2-benzothiazolyl propargyl sulfides: Versatile precursors for enantiopure allenes, E-α,β-unsaturated ketones and Z-sulfonylalkenes

Article abstract of DOI:10.1055/s-0030-1258259

A novel, stereospecific route to allenes is described. The approach proceeds via a retro-ene reaction, initiated by lithium aluminium hydride mediated cleavage of benzothiazole from the respective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As

Full text of DOI:10.1055/s-0030-1258259

PAPER
3811
2-Benzothiazolyl Propargyl Sulfides: Versatile Precursors for Enantiopure
Allenes, E-a,b-Unsaturated Ketones and Z-Sulfonylalkenes
Dagmar C. Kapeller,* Philip J. Kocienski*
School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
Fax +44(113)3436401; E-mail: P.J.Kocienski@leeds.ac.uk; E-mail: Dagmar.Kapeller@gmx.at
Received 30 June 2010; revised 23 August 2010
Abstract: A novel, stereospecific route to allenes is described. The
approach proceeds via a retro-ene reaction, initiated by lithium alu-
N
H
O
NaBH4
MeOH
minium hydride mediated cleavage of benzothiazole from the re-
spective (chiral) 2-benzothiazolyl propargyl sulfone precursors. As
such, allenes in up to 92% yield are formed under evolution of sul-
fur dioxide at ambient temperature. Furthermore, a new and mild
way to generate E-a,b-unsaturated ketones has been discovered.
These substrates are formed in around 50% yield by treating 2-ben-
zothiazolyl propargyl sulfides with hydrogen peroxide and a cata-
lytic amount of ammonium molybdate at room temperature. In the
course of this research it was also found that treatment of 2-ben-
zothiazolyl propargyl sulfones with sodium borohydride led to re-
duction of the triple bond exclusively to the Z-double bond.
S
R1
·
H
S
+
N
O
H
R1
R2
S
R2
1
2
3
– SO2
O
O
O
O
S
S
H
R1
R1
Key words: allenes, a,b-unsaturated ketones, oxidations, rear-
rangements, sulfones
R2
R2
4
5
Scheme 1 Planned route to chiral allenes and mechanism
In the last few decades the interest of preparative chemists
in allenes has risen dramatically. These substrates do not
only occur in natural products or compounds with phar- The latter is in accordance with work reported by Julia et
macological activity but are also used as versatile building al., who synthesized allenes via 5 by treating propargylic
blocks in modern organic synthesis.1 They undergo many
sulfinamides with boron trifluoride under hydrolytic con-
ditions.6a–d Further examples describing the fragmentation
of sulfinic acids6e–g or the pyrolysis of trimethylsilyl pro-
pargyl ethers6h are also available.
regio- and stereoselective C–C bond-forming reactions
and can transfer axial chirality to one or more stereogenic
centres.2 The growing demand for allenes has led to the
development of several, partly enantioselective methods
for their synthesis.3 Some of the main approaches include
SN2¢ reactions with aluminium hydride reagents, skeletal
rearrangements, homologations, b-eliminations, deoxy-
stannylations or various transition-metal-catalysed reac-
tions.
To establish the feasibility of this reaction sequence, we
started out with racemic propargylic alcohols 7, which
were prepared by addition of lithiated alkynes to alde-
hydes in 69–99% yield (Scheme 2, Table 1).
Subsequent Mitsunobu reaction yielded sulfides 8
smoothly in 58–93% yield.7 Surprisingly, when attempt-
ing to oxidize the sulfides with m-chloroperoxybenzoic
In this approach to the synthesis of chiral allenes, we en-
visaged the use of chiral 2-benzothiazolyl-substituted pro-
pargyl sulfones 1. Such compounds are easily accessible
from their respective alcohols (prepared either by enantio-
selective alkynylations of aldehydes4 or stereospecific
reductions of the respective ketones5) via Mitsunobu reac-
tion and oxidation. When treated with a hydride-donating
reagent (e.g., NaBH4), attack on the most electrophilic
carbon atom would occur (Scheme 1). This, in turn, would
effect cleavage of benzothiazole (2) to give 4, followed by
immediate solvent-mediated protonation of the sulfinate
anion. Intermediate 5 would then undergo a retro-ene re-
action to form the allene under evolution of sulfur dioxide.
N
S
OH
S
SH
Ph3P, DIAD
N
S
R1
THF
R2
R1
R2
MCPBA
BT
7a–k
8a–k
X
1. n-BuLi
2. R1CHO
O
S
H
O
R1
R2
R2
6a–k
1a–k
SYNTHESIS 2010, No. 22, pp 3811–3821
x
x.
x
x
.
2
0
1
0
Advanced online publication: 22.09.2010
DOI: 10.1055/s-0030-1258259; Art ID: T34210SS
© Georg Thieme Verlag Stuttgart · New York
Scheme 2 Synthesis of racemic 2-benzothiazolyl propargyl sulfides
(8)

3812
D. C. Kapeller, P. J. Kocienski
PAPER
As there was no precedence in the literature for a similar
reaction under these conditions to the best of our knowl-
edge, we decided to investigate its scope by employing
various substrates (Table 2).
Table 1 Preparation of Propargylic Alcohols 7 and 2-Benzothia-
zolyl Propargyl Sulfides 8
Entry Alkyne 6
Aldehyde
(R1)
Yield of 7 Yield of 8
(R2)
(%)
(%)
Table 2 Scope of the Reaction
1
2
Bu
c-C6H11
c-C3H5
i-Pr
7a: 92
7b: 86
7c: 98
7d: 93
7e: 90
7f: 92
7g: 99
7h: 99
7i: 90
7j: 69
7k: 80
8a: 82
8b: 68
8c: 85
8d: 87
8e: 93
8f: 83
8g: 85
8h: 90
8i: 90
8j: 58
8k: 65
Entry Starting Cat.
R1
R2
Product yield
(%)
Bu
material 8 (equiv)
3
Bu
1
2
8a
8b
8c
8d
8e
8f
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
c-C6H11
c-C3H5
i-Pr
Bu
Bu
Bu
Bu
Bu
9a: 51
9b: 58
9c: 60
9d: 48
4
Bu
t-Bu
5
Bu
Me
3
6
heptyl
Me
4
t-Bu
7
Bu
PhCH2CH2
PhCH2CH2
c-C6H11
c-C6H11
c-C6H11
5
Me
9e: 21
1e: 22
8
Ph
6
Me
heptyl 9f: 20
1f: 10
1g: 8
9
MeCH(OTBS)
SEMOCH2CH2
PMBOCH2CH2
7
8g
8h
8a
8a
8f
PhCH2CH2
PhCH2CH2
c-C6H11
c-C6H11
Me
Bu
Ph
Bu
Bu
9g: 33
9h: 31
9a: 38
9a: 55
10
11
8
1h: 6
1a: 14
1a: –
9
10
11
12
acid using Bonini’s method for the preparation of primary
2-benzothiazolyl propargyl sulfones,8 almost complete
decomposition was observed. Even after purification and
drying of the peracid, only 30% of sulfone 1a could be
heptyl 9f: 27
1f: 37
1g: 9
8g
8h
PhCH2CH2
PhCH2CH2
Bu
Ph
9g: 57
9h: 34
isolated at best from a complex mixture, rendering these 13
conditions unsuitable for more sterically demanding sub-
strates. Employing ammonium molybdate-catalysed oxi-
dation with hydrogen peroxide for 8a did not lead to the
expected result either.9 Instead, E-a,b-unsaturated ketone
9a and 2 were formed cleanly in a 1:1 ratio (Scheme 3).
No other side products were visible in the 1H NMR spec-
trum of the crude product.
1h: 25
In cases where R1 is a bulky substituent, such as cyclohex-
yl, cyclopropyl, isopropyl or tert-butyl (Table 2, entries
1–4), the isolated yields were reproducibly between 48–
60%, independent of the scale of the reaction (0.5–10
mmol). However, if a non-bulky residue, such as methyl
or 2-phenylethyl was employed, the yields of ketones 9e–h
were lower, and a few percent of sulfones 1e–h could be
detected by 1H NMR spectral analysis of the crude prod-
uct (Table 2, entries 5–8). The choice of R2 did not seem
to have a significant influence on the reaction (cf. Table 2,
entries 7 and 8). Furthermore, increasing the amount of
catalyst from 0.1 to 0.2 equivalents led to a higher yield of
the ketones as well as the sulfones and to reduced reaction
times (from 16 to 4 h) in the case of non-bulky substitu-
ents (Table 2, entries 11–13). For the bulky, cyclohexyl-
substituted compound 8a the increase in catalyst loading
at first caused formation of 14% of sulfone 1a (Table 2,
entry 9), but when 0.5 equivalents of catalyst was used,
the result was the same as with only 0.1 equivalents.
