1,3-Chirality transfer by fragmentation of allylsulfinic acids: A diastereoselective approach to vinyl bromides related to trans-hydrindane or trans-decalin

Article abstract of DOI:10.1002/ejoc.200700006

Diastereoselective approaches to vinyl bromides from bromoallylic alcohols by fragmentation of the respective allylsulfinic acids have been investigated. Bromoallylic alcohols 1a and 6 were transformed into the respective 1,3-benzothiazol-2-yl sulfides 2a and 7 by the Mitsunobu inversion reaction under modified conditions. The sulfides were then oxidized into sulfones 11a and 12a, respectively. Reduction of 11a and 12a with sodium borohydride gave the respective allylsulfinic acid salts 13a and 15 which, without isolation, were treated with aqeous tartaric acid. The salt 13a gave exclusively 5α-cholestane derivative 14a whereas 15 provided a mixture of the 5α and 5β derivatives 16 and 17 (after deprotection), the former prevailing. In an alternative approach, benzothiazolyl sulfides 2a and 7 were treated sequentially with BH₃·THF and LiAlH₄ to give thiols 18a and 19a, respectively. Oxidation of thiols 18a and 19a with oxaziridine 21 gave the respective sulfinic acids which, on gentle heating, afforded bromoolefins 14a and 22a, respectively, as the only products. Analogous reaction sequences starting from allylic alcohols devoid of the bromine substituent 1b and 8 have also been studied. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejoc.200700006

FULL PAPER
DOI: 10.1002/ejoc.200700006
1,3-Chirality Transfer by Fragmentation of Allylsulfinic Acids: A
Diastereoselective Approach to Vinyl Bromides Related to trans-Hydrindane or
trans-Decalin
Paweł Chochrek[a] and Jerzy Wicha*[a]
Keywords: Synthetic methods / Diastereoselectivity / trans-Decalin / trans-Hydrindane / Allylic thiols / Allylsulfinic acids
Diastereoselective approaches to vinyl bromides from bromo-
allylic alcohols by fragmentation of the respective allylsul-
finic acids have been investigated. Bromoallylic alcohols 1a
and 6 were transformed into the respective 1,3-benzothiazol-
2-yl sulfides 2a and 7 by the Mitsunobu inversion reaction
under modified conditions. The sulfides were then oxidized
into sulfones 11a and 12a, respectively. Reduction of 11a and
12a with sodium borohydride gave the respective allylsul-
finic acid salts 13a and 15 which, without isolation, were
treated with aqeous tartaric acid. The salt 13a gave exclu-
sively 5α-cholestane derivative 14a whereas 15 provided a
tection), the former prevailing. In an alternative approach,
benzothiazolyl sulfides 2a and 7 were treated sequentially
with BH3·THF and LiAlH4 to give thiols 18a and 19a, respec-
tively. Oxidation of thiols 18a and 19a with oxaziridine 21
gave the respective sulfinic acids which, on gentle heating,
afforded bromoolefins 14a and 22a, respectively, as the only
products. Analogous reaction sequences starting from allylic
alcohols devoid of the bromine substituent 1b and 8 have
also been studied.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
mixture of the 5α and 5β derivatives 16 and 17 (after depro- Germany, 2007)
sulfinic acid fragmentation in diastereospecific synthesis.
Introduction
However, this method of “1,3-chirality transfer” has re-
ceived little attention thus far[11] even though it is of interest
in its own right. In this paper we describe the synthesis of
the vitamin D building block 22a (see Scheme 7) from dione
Vinyl halides are important intermediates in convergent
syntheses owning to their applications in various cross-
coupling reactions.[1] In conjunction with our work in the
field of vitamin D synthesis,[2,3] we were interested in de-
veloping a synthetic approach to vinyl bromides related to
trans-hydrindane[4] (i, n = 1, Figure 1). Bromoallylic
alcohols ii (n = 2) appear to be plausible intermediates in
the synthesis as these compounds are easily accessible from
common α,β-unsaturated ketones iii (n = 1). It was thought
that the hydroxy group in ii (n = 1) could be substituted by
the 1,3-benzothiazole-2-thio group in an Mitsunobu inver-
sion reaction[5] to provide iv (n = 1). Oxidation of sulfides
iv (n = 1) would then afford sulfones v (n = 1) which could
be transformed into the corresponding sulfinic acid salts by
reduction with sodium borohydride under mild condi-
tions.[6] Free allylsulfinic acids vi (n = 1) could be generated
from the salts by acidification.[7] Alternatively, removal of
the benzothiazolyl group in iv (n = 1) would afford the re-
spective thiols vii (n = 1) which could be oxidized directly
to the allylsulfinic acids vi (n = 1). This latter species readily
undergoes fragmentation with double bond transposition
and expulsion of sulfur dioxide,[7–9] as indicated in Figure 1.
Corey and Engler[10] have pioneered the application of allyl-
[a] Institute of Organic Chemistry, Polish Academy of Sciences,
ul. Kasprzaka 44/52, 01-224 Warsaw 42, Poland
Fax: +48-22-6326681
E-mail: jwicha@icho.edu.pl
Figure 1. Structures involved in the general synthetic plan.
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1,3-Chirality Transfer by Fragmentation of Allylsulfinic Acids
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3 via bromoallylic alcohol 6 (see Scheme 2) and our model
studies on the synthesis and fragmentation of allylsulfinic
acids related to cholestane [the decalin system, transforma-
tion of iii (n = 2) into i (n = 2)].
Results and Discussion
Synthesis of Benzothiazolyl Sulfones 11a, 11b, 12a and 12b
Cholest-4-en-3-one was transformed into its 4-bromo de-
rivative essentially according to the previously reported pro-
cedure[12,13] (for some modifications, see the Exptl. Sect.).
Reduction of the bromo enone with sodium borohydride
in the presence of cerium chloride (the Luche reagent[14]
)
provided allylic alcohol (1a, Scheme 1) in 91% yield. Treat-
ment of 1a with 1,3-benzothiazole-2-thiol, diethyl azodicar-
boxylate (DEAD) or diisopropyl azodicarboxylate (DIAD)
and triphenylphosphane under the usual Mitsunobu inver-
sion conditions[5,15] gave the substitution product in low
yields. Replacement of triphenylphosphane with the more
reactive tributylphosphane allowed benzothiazolyl sulfide
2a to be obtained in 73% yield. Cholest-4-en-3β-ol 1b was
readily transformed into sulfide 2b using DEAD and tri-
phenylphosphane (78% yield).
Scheme 2.
Table 1. Sulfur versus nitrogen substitution in the Mitsunobu inver-
sion reaction of 8 under analogous conditions to the reaction of 1a
and 6.
Phos-
phane
Diazo
compd.
T [°C]
8/THF
[mmol/L]
Product % Yield
Ph3P
Ph3P
Bu3P
Bu3P
Bu3P
DEAD
DIAD
DEAD
DIAD
DEAD
0
185.8
185.8
185.8
35.7
9
10
9
41
13
60
18
0
10
Scheme 1.
9
10
63
19
0
Epoxide 4 (Scheme 2), readily available[16] from the
Hajos dione[17] 3, was treated with 40% aqueous hydro-
bromic acid in acetone to give 5a. The hydroxy group in 5a
was protected as the tert-butyldimethylsilyl ether and the
derivative 5b was subjected to reduction with the Luche rea-
gent to give alcohol 6 in 82% yield from 4. Alcohol 6,
treated with 1,3-benzothiazole-2-thiol, DEAD and tributyl-
phosphane at 0 °C, afforded sulfide 7 as the only isolable
9
10
71
14
–78
–78
9
10
75
12
35.7
Sulfides 2a and 2b were oxidized with potassium per-
product in 88% yield. Interestingly, alcohol 8, lacking the manganate in the presence of iron(III) chloride[18] in ethyl
bromine substituent, under similar conditions gave the S- methyl ketone to give sulfones 11a and 11b (Scheme 3),
and N-substituted products 9 and 10 in 63 and 19% yields, respectively. Sulfides related to hydrindane, 7 and 9, were
respectively. Lowering the reaction temperature to –78 °C conveniently oxidized to sulfones 12a and 12b, respectively,
affected the product ratio, giving 9 and 10 in 75 and 12% using m-CPBA in DCM. The yields are summarized in
yields, respectively (Table 1).
Scheme 3. All the sulfones were crystalline and stable.
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P. Chochrek, J. Wicha
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form and fully characterized. Yields of these products and
the isomer ratios varied somewhat. In a typical experiment
on a 0.5 mmol scale, a mixture of 16 and 17 was obtained
in 80% yield and with an isomer ratio of around 4:1.
Scheme 3.
Reduction of Benzothiazolyl Sulfones and Fragmentation of
Allylsulfinic Acids
Scheme 5.
