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (9:1), 2-deuterio-2-methyl-tetralone [D1]-2 (14 mg, 10%) ([D]:[H]
= 98:2) as a colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl ether
(19:1)] 0.33; vmax(film)/cmꢀ1 2106 (C–D) and 1683 (CO); dH(250 MHz, CDCl3)
8.00 (1 H, d, J 7.7, CH; Ar), 7.47 (1 H, dd, J 7.7 and 7.6, CH; Ar), 7.25 (1 H, t J
7.7, CH; Ar), 7.22 (1 H, d, J 7.6, CH; Ar), 3.00 (2 H, m, CH2CH ¼¼ C), 2.20
(1 H, dt, J 13.2 and 4.4, CHAHB), 1.87 (1 H, m, CHAHB) and 1.28 (3 H, s,
CH3CD); dC(67.5 MHz, CDCl3) 200.8 (C ¼¼ O), 144.2 (iꢀC; Ar), 133.1 (iꢀC;
Ar), 132.4, 128.7, 127.4 and 126.6 (4 ꢁ CH; Ar), 42.0 (1 C, t [1:1:1], J 19.0,
CDMe), 31.3 and 28.8 (2 ꢁ CH2) and 15.3 (CH3) (Found MH+, 162.1034.
C11H12DO requires MH, 162.1029); m/z 162 (100%, M+); the isotopic shift at
42.0 ppm was 75.4. Hz (0.74 ppm at 100.6 MHz); and diastereoisomerically
pure (see foonote z) 1-trimethylsilyloxy-1,2-dideuterio-2-methyl-tetralane
[D2]-syn-19 (0.15 g, 76%) as a colourless oil; RF [light petroleum (b.p.
40–608C)-diethyl ether (19:1)] 0.7; vmax(film)/cmꢀ1 2175 (C–D) and 1058 (C–
O); dH (270 MHz, CDCl3) 7.29–7.26 (2 H, m, 2 ꢁ CH; Ar), 7.16–7.13 (2 H, m,
2 ꢁ CH; Ar), 2.90–2.81 (1 H, m, CHAHB), 2.73–2.70 (1 H, m, CHAHB),
1.82–1.77 (1 H, m, CHCHD), 1.69–1.64 (1 H, m, CHCHD), 0.99 (3 H, s CH3)
and 0.15 (9 H, s, 3 ꢁ CH3; (CH3)3Si); dC (100 MHz, CDCl3) 141.1 (iꢀC; Ar),
135.9 (iꢀC; Ar), 128.5, 128.0, 126.4 and 125.3 (4 ꢁ CH; Ar), 71.7 (1 C, t [1:1:1],
1JC,D 21.2, CDO), 33.6 (1 C, t [1:1:1], 1JC,D 21.2, CD), 27.3 (CH2), 26.4 (CH2),
16.7 (CH3) and 0.2 (3 ꢁ CH3; (CH3)3Si); m/z 222.1 (100%, MH+).
1-Trimethylsilyloxy-1,2-dideuteriotetralane [D2]-20
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-tetral-1-
ene 108 (0.78 g, 3.6 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4 unreduced),
deuterium gas (250 ml) in toluene (2 ml) gave, after column chromatography
on silica gel eluting with light petroleum (b.p. 40–608C)-diethyl ether (9:1)
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1-trimethylsilyloxy-1,2-dideuteriotetralane [D2]-20 (0.50 g, 63%) as a colour-
less oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (9:1)] 0.6; dH
(270 MHz, CDCl3) 7.38 (1 H, d, J 6.9, CH; Ar), 7.16–7.10 (3 H, m, 3 ꢁ CH;
Ar), 2.75 (2 H, t, J 7.6, CH2), 1.99–1.95 (1 H, m, CDH), 1.80–1.73 (2 H, m,
CH2) and 0.22 (9 H, s, 3 ꢁ CH3; Si(CH3)3); dC (100 MHz, CDCl3) 138.4 (iꢀC;