BT
S
O
(NH4)6Mo7O24·4H2O (0.1 equiv)
R1
R1
R2
H2O2 (5 equiv), EtOH
R2
8a–h
9a–h
BT
O
BT
S
S
R1
OH
R1
O
R1
R2
R2
R2
11a–h
10a–h
13a–h
The most probable mechanism for this reaction involves
formation of sulfoxide 10, which is an extremely labile
species that could not be isolated, followed by a [2,3]-sig-
matropic rearrangement. This explanation is supported by
the work of Baudin and Julia, who effected the thermal re-
arrangement of propargylic sulfoxides, which also led to
a,b-unsaturated ketones. However, contrary to our exam-
ple, thiol additives were necessary to promote the cleav-
age of the sulfur–oxygen bond under formation of
disulfides.6b Furthermore, the proposed mechanism is
BT
O
S
H2O
– SO2
R1
O
2
R2
12a–h
Scheme 3 Rearrangement of sulfoxides 10 to a,b-unsaturated
ketones 9 including a possible mechanism
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

PAPER
Chiral Allenes and a,b-Unsaturated Ketones
3813
analogous to the Evans–Mislow rearrangement10 and oth-
er examples in the literature describing rearrangements of
propargylic sulfoxides as initial steps in tandem reac-
tions.11 In our case, compound 11 is probably oxidized to
sulfinic ester 12 and then hydrolyzed to 13 and 2 under
evolution of SO2. The last step is tautomerization of the al-
lenol to ketone 9.
O
O
DMDO
(2.2 equiv)
NaBH4
(5.5 equiv)
BT
H
BT
H
S
S
H
O
R1
O
R1
8a,g–k
R2
H
CH2Cl2
62–91%
MeOH
43%
R2
1a,g–k
17a
Et3N (2 equiv)
MeOH
18a: 85%
1a: 13%
MeO
MeOH
O
This reaction is quite specific for benzothiazolyl-substi-
tuted sulfides (or to a lesser degree the phenyltetrazolyl-
substituted: 38% yield for cyclohexyl/butyl substitution),
which was demonstrated by synthesizing the phenyl ana-
logue 15 (similar to the compounds used by Julia et al.6b)
via mesylation of propargylic alcohol 7a and further treat-
ment with potassium thiophenolate (Scheme 4). Almost
quantitative oxidation to sulfone 16 was observed by em-
ploying ammonium molybdate/hydrogen peroxide or m-
chloroperoxybenzoic acid oxidation.
O
BT
BT
S
NaBH4
S
O
R1
O
R1
H
R2
H
R2
18a
19%
H
19a
H
O
Ph
NaBD4
S
(5.5 equiv)
O
16
Bu
MeOH
69%
O
H
18b
S
Ph
t-BuOK, PhSH
18-crown-6
O
S
O
Scheme 5 Oxidation with DMDO and reduction to the Z-alkene 17a
THF
2 steps: 78%
Bu
Bu
14
15
MsCl, Et3N
CH2Cl2
oxidation
O
7a
Ph
S
O
Yields:
(NH4)6Mo7O24⋅4H2O/H2O2: 87%
MCPBA: 94%
Bu
16
Scheme 4 Oxidation of the phenyl-derivative 15
The problems concerning oxidation of benzothiazolyl sul-
fides 8 were finally resolved by using dimethyldiox-
irane.12 This gave the respective sulfones 1 cleanly in 61–
91% (Scheme 5).
Figure 1 X-ray crystal structure of 17a
With 1a in hand, a first attempt at the synthesis of allene
was made by employing an excess of sodium borohydride
in methanol. However, instead of generating the expected
allene, or even the respective sodium alkanesulfinate/
benzothiazole reported by Ueno et al.,13 Z-alkene 17a was
isolated as the main product (43%); its structure was proven
by X-ray crystal structure analysis (Scheme 5, Figure 1).14
According to these observations, we hypothesised the fol-
lowing mechanism for the NaBH4 reaction: Due to excess
sodium borohydride present in the reaction, sodium meth-
oxide was formed, which caused isomerization to 18a.
Then, the central carbon atom of the allene was attacked
by a hydride ion, giving 19a and, after protonation, the Z-
alkene. We verified this mechanism by performing the re-
action in deuterated methanol, which led to almost quan-
titative deuterium incorporation at positions C-1 and C-3
(red colour in Scheme 5).
Furthermore, allenylsulfone 18a was isolated in 19%
yield, which is in accordance with reports describing the
base-induced isomerization of propargyl sulfones to the
respective allenes.15,16 We could confirm those results by
treating 1a with triethylamine and isolating the allene in
85% yield, together with 13% of recovered starting mate-
rial (Scheme 5). More evidence could be gathered by
treating phenyl sulfone 16 with sodium borodeuteride
(NaBD4), whereby 69% of the respective allene 18b was
isolated, but no deuterium incorporation could be detected
by NMR spectroscopic analysis.
Sheldrake and Wallace had reported another method with
which to reduce phenyl propargyl sulfones to Z-alkenes
by employing excess zinc and aqueous ammonium chlo-
ride.16 To compare these two procedures, 1a was subject-
ed to the same conditions. Surprisingly, no 17a could be
1
detected by H NMR spectroscopic analysis of the crude
product. Instead, allene 3a was isolated in 56% yield by
chromatography.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

3814
D. C. Kapeller, P. J. Kocienski
PAPER
Focusing our attention on our initial target, we reasoned found to be inferior compared to lithium aluminium hy-
that if sodium borohydride in methanol led to unwanted dride.
isomerization, use of a non-protic solvent could circum-
vent this problem. To this end, compound 1a was treated
with two equivalents of lithium aluminium hydride in tet-
rahydrofuran, which gave allene 3a after work-up in an
excellent yield of 92% (Scheme 6, Table 3, entry 1).
O
Ph
LAH
(2 equiv)
S
O
16
H
THF
63%
H
Bu
(E)-21
H
HS
Scheme 7 Reduction of 16 to the E-alkenyl sulfone
hydride reagent
+
R1
H
1a,g–h
THF, acidic work-up
Me
N
R2
H
Again, the result for the benzothiazolyl propargyl sulfone
was compared with its phenyl analogue 16 (Scheme 7).
Treatment with two equivalents of lithium aluminium hy-
dride gave no trace of the allene but 63% of the respective
E-alkenyl sulfone (E)-21, which is comparable to the re-
sults described by Baudin and Julia.6d
3a,g–h
20
Scheme 6 Allene synthesis
After the initial success, a range of substituted sulfones
1g–k were subjected to the same conditions. Both 1g (2-
phenylethyl and butyl substituted) and 1k (cyclohexyl and
2-PMB-oxyethyl substituted) gave the respective allenes
in 83% yield (Table 3, entries 3 and 13). In the case of si-
lyl protective groups (TBS and SEM, Table 3, entries 9
and 12) almost 70% of 3i, as well as 3j, could be isolated.
Applying the 2-phenylethyl/phenyl substituted sulfone 1g
resulted in a less than satisfactory yield of 38% (Table 3,
entry 6).
Having established the feasibility of this approach to al-
lenes, we then addressed the stereoselectivity of the reac-
tion. To this end, an enantiopure starting material was
prepared. We decided to use the cyclohexyl/1-TBS-oxy-
ethyl substitution pattern due to the formation of diaste-
reomers and the consequent ease with which the
diastereomeric excess can be determined. Commercially
available (S)-3-butyn-2-ol was TBS-protected and trans-
formed into ketone (S)-22 via addition to the Weinreb-
amide of cyclohexane carboxylic acid (Scheme 8).
In two cases (Table 3, entries 4 and 7), the amount of LAH
was reduced to only one equivalent, which caused a con-
comitant loss of product. Other hydride-donating reagents
were also assessed. Diisobutylaluminium hydride
(Table 3, entry 5) did not react at all, while lithium trieth-
ylborohydride (‘Superhydride’; Table 3, entries 8 and 10)
gave the allenes in low yields and in admixture with sev-
eral by-products. Red-Al® (Table 3, entry 11) was also
Compound (S)-22 was then stereoselectively reduced by
employing the Noyori catalyst 23 to give enantiomerically
pure diastereomer (1R,4S)-7i in 88% yield.5 Mitsunobu
reaction (Scheme 2) of the latter gave (1S,4S)-8i (>99%
de according to chiral HPLC) and oxidation with dimeth-
yldioxirane (80%, Scheme 5) finally gave sulfone
(1S,4S)-1i. Rearrangement to the allene (aR,2S)-3i was
Table 3 Reduction of Sulfones 1g–k
Entry
1
Reagent (equiv)
LAH (2)
Product
3a
R1
R2
Yield (%)
c-C6H11
Bu
92
56
83
71
–
2
Zn (25)
3a
3
LAH (2)
3g
PhCH2CH2
PhCH2CH2
c-C6H11
Bu
4
LAH (1)
3g
5
DIBAL-H (2)
LAH (2)
3g
6
3h
3h
3h
3i
Ph
38
12
22
68
<10
35
69
83
7
LAH (1)
8
LiBEt3H (2)
LAH (2)
9
MeCH(OTBS)
10
11
12
13
LiBEt3H (1.1)
Red-Al®
3i
3i
LAH (2)
3j
c-C6H11
c-C6H11
SEMOCH2CH2
PMBOCH2CH2
LAH (2)
3k
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

PAPER
Chiral Allenes and a,b-Unsaturated Ketones
3815
substrates are readily available in two steps from propar-
gylic alcohols.
1. n-BuLi, –78 °C
THF
O
OTBS
O
2.
It was also found that by changing the conditions from
lithium aluminium hydride in tetrahydrofuran to sodium
borohydride in methanol, selective reduction of the triple
bond to the Z-double bond occurred.
Me
N
OTBS
(S)-6i
(S)-22
OMe
90%
23
i-PrOH
88%
Furthermore, a new and mild procedure for the prepara-
tion of E-a,b-unsaturated ketones was discovered. These
compounds are formed from 2-benzothiazolyl propargyl
sulfides in about 50% yield under mild, oxidative condi-
tions.