With these sulfones in hand the stage was set to generate
sulfinic acids. Treatment of 11a with 2 mol-equiv. of sodium
borohydride in ethanol/THF at room temperature resulted
in cleavage of the benzothiazole moiety and the production
of a polar product to which the structure of sulfinic acid
salt 13a (Scheme 4) was assigned. The salt could not be iso-
lated from the mixture containing the borohydride excess,
benzothiazole and some side-products. Acidification of the
mixture with dilute hydrochloric or sulfuric acid was ac-
companied by vigorous gas evolution and led to a mixture
of several products.
In an attempt to apply this method to the sulfone devoid
of the bromine substituent (12b) a mixture of trans and cis
isomers, as well as some dienes, was obtained, as deter-
mined by TLC and H NMR analysis. This mixture could
not be separated by column chromatography.
Although high selectivity was achieved in the allylsulfinic
acid fragmentation step in the cholestane series, the method
proved less favourable with the hydrindane derivatives. The
generation of sulfinic acids from their salts under protic
conditions is the likely critical step. It was thought that the
benzothiazole moiety could be removed from the benzothi-
azolyl sulfides and then the allylic thiols would be directly
oxidized to the respective sulfinic acids.
1
Synthesis of Allylsulfinic Acids by Oxidation of Allylic
Thiols
Scheme 4.
Reported methods for the cleavage of non-activated 1,3-
Eventually a procedure for acidification was developed benzothiazol-2-yl alkyl sulfides involve quaternization of
that led exclusively to 14a. After the reduction step the the heterocyclic nitrogen atom followed by treatment of the
crude mixture was evaporated and the semi-solid residue benzothiazolium salt with hydrazine[19] or the use of an ex-
suspended in DCM. To this suspension at reflux, 0.9  cess of butyllithium.[20] In the search for a more suitable
aqueous tartaric acid was added dropwise. After gas evol- method for removing the “protecting” benzothiazolyl
ution had ceased, 14a was isolated in 90% yield. In an anal- group, it was noted that treatment of bromo sulfide 2a with
ogous sequence of reactions 11b was converted into 14b in 2 mol-equiv. of BH3 in THF at –15 °C resulted in consump-
97% yield.
tion of the starting material and the formation of a product
The benzothiazolyl sulfone 12a when treated first with that could be detected on TLC plates. This product (pre-
sodium borohydride and then with aqueous tartaric acid in sumably an adduct), on quenching of the reaction with
DCM afforded a trans-hydrindane derivative contaminated water, yielded the required thiol 18a (Scheme 6) along with
with its cis isomer. The isomers could not be separated by unchanged 2a. The proportions of 18a and 2a appeared to
column chromatography, but the respective alcohols 16 and depend upon the origin of the reagent. However, a substan-
17 (Scheme 5), prepared by treatment of the crude reaction tial amount of 2a was recovered even when freshly prepared
mixture with TBAF in THF, were readily obtained in a pure BH3·THF was used.
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1,3-Chirality Transfer by Fragmentation of Allylsulfinic Acids
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chromatography to give vinyl bromide 14a in 89% yield.
Under similar conditions 18b was transformed into 14b in
57% yield. Gratifyingly, this method could also be success-
fully applied to bromo thiol 19a to give the trans-hydrind-
ane derivative 22a in 67% yield. Thiol 19b, devoid of the
bromine substituent, was transformed into its respective
counterpart 22b in 46% yield.
Scheme 6.
After some experimentation it was found that sulfide 2a
when treated first with BH3·THF (at –15 °C) and then, after
the staring material had been consumed, with lithium alu-
minium hydride affords thiol 18a in 78% yield after
chromatography. Careful rechromatography of the more
polar fractions gave another product: N-methyl-2-(2-meth-
ylaminophenyldisulfanyl)aniline[21] (20). Apparently, the
primary benzothiazolyl moiety reduction product, 2-(meth-
ylamino)benzenethiol, was oxidatively dimerized during the
isolation procedure. Note, benzothiazolyl sulfide 2a was re-
covered unchanged when it was treated with lithium alu-
minium hydride alone at –15 °C.
Under similar conditions using BH3·THF and then Li-
AlH4, three other benzothiazolyl sulfides 2b, 7 and 9 were
readily transformed into their respective thiols 18b, 19a and
19b. The yields are summarized in Scheme 6.
Oxidation of thiol 18a with 2 mol-equiv. of m-
CPBA[10,22] at low temperatures (–90 or –78 °C) and then
gentle warming of the reaction mixture to fragment the sul-
finic acid led to a complex mixture of products. Analysis of
these mixtures showed the presence of only small amounts
of olefin 14a. Similar results were obtained with the thiol
devoid of the bromine substituent (18b). A milder oxidizing
reagent appeared necessary.
Scheme 7.
To gain some insight into the generation of sulfinic acids
via sulfinic acid salts and the subsequent fragmentation
process, the oxidation of lithium thiolates[26] was briefly
scrutinized. Thiol 18a in THF at –78 °C was treated with
1 mol-equiv. of butyllithium in hexanes followed by 2 mol-
equiv. of oxaziridine 21. The cloudy solution was warmed
to room temperature and then evaporated. The residue
(amorphous solid) was triturated with hexanes in an at-
tempt to wash out the sulfonylimine derivative and related
byproducts. However, the lithium sulfinate salt (lithium
counterpart of 13a) could not be obtained in a pure form.
The crude oxidation product was suspended in DCM, the
suspension heated to reflux temperature and then aqueous
tartaric acid was added. After the usual isolation, bromo-
cholestene 14a was obtained in 26% yield from 3a. In the
hydrindane series, thiol 19a afforded the derivative 22a in
46–58% yield. Note that the products obtained via lithium
thiolates were of high purity.
To summarize, synthetic approaches to vinyl bromides
14a and 22a from bromoallylic alcohols 1a and 6, respec-
tively, through sulfinic acid fragmentation have been devel-
oped. As part of this strategy, a new method for the synthe-
sis of thiols from alcohols via benzothiazolyl sulfides has
been developed.
We next turned our attention to Davis’ oxaziridines,[23]
which have previously been used for the oxidation of thiols
to sulfinic acids.[24] Readily available rac-trans-3-phenyl-2-
(phenylsulfonyl)oxaziridine[25] (21) (Scheme 7) was chosen.
The best results were obtained when a solution of thiol 18a
in DCM was added to a solution of 2 mol-equiv. of 21 in
DCM at 0 °C and the mixture then warmed to room tem-
perature. The solvent was evaporated under reduced pres-
Experimental Section
Melting points were determined on a hot-stage apparatus and are
uncorrected. Optical rotations were measured in CHCl3 on a Per-
sure in a warm water bath. The product was purified by kin-Elmer model 141 polarimeter using a 1 mL capacity cell (10 cm
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P. Chochrek, J. Wicha
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path length). NMR spectra were recorded in CDCl3: 1H at 200
MHz and 13C at 50 MHz with a Varian Gemini spectrometer or
1H at 400 MHz and 13C at 100 MHz with a Varian Mercury spec-
trometer or 1H at 500 MHz and 13C at 125 MHz with a Bruker
AMX instrument. Chemical shifts are quoted on the δ scale with
at 0 °C. The mixture was left at 0 °C for 2 h and then acetone
(3 mL) was added followed (after another 2 h) by water (100 mL).
The product was extracted with DCM (3ϫ50 mL). The organic
extract was dried and the solvents evaporated. The residue was
purified by chromatography on silica gel (40 g, 2% EtOAc/hexanes)
to give 1a (1.20 g, 91%). M.p. 122–123 °C (acetone). [α]2D3 = +62.7
(c = 1.04). 1H NMR (200 MHz): δ = 0.68 (s, 3 H, 18-H), 0.858 and
0.861 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.89 (d, J = 7.2 Hz, 3 H,
21-H), 1.09 (s, 3 H, 19-H) overlapping 0.72–2.17 (m, 27 H), 2.38–
2.48 (br. s, 1 H, OH), 2.80–2.94 (m, 1 H), 4.15–4.22 (m, 1 H, 3-
H) ppm. C27H45BrO (465.56): calcd. C 69.64, H 9.76, Br 17.16;
found C 69.41, H 9.74, Br 17.19.
1
the solvent signal as the internal standard (CHCl3: H NMR δ =
7.26 ppm; CDCl3: 13C NMR δ = 77.00 ppm). The signals in the
13C NMR spectra were assigned using the DEPT technique. MS
(electron impact, 70 eV) were recorded with an AMD 604 spec-
trometer (AMD Intectra GmbH). GC analyses were performed
using a Shimadzu GC-14A chromatograph equipped with a
0.32 mmϫ30 m, Q5-30W-0.5F 0.5 µm 007–5 phase capillary col-
umn; injection temperature 150 °C, programmed temperature
10 °C/min. Column chromatography was performed on Merck sil-
ica gel 60, 230–400 mesh. TLC was performed on aluminium
sheets, Merck 60F 254. Anhydrous solvents were obtained by distil-
lation from benzophenone ketyl (THF) or calcium hydride
(CH2Cl2). Commercially available hexane, as a mixture of isomers
(Aldrich), was used. Air-sensitive reactions were performed in
oven- or flame-dried glassware under argon. Organic extracts were
dried with anhydrous Na2SO4 and solvents were evaporated in a
rotary evaporator. Microanalyses were performed at our analytical
laboratory.