Ar), 135.2 (iꢀC; Ar), 128.1, 127.9, 126.9 and 125.3 (4 ꢁ CH; Ar), 68.3 (1 C, t
1
1
[1:1:1], JC,D 22.1, CDO), 32.2 (1 C, t [1:1:1], JC,D 19 Hz, CD), 26.4 and 25.5
(2 ꢁ CH2) and 0.1 (3 ꢁ CH3; (CH3)3Si); m/z 222.1 (100%, M+). The isotopic
shift at C(1) (68.3 ppm) was 34.2 Hz (0.34 ppm at 100.6 MHz) and at C(1) was
38.2 Hz (0.38 ppm at 100.6 MHz).
1-Trimethylsilyloxy-1,2-dideuterio-5-methoxytetralane [D2]-21
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-5-
methoxy-tetral-1-ene 12 (0.2 g, 0.8 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), deuterium gas (250 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (9:1) the 1-trimethylsilyloxy-1,2-dideuterio-5-methoxytetralane
[D2]-21 (0.10 g, 51%) as a colourless oil; RF [light petroleum (b.p. 40–608C)-
diethyl ether (9:1)] 0.8; vmax(film)/cmꢀ1 2102 (C–D); dH(270 MHz, CDCl3) 7.17
(1 H, t, J 7.9, CH; Ar), 6.95 (1 H, d, J 7.9, CH; Ar), 6.70 (1 H, d, J 7.9, CH;
Ar), 3.78 (3 H, s, OCH3), 2.66–2.54 (2 H, m, CH2), 2.00–1.93 (1 H, m, CH),
1.76–1.68 (2 H, m, CH2) and 0.16 (9 H, s, 3 ꢁ CH3; Si(CH3)3); dC(100 MHz,
CDCl3) 156.4 (iꢀCO; Ar), 140.0 and 125.3 (2 ꢁ iꢀC; Ar), 125.4, 120.0 and
108.0 (3 ꢁ CH; Ar), 68.3 (1 C, t [1:1:1], 1JC,D 21.0, CDO), 55.2 (COCH3), 31.5
1
(1 C, t [1:1:1], JC,D 19.0, CD), 22.5 and 18.3 (2 ꢁ CH2) and 0.4 (3 ꢁ CH3;
Si(CH3)3); m/z 253.1 (100%, MH+). The isotopic shift at C(1) (68.3 ppm) was
31.2 Hz (0.31 ppm at 100.6 MHz) and at C(2) (31.5 ppm) was 49.3 Hz
(0.49 ppm at 100.6 MHz).
1-Trimethylsilyloxy-1,2-dideuterioindanane [D2]-22
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-indan-1-
ene 148 (0.2 g, 0.98 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4 unreduced),
deuterium gas (250 ml) in toluene (2 ml) gave, after column chromatography
on silica gel eluting with light petroleum (b.p. 40–608C)-diethyl ether (9:1) the
1-trimethylsilyloxy-1,2-dideuterioindanane [D2]-22 (0.1 g 50%) as a colourless
oil; RF [light petroleum (b.p. 40–608C)-diethyl ether (9:1)] 0.86; vmax(film)/
cmꢀ1 2074 (C–D); dH(270 MHz, CDCl3) 7.28–7.19 (4 H, m, 4 ꢁ CH; Ar), 2.98
(1 H, dd, J 15.8 and 8.7, CHAHB), 2.77 (1 H, dd, J 15.8 and 7.9, CHAHB), 1.90
(1 H, dd, 8.7 and 7.9, CHD) and 0.18 (3 H, s, 3 ꢁ CH3; (CH3)3Si); dC(100 MHz,
CDCl3) 144.9 (iꢀC; Ar), 142.4 (i-C; Ar), 127.4, 126.2, 124.4 and 123.8
1
(4 ꢁ CH; Ar), 75.5 (1 C, t [1:1:1], JC,D 22.0, CDO), 35.7 (1 C, t [1:1:1],
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1JC,D 20.0, CHD), 29.3 (CH2) and 0.2 (3 ꢁ CH3; Si(CH3)3); m/z 209.1 (100%,
