Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring Catabolite and FadD3 Substrate

Article abstract of DOI:10.1002/ejoc.201500698

DOHNAA (2) is a key catabolite in the Mycobacterium tuberculosis (Mtb) cholesterol degradation pathway. The CoA ester of 2 has been implicated in regulation of gene transcription that is ultimately responsible for degradation of the C and D rings of cholesterol. A synthetic route to 2 is reported here, by a key DMSO-mediated Morita-Bayliss-Hillman-type alkylation of the Hajos-Parrish dione. As DOHNAA has to date only been available from microbial sources in very small quantities, the synthesis described will enable further studies of the enzymes involved in cholesterol degradation in Mtb and facilitate ongoing structure-activity studies based on this compound scaffold.

Full text of DOI:10.1002/ejoc.201500698

FULL PAPER
DOI: 10.1002/ejoc.201500698
Synthesis of DOHNAA, a Mycobacterium tuberculosis Cholesterol CD Ring
Catabolite and FadD3 Substrate
Louise A. Stubbing,[a,b] J. Shaun Lott, Stephanie S. Dawes, Daniel P. Furkert,* and
[c]
[c]
[a]
Margaret A. Brimble*[
a,b]
Keywords: Cholesterol catabolism / Asymmetric synthesis / Mycobacterium tuberculosis / Steroids / DOHNAA
DOHNAA (2) is a key catabolite in the Mycobacterium tuber-
culosis (Mtb) cholesterol degradation pathway. The CoA es-
ter of 2 has been implicated in regulation of gene transcrip-
tion that is ultimately responsible for degradation of the C
and D rings of cholesterol. A synthetic route to 2 is reported
here, by a key DMSO-mediated Morita–Bayliss–Hillman-
type alkylation of the Hajos–Parrish dione. As DOHNAA has
to date only been available from microbial sources in very
small quantities, the synthesis described will enable further
studies of the enzymes involved in cholesterol degradation
in Mtb and facilitate ongoing structure–activity studies based
on this compound scaffold.
Introduction
of cholesterol catabolism in disease is unclear, the virulence
of Mtb has been correlated to the pathogen’s ability to uti-
lise host cholesterol as a source of carbon for growth.[
Some strains have been shown to induce cholesterol synthe-
Tuberculosis (TB), historically known as consumption or
the white plague, is an infectious disease primarily affecting
the lungs caused by the actinobacterium Mycobacterium tu-
berculosis (Mtb). In 2013, ca. 9 million people fell ill with
TB, and ca. 1.5 million died from the disease, making TB
the second largest cause of death due to a single infective
agent worldwide, after HIV/AIDS.[ Most TB infections
are classed as “latent” or asymptomatic, but around 5–10%
will progress to the active, contagious, disease.[ People
with compromised immune systems are particularly suscep-
tible to Mtb infection, and one quarter of HIV-related
deaths are attributed to TB.[ The World Health Organis-
ation’s current goal of eliminating TB by 2050 is reliant on
the development of tools to improve diagnosis, and im-
proved vaccination and treatment of the disease.
5]
[
6]
sis in macrophages and others to sequester it from choles-
[
7]
terol-rich granuloma membranes. VanderVen and co-
workers have recently shown that inhibitors of a known en-
zyme in the degradative pathway (the HsaA/B complex) li-
mit the growth of Mtb in macrophages, thereby providing
some validation of cholesterol catabolism as a target for
1]
2]
[
8]
new therapeutics.
Indeed, the first vaccine effective
against the related equine pathogen Rhodococcus equi is
based upon mutation of the genes related to metabolism of
1]
[
9]
cholesterol in that organism.
The Cho-region is an 83 gene region of the Mtb genome,
containing at least 52 open reading frames related to choles-
[
10]
terol metabolism.
shown to be controlled by at least two transcriptional regu-
Transcription in this region has been
Although Mtb was the first bacterium to be identified as
[
3]
the causative agent of the disease, the contributions of its
biochemistry and physiology to TB pathology are still not
fully understood. It is hoped that a better understanding of
these processes will lead to the rational identification of tar-
gets for improved future pharmaceutical intervention.