Ts
Ph
Ph
N
Ru
OH
N
H
23
OTBS
Solvents and reagents were dried by distillation from standard dry-
ing agents prior to use: Et2O and THF from sodium/benzophenone;
CH2Cl2 and toluene from CaH2; DIPEA, pyridine and Et3N from
KOH. The titre of lithium reagents was determined by the method
of Lipton.17 All reactions were magnetically stirred and monitored
by thin layer chromatography (TLC) using SiO2 on pre-coated alu-
minium foil sheets, layer thickness 0.25 mm. Compounds were vi-
sualised under UV light (254 and 366 nm) and by dipping into a
solution of (NH4)6Mo7O24·4H2O (23 g) and Ce(SO4)2 (1 g) in 10%
H2SO4 (500 mL). Column chromatography was performed on silica
gel 60 (35–70 micron). Optical rotations were recorded with an Op-
tical Activity AA-1000 polarimeter (units in 10–1 deg·cm2·g–1). IR
spectra were recorded with a Perkin–Elmer Spectrum One FT-IR
spectrometer as thin films supported on NaCl plates or on a diffuse
reflectance sampling cell. Absorptions are reported as values in cm–1.
1H and 2D NMR spectra were recorded with a Bruker Avance 500
Fourier Transform spectrometer, 13C NMR spectra with a Bruker
DPX300, and 19F NMR with an Avance 500 Fourier Transform
spectrometer using an internal deuterium lock. The chemical shift
(ppm) is quoted relative to the residual signals of chloroform
(dH = 7.26 ppm, dC = 77.0 ppm), acetone (dH = 2.04 ppm, dC = 29.8
ppm) or DMSO (dH = 2.49 ppm, dC = 39.5 ppm) as the internal stan-
dard. Coupling constants (J) are reported in Hz. The numbers of
protons attached to carbon in the 13C NMR spectra were revealed by
the DEPT spectral editing technique. Signal assignments were
based on COSY, HMQC and HMBC correlations. The program
WINNMR was used for peak assignments, and MestReC for print-
ing of the spectra. Mass spectrometry was carried out on a VG au-
tospec mass spectrometer, operating at 70 eV, using electron impact
ionisation (EI). Electrospray ionisation (ESI) was performed with
either a Micromass LCT TOF spectrometer or a Waters-Micromass
ZMD spectrometer. High-resolution mass spectra (HRMS) were
obtained by peak matching using perfluorokerosene or reserpine as
a standard.
(1R,4S)-7i
Scheme 8 Preparation of enantiomerically pure propargylic alcohol
(1R,4S)-7i
O
BT
S
H
O
LAH (2 equiv)
H
THF
68%
OTBS
OTBS
(1S,4S)-1i
(aR,2S)-3i
TBAF, MeCN
76%
H
H
(S)-MTPA
DCC, DMAP
H
H
CH2Cl2, quant.
OMTPA-(S)
(aR,2S)-24⋅MTPA-(S)
OH
(aR,2S)-24
Scheme 9 Rearrangement of enantiopure sulfone (1S,4S)-1i to the
allene and determination of its enantiomeric excess
achieved with two equivalents of lithium aluminium hy-
dride (Scheme 9).
The NMR spectra of (aR,2S)-3i displayed only one set of
diastereotopic signals, indicating that the formation of the
allene proceeded stereospecifically. To be able to also de-
termine the enantiomeric excess, a sample of (aR,2S)-3i
was deprotected with tetrabutylammonium fluoride and
the resulting alcohol (aR,2S)-24 was transformed into the
(S)-Mosher ester. 19F NMR spectroscopic analysis
showed only one peak, in contrast to the four signals of the
racemic compound. This allowed the assignment of >99%
de and ee.
The data for the X-ray crystal structure determination of 17a was
collected at 150 2 K with a Bruker-Nonius X8 Apex/FR591 rotat-
ing anode diffractometer using Mo-Ka radiation and a graphite
monochromator. The structure was solved by direct methods and re-
fined by the full matrix least squares method using SHELXS and
SHELXL software.
Preparation of Racemic Propargylic Alcohols (7); General Pro-
cedure
In conclusion, we have developed a novel, stereospecific
allene synthesis starting from 2-benzothiazolyl propargyl
sulfones. The formation of the allene is initiated by a re-
ductive, lithium aluminium hydride mediated removal of
benzothiazole. The sulfonate, which is generated as an in-
termediate, is converted into the sulfinic acid on acidic
work-up, which undergoes a retro-ene reaction to the de-
sired allene. This method is compatible with various pro-
tective groups and allows yields of up to 92%. The
To a solution of alkyne (30 mmol) in anhydrous THF (100 mL) un-
der a nitrogen atmosphere, was added n-BuLi (20 mL, 1.5 M in hex-
ane, 30 mmol) at –78 °C. The mixture was stirred for 30 min at low
temperature, then for 30 min at –30 °C before addition of the alde-
hyde (30 mmol) at –78 °C. The solution was allowed to warm to r.t.
over 1 h, before sat. NaHCO3 (200 mL) and Et2O (100 mL) were
added. The organic phase was separated and the aqueous layer was
extracted with Et2O (2 × 100 mL). The combined organic layers
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

3816
D. C. Kapeller, P. J. Kocienski
PAPER
were dried (Na2SO4), concentrated under reduced pressure and pu-
rified by flash chromatography.
2-{[4-(tert-Butyldimethylsilyloxy)-1-cyclohexylpent-2-
ynyl]thio}benzo[d]thiazole (8i) and (1S,4S)-8i
Yield: 90%; slightly yellow oil; Rf = 0.29 (hexane–CH2Cl2, 2:1).
1-Cyclohexyl-2-heptyn-1-ol (7a)18
Yield: 92%; colourless oil; Rf = 0.35 (hexane–CH2Cl2, 1:1).
8i
HPLC (AS-RH; eluent: MeOH–H2O, 85–87%; flow: 1 mL/min)
tR = 16.08, 18.45 min.
IR (film): 3063, 2979, 2928, 2854, 1461, 1427, 1250, 1101 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.89 (d, J = 8.1 Hz, 1 H, ArH),
7.76 (d, J = 8.1 Hz, 1 H, ArH), 7.42 (td, J = 8.1, 1.0 Hz, 1 H, ArH),
7.30 (td, J = 8.1, 1.0 Hz, 1 H, ArH), 4.72–4.67 (m, 1 H, SCH), 4.54
(qd, J = 6.4, 1.7 Hz, 1 H, OCH), 2.01–1.75 (m, 5 H, CH, CH2),
1.71–1.64 (m, 1 H, CH2), 1.37 (dd, J = 6.4, 2.1 Hz, 3 H, CH3), 1.36–
1.11 (m, 5 H, CH2), 0.87 and 0.86 (s, 9 H, 3 × CH3), 0.09–0.04 (m,
6 H, 2 × CH3).
1H NMR (500 MHz, CDCl3): d = 4.13 (td, J = 6.0, 2.1 Hz, 1 H,
OCH), 2.22 (td, J = 7.0, 2.1 Hz, 2 H, CH2), 1.87–1.81 (m, 2 H,
CH2), 1.79–1.74 (m, 2 H, CH2), 1.70–1.64 (m, 1 H, CH2), 1.54–1.46
(m, 3 H, CH2), 1.45–1.37 (m, 2 H, CH2), 1.30–1.00 (m, 5 H, CH2),
0.91 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 86.3, 80.1, 67.5, 44.4, 30.8, 28.6,
28.1, 26.5, 26.0, 25.9, 21.9, 18.4, 13.5.
4-(tert-Butyldimethylsilyloxy)-1-cyclohexylpent-2-yn-1-ol (7i)
Yield: 90%; colourless oil; Rf = 0.16 (hexane–CH2Cl2, 2:3).
IR (film): 3358, 2980, 2928, 2855, 1450, 1255, 1154, 1101, 1027
cm–1.
1H NMR (500 MHz, CDCl3): d = 4.55 (q, J = 6.6 Hz, 1 H, OCH),
4.17–4.13 (m, 1 H, OCH), 1.87–1.63 (m, 5 H, CH2), 1.68 (d, J =
5.6 Hz, 1 H, OH), 1.41 (d, J = 6.6 Hz, 3 H, CH3), 1.29–1.01 (m, 5 H,
CH2), 0.90 (s, 9 H, CH3), 0.12 (s, 3 H, CH3), 0.11 (s, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 165.4, 153.2, 135.6, 126.0, 124.3,
121.8, 120.9, 88.4, 80.31 and 80.26, 59.2, 44.91 and 44.88, 42.4,
31.0, 29.2, 26.14, 26.05, 25.9, 25.8 (3C), 25.40 and 25.37, –4.6,
–5.0.
HRMS (ESI): m/z [M + H+] calcd for C24H36NOS2Si: 446.2002;
found: 446.2005.
13C NMR (300 MHz, CDCl3): d = 88.32 and 88.27, 83.1, 67.2, 59.0,
44.19 and 44.15, 28.5, 28.1, 26.4, 25.9, 25.9, 25.8 (3C), 25.5, 18.2,
–4.6, –4.9.
Anal. Calcd for C24H35NOS2Si: C, 64.67; H, 7.91; N, 3.14; S, 14.39.
Found: C, 64.75; H, 7.95; N, 3.20; S, 14.15.
(1S,4S)-8i
HRMS (ESI): m/z [M + Na+] calcd for C17H32NaO2Si: 319.2064;
found: 319.2065.
25
[a]D –245 (c 1.18, CHCl3); ee >99% [HPLC (AS-RH; eluent:
MeOH–H2O, 85–87%; flow: 1 mL/min) tR = 15.15 min].