MH+). The isotopic shift at C(1) (75.5 ppm) was 37.2 Hz (0.37 ppm at
100.6 MHz) and at C(2) was 35.7 Hz (35.5 ppm at 100.6 MHz).
1-Trimethylsilyloxy-1,2-dideuterio-2-methylindanane [D2]-23 and 2-deuterio-2-
methyl-indan-1-one [D1]-15
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-2-methyl-
inden-1-ene 168 (0.21 g, 0.98 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), deuterium gas (250 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (9:1) the 1-trimethylsilyloxy-1,2-dideuterio-2-methylindanane
[D2]-23 (0.13 g, 60%) as a colourless oil; RF [light petroleum (b.p. 40–608C)-
diethyl ether (9:1)] 0.77; vmax(film)/cmꢀ1 2074 (CD); dH (270 MHz, CDCl3)
7.24–7.18 (4 H, m, 4 ꢁ CH), 2.90 (1 H, d, J 9.3, CHAHB), 2.65 (1 H, d, J 9.3,
CHAHB), 1.01 (3 H, s, CH3) and 0.22 (9 H, s, 3 ꢁ CH3; (CH3)3Si); dC
(100 MHz, CDCl3) 147.2 (iꢀC; Ar), 142.4 (iꢀC; Ar), 127.3, 126.0, 125.6 and
1
1
124.1 (4 ꢁ CH2), 77.0 (1 C, t, JC,D 22.1, CDO), 39.2 (1 C, t, JC,D 20.0, CD),
37.5 (CH2), 13.6 (CH3) and 0.41 (3 ꢁ CH3; (CH3)3Si); (m/z) 132.1 (50, [D2]-
M}Me3SiOD + H) and 131.1 (100, [D1]-M}Me3SiOD + H); the isotopic
shift at C(2) (39.2 ppm) was 20.1 Hz (0.20 ppm at 100.6 MHz), whereas, the
isotopic shift at C(1) (77.0 ppm) could not be measured accurately due to
overlap with CDCl3; and 2-deuterio-2-methyl-indan-1-one [D1]-15 (36 mg,
25%) ([D]:[H] = 75:25); RF [light petroleum (b.p. 40–608C)-diethyl ether (9:1)]
0.40; vmax(film)/cmꢀ1 1716 (CO); dH (250 MHz, CDCl3) 7.76 (1 H, d, J 7.6,
CH, Ar), 7.58 (1 H, t, J 7.6, CH, Ar), 7.45 (1 H, d, J 7.6, CH, Ar), 7.35 (1 H, t,
J 7.6, CH, Ar), 3.39 (1 H, d, J 17.1, CHAHB), 2.72 (1 H, d, J 17.1, CHAHB) and
1.30 (3 H, s, Me); dC(67 MHz, CDCl3) 209.5 (C ¼¼ O), 153.5 (iꢀC; Ar), 136.4
(iꢀC; Ar), 134.6, 127.3, 126.6 and 124.0 (4 ꢁ CH; Ar), 41.5 (1 C, t [1:1:1], 1JC,D
20.1, CDMe), 34.9 (CH2) and 16.2 (CH3); m/z 147.1 (42%, [D0]-M+) and 33
(100, [D0]-MH+}CH2); the isotopic shift at C(2) (41.5 ppm) was 42.3 Hz
(0.42 ppm at 100.6 MHz).