The cholesterol catabolism pathway is one of the pro-
cesses of current research interest.[ Although the exact role
[
11]
lators, KstR and KstR2. They are both members of the
TetR family of repressors, which block RNA polymerase
binding to the regulon they control; binding of a ligand
induces a conformational change, releasing the repressor
from the DNA and thereby allowing transcription of the
genes in the regulon.
4]
KstR2 controls a 15 gene regulon within the Cho-region,
and Eltis and co-workers have recently shown that
DOHNAA (9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-
oic acid, aka HIP, 2; Figure 1), when transformed to the
[
[
[
a] School of Chemical Sciences, The University of Auckland,
2
3 Symonds St, Auckland 1142, New Zealand
E-mail: m.brimble@auckland.ac.nz
http://brimble.chem.auckland.ac.nz
[
12]
b] Maurice Wilkins Centre for Molecular Biodiscovery, University corresponding CoA ester by FadD3,
triggers release of
of Auckland,
Private Bag 92019, Auckland 1102, New Zealand
http://www.mauricewilkinscentre.org
[13]
KstR2 from its operator sequence in Mtb.
Eltis and co-workers also published the structure of a
dimeric KstR2Mtb·HIP-CoA complex, where the ligand was
obtained by incubation of an RHA1 ΔfadD3 mutant with
cholesterol; incubation of 2 with FadD3 then gave the CoA
c] School of Biological Sciences, The University of Auckland,
Private Bag 92019, Auckland 1142, New Zealand
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201500698.
Eur. J. Org. Chem. 2015, 6075–6083
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6075

L. A. Stubbing, J. S. Lott, S. S. Dawes, D. P. Furkert, M. A. Brimble
FULL PAPER
Scheme 2. Attempted conjugate reduction/Al enolate trapping re-
action. Reagents and conditions: (a) (i) tBuLi, CuI, THF/DMPU
(
–
5:1), –45 °C, 0.25 h; (ii) 4, THF, DIBAL-H, DMPU/THF (1:1),
78 Ǟ –45 °C, 0.25 h; (iii) CuI, allyl bromide, –45 °C Ǟ room
temp., 24 h.
Figure 1. Structure of the M. tuberculosis cholesterol catabolite
DOHNAA (2).
First Revised Retrosynthetic Analysis
As an alternative, the 3-carbon side-chain could be in-
ester.[13] We set out to design a synthetic route towards ca- stalled by Michael addition of (+)-(S)-Hajos–Parrish dione
tabolite 2 that would also allow for the facile synthesis of 4 to ethyl acrylate according to the procedure reported by
[
18]
derivatives with which to probe its role as a ligand of KstR2 Jih et al. (Scheme 3). The C-4 side-chain would be in the
and FadD3. While a synthesis of 2 has been reported pre- correct oxidation state, requiring only stereoselective re-
viously, the route to 2 was long and unsuitable to support duction of enone 8 and final hydrolysis of the ester to afford
[
14]
SAR studies.
DOHNAA (2).
Results and Discussion
Retrosynthetic Analysis
Taking inspiration from classical steroid syntheses, a
route starting from the well-known Hajos–Parrish dione 4
was devised (Scheme 1). The main synthetic challenges in a
route towards DOHNAA are installation of the 3-carbon
side-chain at C-4 and control of the trans ring junction ste-
reochemistry.
Scheme 3. First revised retrosynthesis of DOHNAA.
This approach had only been successfully reported in the
[
18,19]
literature for cyclohexenone;
would rapidly provide access to DOHNAA, we nevertheless
attempted the reaction with Hajos–Parrish dione
Scheme 4).
however, as the reaction
4
(
Initially, we planned to install the side-chain and set the
ring junction stereochemistry at the same time, using stereo-
selective conjugate reduction/aluminium enolate methodol-
ogy reported by Daniewski et al.[ Hydroboration and
oxidation of the pendant allyl group to the alcohol, fol-
lowed by further oxidation to the carboxylic acid, would
then furnish DOHNAA (2).
15]
(
+)-(S)-Hajos–Parrish dione 4 was prepared according to
[16]
literature procedures.