IR (film): 3063, 2979, 2928, 2854, 1461, 1427, 1250, 1101 cm–1.
Anal. Calcd for C17H32O2Si: C, 68.86; H, 10.88. Found: C, 69.15;
H, 10.95.
1H NMR (500 MHz, CDCl3): d = 7.89 (d, J = 8.1 Hz, 1 H, ArH),
7.76 (d, J = 8.1 Hz, 1 H, ArH), 7.42 (td, J = 8.1, 1.0 Hz, 1 H, ArH),
7.30 (td, J = 8.1, 1.0 Hz, 1 H, ArH), 4.70 (dd, J = 4.7, 1.3 Hz, 1 H,
SCH), 4.53 (qd, J = 6.4, 1.3 Hz, 1 H, OCH), 2.01–1.75 (m, 5 H, CH,
CH2), 1.71–1.63 (m, 1 H, CH2), 1.37 (dd, J = 6.4, 1.3 Hz, 3 H, CH3),
1.39–1.11 (m, 5 H, CH2), 0.86 (s, 9 H, 3 × CH3), 0.07 (s, 3 H,
SiCH3), 0.06 (s, 3 H, SiCH3).
13C NMR (300 MHz, CDCl3): d = 165.4, 153.2, 135.6, 126.0, 124.3,
121.8, 120.9, 88.4, 80.3, 59.1, 44.9, 42.4, 31.0, 29.2, 26.14, 26.05,
25.9, 25.8 (3C), 25.4, –4.6, –5.0.
Mitsunobu Reaction (8);19 General Procedure
The propargylic alcohol (25.0 mmol), 2-mercaptobenzothiazole
(6.26 g, 37.5 mmol) and Ph3P (10.5 g, 40.0 mmol) were dissolved
in anhydrous THF (125 mL) under argon. The solution was cooled
to –20 °C, then DIAD (7.58 g, 7.35 mL, 37.5 mmol) dissolved in an-
hydrous THF (5 mL) was added. The reaction was allowed to warm
to r.t. and stirred overnight. The solvent was removed under reduced
pressure and the residue was taken up in pentane (100 mL). The pre-
cipitate (triphenylphosphane oxide, hydrazo ester) was filtered off
and washed several times with pentane. The filtrate and washings
were concentrated under reduced pressure and the resulting crude
product was purified by flash chromatography.
5-[(1-Cyclohexylhept-2-ynyl)thio]-1-phenyl-1H-tetrazole
1-Cycloheyl-2-hexyn-1-ol (970 mg, 5.00 mmol), 1-phenyl-1H-tet-
razole-5-thiol (1.34 g, 7.50 mmol) and Ph3P (2.10 g, 8.00 mmol)
were dissolved in anhydrous THF (25 mL) under argon. The solu-
tion was cooled to –20 °C, then DIAD (1.47 mL, 7.50 mmol) dis-
solved in anhydrous THF (1.5 mL) was added. The reaction was
allowed to warm to r.t. and stirred overnight. The solvent was re-
moved under reduced pressure and the residue was purified by flash
chromatography.
2-[(1-Cyclohexylhept-2-ynyl)thio]benzo[d]thiazole (8a)
Yield: 82%; colourless, viscous oil; Rf = 0.46 (hexane–CH2Cl2,
2:1).
IR (film): 3062, 2954, 2928, 2853, 2236, 1459, 1427, 1309, 1238,
992 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.90 (d, J = 7.9 Hz, 1 H, ArH),
7.77 (d, J = 7.9 Hz, 1 H, ArH), 7.42 (td, J = 7.9, 1.3 Hz, 1 H, ArH),
7.31 (td, J = 7.9, 1.3 Hz, 1 H, ArH), 4.64 (td, J = 4.9, 2.4 Hz, 1 H,
SCH), 2.21 (td, J = 6.8, 2.4 Hz, 2 H, CH2), 2.01–1.95 (m, 1 H, CH2),
1.94–1.85 (m, 1 H, CH2), 1.89–1.75 (m, 3 H, CH, CH2), 1.71–1.64
(m, 1 H, CH2), 1.49–1.41 (m, 2 H, CH2), 1.46–1.12 (m, 7 H, CH2),
0.85 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 165.9, 153.1, 135.5, 126.0, 124.3,
121.8, 120.9, 86.7, 45.5, 42.6, 31.1, 30.7, 29.1, 26.2, 26.1, 26.0,
21.9, 18.6, 13.5.
Yield: 87%; colourless crystals; mp 63 °C (pentane); Rf = 0.50
(hexane–CH2Cl2, 2:3).
IR (film): 3057, 2930, 2852, 1595, 1498, 1457, 1447, 1383, 1278
cm–1.
1H NMR (500 MHz, CDCl3): d = 7.60–7.51 (m, 5 H, ArH), 4.75 (td,
J = 4.3, 2.4 Hz, 1 H, SCH), 2.17 (td, J = 7.3, 2.4 Hz, 2 H, CH2),
1.93–1.82 (m, 3 H, CH, CH2), 1.80–1.74 (m, 2 H, CH2), 1.70–1.64
(m, 1 H, CH2), 1.48–1.40 (m, 2 H, CH2), 1.39–1.30 (m, 2 H, CH2),
1.30–1.09 (m, 5 H, CH2), 0.88 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 153.6, 133.8, 130.1, 129.7 (2C),
124.1 (2C), 87.4, 76.1, 46.2, 42.2, 31.0, 30.6, 28.7, 26.1, 26.0, 25.8,
21.9, 18.5, 13.5.
HRMS (ESI): m/z [M + H+] calcd for C20H26NS2: 344.1501; found:
344.1489.
Anal. Calcd for C20H25NS2: C, 69.92; H, 7.33; N, 4.08; S, 18.67.
Found: C, 69.75; H, 7.35; N, 4.00; S, 18.80.
HRMS (ESI): m/z [M]+ calcd for C20H27N4S: 355.1951; found:
355.1948.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

PAPER
Chiral Allenes and a,b-Unsaturated Ketones
3817
Anal. Calcd. for C20H26N4S: C, 67.76; H, 7.39; N, 15.80; S, 9.04.
Found: C, 67.95; H, 7.35; N, 16.00; S, 8.90.
Anal. Calcd for C19H26S: C, 79.66; H, 9.15. Found: C, 79.40; H,
9.15.
Preparation of E-a,b-Unsaturated Ketones (9); General Proce-
dure
[(1-Cyclohexylhept-2-ynyl)sulfonyl]benzene (16)
To a solution of 15 (286 mg, 1.00 mmol) dissolved in EtOH (4 mL),
were added (NH4)6Mo7O24·4H2O (124 mg, 0.10 mmol) and 30%
H2O2 (0.60 mL). The mixture was stirred overnight, then aq
Na2S2O3 (5%, 10 mL) and Et2O (10 mL) were added. The organic
phase was separated and the aqueous layer was extracted with Et2O
(2 × 10 mL). The combined organic layers were washed with brine,
dried (Na2SO4), concentrated under reduced pressure and purified
by chromatography.
To the sulfide 8 (1.00 mmol) dissolved in EtOH (4 mL) were added
(NH4)6Mo7O24·4H2O (124 mg, 0.10 mmol) and 30% H2O2 (0.60
mL). The mixture was stirred overnight, then aq Na2S2O3 (5%, 10
mL) and Et2O (10 mL) were added. The organic phase was separat-
ed and the aqueous phase was extracted with Et2O (2 × 10 mL). The
combined organic layers were washed with brine (20 mL), dried
(Na2SO4), concentrated under reduced pressure and purified by
flash chromatography.
To a solution of 15 (77 mg, 0.27 mmol) in CH2Cl2 (2.7 mL) was
added pure MCPBA (118 mg, 0.68 mmol) dissolved in CH2Cl2 (2.7
mL) at 0 °C. The mixture was stirred for 3 h (temperature up to r.t.),
before aq Na2S2O3 (10%, 3 mL), H2O (10 mL) and Et2O (10 mL)
were added. The organic phase was separated and the aqueous layer
was extracted with Et2O (2 × 10 mL). The combined organic layers
were washed with sodium phosphate buffer (15 mL, pH 7.4), dried
(Na2SO4), concentrated under reduced pressure and purified by
chromatography.
E-1-Cyclohexylhept-1-en-3-one (9a)
Yield: 62%; yellow oil; Rf = 0.19 (hexane–CH2Cl2, 2:1).
IR (film): 2956, 2928, 2853, 1697, 1675, 1627, 1449 cm–1.
1H NMR (500 MHz, CDCl3): d = 6.76 (dd, J = 16.0, 6.8 Hz, 1 H,
CH=), 6.04 (dd, J = 16.0, 1.5 Hz, 1 H, CH=), 2.53 (t, J = 7.6 Hz,
2 H, CH2), 2.17–2.08 (m, 1 H, CH), 1.80–1.62 (m, 5 H, CH2), 1.58
(quin, J = 7.7 Hz, 2 H, CH2), 1.33 (sext, J = 7.5 Hz, 2 H, CH2),
1.32–1.09 (m, 5 H, CH2), 0.91 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 201.3, 152.0, 127.8, 40.6, 39.9,
31.8 (2C), 26.5, 25.9, 25.7 (2C), 22.4, 13.9.
Yield: 87% (with H2O2 as oxidant) and 94% (with MCPBA); co-
lourless crystals; mp 49–50 °C (hexane–Et2O); Rf = 0.20 (hexane–
CH2Cl2, 1:1).