2-(4-Bromocholest-4-en-3α-ylthio)-1,3-benzothiazole (2a): DEAD
(0.48 g, 0.43 mL, 2.76 mmol) in THF (7 mL) was added dropwise,
at 0 °C, to a stirred solution of 1a (0.85 g, 1.83 mmol), 1,3-benzo-
thiazole-2-thiol (0.37 g, 2.20 mmol) and tributylphosphane (0.56 g,
0.68 mL, 2.77 mmol) in THF (10 mL). The mixture was stirred at
0 °C for 1 h and then it was warmed to room temp. After 2 h the
solvent was evaporated. The residue was purified by chromatog-
raphy on silica gel (40 g, 1% EtOAc/hexanes) to give 2a (0.91 g,
81%). M.p. 131–133 °C (acetone). [α]2D3 = +14.6 (c = 1.16). 1H
NMR (200 MHz): δ = 0.68 (s, 3 H, 18-H), 0.865 and 0.870 (2d, J
= 6.6 Hz, 6 H, 26-H, 27-H), 0.90 (d, J = 6.2 Hz, 3 H, 21-H), 1.11
(s, 3 H, 19-H) overlapping 0.71–2.40 (m, 27 H), 2.88–3.02 (m, 1
H), 4.90–4.98 (br., 1 H, 3-H), 7.20–7.46 (m, 2 H, aromatic-H),
7.70–7.91 (m, 2 H, aromatic-H) ppm. C34H48BrNS2 (614.78): calcd.
C 66.41, H 7.88, Br 13.00, N 2.28, S 10.43; found C 66.29, H 7.96,
Br 13.03, N 2.18, S 10.51.
4β,5-Epoxy-5β-cholest-3-one and 4α,5-Epoxy-5α-cholest-3-one: Per-
hydrol (30%, 12 mL) and aqueous NaOH (10%, 4 mL), precooled
in an ice–water bath, were added to a solution of cholest-4-en-3-
one (2.10 g, 5.46 mmol) in methanol (180 mL) stirred at 0 °C. The
mixture was set aside at 0 °C for 48 h and then diluted with water
(100 mL) and extracted with DCM (3ϫ80 mL). The organic ex-
tract was dried and the solvent was evaporated. The residue was
purified by chromatography on silica gel (40 g, 1.5% EtOAc/hex-
anes) to give consecutively the 4β,5β-epoxide (1.21 g, 55%) and the
4α,5α-epoxide (0.09 g, 4%). 4β,5β-Epoxide: M.p. 117–119 °C (ace-
tone). 1H NMR (200 MHz): δ = 0.68 (s, 3 H, 18-H), 0.861 and
0.865 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.90 (d, J = 6.8 Hz, 3 H,
21-H), 1.15 (s, 3 H, 19-H) overlapping 0.89–1.64 (m, 22 H), 1.66–
2.40 (m, 6 H), 2.98 (s, 1 H, 4-H) ppm, in agreement with data
reported elsewhere.[12,13] 4α,5α-Epoxide (0.09 g, 4%): M.p. 119–
121 °C (acetone). 1H NMR (200 MHz): δ = 0.70 (s, 3 H, 18 H),
0.86 and 0.87 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.91 (d, J = 6.4 Hz
3 H, 21-H), 1.05 (s, 3 H, 19-H) overlapping 1.00–2.49 (m, 28 H),
3.03 (s, 1 H, 4-H) ppm. C27H44O2 (400.64): calcd. C 80.92, H 11.09;
found C 80.90, H 11.11.
2-(Cholest-4-en-3α-ylthio)-1,3-benzothiazole (2b): DEAD (0.58 g,
0.52 mL, 3.33 mmol) in THF (8 mL) was added dropwise, at 0 °C,
to a stirred solution of alcohol 1b (0.85 g, 2.20 mmol), 1,3-benzo-
thiazole-2-thiol (0.44 g, 2.63 mmol) and triphenylphosphane
(0.87 g, 3.32 mmol) in THF (12 mL). The mixture was stirred at
0 °C for 1 h and then it was warmed to room temp. After 2 h the
solvent was evaporated and the residue was purified by chromatog-
raphy on silica gel (30 g, 1% EtOAc/hexanes) to give 2b (0.92 g,
78%). M.p. 170–171 °C (DCM). [α]2D3 = +53.6 (c = 0.98). 1H NMR
(200 MHz): δ = 0.69 (s, 3 H, 18-H), 0.87 (d, J = 6.7 Hz, 6 H, 26-
H, 27-H), 0.90 (d, J = 7.4 Hz, 3 H, 21-H), 1.04 (s, 3 H, 19-H)
overlapping 1.06–2.40 (m, 28 H), 4.60–4.70 (m, 1 H, 3-H), 5.50 (dd,
J = 5.1, 1.3 Hz, 1 H, 4-H), 7.26–7.62 (m, 2 H, aromatic-H), 7.72–
7.79 (m, 1 H, aromatic-H), 7.83–7.91 (m, 1 H, aromatic-H) ppm.
C34H49NS2 (535.89): calcd. C 76.20, H 9.22, N 2.61, S 11.98; found
C 76.17, H 9.29, N 2.64, S 11.86.
4-Bromocholest-4-en-3-one: Aqueous HBr (40%, 1.2 mL) was
added to
a solution of 4β,5-epoxy-5β-cholest-3-one (1.21 g,
(1S,7aS)-4-Bromo-1-hydroxy-7a-methyl-1,2,3,6,7,7a-hexahydro-5H-
inden-5-one (5a): Aqueous HBr (40%, 2.00 mL) was added to a
solution of 4[16] (1.37 g, 5.14 mmol) in acetone (65 mL). The mix-
ture was stirred for 24 h and then diluted with water (150 mL) and
extracted with DCM (3ϫ80 mL). The organic extract was dried
with MgSO4 and the solvent was evaporated. The residue was puri-
fied by chromatography on silica gel (35 g, 20% and then 50%
EtOAc/hexanes) to give 5a (1.24 g, 98%). M.p. 112–113 °C (ace-
3.02 mmol) in acetone (37 mL). The mixture was stirred for 2 h and
then it was diluted with water (80 mL) and extracted with hexanes
(3ϫ50 mL). The organic extract was dried and evaporated to give
4-bromocholest-4-en-3-one (1.34 g, 96%). M.p. 115–116 °C (ace-
tone). 1H NMR (200 MHz): δ = 0.71 (s, 3 H, 18-H), 0.860 and
0.862 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.90 (d, J = 6.6 Hz, 3 H,
21-H), 1.23 (s, 3 H, 19-H) overlapping 0.94–2.10 (m, 24 H), 2.25
(dt, J = 14.8, 5.2 Hz, 1 H), 2.42–2.71 (m, 2 H), 3.2–3.4 (m, 1
H) ppm, in agreement with data reported elsewhere.[13]
1
tone/pentane). [α]2D3 = +49.7 (c = 1.15). H NMR (500 MHz): δ =
1.20 (d, J = 0.7 Hz, 3 H, CH3), 1.80–1.93 (m, 3 H), 2.09–2.14 (m,
1 H), 2.16–2.23 (m, 1 H), 2.47–2.56 (m, 1 H), 2.63–2.80 (m, 3 H)
3.90–3.96 (m, 1 H, 1-H) ppm. 13C NMR (50 MHz): δ = 15.1 (CH3),
29.3, 29.8, 33.6, 34.1 (C-2, C-3, C-6, C-7), 48.9 (C-7a), 80.7 (C-1),
118.9 (C-4), 172.9 (C-3a), 190.4 (C-5) ppm. C10H13BrO2 (245.12):
calcd. C 49.00, H 5.35, Br 32.60; found C 48.97, H 5.50, Br 32.45.
Typically, a crude mixture of 4β,5β- and 4α,5α-epoxides obtained
as described above was used for this reaction. Chromatography of
the product gave 4-bromocholest-4-en-3-one and unchanged 4α,5α-
epoxide.
4-Bromocholest-4-en-3β-ol (1a): CeCl3·7H2O (1.01 g, 2.71 mmol)
followed (after the salt has dissolved) by NaBH4 (0.12 g,
3.17 mmol) were added to a solution of 4-bromocholest-4-en-3-one
(1.31 g, 2.83 mmol) in THF (22 mL) and methanol (7 mL) stirred
(1S,7aS)-4-Bromo-1-(tert-butyldimethylsilyloxy)-7a-methyl-
1,2,3,6,7,7a-hexahydro-5H-inden-5-one (5b): Imidazole (0.41 g,
6.02 mmol) and tert-butyldimethylsilyl chloride (0.91 g 6.04 mmol)
2538
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Eur. J. Org. Chem. 2007, 2534–2542

1,3-Chirality Transfer by Fragmentation of Allylsulfinic Acids
FULL PAPER
were added to a solution 5a (1.23 g, 5.02 mmol) in DCM (35 mL).