The enantioselective conjugate re-
[17]
Scheme 4. Attempted reaction of dione 4 with ethyl acrylate 9. Rea-
gents and conditions: (a) DBU, 180 °C, DMF.
duction/Al enolate trapping reaction was attempted with
DMPU in place of HMPA; however, none of the desired
adduct 3 was observed (Scheme 2), and we were forced to
revise our retrosynthetic analysis.
Thus, a solution of dione 4, ethyl acrylate, and catalytic
DBU in DMF was heated at 180 °C in a sealed tube for
Scheme 1. Retrosynthetic analysis of DOHNAA (2).
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© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 6075–6083

DOHNAA, a Cholesterol CD Ring Catabolite and FadD3 Substrate
Scheme 5. Attempted reaction of protected enone 11 with ethyl acrylate 9. Reagents and conditions: (a) NaBH
4
, EtOH, 0 °C, 85%; (b)
, 0 °C Ǟ room temp., 2 h, 11
2
, THF, room temp., 2 d, quant.; (e) 2 m aq. HCl, THF, room temp., 0.5 h, 11 82%, 10
TBSCl, imidazole, cat. DMAP, CH
2
Cl
4%, 12 35%; (d) TBSCl, N-methylimidazole, I
0%; (f) DBU, 180 °C, DMF.
2 2 2
, 0 °C Ǟ room temp., 3 d, 66%; (c) TBSOTf, 2,6-lutidine, CH Cl
4
1
2
4 h. Three new products were observed by TLC. Unfortu- proposed synthesis, DOHNAA would be available from de-
1
nately H NMR analysis of each revealed that none was protection/oxidation of the hexahydroindanone 14, which
the desired product, instead indicating dimerisation of the would in turn be available from alkylation of the anion of
[
26]
indenone core or reaction at C-1 had taken place.
11 by propyl iodide fragment 16 (Scheme 6). Both part-
Attempting to at least prevent reaction at C-1, we de- ners for the alkylation would be protected as TBS ethers
cided to reduce the C-1 ketone and protect the resultant for convenient global deprotection. Hexahydroindanone 14
alcohol as a TBS ether, then resubject the protected enone would be available by reduction of enone 15.
11 to the same reaction conditions (Scheme 5). Reduction
of Hajos–Parrish dione 4 with sodium borohydride in eth-
anol according to the procedure of Micheli et al. afforded
the alcohol 10 in excellent yield, exclusively as the (S) iso-
[
20]
mer.
Protection as the TBS ether under previously reported
[
21]
conditions
with TBSCl and imidazole gave the desired
protected enone 11 in only moderate yield. Alternately, use
of TBSOTf and 2,6-lutidine for the protection[ was com-
plicated by concurrent enolisation and silyl trapping of the
enone, affording desired enone 11 and unstable diene 12 in
an approximately 1:1 ratio. Ultimately, use of Stawinski and
co-workers’ silyl chloride/N-methylimidazole/iodine sys-
22]
[
23]
tem afforded the protected enone 11 in high yield.
With 11 in hand, we next attempted the high-pressure
Michael reaction with ethyl acrylate and catalytic DBU.
Unfortunately, reaction of 11 with ethyl acrylate and cata-
lytic DBU in DMF in a sealed vessel at 180 °C also failed
to provide the desired enone 13, with dimerisation again
Scheme 6. Second revised retrosynthesis of DOHNAA (2).
The α-alkylation was carried out by treating protected
enone 11 with freshly prepared dimsylsodium, followed by
addition of a solution of iodide 16 (Scheme 7). Pleasingly,
the desired product 15 was obtained in 25% yield, in ad-
dition to a small portion (10%) of recovered enone 11. We
1
observed by H NMR analysis.