IR (diamond compression system): 3067, 2928, 2857, 2240, 1446,
1305, 1143, 1082 cm–1.
HRMS (ESI): m/z [M + H+] calcd for C13H23O: 195.1743; found:
195.1739.
1H NMR (500 MHz, CDCl3): d = 7.96–7.92 (m, 2 H, ArH), 7.66–
7.61 (m, 1 H, ArH), 7.56–7.51 (m, 2 H, ArH), 3.69 (td, J = 2.9,
2.5 Hz, 1 H, SCH), 2.37–2.29 (m, 1 H, CH), 2.16 (td, J = 7.1,
2.5 Hz, 2 H, CH2), 2.11–2.06 (m, 1 H, CH2), 1.80–1.72 (m, 2 H,
CH2), 1.69–1.61 (m, 2 H, CH2), 1.44–1.25 (m, 8 H, CH2), 1.19–1.10
(m, 1 H, CH2), 0.87 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 138.8, 133.5, 129.1 (2C), 128.7
(2C), 90.3, 70.9, 65.2, 36.7, 32.2, 30.3, 28.8, 26.3, 25.8, 25.6, 21.8,
18.5, 13.5.
Anal. Calcd for C13H22O: C, 80.35; H, 11.41. Found: C, 80.10; H,
11.45.
[(1-Cyclohexylhept-2-ynyl)thio]benzene (15)
To a solution of the alcohol (776 mg, 4.00 mmol) dissolved in
CH2Cl2 (4 mL), were added Et3N (808 mg, 1.11 mL, 8.00 mmol)
and MsCl (690 mg, 0.47 mL, 6.00 mmol) at 0 °C. The mixture was
stirred for 7 h at r.t. then H2O (30 mL) was added. The organic phase
was separated and the aqueous phase was extracted with CH2Cl2
(2 × 30 mL). The combined organic layers were dried (Na2SO4) and
concentrated under reduced pressure.20
+
HRMS (ESI): m/z [M + NH4 ] calcd for C19H30NO2S: 336.1992;
found: 336.1980.
t-BuOK (672 mg, 6.00 mmol) and 18-crown-6 (1.58 g, 6.00 mmol)
were dissolved in anhydrous THF (20 mL) at 0 °C under argon.
Thiophenol (660 mg, 0.61 mL, 6.00 mmol) was added and the mix-
ture was stirred for 10 min at 0 °C and at r.t. for 15 min. The reaction
was cooled again to 0 °C and the crude mesylate (1.10 g) was added.
Stirring was continued for 30 min at 0 °C, then at r.t. for 1.5 h. The
reaction was quenched with H2O (30 mL) and the mixture was
transferred to a separating funnel with Et2O (10 mL). The organic
layer was separated and the aqueous layer was extracted with Et2O
(2 × 20 mL). The combined organic layers were washed with 1 M
HCl (25 mL), aq NaHCO3 (25 mL), and brine (25 mL), dried
(Na2SO4) and concentrated under reduced pressure. The crude mix-
ture was purified by chromatography (hexane–CH2Cl2, 30:1).
Anal. Calcd for C19H26O2S: C, 71.66; H, 8.23; S, 10.07. Found: C,
71.45; H, 8.25; S, 9.80.
DMDO Oxidation to Sulfones 1; General Procedure
To a mixture of DMDO (1.2 mmol, 0.05 M in acetone) and CH2Cl2
(20 mL) was added the sulfide (0.5 mmol) dissolved in CH2Cl2 (15
mL) at 0 °C. The mixture was stirred for 1–2 h at 0 °C, then the sol-
vents were distilled off under reduced pressure (5 mbar) at 0 °C.
The crude product was purified by flash chromatography.
2-[(1-Cyclohexylhept-2-ynyl)sulfonyl]benzo[d]thiazole (1a)
Yield: 84%; colourless crystals; mp 68–69 °C (Et2O–pentane);
Rf = 0.35 (hexane–CH2Cl2, 2:3).
Yield: 890 mg (78%); colourless oil, fast decomposition; Rf = 0.20
(hexane–CH2Cl2, 30:1), 0.50 (hexane–CH2Cl2, 10:1).
IR (film): 3058, 2927, 2853, 1479, 1465, 1449, 1438 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.50–7.46 (m, 2 H, ArH), 7.32–
7.21 (m, 3 H, ArH), 3.75 (td, J = 5.4, 2.2 Hz, 1 H, SCH), 2.18 (td,
J = 7.1, 2.2 Hz, 2 H, CH2), 2.04–1.97 (m, 1 H, CH2), 1.88–1.82 (m,
1 H, CH2), 1.80–1.73 (m, 2 H, CH2), 1.69–1.57 (m, 2 H, CH, CH2),
1.46–1.11 (m, 9 H, CH2), 0.88 (t, J = 7.3 Hz, 3 H, CH3).
IR (diamond compression system): 2929, 2857, 2245, 1552, 1470,
1451, 1328, 1317, 1169, 1149, 1128 cm–1.
1H NMR (500 MHz, CDCl3): d = 8.24 (d, J = 7.7 Hz, 1 H, ArH),
8.02 (d, J = 7.7 Hz, 1 H, ArH), 7.64 (td, J = 7.7, 1.3 Hz, 1 H, ArH),
7.59 (td, J = 7.7, 1.3 Hz, 1 H, ArH), 4.40 (td, J = 3.4, 2.6 Hz, 1 H,
SCH), 2.49–1.41 (m, 1 H, CH), 2.20–2.14 (m, 1 H, CH2), 2.10 (td,
J = 6.8, 2.6 Hz, 2 H, CH2), 1.83–1.65 (m, 4 H, CH2), 1.50–1.10 (m,
9 H, CH2), 0.71 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 135.5, 132.0 (2C), 128.6 (2C),
126.9, 85.9, 78.4, 45.9, 42.1, 31.4, 30.9, 29.3, 26.3, 26.2, 26.1, 21.8,
18.5, 13.6.
13C NMR (300 MHz, CDCl3): d = 166.0, 152.7, 137.3, 127.8, 127.5,
125.6, 122.1, 91.9, 69.8, 64.2, 36.7, 31.9, 30.2, 29.0, 26.2, 25.7,
25.6, 21.7, 18.5, 13.4.
HRMS (EI, 70 eV): m/z [M]+ calcd for C19H26S: 286.1755; found:
HRMS (ESI): m/z [M + Na+] calcd for C20H25NNaO2S2: 398.1219;
286.1745.
found: 398.1223.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

3818
D. C. Kapeller, P. J. Kocienski
PAPER
Anal. Calcd for C20H25NO2S2: C, 63.96; H, 6.71; N, 3.73; S, 17.08.
Found: C, 64.00; H, 6.75; N, 3.85; S, 17.10.
3.8 Hz, 1 H, SCH), 2.56–2.47 (m, 1 H, CH), 2.16–2.09 (m, 1 H,
CH2), 1.85–1.53 (m, 6 H, CH2), 1.43–1.07 (m, 5 H, CH2), 0.99–0.85
(m, 3 H, CH2), 0.71–0.61 (m, 1 H, CH2), 0.58 (t, J = 7.3 Hz, 3 H,
CH3).
13C NMR (300 MHz, CDCl3): d = 166.7, 152.8, 140.3, 137.2, 127.7,
127.4, 125.3, 122.2, 118.2, 67.5, 37.1, 31.8, 31.1, 28.6, 27.4, 26.3,
26.0, 25.9, 22.2, 13.6.
2-{[4-(tert-Butyldimethylsilyloxy)-1-cyclohexylpent-2-ynyl]sul-
fonyl}benzo[d]thiazole (1i) and (1S,4S)-1i
Yield: 74%; colourless crystals; Rf = 0.27 (hexane–CH2Cl2, 2:3).
1i
HRMS (ESI): m/z [M + H+] calcd for C20H28NO2S2: 378.1556;
found: 378.1548.
Mp 96–97 °C (hexane).
IR (diamond compression system): 3059, 2930, 2857, 1551, 1469,
1331, 1316, 1256, 1151, 1128, 1105 cm–1.
Anal. Calcd for C20H27NO2S2: C, 63.62; H, 7.21; N, 3.71; S, 16.99.
Found: C, 63.65; H, 7.15; N, 3.95; S, 17.25.
1H NMR (500 MHz, CDCl3): d = 8.23 (d, J = 8.1 Hz, 1 H, ArH),
8.01 (d, J = 8.1 Hz, 1 H, ArH), 7.64 (td, J = 8.1, 1.3 Hz, 1 H, ArH),
7.58 (td, J = 8.1, 1.3 Hz, 1 H, ArH), 4.48–4.36 (m, 2 H, OCH and
SCH), 2.53–2.45 (m, 1 H, CH), 2.22–2.15 (m, 1 H, CH2), 1.83–1.66
(m, 4 H, CH2), 1.50–1.30 (m, 4 H, CH2), 1.26 and 1.19 (d, J =
6.4 Hz, 3 H, CH3), 1.19–1.11 (m, 1 H, CH2), 0.80 and 0.76 (s, 9 H,
3 × CH3), 0.01, –0.02, –0.09, –0.10 (s, 3 H, SiCH3).
13C NMR (300 MHz, CDCl3): d = 165.6 and 165.5, 152.7, 137.2,
127.9, 127.5, 125.6, 122.1, 93.33 and 93.27, 72.9, 63.8 and 63.7,
58.9, 36.6, 29.0, 26.2, 25.7, 25.64 and 25.60 (3C), 25.6, 25.1 and
25.0, 18.1 and 18.0, –4.87 and –4.94, –5.1 and –5.3.