The mixture was set aside for 48 h and then it was poured into
water (80 mL) and extracted with DCM (3ϫ50 mL). The organic
extract was dried and the solvents evaporated. The residue was
purified by chromatography on silica gel (30 g, 10% EtOAc/hex-
another 2 h water was added (30 mL) and the mixture was ex-
tracted with DCM (3ϫ20 mL). The organic extract was dried and
the solvent was evaporated to give 8 (0.30 g, 99%). M.p. 63–65 °C.
1H NMR (200 MHz): δ = 0.99 (s, 3 H, CH3), 1.14 (s, 9 H,
C(CH3)3), 1.19–2.16 (m, 9 H), 2.34–2.56 (m, 1 H), 3.37 (t, J =
anes) to give 5b (1.63 g, 90 %). M.p. 64–65 °C (ethanol/water). 8.2 Hz, 1 H, 1-H), 4.16–4.34 (br., 1 H, 5-H), 5.28–5.36 (m, 1 H, 4-
1
[α]2D3 = +36.6 (c = 1.07). H NMR (200 MHz): δ = 0.05 and 0.06
(2s, 6 H, Si(CH3)2), 0.90 (s, 9 H, C(CH3)3), 1.15 (d, J = 0.4 Hz, 3
H, CH3), 1.70–2.11 (m, 4 H), 2.35–2.86 (m, 4 H), 3.82 (dd, J =
10.6, 7.2 Hz, 1 H, 1-H) ppm. 13C NMR (50 MHz): δ = –4.9, –4.5
(Si(CH3)2), 15.3 (CH3), 18.0 (C(CH3)3), 25.7 (C(CH3)3), 29.7, 29.9,
33.8, 34.2 (C-2, C-3, C-6, C-7), 49.4 (C-7a), 80.8 (C-1), 118.7 (C-
4), 173.1 (C-3a), 190.5 (C-5) ppm. C16H27BrO2Si (359.38): calcd. C
53.47, H 7.57, Br 22.23; found C 53.43, H 7.48, Br 22.32.
H) ppm. 13C NMR (50 MHz): δ = 17.3 (CH3), 26.0, 28.8
(C(CH3)3), 29.7, 29.8, 34.2, 43.3 (C-7a), 68.8 (C-5), 72.6
(C(CH3)3), 80.2 (C-1), 122.2 (C-4), 149.4 (C-3a) ppm, in agreement
with data reported elsewhere.[28]
2-[(1S,5R,7aS)-1-tert-Butoxy-7a-methyl-2,3,5,6,7,7a-hexahydro-1H-
inden-5-ylthio]-1,3-benzothiazole (9) and (1S,5R,7aS)-3-(1-tert-But-
oxy-7a-methyl-2,3,5,6,7,7a-hexahydro-1H-inden-5-yl)-1,3-benzothi-
azole-2(3H)-thione (10): DEAD (0.28 g, 0.25 mL, 1.61 mmol) in
THF (5 mL) was added dropwise to a solution of 8 (0.24 g,
1.07 mmol), tributylphosphane (0.33 g, 0.40 mL, 1.63 mmol) and
1,3-benzothiazole-2-thiol (0.20 g, 1.20 mmol) in THF (30 mL)
stirred at –78 °C. After 1 h the mixture was warmed to room temp.
and set aside for 12 h. The solvent was evaporated and the residue
was purified by chromatography on silica gel (40 g, 1% EtOAc/
hexanes) to give 9 (colorless oil, 0.30 g, 75%) and 10 (colorless
crystals, 48 mg, 12%).
(1S,5S,7aS)-4-Bromo-1-(tert-butyldimethylsilyloxy)-7a-methyl-
1,2,3,6,7,7a-hexahydro-5H-inden-5-ol (6): CeCl3·7H2O (0.90 g,
2.42 mmol) was added to a solution of 5b (0.90 g, 2.50 mmol) in
methanol (15 mL) and THF (30 mL). After the salt had dissolved,
the solution was cooled to 0 °C and NaBH4 (0.12 g, 3.17 mmol)
was added in portions. The mixture was stirred at 0 °C for 2 h and
then acetone (3 mL) was added. After another 2 h the mixture was
diluted with water (90 mL) and extracted with DCM (3ϫ70 mL).
The organic extract was dried and the solvent was evaporated. The
residue was purified by chromatography on silica gel (30 g, 10%
1
Benzothiazole 9: [α]2D4 = +50.8 (c = 0.97). H NMR (200 MHz): δ
= 0.97 (s, 3 H, CH3), 1.16 (s, 9 H, C(CH3)3), 1.20–2.60 (m, 8 H),
3.45 (t, J = 8.8 Hz, 1 H, 1-H), 4.64–4.74 (br. s, 1 H, 5-H), 5.46–
4.58 (br. s, 1 H, 4-H) 7.24–7.48 (m, 2 H, aromatic-H), 7.70–7.93
(m, 2 H, aromatic-H) ppm. 13C NMR (50 MHz): δ = 17.1 (CH3),
26.2 (CH2), 26.5 (CH2), 28.8 (C(CH3)3), 29.8 (CH2), 30.8 (CH2),
43.2 (C-7a), 45.8 (C-5), 72.7 (C-1), 80.4 (C(CH3)3), 116.4 (C-4),
120.9, 121.5, 124.2, 125.9 (4 aromatic C), 135.2, 151.4 (C-3a),
153.3, 166.8 (N=C(-S)-S) ppm. C21H27NOS2 (373.58): calcd. C
67.52, H 7.28, N 3.75, S 17.17; found C 67.47, H 7.24, N 3.72, S
16.99.
EtOAc/hexanes) to give 6 (0.84 g, 93%). M.p. 73–75 °C. [α]2D4
=
1
+13.5 (c = 1.38). H NMR (200 MHz): δ = 0.03 (s, 6 H, Si(CH3)2)
0.88 (s, 9 H, C(CH3)3) 1.02 (s, 3 H, CH3), 1.16–1.44 (m, 1 H), 1.60–
2.00 (m, 4 H), 2.11–2.41 (m, 4 H) 3.62 (dd, J = 10.2, 7.6 Hz, 1 H,
1-H), 4.18–4.33 (m, 1 H, 4-H) ppm. 13C NMR (50 MHz): δ = –4.9,
–4.4 (Si(CH3)2), 16.7 (CH3), 18.0 (C(CH3)3), 25.8 (C(CH3)3), 27.8,
29.6, 29.7, 33.5, (C-2, C-3, C-6, C-7), 48.3 (C-7a), 71.7 (C-5), 81.1
(C-1), 121.8 (C-4), 148.0 (C-3a) ppm. C16H29BrO2Si (361.39):
calcd. C 53.18, H 8.09, Br 22.11; found C 53.12, H 8.26, Br 21.80.
Benzothiazole 10: M.p. 180–181 °C (acetone). [α]2D3 = +134.2 (c =
1.10). H NMR (200 MHz): δ = 0.99 (s, 3 H, CH3), 1.21 (s, 9 H,
2-[(1S,5R,7aS)-4-Bromo-1-(tert-butyldimethylsilyloxy)-7a-methyl-
2,3,5,6,7,7a-hexahydro-1H-inden-5-ylthio]-1,3-benzothiazole (7):
Tributylphosphane (0.83 g, 1.02 mL, 4.10 mmol) was added fol-
lowed by DIAD (0.83 g, 0.79 mL, 4.10 mmol) in THF (3 mL) to
a solution of 6 (0.80 g, 2.21 mmol) and 1,3-benzothiazole-2-thiol
(0.56 g, 3.35 mmol) in THF (19 mL) stirred at 0 °C. After 1 h the
mixture was warmed to room temp. and left aside for an additional
1 h. Silica gel (2 g) was added and the solvent was evaporated in a
rotary evaporator. The residue was transferred to a silica gel col-
umn (35 g). The column was eluted with 0.5% EtOAc in hexanes
to give 7 (0.99 g, 88%). M.p. 104–105 °C (methanol). [α]2D2 = –35.2
1
C(CH3)3), 1.30–2.70 (m, 8 H), 3.64 (dd, J = 9.6, 7.6 Hz, 1 H, 1-H),
5.48 (d, J = 1.6 Hz, 1 H, 5-H), 6.22–6.41 (m, 1 H, 4-H), 7.18–7.35
(m, 2 H, aromatic-H), 7.49–7.50 (m, 1 H, aromatic-H), 7.55–7.65
(m, 1 H, aromatic-H) ppm. 13C NMR (50 MHz): δ = 16.8 (CH3),
24.4 (CH2), 26.2 (CH2), 28.8 (C(CH3)3), 29.9 (CH2), 31.5 (CH2),
43.0, (C-7a), 52.8 (C-5), 72.7 (C-1), 79.2 (C(CH3)3), 113.8, 117.1,
121.0, 124.0 (4 aromatic C), 125.9 (C-4), 127.3, 141.3, 150.6 (C-3a),
189.2 (C=S) ppm. C21H27NOS2 (373.57): calcd. C 67.52, H 7.28, N
3.75, S 17.17; found C 67.87, H 7.25, N 3.80, S 17.36.