Second Revised Retrosynthetic Analysis
With our first two approaches proving unsuccessful, we attempted to further optimise the alkylation, varying the
again adjusted our retrosynthesis of DOHNAA (2). Earlier temperature, stoichiometry, and reaction duration, with
work by Hajos et al. in their total synthesis of (Ϯ)-17β- limited success. The final conditions provided 15 in a reli-
9
(10)
hydroxy-Δ
-des-A-androsten-5-one showed that a side- able 47–53% yield on a gram scale, which is comparable to
chain could be installed at C-4 of a protected Hajos–Parrish the yields obtained in similar systems in the literature.[
25]
dione derivative by alkylation.[ The same methodology
24]
With a reliable route towards 15, we next examined the
has been used many times since, most recently by Hirama reduction to give hexahydroindanone 14. Hirama et al. had
et al. in their syntheses of cortistatins A and J.[ In our screened several conditions for the reduction of a very sim-
25]
Eur. J. Org. Chem. 2015, 6075–6083
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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6077

L. A. Stubbing, J. S. Lott, S. S. Dawes, D. P. Furkert, M. A. Brimble
FULL PAPER
Scheme 7. Synthesis of indanone 14 and attempted deprotection. Reagents and conditions: (a) (i) NaH, DMSO, 50 °C, 1 h; (ii) 11, THF,
°C Ǟ room temp., 2 h; (iii) 16, DMSO, room temp., 18 h, 47–53%; (b) NiCl ·6H O, NaBH , MeOH, –90 Ǟ –70 °C, 1 h, 35%; (c)
TBAF, THF, 0 °C Ǟ room temp., 18 h.
0
2
2
4
ilar system, with nickel boride generated in situ giving the tection of the primary TBS group was taking place, cyclis-
[
25]
best results. According to their procedure, enone 15 was ation of the resultant alcohol onto the C-5 ketone was oc-
treated with nickel(II) chloride hexahydrate and sodium curring prior (or concurrently) to deprotection of the sec-
borohydride at –90 °C in methanol for 1 h. After quenching ondary alcohol. A one-pot deprotection/oxidation sequence
and workup, TLC analysis of the crude product showed with catalytic chromium(VI) oxide and periodic acid[ was
four new spots in addition to unreacted starting material. also attempted; however, this also failed to provide the de-
Separation of the individual fractions by flash column sired product 2.
32]
1
13
chromatography and H and C NMR analysis revealed
the main unidentified fraction to be the desired trans-indan-
one 14.
Revision of Protecting Group Strategy
Though many of the relevant signals overlapped in the
NMR spectra, the stereochemistry at C-4 could be con-
firmed by observation of a NOESY correlation between H-
It appeared that we required a protecting group on the
side-chain that could be removed under conditions that
would circumvent cyclisation onto the C-5 ketone. We
therefore selected acetonide-protected iodide 20 as our al-
ternative side-chain fragment, as oxidative cleavage of the
4
and the 7a-methyl group protons (Figure 2). Stereochem-
istry at the ring junction was confirmed by NOESY corre-
lations between H-3a and H-1 and H-3Ј.
[33]
acetonide would afford aldehyde 18 directly (Scheme 8).
Figure 2. NOESY correlations between H-4 and the 7a-methyl
group, and between H-3a and H-1 and H-3Ј in hexahydroindanone
14.
Excluding unreacted starting material, the remainder of
the crude material was found to consist of the C-5 alcohol,
where 1,2- rather than 1,4-reduction was occurring. Varying
the temperature (–78, –70, or –35 °C) and duration (1–5 h)
of the reaction ultimately culminated in minor improvement
to the yield when performed at –35 °C for 1 h.
Scheme 8. Revision of the protecting group strategy in the retrosyn-
thesis of DOHNAA (2).
Deprotection of hexahydroindanone 14 was not as
straightforward as expected; treatment with either TBAF,
Thus, acetonide-protected iodide 20 was prepared ac-
[
27]
acetic acid, catalytic PPTS in ethanol,
DOWEX 50W- cording to literature procedures from 1,2,4-butanetriol in
X8,[ or iodine
28]
[29]
in methanol, LiCl in DMF/H O,
[30]
or good yield. Alkylation of enone 11 with iodide 20 pro-
2
catalytic aqueous periodic acid[ all failed to provide the ceeded smoothly under the previously determined condi-
31]
desired diol 17. NMR analysis indicated that, while depro- tions to give enone 21 in moderate yield (Scheme 9). The
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Eur. J. Org. Chem. 2015, 6075–6083

DOHNAA, a Cholesterol CD Ring Catabolite and FadD3 Substrate
Scheme 9. Synthesis of DOHNAA (2). Reagents and conditions: (a) (i) NaH, DMSO, 50 °C, 1 h; (ii) 11, THF, 0 °C Ǟ room temp., 2 h;
(
(
iii) 20, DMSO, room temp., 18 h, 48%; (b) NiCl
d) IBX, DMSO, room temp., 18 h, 71%; (e) H IO
O (5:1), room temp., 18 h, 40%.