[D2]-17a
Deuterium incorporation >90%.
Spectroscopic data are according to the unlabeled compound, ex-
cept for:
1H NMR (500 MHz, CDCl3): d = 5.51 (s, 1 H, CH=), 2.51 (tt,
J = 12.0, 3.0 Hz, 1 H, CH).
13C NMR (300 MHz, CDCl3): d = 139.92 (t, J = 22.6 Hz), 67.03 (t,
J = 20.8 Hz).
HRMS (ESI): m/z [M + H+] calcd for C20H26D2NO2S2: 380.1682;
HRMS (ESI): m/z [M + H+] calcd for C24H36NO3S2Si: 478.1900;
found: 478.1888.
found: 380.1670.
18a
Anal. Calcd for C24H36NO3S2Si: C, 60.34; H, 7.38; N, 2.93; S,
13.42. Found: C, 60.20; H, 7.45; N, 3.00; S, 13.15.
Yield: 19%; white crystals; mp 97–98 °C (hexane); Rf = 0.24 (hex-
ane–CH2Cl2, 2:3).
IR (film): 3064, 2928, 2853, 1954, 1471, 1331, 1150 cm–1.
(1S,4S)-1i
[a]D25 –103 (c 0.53, CHCl3); mp 46–48 °C (petroleum ether).
1H NMR (500 MHz, CDCl3): d = 8.21 (d, J = 8.1 Hz, 1 H, ArH),
7.99 (d, J = 7.7 Hz, 1 H, ArH), 7.61 (td, J = 8.1, 1.3 Hz, 1 H, ArH),
7.57 (td, J = 7.7, 1.3 Hz, 1 H, ArH), 5.95 (t, J = 6.2 Hz, 1 H, =CH),
2.58 (br tt, J = 11.3, 2.6 Hz, 1 H, CH), 2.17–2.08 (m, 2 H, CH2),
1.97–1.89 (m, 1 H, CH2), 1.76–1.60 (m, 3 H, CH2), 1.40–1.06 (m,
9 H, CH2), 0.84 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 205.9, 167.7, 152.7, 137.1, 127.7,
127.4, 125.5, 122.2, 117.7, 103.2, 37.1, 33.3, 33.1, 30.5, 27.8, 26.2,
26.1, 25.7, 22.2, 13.7.
IR (diamond compression system): 3065, 2929, 2855, 1471, 1336,
1316, 1252, 1151, 1101 cm–1.
1H NMR (500 MHz, CDCl3): d = 8.22 (d, J = 7.7 Hz, 1 H, ArH),
8.00 (d, J = 7.7 Hz, 1 H, ArH), 7.63 (td, J = 7.7, 1.3 Hz, 1 H, ArH),
7.59 (td, J = 7.7, 1.3 Hz, 1 H, ArH), 4.46 (dd, J = 3.4, 1.7 Hz, 1 H,
SCH), 4.39 (qd, J = 6.4, 1.7 Hz, 1 H, OCH), 2.54–2.45 (m, 1 H,
CH), 2.22–2.14 (m, 1 H, CH2), 1.83–1.65 (m, 4 H, CH2), 1.50–1.30
(m, 4 H, CH2), 1.25 (d, J = 6.4 Hz, 3 H, CH3), 1.21–1.11 (m, 1 H,
CH2), 0.75 (s, 9 H, 3CH3), –0.09 (s, 3 H, SiCH3), –0.11 (s, 3 H,
SiCH3).
HRMS (ESI): m/z [M + H+] calcd for C20H26NO2S2: 376.1399;
found: 376.1394.
13C NMR (300 MHz, CDCl3): d = 165.6, 152.7, 137.2, 127.9, 127.5,
125.6, 122.2, 93.3, 72.9, 63.6, 58.9, 36.6, 29.0, 26.2, 25.7, 25.6
(3C), 25.5, 25.1, 18.0, –5.0, –5.3.
Anal. Calcd for C20H25NO2S2: C, 63.96; H, 6.71; N, 3.73; S, 17.08.
Found: C, 63.95; H, 6.70; N, 3.65; S, 17.25.
[D1]-18a
NaBH4-Mediated Reduction of 1a
Yield: 5%; deuterium incorporation 94%.
Sulfone 1a was stirred with NaBH4 (5.5 equiv) in MeOH/CD3OD
(10 mL/mmol) first at 0 °C for 2 h then at r.t. for 6 h. 1 M HCl (6
mL) and Et2O (6 mL) were added and the aqueous phase was sepa-
rated and extracted with Et2O (2 × 10 mL). The combined organic
layers were dried (Na2SO4), concentrated under reduced pressure
and purified by chromatography.
Spectroscopic data are according to the unlabeled compound, ex-
cept for:
1H NMR (500 MHz, CDCl3): d = 5.95, 2.58 (sharp tt, J = 11.5,
3.4 Hz, 1 H, CH).
13C NMR (300 MHz, CDCl3): d = 103.1 (t, J = 25.2 Hz).
HRMS (ESI): m/z [M + H+] calcd for C20H25DNO2S2: 377.1462;
found: 377.1449.
3a
Yield: 10%.
17a
[(1-Cyclohexylhept-1,3-dienyl)sulfonyl]benzene (18b)
Sulfone 1a was stirred with NaBD4 (115 mg, 2.75 mmol) in MeOH
(5 mL) at r.t. for 4 h. Then 1 M HCl (10 mL) and Et2O (10 mL) were
added and the aqueous phase was separated and extracted with Et2O
(2 × 10 mL). The combined organic layers were dried (Na2SO4),
concentrated under reduced pressure and purified by flash chroma-
tography.
Yield: 43%; colourless crystals; mp 70–71 °C (hexane); Rf = 0.36
(hexane–CH2Cl2, 2:3).
IR (film): 3090, 2930, 2859, 1652, 1470, 1455, 1424, 1319, 1169,
1238, 1141 cm–1.
1H NMR (500 MHz, CDCl3): d = 8.19 (d, J = 8.1 Hz, 1 H, ArH),
7.98 (d, J = 8.1 Hz, 1 H, ArH), 7.61 (td, J = 8.1, 1.3 Hz, 1 H, ArH),
7.56 (td, J = 8.1, 1.3 Hz, 1 H, ArH), 5.64 (td, J = 11.1, 7.3 Hz, 1 H,
=CH), 5.52 (dd, J = 11.1, 11.1 Hz, 1 H, =CH), 4.45 (dd, J = 11.1,
Yield: 69%; colourless oil; Rf = 0.16 (hexane–CH2Cl2–Et2O,
30:8:1).
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

PAPER
Chiral Allenes and a,b-Unsaturated Ketones
3819
IR (film): 3065, 2928, 2853, 1957, 1447, 1317, 1304, 1148, 1086
cm–1.
(aR,2S)-3i
[a]D25 –90.0 (c 1.16, CHCl3).
1H NMR (500 MHz, CDCl3): d = 7.88 (d, J = 7.3 Hz, 2 H, ArH),
7.59 (t, J = 7.3 Hz, 1 H, ArH), 7.50 (t, J = 7.3 Hz, 2 H, ArH), 5.72
(t, J = 6.8 Hz, 1 H, CH), 2.34 (tt, J = 11.5, 3.0 Hz, 1 H, CH), 2.01
(td, J = 7.3, 6.8 Hz, 2 H, CH2), 1.85–1.77 (m, 2 H, CH2), 1.73–1.59
(m, 3 H, CH2), 1.35–1.20 (m, 6 H, CH2), 1.16–1.03 (m, 3 H, CH2),
0.87 (t, J = 6.8 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 203.6, 141.1, 133.0, 128.8 (2C),
128.0 (2C), 119.2, 102.0, 36.6, 32.4, 33.2, 30.6, 27.9, 26.24, 26.19,
25.7, 22.2, 13.7.
IR (film): 2955, 2927, 2854, 1961, 1471, 1462, 1448, 1254, 1089
cm–1.
1H NMR (500 MHz, CDCl3): d = 5.19 (ddd, J = 6.0, 6.0, 3.0 Hz,
1 H, CH=), 5.14 (ddd, J = 6.0, 6.0, 2.1 Hz, 1 H, CH=), 4.34 (qdd,
J = 6.0, 6.0, 2.1 Hz, 1 H, OCH), 2.02–1.94 (m, 1 H, CH), 1.78–1.59
(m, 5 H, CH2), 1.32–1.03 (m, 5 H, CH2), 1.24 (d, J = 6.0 Hz, 3 H,
CH3), 0.89 (s, 9 H, 3 × CH3), 0.07 (s, 6 H, 2 × CH3).
13C NMR (300 MHz, CDCl3): d = 201.0, 98.9, 97.9, 67.5, 37.4, 33.2
(2C), 26.2, 26.0 (2C), 25.9 (3C), 24.4, 18.3, –4.5, –4.7.
HRMS (ESI): m/z [M + Na+] calcd for C19H26NaO2S: 341.1546;
found: 341.1535.
(S)-4-(tert-Butyldimethylsilyloxy)-1-cyclohexylpent-2-yn-1-one
[(S)-22]21
Preparation of Allenes (3); General Procedure
To a solution of (S)-6i (184 mg, 1.00 mmol) in anhydrous THF (5
mL) under argon, was added n-BuLi (733 mL, 1.5 M in hexane, 1.10
mmol) at –78 °C. The solution was stirred for 45 min then a solution
of N-methoxy-N-methyl-cyclohexanecarboxamide (188 mg, 1.1
mmol) in anhydrous THF (0.5 mL) was added. The mixture was
stirred overnight and the temperature was allowed to rise to 0 °C.