1
(c = 1.07). H NMR (200 MHz): δ = 0.04 (s, 6 H, Si(CH3)2) 0.88
2-(4-Bromocholest-4-en-3α-ylsulfonyl)-1,3-benzothiazole (11a):
KMnO4 (0.72 g, 4.56 mmol) and FeCl3·6H2O (0.72 g, 2.66 mmol)
were added to a solution of 2a (0.67 g 1.09 mmol) in methyl ethyl
ketone (30 mL) stirred at room temp. After 1 h the solvent was
evaporated. The residue was taken up in DCM (30 mL) and filtered
through a pad of Celite. The filtrate was washed with water (50 mL)
and dried. The solvent was evaporated and the residue was tritu-
rated with hexanes (10 mL) and filtered to give 11a (0.44 g, 62%).
M.p. 217–219 °C (acetone). [α]2D3 = +258.8 (c = 0.97). 1H NMR
(400 MHz): δ = 0.63 (s, 3 H, 18-H), 0.87 and 0.88 (2d, J = 6.6 Hz,
6 H, 26-H, 27-H), 0.90 (d, J = 6.7 Hz, 3 H, 21-H), 1.05 (s, 3 H, 19-
H) overlapping 0.55–2.20 (m, 26 H), 2.70–2.90 (m, 2 H), 4.60–4.70
(br. s, 1 H, 3-H), 7.48–7.68 (m, 2 H, aromatic-H), 7.97–8.06 (m, 1
H, aromatic-H), 8.20–8.28 (m, 1 H, aromatic-H) ppm.
C34H48BrNO2S2 (646.78): calcd. C 63.13, H 7.50, N 2.17, S 9.92,
Br 12.35; found C 63.03, H 7.53, N 2.00, S 9.91, Br 12.22.
(s, 9 H, C(CH3)3) 1.01 (s, 3 H, CH3), 1.45–2.01 (m, 4 H), 2.21–2.60
(m, 4 H), 3.66 (dd, J = 10.0, 7.6 Hz, 1 H, 1-H), 4.88–4.95 (m, 1 H,
5-H), 7.24–7.47 (m, 2 H, aromatic-H), 7.72–7.80 (m, 1 H, aromatic-
H), 7.84–7.92 (m, 1 H, aromatic-H) ppm. 13C NMR (50 MHz): δ
= –4.8, –4.5 (Si(CH3)2), 17.0 (CH3), 18.0 (C(CH3)3), 25.8 (C-
(CH3)3), 28.5, 29.0, 29.5, 30.2, (C-2, C-3, C-6, C-7), 48.3 (C-7a),
54.0 (C-5), 80.9 (C-1), 113.9 (C-4), 120.9, 121.6, 124.3, 126.0 (4
aromatic C), 135.3, 150.9 (C-5), 153.2, 165.9 (N=C(-S)-S) ppm.
C23H32BrNOS2Si (510.63): calcd. C 54.10, H 6.32, Br 15.65, N
2.74, S 12.56; found C 54.09, H 6.39, Br 15.74, N 2.79, S 12.32.
(1S,5S,7aS)-1-tert-Butoxy-7a-methyl-2,3,5,6,7,7a-hexahydro-1H-
inden-5-ol (8): CeCl3·7H2O (0.49 g, 1.32 mmol) was added to
(1S,7aS)-1-tert-butoxy-7a-methyl-1,2,3,6,7,7a-hexahydro-5H-
inden-5-one[27] (0.30 g, 1.35 mmol) in methanol (10 mL) and THF
(5 mL). After the salt had dissolved, the solution was cooled to
0 °C and NaBH4 (60 mg, 1.59 mmol) was added. The mixture was
stirred at 0 °C for 1 h and then acetone (2 mL) was added. After
2-(Cholest-4-en-3α-ylsulfonyl)-1,3-benzothiazole (11b): KMnO4
(1.08 g, 6.83 mmol) and FeCl3·6H2O (1.08 g, 4.00 mmol) were
Eur. J. Org. Chem. 2007, 2534–2542
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2539

P. Chochrek, J. Wicha
FULL PAPER
added to a solution of 2b (0.90 g, 1.68 mmol) in ethyl methyl ketone
(45 mL), stirred at room temp. After 1 h the solvent was evapo-
rated. The residue was taken up in DCM (50 mL) and filtered
through a pad of Celite. The filtrate was washed with water (70 mL)
and dried. The solvent was evaporated and the residue was tritu-
rated with hexanes (15 mL). The solid was collected to give sulfone
THF (12 mL) and ethanol (12 mL) stirred at room temp. After
18 h, the solvent was evaporated under reduced pressure at room
temp. DCM (25 mL) was added to the residue and the mixture
was brought to reflux (preheated oil bath) and then aqueous 0.9 
tartaric acid (5 mL) was added dropwise. Vigorous gas evolution
occurred. After 30 min the mixture was cooled and extracted with
hexanes (3ϫ50 mL). The organic extract was dried and the solvent
11b (0.67 g, 70%). M.p. 225–228 °C (DCM/acetone). [α]2D3 = +150.9
1
(c = 0.37). H NMR (400 MHz): δ = 0.51 (dt, J = 12.1, 4.3 Hz, 2 was evaporated. The residue was purified by chromatography on
H), 0.62 (s, 3 H, 18-H), 0.64–0.84 (m, 2 H), 0.87 and 0.88 (2d, J = silica gel (10 g, hexanes) to give 14a (0.22 g, 92%, 95% pure by
6.6 Hz, 6 H, 26-H, 27-H), 0.89 (d, J = 6.6 Hz, 3 H, 21-H), 1.05 (s, GC). M.p. 96–97 °C (acetone). [α]2D3 = +5.3 (c = 1.03). 1H NMR
3 H, 19-H) overlapping 0.91–1.06 (m, 3-H), 1.07–1.40 (m, 10 H), (400 MHz): δ = 0.66 (s, 3 H, 18-H), 0.69–0.77 (m, 1 H), 0.85 (s, 3
1.42–1.58 (m, 3 H), 1.60–1.99 (m, 5 H), 2.01–2.37 (m, 3 H), 4.17 H, 19-H), 0.86 and 0.87 (2d, J = 6.7 Hz, 6 H, 26-H, 27-H), 0.89
(sym. m, 1 H, 3-H), 5.46 (d, J = 4.5 Hz, 1 H, 4-H), 7.57–7.66 (m, (d, J = 7.3 Hz, 3 H, 21-H) overlapping 0.90–1.61 (m, 20 H), 1.70–
2 H, aromatic-H), 8.00–8.04 (m, 1 H, aromatic-H), 8.22–8.27 (m,
1 H, aromatic-H) ppm. C34H49NO2S2 (567.89): calcd. C 71.90, H
8.69, N 2.46, S 11.29; found C 71.90, H 8.79, N 2.48, S 11.35.
1.89 (m, 3 H), 1.92–2.13 (m, 5 H), 6.00–6.07 (m, 1 H, 3-H) ppm.
27H45Br (449.55): calcd. C 72.14, H 10.09, Br 17.77; found C
72.13, H 10.03, Br 17.68. GC analysis: Rt1 = 30.95 min (4.49%),
Rt2 = 31.78 min (0.40%), Rt3 = 34.89 min (95.11%).
C
2-[(1S,5R,7aS)-4-Bromo-1-(tert-butyldimethylsilyloxy)-7a-methyl-
2,3,5,6,7,7a-hexahydro-1H-inden-5-ylsulfonyl]-1,3-benzothiazole
(12a): m-CPBA (70 %, 0.44 g, 1.80 mmol) in DCM (6 mL) was
added dropwise to a stirred solution of 7 (0.40 g, 0.78 mmol) in
DCM (6 mL) containing powdered NaHCO3 (0.30 g, 3.57 mmol).