2
·6H
6
2
O, NaBH
4
, MeOH, –35 °C, 1 h, 37%; (c) TBAF, THF, room temp., 18 h, 78%;
, 2-methyl-2-butene, NaH PO ·2H O,
5
, EtOAc, room temp., 1.5 h, 59%; (f) NaClO
2
2
4
2
tBuOH/H
2
enone 21 was then reduced, using the previously established and report the signals as multiplets centred about a single
nickel(II) chloride/sodium borohydride conditions to afford signal rather than as a range. Taking all this into account,
1
hexahydroindanone 19 in moderate yield.
we were pleased to find that the H NMR spectrum for 2
[35]
To our delight, treatment of TBS-acetonide hexahydro- appeared to match that reported by Horinouchi et al.
indanone 19 with TBAF in THF at room temp. afforded Importantly, the 13C NMR spectrum obtained for 2 closely
the alcohol 22 in good yield. Oxidation of alcohol 22 to the matches that reported by the same authors. Moreover, when
ketone with IBX in DMSO gave hexahydroindanedione 23 the NMR solvent was changed to deuterated methanol
1
in high yield. The acetonide was transformed into aldehyde rather than chloroform, the resulting H NMR spectra
8 by deprotection/oxidative cleavage using periodic acid in more closely matched that reported by Eltis et al.[ We
12]
1
[33]
ethyl acetate in moderate yield.
The final step to com- propose that the discrepancies between the two reported
plete the synthesis of DOHNAA was a Pinnick oxidation. spectra are due to Horinouchi et al. mistakenly reporting
Treatment of aldehyde 18 with sodium chlorite and 2- their NMR solvent as deuterated methanol, rather than
methyl-2-butene in water/tert-butyl alcohol buffered with deuterated chloroform.
NaH PO at room temp. for 24 h[
34]
cleanly afforded
The specific rotation of synthetic 2 was consistent with
2
4
25
[36a]
DOHNAA (2) as a colourless solid in 40% yield.
Comparison to the literature data was somewhat compli- Komeno et al. ([αD]25 = +109).
cated. There are only three reported NMR spectra in the With a successful synthesis of DOHNAA completed, we
literature for DOHNNA – one of which is for the racemic returned to the problematic reduction step (21 to 19;
the values reported by Sih et al. ([α ] = +121)
and
D
[36b]
[14]
[12,35]
compound and incomplete;
of the other two,
only Scheme 9). A variety of conditions and reducing agents
1
13
one gives both H and C data. In addition, the two re- were examined in an attempt to improve the yield and selec-
ported proton spectra do not agree very well with one an- tivity of this step including Pd/C, Crabtree’s catalyst,[
other, differ in their assignment of signals to the structure, MacMillan’s organocatalytic transfer hydrogenation meth-
37]
Figure 3. NOESY correlations and assignment of stereochemistry of the products of the reduction of enone 21.
Eur. J. Org. Chem. 2015, 6075–6083
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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L. A. Stubbing, J. S. Lott, S. S. Dawes, D. P. Furkert, M. A. Brimble
odology[38] and Stryker-type reagents.[39] Unfortunately, l-proline (0.26 g, 2.27 mmol), to afford 4 (0.99 g, 68% over 2 steps)
FULL PAPER
[
24a]
25
as a pale orange solid. M.p. 59–61 °C (ref.
66–66.5 °C). [α]
= +360 (benzene)}. 1H
): δ = 5.97 (d, J = 2.4 Hz, 1 H), 3.01–2.91
m, 1 H), 2.84–2.72 (m, 2 H), 2.58–2.39 (m, 3 H), 2.11 (ddd, J =
D
=
none of these conditions afforded any improvement in yield,
and use of Pd/C afforded mixtures of 19 and diastereomer
) {ref.[
24a]
[α]
D
25
+314 (c = 0.19 in CHCl
3
NMR (400 MHz, CDCl
3
24, favouring the undesired trans-cis hexahydroindanone
(
(Figure 3).