Then it was poured onto sat. aq NH4Cl (10 mL) and extracted with
Et2O (3 × 10 mL). The combined organic layers were washed with
brine (20 mL), dried (Na2SO4), concentrated and purified by flash
chromatography.
To the sulfone (0.5 mmol) dissolved in anhydrous THF (10 mL),
was added LAH (1.0 mL, 1.0 M in THF, 1.0 mmol) at –30 °C. The
solution was stirred for 2 h (bath temperature was allowed to rise to
r.t.), then at r.t. for 30 min. Excess LAH was quenched with H2O
(0.5 mL) at 0 °C, then 1 M HCl (10 mL) was added. The reaction
was stirred for 5 min, then diluted with Et2O (5 mL). The aqueous
layer was separated and extracted with Et2O (2 × 10 mL). The com-
bined organic layers were washed with sat. aq NaHCO3 (15 mL) and
brine (15 mL), then dried (Na2SO4) and concentrated under reduced
pressure. The crude mixture was purified by flash chromatography.
25
Yield: 90%; colourless oil; Rf = 0.50 (hexane–CH2Cl2, 1:1); [a]D
–51.6 (c 0.56, CHCl3).
1-Cyclohexylhepta-1,2-diene (3a)
Yield: 92%; colourless oil; Rf = 0.88 (hexane–Et2O, 100:1).
IR (film): 2958, 2925, 2852, 1960, 1448, 1260, 1097, 1018 cm–1.
1H NMR (500 MHz, CDCl3): d = 5.11 (tdd, J = 6.6, 6.6, 3.0 Hz, 1 H,
=CH), 5.08–5.03 (m, 1 H, =CH), 2.01–1.90 (m, 3 H, CH, CH2),
1.78–1.67 (m, 4 H, 2 × CH2), 1.66–1.59 (m, 1 H, CH2), 1.41–1.02
(m, 9 H, 5 × CH2), 0.90 (t, J = 7.3 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 202.7, 97.0, 91.8, 37.3, 33.18,
33.15, 31.4, 28.8, 26.2, 26.1 (2C), 22.2, 13.9.
IR (film): 2948, 2932, 2857, 2214, 1675, 1450, 1252, 1161, 1133,
1104 cm–1.
1H NMR (500 MHz, CDCl3): d = 4.66 (q, J = 6.4 Hz, 1 H, OCH),
2.39 (tt, J = 11.1, 3.4 Hz, 1 H, CH), 2.00–1.82 (m, 2 H, CH2), 1.80–
1.74 (m, 2 H, CH2), 1.68–1.62 (m, 1 H, CH2), 1.46 (d, J = 6.4 Hz,
3 H, CH3), 1.46–1.15 (m, 5 H, CH2), 0.91 (s, 9 H, CH3), 0.14 (s,
3 H, CH3), 0.12 (s, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 191.1, 94.5, 81.6, 58.9, 52.3, 28.2,
28.1, 25.8, 25.7 (3C), 25.3 (2C), 24.6, 18.2, –4.7, –5.0.
HRMS (EI, 70 eV): m/z [M+] calcd for C13H22: 178.1722; found:
178.1721.
+
HRMS (ESI): m/z [M + NH4 ] calcd for C17H34NO2Si: 312.2353;
found: 312.2365.
Anal. Calcd for C13H22: C, 87.56; H, 12.44. Found: C, 87.55; H,
12.60.
Anal. Calcd for C17H30O2Si: C, 69.33; H, 10.27. Found: C, 68.90;
H, 10.20.
tert-Butyldimethylsilyl 4-Cyclohexyl-1-methylpenta-2,3-dienyl
Ether (3i) and (aR,2S)-3i
Yield: 68%; colourless oil; Rf = 0.67 (hexane–Et2O, 50:1).
(1R,4S)-4-(tert-Butyldimethylsilyloxy)-1-cyclohexylpent-2-yn-
1-ol [(1R,4S)-7i]
2-Propanol was degassed (argon) for 1 h before being used. The
Noyori-catalyst 23 (44 mg, 0.07 mmol) was dissolved in 2-propanol
(40 mL) and degassed for a further 10 min. A solution of (S)-22
(1.76 g, 6.00 mmol) in 2-propanol (5 mL; also degassed for 10 min),
was added. The colour changed from brown to purple to brown.
Stirring was continued for 4 h, then the mixture was concentrated
under reduced pressure and purified by flash chromatography.
3i
IR (film): 2956, 2927, 2854, 1961, 1472, 1462, 1448, 1256, 1090
cm–1.
1H NMR (500 MHz, CDCl3): d = 5.22–5.12 (m, 2 H, 2 × CH=),
4.38–4.28 (m, 1 H, OCH), 2.02–1.93 (m, 1 H, CH), 1.79–1.58 (m,
5 H, CH2), 1.31–1.00 (m, 5 H, CH2), 1.25 (d, J = 7.3 Hz, 3 H, CH3)
and 1.24 (d, J = 6.4 Hz, 3 H, CH3), 0.894 and 0.890 (s, 9 H, 3 ×
CH3), 0.07 (s, 6 H, 2 × CH3).
13C NMR (300 MHz, CDCl3): d = 200.98 and 200.95, 98.9 and 98.6,
98.1 and 97.9, 68.1 and 67.5, 37.4 and 37.1, 33.2 (2C) and 33.1 and
33.0, 26.2, 26.0 (2C), 25.9 (3C), 24.8 and 24.4, 18.3, –4.4 and –4.5,
–4.7.
25
Yield: 88%; colourless oil; Rf = 0.53 (CH2Cl2–Et2O, 100:1); [a]D
–48.1 (c 1.48, CHCl3).
IR (film): 3369, 2980, 2929, 2855, 1450, 1255, 1154, 1101, 1027
cm–1.
1H NMR (500 MHz, CDCl3): d = 4.56 (qd, J = 6.4, 1.3 Hz, 1 H,
OCH), 4.16 (ddd, J = 6.0, 5.6, 1.3 Hz, 1 H, OCH), 1.88–1.73 (m,
4 H, CH2), 1.70–1.64 (m, 1 H, CH2), 1.64 (d, J = 5.6 Hz, 1 H, OH),
1.58–1.49 (m, 1 H, CH), 1.41 (d, J = 6.6 Hz, 3 H, CH3), 1.29–1.01
(m, 5 H, CH2), 0.90 (s, 9 H, CH3), 0.12 (s, 3 H, CH3), 0.11 (s, 3 H,
CH3).
HRMS (EI, 70 eV): m/z [M+ – CH3] calcd for C16H29OSi: 265.1988;
found: 265.1991.
HRMS (EI, 70 eV): m/z [M+ – C(CH3)3] calcd for C13H23OSi:
223.1518; found: 223.1513.
13C NMR (300 MHz, CDCl3): d = 88.3, 83.1, 67.2, 59.0, 44.2, 28.5,
28.1, 26.4, 25.9 (2C), 25.8 (3C), 25.4, 18.2, –4.6, –4.9.
Anal. Calcd for C17H32OSi: C, 72.11; H, 11.35. Found: C, 72.30; H,
11.55.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

3820
D. C. Kapeller, P. J. Kocienski
PAPER
5-Cyclohexylpenta-3,4-dien-2-ol (24) and (aR,2S)-24
To 3i (73 mg, 0.26 mmol) in anhydrous MeCN (1.5 mL), was added
TBAF·3H2O (164 mg, 0.52 mmol). The mixture was stirred over-
night, then brine was added (10 mL) and the mixture was extracted
with Et2O (3 × 10 mL). The combined organic layers were dried,
concentrated under reduced pressure and purified by flash chroma-
tography.
Supporting Information for this article is available online at
http://www.thieme-connect.de/ejournals/toc/synthesis. It contains
experimental procedures and full characterizations of all com-
pounds, including 1H and 13C NMR spectra, the latter are also avail-
able as primary data.
Primary Data for this article are available online at
http://www.thieme-connect.com/ejournals/toc/synthesis and can be
cited using the following DOI: 10.4125/pd0005th.
Yield: 93%; colourless oil, slightly impure; Rf = 0.20 (hexane–
Et2O, 5:1).
24
IR (film): 3328, 2971, 2925, 2851, 1961, 1448, 1079 cm–1.
Acknowledgment
1H NMR (500 MHz, CDCl3): d = 5.34–5.27 (m, 2 H, 2 × CH=),
4.35–4.27 (m, 1 H, OCH), 2.04–1.95 (m, 1 H, CH), 1.79–1.55 (m,
5 H, CH2), 1.35–1.04 (m, 5 H, CH2), 1.29 (d, J = 6.4 Hz, 3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 200.6 and 200.4, 100.8 and 100.5,
97.9 and 97.8, 66.2 and 65.9, 37.1, 33.1 and 33.0 (2C), 26.1, 26.00
and 25.98 (2C), 23.48 and 23.45.
We thank Martin Huscroft for HPLC analysis, Colin Kilner for the
X-ray crystal structure analysis, Tanya Marinko-Covell for mass
spectrometric analysis and Ian Blakeley for elemental analysis.
References
HRMS (EI, 70 eV): m/z [M]+ calcd for C11H18O: 166.1358; found:
166.1356.