After 24 h water (80 mL) was added and the mixture was extracted
with DCM (3ϫ50 mL). The organic extract was washed consecu-
tively with aqueous Na2S2O3, NaHCO3 and brine, dried and the
solvent was evaporated. The residue was purified by chromatog-
raphy on silica gel (15 g, 4% EtOAc/hexanes) to give 12a (0.35 g,
82%). M.p. 143–144 °C (pentane). [α]2D3 = +186.6 (c = 0.96). 1H
NMR (200 MHz): δ = 0.006 and 0.011 (2s, 6 H, Si(CH3)2), 0.87 (s,
9 H, C(CH3)3) 0.99 (s, 3 H, CH3), 1.60–2.00 (m, 4 H), 2.20–2.42
5α-Cholest-3-ene (14b) from 11b: NaBH4 (60 mg, 1.59 mmol) was
added to a solution of 11b (0.60 g, 1.06 mmol) in THF (24 mL)
and ethanol (24 mL) stirred at room temp. After 18 h the solvent
was evaporated at room temp. under reduced pressure. DCM
(40 mL) was added to the residue. The mixture was brought to
reflux (oil bath) and 0.9  aqueous tartaric acid (10 mL) was added
dropwise. Vigorous evolution of a gas occurred. After 30 min the
mixture was cooled and extracted with hexanes (3ϫ50 mL). The
extract was dried and the solvents evaporated. The residue was
purified by chromatography on silica gel (10 g, hexanes) to give 14b
1
(0.38 g, 97%). M.p. 74–76 °C. H NMR (200 MHz): δ = 0.66 (s, 3
H, 18-H), 0.77 (s, 3 H, 19-H), 0.861 and 0.864 (2d, J = 6.6 Hz, 6
(m, 3 H), 2.82–2.96 (m, 1 H), 3.67 (dd, J = 9.8, 7.8 Hz, 1 H, 1-H), H, 26-H, 27-H), 0.90 (d, J = 8.2 Hz, 3 H, 21-H), 1.00–2.20 (m, 29
4.65–4.75 (m, 1 H, 5-H), 7.53–7.69 (m, 2 H, aromatic-H), 7.96– H), 5.20–5.26 (m, 1 H, 4-H), 5.49–5.60 (m, 1 H, 3-H) ppm. GC:
8.05 (m, 1 H, aromatic-H), 8.17–8.26 (m, 1 H, aromatic-H) ppm. Rt1 = 22.12 min (5.48%), Rt2 = 23.35 (92.72%), Rt3 = 24.02 min
13C NMR (50 MHz): δ = –4.9, –4.5 (Si(CH3)2), 17.0 (CH3), 18.0 (1.80%).
(C(CH3)3) 22.6 (CH2), 25.7 (C(CH3)3), 28.9 (CH2), 29.5 (CH2), 30.1
(CH2), 48.5 (C-7a), 68.2 (C-5), 80.2 (C-1), 105.1 (C-4), 122.3, 125.4,
127.5, 127.8 (4 aromatic C), 137.1, 152.6 (C-3a), 155.7, 167.4
(N=C(-S)-S) ppm. C23H33BrNO3S2Si (542.62): calcd. C 50.91, H
5.94, Br 14.73, N 2.58, S 11.82; found C 50.89, H 5.97, Br 14.70,
N 2.45, S 11.71.
(1S,3aR,7aS)-4-Bromo-7a-methyl-2,3,3a,6,7,7a-hexahydro-1H-
inden-1-ol (16) and (1S,3aS,7aS)-4-Bromo-7a-methyl-2,3,3a,6,7,7a-
hexahydro-1H-inden-1-ol (17): NaBH4 (15 mg. 0.40 mmol) was
added to a solution of 12a (200 mg, 0.36 mmol) in ethanol (5 mL).
After 16 h the solvent was evaporated. CH2Cl2 (40 mL) was added
to the residue and the mixture was heated at 50–60 °C (oil bath)
2-[(1S,5R,7aS)-1-tert-Butoxy-7a-methyl-2,3,5,6,7,7a-hexahydro-1H- while aqueous 0.9  tartaric acid (3 mL) was added dropwise. After
inden-5-ylsulfonyl]-1,3-benzothiazole (12b): A solution of m-CPBA
(70%, 0.30 g, 1.22 mmol) in DCM (5 mL) was added dropwise over
gas evolution had ceased, water (20 mL) was added. The organic
layer was separated. The aqueous layer was washed with DCM
15 min to a stirred solution of 9 (0.21 g, 0.56 mmol) in DCM (2ϫ10 mL). The combined organic extracts were dried and the sol-
(10 mL) containing powdered NaHCO3 (0.50 g, 5.95 mmol). After vent evaporated. The residue was purified by chromatography on
4 h, water (80 mL) was added and the mixture was extracted with silica gel (7 g, hexanes) to give the main fraction consisting of two
DCM (3ϫ50 mL). The organic extract was washed consecutively
with aq. Na2S2O3, aq. NaHCO3 and brine, dried and the solvents
evaporated. The residue was purified by chromatography on silica
gel (10 g, 10% EtOAc/hexanes) to give 12b (0.16 g. 70 %). M.p.
compounds (97 mg 77%). Part of this product (60 mg) was dis-
solved in THF (3 mL) and TBAF·3H2O (101 mg, 0.32 mmol) was
added to the solution. The mixture was stirred at room temp. for
24 h and then silica gel (0.2 g) was added and the solvent was evap-
orated. The residue was transferred to a silica gel column (3 g) and
1
124–126 °C (pentane/acetone). [α]2D9 = +155.5 (c = 1.16). H NMR
(200 MHz): δ = 0.90 (s, 3 H, CH3), 1.04 (s, 9 H, C(CH3)3), 1.16– the column was eluted with 5 % EtOAc in hexanes to give 16
2.61 (m, 8 H), 3.26 (t, J = 8.2, Hz, 1 H. 1-H), 4.15–4.28 (m, 1 H, (28 mg, 71%) and 17 (9 mg, 22%).
5-H), 5.50–5.58 (br. s, 1 H, 4-H), 7.54–7.69 (m, 2 H, aromatic-
1
Inden-1-ol 16: [α]2D4 = –15.5 (c = 1.715). H NMR (500 MHz): δ =
H), 7.97–8.06 (m, 1 H, aromatic-H), 8.18–8.28 (m, 1 H, aromatic-
0.84 (d, J = 0.7 Hz, 3 H, CH3), 1.32–1.40 (m, 1 H, CH2), 1.48–1.57
H) ppm. 13C NMR (50 MHz): δ = 17.0 (CH3), 19.1 (CH2), 26.7
(m, 1 H, CH2), 1.58–1.66 (m, 2 H, CH2, OH), 1.73–1.81 (m, 1 H,
(CH2), 28.5 (C(CH3)3), 29.5 (CH2), 30.1 (CH2), 42.7 (C-7a), 60.8
CH2), 1.81–1.86 (dt, J = 12.6, 4.10 Hz, 1 H, CH2), 2.10–2.17 (m, 1
H, CH2), 2.17–2.22 (m, 2 H, CH2), 2.36–2.43 (m, 1 H, 3aH), 3.78
(C-5), 72.5 (C-1), 79.7 (C(CH3)3), 107.4 (C-4), 122.1, 125.2, 127.4,
127.7 (4 aromatic C), 136.8, 152.5, 156.9 (C-3a), 165.2 (N=C(-S)-
S) ppm. C21H27NO3S2 (405.58): calcd. C 62.19, H 6.71, N 3.45, S
15.81; found C 62.23, H 6.74, N 3.39, S 15.86.
(dd, J = 9.1, 7.6 Hz, 1 H, 1-H), 5.90 (q, J = 3.5 Hz, 1 H, 5-H) ppm.
13C NMR (125 MHz): δ = 10.6 (CH3), 25.0, 26.5, 29.9, 32.5 (C-2,
C-3, C-6, C-7), 45.3 (C-7a), 48.9 (C-3a), 80.2 (C-1), 123.2 (C-4),
4-Bromo-5α-cholest-3-ene (14a) from 11a: NaBH4 (38 mg, 127.3 (C-5) ppm. HRMS: calcd. for C10H1579BrO: 230.03063;
1.00 mmol) was added to a solution of 11a (0.34 g, 0.53 mmol) in
found 230.02998.
2540
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 2534–2542

1,3-Chirality Transfer by Fragmentation of Allylsulfinic Acids
FULL PAPER
Inden-1-ol 17: M.p. 45–46 °C (pentane). [α]2D3 = +29.0 (c = 0.735).