1-Trimethylsilyloxy-1,2-dideuteriobenzosuberane [D2]-24
Using the same method as the silyl ether syn-19, 1-trimethylsilyloxy-
benzosuber-1-ene 188 (0.19 g, 0.8 mmol), Pd-on-BaSO4 (40 mg, 5% on BaSO4
unreduced), deuterium gas (250 ml) in toluene (2 ml) gave, after column
chromatography on silica gel eluting with light petroleum (b.p. 40–608C)-
diethyl ether (9:1) the 1-trimethylsilyloxy-1,2-dideuteriobenzosuberane [D2]-24
(0.15 g, 79%) as a colourless oil; RF [light petroleum (b.p. 40–608C)-diethyl
ether (9:1)] 0.9; vmax(film)/cmꢀ1 2097 (C–D) and 1194 (C–O); dH (270 MHz,
CDCl3) 7.39 (1 H, d, J 7.6, CH; Ar), 7.18–7.03 (3 H, m, 3 ꢁ CH3), 2.95–2.87
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INVESTIGATIONS INTO THE C-DEUTERIATION OF SILYL ENOL ETHERS
771
(1 H, m, CHAHB), 2.72–2.63 (1 H, m, CHAHB), 2.02–1.98 (1 H, m, CHCHD),
1.76–1.68 (3 H, m, CH2 and CHD), 1.52–1.40 (1 H, m, CHCHD) and 0.08 (9 H,
s, 3 ꢁ CH3; Si(CH3)3); dC (100 MHz, CDCl3) 144.7 (iꢀC; Ar), 140.6 (iꢀC; Ar),
1
126.1, 126.5, 125.8 and 125.2 (4 ꢁ CH; Ar), 74.8 (1 C, t [1:1:1], JC,D 21.0,
CDO), 37.2 (1 C, t [1:1:1], 1JC,D 20.0, CDH), 35.8, 27.8 and 27.6 (3 ꢁ CH2) and
0.3 (3 ꢁ CH3; Si(CH3)3); m/z 146.1 (100%, [D2]-M}Me3SiOD + H) and
145.1. (50, [D1]-M}Me3SiOD + H+); m/z 235.1 (100%, MH+). The isotopic
shift at C(1) (74.8 ppm) was 35.2 Hz (0.35 ppm at 100.6 MHz).
References
1. (a) Chappelle MR, Harding JR, Kent BB, Jones JR, Lu S-Y, Morgan AD. J Label
Compd Radiopharm 2003; 46: 567–574; (b) Lei HS, Atkinson J. J Label Compd
Radiopharm 2001; 44: 215–233; (c) Anet FAL, Leyendecker F. J Am Chem Soc
1973; 95: 156–159; (d) McDonald RN, Schell PL, Chowdhury AK. J Am Chem Soc
1985; 107: 5578–5579; (e) Oba M, Ishihara T, Satake H, Nishiyama K. J Label
Compd Radiopharm 2002; 45: 619–627; (f) Ellames GJ, Gibson JS, Herbert JM,
Kerr WJ, McNeill AH. J Label Compd Radiopharm 2004; 47: 1–10.
2. (a) Conner WC, Kokes RJ. J Phys Chem 1969; 73: 2436–2438; (b) Salter R,
Bosser I. J Label Compd Radiopharm 2003; 46: 489–498.
3. (a) Oba M, Ishihara T, Satake H, Nishiyama K. J Label Compd Radiopharm 2002;
45: 619–627; (b) Jung HM, Koh JH, Kim MJ, Park J. Org Lett 2000; 2: 2487–2490.
4. Sugiura M, Nakai T. Angew Chem Int Ed Engl 1997; 36: 2366–2368.
5. (a) Aboulhoda SJ, Reiners I, Wilken J, Henin F, Martens J, Muzart J.
Tetrahedron: Asymmetry 1998; 9: 1847–1850; (b) Muzart J, Henin F,
Aboulhoda SJ. Tetrahedron: Asymmetry 1997; 8: 381–389.
6. (a) Eames J, Coumbarides GS, Suggate MJ, Weerasooriya N. Eur J Org Chem
2003; 634–641; (b) Eames J, Coumbarides GS, Weerasooriya N. J Label Compd
Radiopharm 2001; 44: 871–879; (c) Boyd E, Coumbarides GS, Eames J, Hay A,
Jones RVH, Stenson RA, Suggate MJ. Tetrahedron Lett 2004; 45: 9465–9468; (d)
Coumbarides GS, Eames J, Ghilagaber S, Suggate MJ. Tetrahedron Lett 2004; 45:
9469–9474; (e) Coumbarides GS, Eames J, Scheuermann JEW, Sibbons KF,
Suggate MJ, Watkinson M. Bull Chem Soc Jpn 2005; 78: 906–909.
7. Buksha S, Coumbarides GS, Dingjan M, Eames J, Suggate MJ, Weerasooriya N.
J Label Compd Radiopharm 2005; 48: 337–352.
8. Eames J, Coumbarides GS, Weerasooriya N. Eur J Org Chem 2002; 181–187; and
references therein.
Copyright # 2006 John Wiley & Sons, Ltd.
J Label Compd Radiopharm. 2006; 49: 757–771
DOI: 10.1002/jlcr