2
.2, 5.0, 13.5 Hz, 1 H), 1.85 (td, J = 5.9, 13.8 Hz, 1 H), 1.32 (s, 3
The stereochemistry of 19 and 24 were confirmed by
13
H) ppm. C NMR (100 MHz, CDCl
3
): δ = 216.4, 198.1, 169.7,
NOESY experiments (Figure 3). The trans-trans-hexa-
hydroindanone 19 showed the same pattern of NOESY cor-
relations as the bis-TBS hexahydroindanone 14 – that is, a
correlation between H-4 to the protons of the 7a-methyl
group – and a correlation between H-1 and H-3a, leading
to assignment as the (1S,3aS,4S,7aS) diastereomer. In
comparison, trans-cis-hexahydroindanone 24 did not
1
23.9, 111.0, 48.7, 35.8, 32.9, 29.2, 26.8, 20.5 ppm. Spectral data
[16]
are in agreement with literature values.
Alcohol 10: Prepared according to a literature procedure,[20] from
dione 4 (1.71 g, 10.4 mmol) and sodium borohydride (0.102 g,
2
7
.70 mmol) in ethanol (abs., 30 mL) at 0 °C to afford 10 (1.28 g,
25
[40]
4%) as a pale yellow oil. [α]
D
= +79.2 (c = 0.19 in CHCl
3
) {ref.
25
1
[α]
D
= +80 (c = 0.1 in CHCl
3
)}. H NMR (400 MHz, CDCl ): δ =
3
show a correlation between H-4 and the 7a-methyl group; 5.79 (br. s, 1 H), 3.89–3.83 (m, 1 H), 2.72 (ddt, J = 1.9, 11.5,
instead correlations between H-4 and H-3a, and H-3a 19.4 Hz, 1 H), 2.58–2.49 (m, 1 H), 2.47–2.36 (m, 2 H), 2.19–2.08
(
3
8
m, 2 H), 1.88–1.79 (m, 2 H), 1.70 (br. d, J = 5.1 Hz, 1 H), 1.15 (s,
and H-1 were observed, leading to assignment as the
1S,3aS,4R,7aS) diastereomer.
1
3
H) ppm. C NMR (100 MHz, CDCl
3
): δ = 199.1, 174.7, 123.5,
(
0.7, 45.1, 34.1, 33.3, 29.2, 26.4, 15.1 ppm. Spectral data are in
[40]
agreement with literature values.
Conclusions
TBS Ether 11: TBSCl (171 mg, 1.13 mmol) was added to a solution
of alcohol 10 (171 mg, 1.03 mmol), N-methylimidazole (250 μL,
The successful synthesis of the Mtb cholesterol catabolite
DOHNAA (2) from the well-known Hajos–Parrish dione 4
in eight steps is reported. Unsuccessful attempted ap- showed a significant amount of starting material remained; an ad-
3.14 mmol) and iodine (522 mg, 2.06 mmol) in THF (2 mL), and
the dark brown mixture stirred at room temp. for 24 h. TLC
proaches are also described. Key transformations in the ditional portion of TBSCl (171 mg, 1.13 mmol) was added, and the
successful sequence include the conjugate anion alkylation mixture stirred at room temp. for a further 18 h. Satd. aq. Na
2
S
2
O
3
(
(
25 mL) was added, and the mixture extracted with ethyl acetate
3ϫ 20 mL). The combined organic extracts were washed with
(50 mL), brine (50 mL), dried with MgSO , and
to install the 3-carbon side-chain at C-4, giving the com-
plete carbon framework of the final product, and the re-
duction of the resultant enone to selectively install the re-
quired stereochemistry at C-4 and the trans ring junction.
Subsequent protecting-group manipulations and oxidation
afforded the final product in 2.5% overall yield, on a scale
suitable for support of ongoing biological studies.
satd. aq. Na
2
S
2
O
3
4
concentrated under reduced pressure to give the crude product as
a yellow-brown oil with beige solids suspended within. The crude
product was purified by flash column chromatography (silica gel;
ethyl acetate/hexanes, 1:9 as eluent) to give 11 (247 mg, 85%) as a
25
[41]
pale yellow oil. [α]
D
= +41.3 (c = 0.32 in CHCl
3
) {ref.