1H NMR (500 MHz): δ = 1.02 (s, 3 H, CH3), 1.27–1.34 (m, 1 H,
6.6 Hz, 3 H, 21-H), 0.99 (s, 3 H, 19-H) overlapping 0.76–1.06 (m,
2 H), 1.08 –1.45 (m, 11 H), 1.48–1.74 (m, 10 H), 1.77–1.87 (m, 2
CH2), 1.36–1.43 (m, 1 H, CH2), 1.43–1.47 (br. s, 1 H, OH), 1.52– H), 1.93–2.06 (m, 3 H), 2.12–2.23 (m, 1 H), 3.51–3.58 (m, 1 H, 3-
1.64 (m, 2 H, CH2), 2.02–2.10 (m, 1 H, CH2), 2.10–2.20 (m, 2 H,
H), 5.40 (d, J = 4.8 Hz, 1 H, 4-H) ppm. 13C NMR (100 MHz): δ
CH2), 2.22–2.31 (m, 1 H, CH2), 2.51 (br. t, J = 8.7 Hz, 1 H, 3a- = 12.0, 18.6, 18.9, 21.5, 22.6, 22.8, 23.8, 24.2, 28.0, 28.2, 28.9, 32.1,
H), 3.84, (dd, J = 5.8, 4.2 Hz, 1 H, 1-H), 5.93–5.96 (m, 1 H, 5-
32.3, 32.8, 35.4, 35.8, 35.9, 36.1, 37.2, 39.5, 39.9, 42.5, 54.3, 56.1,
H) ppm. 13C NMR (125 MHz): δ = 18.6 (CH3), 24.4, 28.5, 29.0, 56.2, 121.8, 146.6 ppm. C27H46S (402.72): calcd. C 80.52, H 11.51,
31.7 (C-2, C-3, C-6, C-7), 46.3 (C-7a), 51.9 (C-3a), 80.0 (C-1), 126.4 S 7.96; found C 80.56, H 11.52, S 8.06.
(C-5), 127.3 (C-4) ppm. C10H15BrO (231.13): calcd. C 51.97, H
(1S,5R,7aS)-4-Bromo-7a-methyl-1-(tert-butyldimethylsilyloxy)-
2,3,5,6,7,7a-hexahydro-1H-indene-5-thiol (19a): BH3·THF (1 ,
4.3 mL, 4.3 mmol) was added dropwise to a solution of sulfide 7
6.54, Br 34.5; found C 52.20, H 6.58, Br 34.58. HRMS: calcd. for
C10H1579BrO [M]+: 230.03063; found 230.03172.
(1.10 g, 2.15 mmol) in THF (30 mL) stirred at –15 °C. After 1 h
LiAlH4 (225 mg, 5.89 mmol) was added and the mixture was left
at –15 °C for a further 3 h. The reagent excess was quenched with
saturated aq. Na2SO4. The solid was filtered off and washed with
diethyl ether (20 mL). The combined filtrates were evaporated. The
residue was purified by chromatography on silica gel (15 g, pen-
tane) to give thiol 19a (594 mg, 73%). M.p. 36–40 °C (methanol/
pentane). [α]2D2 = +130.5 (c = 0.39). 1H NMR (400 MHz): δ = 0.037
and 0.044 (2s, 6 H, Si(CH3)2), 0.89 (s, 9 H, C(CH3)3), 0.95 (d, J =
0.4 Hz, 3 H, CH3), 1.56–1.74 (m, 3 H), 1.84–2.02 (m, 2 H), 2.20–
2.41 (m, 4 H), 3.67 (dd, J = 9.9, 7.7 Hz, 1 H, 1-H), 3.78–3.82 (m,
1 H, 5-H) ppm. 13C NMR (100 MHz): δ = –4.8, –4.5 (Si(CH3)3),
17.0 (CH3), 18.0 (C(CH3)3), 25.7 (C(CH3)3), 28.1, 29.2, 29.5, 29.9
(C-2, C-3, C-6, C-7), 43.4 (C-5), 48.1 (C-7a), 81.0 (C-1), 120.0 (C-
4), 146.1 (C-3a) ppm. C16H29BrOSSi (377.45): calcd. C 50.91, H
7.74, Br 21.17, S 8.50; found C 51.10, H 7.83, Br 21.18, S 8.57.
Attempted Preparation of (1S,3aS,7aS)-1-tert-Butoxy-7a-methyl-
2,3,3a,6,7,7a-hexahydro-1H-indene from 12b: NaBH4 (28 mg,
0.74 mmol) was added to a solution 12b (250 mg, 0.62 mmol) in
THF (10 mL) and ethanol (10 mL). The mixture was stirred at
room temp. for 12 h and then the solvent was evaporated and the
residue was triturated with DCM (40 mL). The slurry was brought
to boiling and 0.9  aqueous tartaric acid (6 mL) was added drop-
wise. Vigorous gas evolution occurred. After 0.5 h water (20 mL)
was added and the mixture was extracted with DCM (3ϫ15 mL).
The organic extract was dried and the solvent was evaporated. The
residue was purified by chromatography on silica gel (10 g, 1 %
EtOAc/hexanes) to give a mixture of isomers (63 mg, 48%). All
attempts to separate this mixture by chromatography failed.
4-Bromocholest-4-ene-3α-thiol (18a): BH3·THF (1 , 2 mL,
2.00 mmol) was added dropwise to a solution of sulfide 2a (615 mg,
1.00 mmol) in THF (15 mL) stirred at –15 °C. After 1 h LiAlH4
(100 mg, 2.6 mmol) was added. The mixture was stirred at –15 °C
for a further 3 h and then the excess reagent was quenched with
saturated aq. Na2SO4. The solid was filtered off and washed with
diethyl ether (25 mL). The combined filtrates were evaporated and
the residue was purified by chromatography on silica gel (25 g, pen-
(1S,5R,7aS)-1-tert-Butoxy-7a-methyl-2,3,5,6,7,7a-hexahydro-1H-in-
dene-5-thiol (19b): BH3·THF (1 , 3.6 mL, 3.6 mmol) was added
dropwise to a solution of sulfide 9 (669 mg, 1.78 mmol) in THF
(24 mL) stirred at –15 °C. After 1 h LiAlH4 (183 mg, 4.8 mmol)
was added and the mixture was stirred at –15 °C for a further 3 h.
The excess reagent was quenched with saturated aq. Na2SO4. The
solid was filtered off and washed with diethyl ether (15 mL). The
combined filtrates were evaporated and the residue was purified by
chromatography on silica gel (10 g, pentane) to give thiol 19b
tane) to give 18a (376 mg, 78%). M.p. 71–73 °C (acetone). [α]2D5
=
1
+169.8 (c = 1.045). H NMR (400 MHz): δ = 0.68 (s, 3 H, 18-H),
0.86 and 0.87 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.90 (d, J =
6.4 Hz, 3 H, 21-H), 0.94–1.05 (m, 2 H), 1.06 (s, 3 H, 19-H) overlap-
ping 1.07–1.19 (m, 4 H), 1.20–1.46 (m, 8 H), 1.46 –1.61 (m, 4 H),
1.61–1.89 (m, 6 H), 1.94–2.05 (m, 2 H), 2.23–2.28 (m, 2 H), 2.87
(ddd, J = 13.8, 4.0, 2.8 Hz, 1 H), 3.83 (br. t, J = 5.7 Hz, 1 H, 3-
H) ppm. 13C NMR (100 MHz): δ = 11.9, 18.6, 19.4, 21.5, 22.5,
22.8, 23.8, 24.1, 28.0, 28.2, 28.9, 30.8, 31.5, 32.3, 35.6, 35.8, 36.1,
39.5, 39.7, 41.4, 42.4, 45.6, 54.6, 55.8, 56.1, 121.3, 144.3 ppm.
C27H45BrS (481.62): calcd. C 67.34, H 9.42, Br 16.59, S 6.66; found
C 67.57, H 9.44, Br 16.84, S 6.64.
1
(250 mg, 58%). H NMR (400 MHz): δ = 0.91 (s, 3 H, CH3), 1.17
(s, 9 H, C(CH3)3), 1.50 (dt, J = 13.3, 2.9 Hz, 1 H), 1.56–1.72 (m, 2
H), 1.74–1.82 (m, 1 H), 1.83–1.93 (m, 2 H), 2.04–2.19 (m, 2 H),
2.38–2.49 (m, 1 H), 3.43 (t, J = 8.8 Hz, 1 H, 1-H), 3.60–3.68 (m, 1
H, 5-H), 5.37–5.42 (m, 1 H, 4-H) ppm. 13C NMR (100 MHz): δ =
17.1 (CH3), 26.2 (CH2), 28.8 (C(CH3)3), 29.1 (CH2), 29.5 (CH2),
29.9 (CH2), 35.4 (C-5), 42.9 (C-7a), 72.6 (C(CH3)3), 80.6 (C-1),
121.4 (C-4), 146.6 (C-3a) ppm. HRMS (EI): calcd. for C14H24OS
[M]+: 240.15479; found 240.15374.