(1) (a) Zimmer, R. Synthesis 1993, 165. (b) Guzmán-Durán,
A.; Guzmán, E.; Pannell, K. H.; Lloyd, W. D. Synth.
Commun. 2003, 33, 3271. (c) Hofmann-Röder, A.; Krause,
N. Angew. Chem. Int. Ed. 2004, 43, 1196; Angew. Chem.
2004, 116, 1216. (d) Kimura, H.; Fujiwara, T.; Katoh, T.;
Nishide, K.; Kajimoto, T.; Node, M. Chem. Pharm. Bull.
2006, 54, 399. (e) Sabot, C.; Bérard, D.; Canesi, S. Org.
Lett. 2008, 10, 4629.
(2) (a) Schuster, H. F.; Coppola, G. M. In Allenes in Organic
Synthesis; Wiley: New York, 1984. (b) Harrington, P. E.;
Tius, M. A. Org. Lett. 2000, 2, 2447. (c) Wurz, R. P.; Fu, G.
C. J. Am. Chem. Soc. 2005, 127, 12234. (d) Nishina, N.;
Yamamoto, Y. J. Angew. Chem. Int. Ed. 2006, 45, 3314;
Angew. Chem. 2006, 118, 3392.
(aR,2S)-24
[a]D20 –88.0 (c 0.9, CHCl3).
IR (film): 3338, 2971, 2924, 2851, 1961, 1448, 1078 cm–1.
1H NMR (500 MHz, CDCl3): d = 5.31 (dd, J = 4.3, 3.8 Hz, 2 H, 2 ×
CH=), 4.35–4.27 (m, 1 H, OCH), 2.04–1.95 (m, 1 H, CH), 1.80–
1.55 (m, 5 H, CH2), 1.33–1.03 (m, 5 H, CH2), 1.29 (d, J = 6.0 Hz,
3 H, CH3).
13C NMR (300 MHz, CDCl3): d = 200.5, 100.7, 97.9, 65.9, 37.1,
33.1, 33.0, 26.1, 26.0, 23.5.
(3) (a) Schultz-Fademrecht, C.; Wibbeling, B.; Fröhlich, R.;
Hoppe, D. Org. Lett. 2001, 3, 1221. (b) Hofmann-Röder,
A.; Krause, N. Angew. Chem. Int. Ed. 2002, 41, 2933;
Angew. Chem. 2002, 114, 3057. (c) Krause, N.; Hofmann-
Röder, A. Tetrahedron 2004, 60, 11671. (d) Brummond, K.
M.; DeForrest, J. E. Synthesis 2007, 795. (e) Ruano, J. L.
G.; Marcos, V.; Alemán, J. Angew. Chem. Int. Ed. 2008, 47,
6836; Angew. Chem. 2008, 120, 6942. (f) Ogasawara, M.
Tetrahedron: Asymmetry 2009, 20, 259.
(S)-Mosher Ester of 5-Cyclohexylpenta-3,4-dien-2-ol
[24·MTPA-(S)] and (aR,2S)-24·MTPA-(S)
To the alcohol (10 mg, 0.06 mmol) in anhydrous CH2Cl2 (2.0 mL),
was added DCC (25 mg, 0.12 mmol), DMAP (15 mg, 0.12 mmol)
and (S)-Mosher’s acid (23 mg, 0.10 mmol). The mixture was stirred
overnight, then 1 M HCl (10 mL) was added. The mixture was ex-
tracted with CH2Cl2 (3 × 10 mL) and the combined organic layers
were washed with sat. aq NaHCO3 (20 mL) and H2O (20 mL), dried
and concentrated under reduced pressure. The racemic ester was pu-
rified by flash chromatography, leading to a slight enrichment of
one diastereomer. To avoid this, in the case of the stereospecific
route, the ester was only filtered over a small pad of silica.
(4) Frantz, D. E.; Fässler, R.; Carreira, E. M. J. Am. Chem. Soc.
2000, 122, 1806.
(5) (a) Matsumura, K.; Hashiguchi, S.; Ikariya, T.; Noyori, R.
J. Am. Chem. Soc. 1997, 119, 8738. (b) Marshall, J. A.;
Eidam, P.; Schenck Eidam, H. Org. Synth. 2007, 84, 120.
(6) (a) Baudin, J.-B.; Julia, S. A.; Ruel, O.; Wang, Y.
Tetrahedron Lett. 1990, 31, 213. (b) Baudin, J.-B.; Julia, S.
A.; Lorne, R. Bull. Soc. Chim. Fr. 1992, 129, 440.
(c) Baudin, J.-B.; Julia, S. A.; Wang, Y. Bull. Soc. Chim. Fr.
1995, 132, 754. (d) Baudin, J.-B.; Julia, S. A. Bull. Soc.
Chim. Fr. 1995, 132, 952. (e) Braverman, S. In The
chemistry of sulfinic acids, esters and their derivatives.
Rearrangements; Patai, S., Ed.; Wiley: Chichester, 1990,
297. (f) Braverman, S.; Cherkinsky, M. Top. Curr. Chem.
2007, 275, 67. (g) Chochrek, P.; Wicha, J. Eur. J. Org.
Chem. 2007, 2534. (h) Hopf, H.; Naujoks, E. Tetrahedron
Lett. 1988, 29, 609.
Yield: 99%; colourless oil; Rf = 0.32 (hexane–CH2Cl2, 4:1).
24·MTPA-(S)
1H NMR (500 MHz, CDCl3): d = 7.56–7.51 (m, 2 H, ArH), 7.42–
7.37 (m, 3 H, ArH), 5.63–5.55 (m, 1 H, OCH), 5.40–5.23 (m, 2 H,
2 × CH=), 3.57 (q, J = 1.5 Hz, 3 H, OCH3), 2.04–1.92 (m, 1 H, CH),
1.78–1.59 (m, 5 H, CH2), 1.434, 1.430 and 1.36 (d, J = 6.4 Hz, 3 H,
CH3), 1.32–1.00 (m, 5 H, CH2).
19F NMR (376.50 MHz, CDCl3): d = –71.55, –71.58, –71.65,
–71.77.
(aR,2S)-24·MTPA-(S)
1H NMR (500 MHz, CDCl3): d = 7.56–7.52 (m, 2 H, ArH), 7.42–
7.36 (m, 3 H, ArH), 5.60 (td, J = 6.4, 1.7 Hz, 1 H, OCH), 5.35 (td,
J = 6.4, 3.0 Hz, 1 H, =CH), 5.30 (td, J = 6.4, 2.1 Hz, 1 H, =CH),
3.57 (br. s, 3 H, OCH3), 2.04–1.95 (m, 1 H, CH), 1.78–1.60 (m, 5 H,
CH2), 1.35–1.01 (m, 5 H, CH2), 1.37 (d, J = 6.4 Hz, 3 H, CH3).
(7) (a) Mitsunobu, O. Synthesis 1981, 1. (b) Hughes, D. L. Org.
React. 1992, 42, 335.
(8) Bonini, C.; Chiummiento, L.; Videtta, V. Synlett 2005, 3067.
(9) Sorg, A.; Brückner, R. Synlett 2005, 289.
(10) (a) Tang, R.; Mislow, K. J. Am. Chem. Soc. 1970, 92, 2100.
(b) Evans, D. A.; Andrews, G. C. J. Am. Chem. Soc. 1972,
94, 3672.
19F NMR (376.50 MHz, CDCl3): d = –71.58.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York

PAPER
Chiral Allenes and a,b-Unsaturated Ketones
3821
(11) (a) Majumdar, K. C.; Thyagarajan, B. S. J. Chem. Soc.,
Chem. Commun. 1972, 83. (b) Majumdar, K. C.; Ghosh, S.
K. Tetrahedron Lett. 2002, 43, 2123. (c) Aoyagi, S.;
Makabe, M.; Shimada, K.; Takikawa, Y.; Kabuto, C.
Tetrahedron Lett. 2007, 48, 4639.
(12) (a) Adam, W.; Chan, Y.-Y.; Cremer, D.; Gauss, J.;
Scheutzow, D.; Schindler, M. J. Org. Chem. 1987, 52, 2800.
(b) Birsa, M. L.; Hopf, H. Synlett 2007, 2753.
(15) Kar, M.; Basak, A. Chem. Commun. 2006, 3818.
(16) Sheldrake, H. M.; Wallace, T. W. Tetrahedron Lett. 2007,
48, 4407.
(17) Lipton, M. F.; Sorenson, C. M.; Sadler, A. C.; Shapiro, R. H.
J. Organomet. Chem. 1980, 186, 155.
(18) Lettan, R. B. II; Scheidt, K. A. Org. Lett. 2005, 7, 3227.
(19) Blakemore, P. R.; Kocienski, P. J.; Marzcak, S.; Wicha, J.
Synthesis 1999, 1209.
(13) Ueno, J.; Kojima, A.; Okawara, M. Chem. Lett. 1984, 2125.
(14) X-ray crystallographic data for 17a have been deposited at
the Cambridge Crystallographic Data Centre. CCDC
781560 contains the supplementary crystallographic data for
this paper and these data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif
(20) Carroll, L.; McCullough, S.; Rees, T.; Claridge, T. D. W.;
Gouverneur, V. Org. Biomol. Chem. 2008, 6, 1731.
(21) Gershock, T. J.; Johns, D. M.; Noguchi, Y.; Williams, R. M.
Org. Lett. 2008, 10, 613.
Synthesis 2010, No. 22, 3811–3821 © Thieme Stuttgart · New York