Rechromatography of the more polar fractions gave N-methyl-2-(2-
1
4-Bromo-5α-cholest-3-ene (14a) from 18a
methylaminophenyldisulfanyl)aniline (20): H NMR (200 MHz): δ
= 2.78 (s, 3 H, CH3), 2.80 (s, 3 H, CH3) 4.8–5.0 (br., 2 H, N-
H), 6.46–6.64 (m, 4 H, aromatic-H), 7.11–7.31 (m, 4 H, aromatic-
H) ppm. 13C NMR (50 MHz): δ = 30.3, 109.7, 116.1, 118.4, 132.0,
Method A: Thiol 18a (120 mg, 0.25 mmol) in DCM (2 mL) was
added to a solution of oxaziridine 21 (144 mg, 0.54 mmol) in DCM
(1 mL) stirred at 0 °C. The mixture was set aside at room temp. for
3 h and then the solvent was evaporated using a rotary evaporator
(water bath temp. 40–50 °C). The residue was purified by
chromatography on silica gel (2 g, pentane) to give 14a (100 mg,
89 %). GC analysis: Rt1 = 31.18 min (1.46 %), Rt2 = 34.89 min
(98.54%).
137.0, 150.3 ppm, in agreement with data previously reported.[21]
.
LRMS (EI): m/z = 276 [M]+.
Cholest-4-ene-3α-thiol (18b): BH3·THF (1 , 2 mL, 2.00 mmol) was
added dropwise to a solution of sulfide 2b (536 mg, 1.00 mmol) in
THF (15 mL) stirred at –15 °C. After 1 h LiAlH4 (100 mg,
2.6 mmol) was added and the mixture was stirred at –15 °C for a
further 3 h. The excess reagent was quenched with saturated aque-
ous Na2SO4. The precipitate was filtered off and washed with di-
ethyl ether (25 mL). The combined filtrates were evaporated and
the residue was purified by chromatography on silica gel (20 g, pen-
Method B: BuLi (2.0  in hexanes, 0.19 mL, 0.38 mmol) was added
dropwise to a solution of thiol 18a (173 mg, 0.36 mmol) in THF
(1 mL) stirred at –78 °C. After 15 min a solution of 21 (207 mg,
0.79 mmol) in THF (0.8 mL) was added dropwise. The mixture was
stirred at –78 °C for 30 min, warmed to room temp. and then left
for an additional 1 h. The cloudy solution was evaporated to give
an amorphous residue. DCM (5 mL) was added and the mixture
was brought to gentle reflux (oil bath). An aqueous solution of
tane) to give 18b (270 mg, 67%). M.p. 81–83 °C (acetone). [α]2D6
+223.4 (c = 1.025). H NMR (400 MHz): δ = 0.68 (s, 3 H, 18-H),
0.86 and 0.87 (2d, J = 6.6 Hz, 6 H, 26-H, 27-H), 0.91, (d, J =
=
1
Eur. J. Org. Chem. 2007, 2534–2542
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2541

P. Chochrek, J. Wicha
FULL PAPER
tartaric acid (0.9 , 2 mL) was added dropwise to this mixture. The
mixture was heated under reflux for a further 25 min, cooled and
water (10 mL) was added. The layers were separated and an aque-
ous layer was extracted with hexanes (3ϫ10 mL). The combined
organic extracts were dried and the solvents evaporated. The resi-
due was purified by chromatography on silica gel (2 g, hexanes) to
give 14a (43 mg, 26%).
were dried and the solvents evaporated. The residue was purified
by chromatography on silica gel (2 g, hexanes) to give 22a (58–
73 mg, 46–58%). [α]2D2 = +1.4 (c = 1.65). 1H NMR (400 MHz): δ =
0.01 (s, 6 H, Si(CH3)2), 0.81 (d, J = 0.7 Hz, 3 H, CH3), 0.88 (s, 9
H, C(CH3)3), 1.23–1.33 (m, 1 H), 1.48–1.66 (m, 2 H), 1.68–1.79
(m, 2 H), 1.91–2.01 (m, 1 H), 2.15–2.22 (m, 2 H), 2.31–2.39 (m, 1
H, 3a-H), 3.66–3.72 (m, 1 H, 1-H), 5.88 (q, J = 3.5 Hz, 1 H, 5-
H) ppm. 13C NMR (100 MHz): δ = –4.9, –4.5 (Si(CH3)2), 10.9
(CH3), 18.0 (C(CH3)), 25.2 (C(CH3)3), 25.8, 26.6, 30.3, 32.9 (C-2,
C-3, C-6, C-7), 45.7 (C-7a), 48.5, (C-3a), 80.2 (C-1), 123.7 (C-4),
127.4 (C-5) ppm. C16H29BrOSi (345.39): calcd. C 55.64, H 8.46, Br
23.13; found C 55.42, H 8.51, Br 23.09. HRMS (EI): calcd. for
C16H29O79BrSi [M]+ 344.11711; found 344.11823.
5α-Cholest-3-ene (14b) from 18b
Method A: A solution of thiol 18b (201 mg, 0.50 mmol) in DCM
(3 mL) was added to a solution of oxaziridine 21 (287 mg,
1.09 mmol) in DCM (2 mL) stirred at 0 °C. The mixture was set
aside at room temp. for 3 h and then the solvent was evaporated
using a rotary evaporator (water bath temp. 40–50 °C). The residue
was purified by chromatography on silica gel (3 g, pentane) to give
Acknowledgments
14b (106 mg, 57 %) contaminated with some diene. GC: Rt1
23.92 min (92.28%), Rt2 = 24.46 min (7.24%).
=
We thank Dr. Alicja Kurek-Tyrlik for discussions and proofread-
Method B: BuLi (2.0  in hexanes, 0.19 mL, 0.38 mmol) was added ing.
dropwise to a solution of thiol 18b (147 mg, 0.36 mmol) in THF
(1 mL) stirred at –78 °C. After 15 min a solution of 21 (207 mg,
0.79 mmol) in THF (0.8 mL) was added dropwise. The mixture was
stirred at –78 °C for 30 min, warmed to room temp. and left for an
additional 1 h. The cloudy solution was evaporated. DCM (5 mL)
was added to the residue and the mixture was brought to reflux
(oil bath). Aqueous tartaric acid (0.9 , 2 mL) was added dropwise.
The mixture was refluxed for 25 min, cooled and then water
(10 mL) was added. The layers were separated. The aqueous layer
was extracted with hexanes (3ϫ10 mL). The combined organic ex-
tracts were dried and the solvent was evaporated. The residue was
purified by chromatography on silica gel (2 g, hexanes) to give 14b
(39 mg, 29%).
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(1S,3aR,7aS)-4-Bromo-7a-methyl-2,3,3a,6,7,7a-hexahydro-1H-
inden-1-yl (tert-Butyl)dimethylsilyl Ether (22a) from 19a: A solution
of thiol 19a (100 mg, 0.26 mmol) in DCM (7 mL) was added drop-
wise to a solution of oxaziridine 21 (150 mg, 0.57 mmol) in DCM
(2 mL) stirred at 0 °C. The mixture was left at room temp. for 3 h.
The solvent was evaporated using a rotary evaporator (bath temp.
40–50 °C). The residue was purified by chromatography on silica
gel (2 g, pentane) to give 22a (62 mg, 67 %) contaminated with
traces of dienes. For the analytical data, see below.
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[20] A. R. Katritzky, J. M. Aurrecoechea, L. M. Vazquez de Mig-
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tert-Butyl (1S,3aS,7aS)-7a-Methyl-2,3,3a,6,7,7a-hexahydro-1H-in-
den-1-yl Ether (22b) from 19b: A solution of thiol 19b (53 mg,
0.22 mmol) in DCM (2 mL) was added dropwise to a solution of
oxaziridine 21 (126 mg, 0.48 mmol) in DCM (1 mL) stirred at 0 °C.
The mixture was set aside for 3 h at room temp. and then the sol-
vent was evaporated using a rotary evaporator (bath temp. 40–
50 °C). The residue was purified by chromatography on silica gel
(1.5 g, pentane) to give 22b contaminated with dienes (21 mg,
46%). Attempted purification of this compound failed.
(1S,3aR,7aS)-4-Bromo-7a-methyl-2,3,3a,6,7,7a-hexahydro-1H-
inden-1-yl (tert-butyl)dimethylsilyl Ether (22a) from 19a via Lithium
Thiolate: BuLi (2.0  in hexanes, 0.19 mL, 0.38 mmol) was added
dropwise to a solution of thiol 19a (135 mg, 0.36 mmol) in THF
(1 mL) stirred at –78 °C. After 15 min a solution of 21 (207 mg,
0.79 mmol) in THF (0.8 mL) was added dropwise. The mixture was
kept at –78 °C for 30 min, warmed to room temp. and left for an
additional 1 h. The cloudy solution was evaporated and DCM
(5 mL) was added. The mixture was brought to gentle reflux (oil
bath). Aqueous tartaric acid (0.9 , 2 mL) was added dropwise.
After 30 min the mixture was cooled and then water (8 mL) was
added. The layers were separated and the aqueous layer was ex-
tracted with hexanes (3ϫ10 mL). The combined organic extracts
[28] W. D. Dauben, T. J. Dietsche, J. Org. Chem. 1972, 37, 1212.
Received: January 3, 2007
Published Online: April 4, 2007
2542
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 2534–2542