= –73.6 (c = 0.53, benzene)}. H NMR (400 MHz,
): δ = 5.77 (br. s, 1 H), 3.75 (dd, J = 7.5, 10.0 Hz, 1 H), 2.68
(ddt, J = 2.0, 11.5, 19.4 Hz, 1 H), 2.56–2.47 (m, 1 H), 2.42–2.32
for
2
5
1
enantiomer [α]
CDCl
D
3
Experimental Section
(
m, 2 H), 2.05–1.94 (m, 2 H), 1.85–1.67 (m, 2 H), 1.11 (s, 3 H),
General: All reactions were carried out in oven-dried glassware un-
der dry nitrogen unless otherwise stated. All reagents were used as
supplied from commercial sources. Tetrahydrofuran and acetone
were dried by passage through a column of activated alumina un-
der nitrogen using an LC Technology solvent purification system.
1
3
0
.90 (s, 9 H), 0.06 (s, 3 H), 0.05 (s, 3 H) ppm. C NMR (100 MHz,
): δ = 199.3 (C), 175.1 (C), 123.3 (CH), 80.8 (CH), 45.6 (C),
4.4 (CH ), 33.4 (CH ), 29.6 (CH ), 26.5 (CH ), 25.8 (3 CH ), 18.0
C), 15.3 (CH ), –4.4 (CH ), –4.9 (CH ) ppm. Spectral data are in
agreement with literature values.
CDCl
3
3
2
2
2
2
3
(
3
3
3
[
25]
DMSO was distilled from CaH
2
under reduced pressure and stored
over 4 Å molecular sieves. Thin layer chromatography (TLC) was General Procedure A. α-Alkylation of Enone 11: DMSO (anhydrous,
performed using Kieselgel F254 0.2 mm (Merck) silica plates, fol-
lowed by visualisation with UV irradiation at 254 nm, and staining
with ethanolic vanillin solution. Flash column chromatography was
performed using Kieselgel S 63–100 μm (Riedel-de Haën) silica gel.
Optical rotations were measured with an Autopol® IV automatic
polarimeter at 589 nm, and the concentration was measured in g/
2.5 mL/mmol enone) was added to sodium hydride (60% disper-
sion in mineral oil, 1.2 equiv.) and the mixture heated at 50 °C for
1 h. The pale yellow mixture was cooled to room temperature, then
diluted with an equal volume of THF and cooled to 0 °C. A solu-
tion of the enone (1 equiv.) in THF (2.5 mL/mmol enone) was
added dropwise, and the resulting highly coloured solution stirred
1
00 mL. Infrared (IR) spectra were recorded with a Perkin–Elmer at room temp. for 2 h. A solution of iodide (1.2 equiv.) in DMSO
Spectrum 100 FT-IR spectrometer using a diamond ATR sampling
accessory. NMR spectra were recorded with either a Bruker
DRX400 or DRX500 spectrophotometer at ambient temperature,
and chemical shifts are referenced to TMS signal at δ = 0.0 ppm
(2.5 mL/mmol enone) was then added slowly, and the mixture
stirred at room temp. overnight. Satd. aq. NH Cl was added, and
the mixture extracted with ethyl acetate three times. The combined
organic extracts were washed with brine, dried with MgSO , and
concentrated under reduced pressure to give the crude products
as orange oils. The crude products were purified by flash column
chromatography.
4
4
1
13
for H spectra, and residual solvent signal at δ = 77.0 ppm for
C
spectra. High-resolution mass spectra were recorded with a Bruker
microTOF QII mass spectrometer.
Hajos-Parrish Dione 4: The dione 4 was prepared according to a
(1S,7aS)-Enone 15: Prepared according to general procedure A
from enone 11 (300 mg, 1.07 mmol) and iodide 16 (385 mg,
1.28 mmol). The crude product was purified by flash column
[
16]
literature procedure,
from 2-methyl-cyclopentane-1,3-dione
(1.00 g, 8.92 mmol), methyl vinyl ketone (0.87 mL, 10.7 mmol), and
6080
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 6075–6083

DOHNAA, a Cholesterol CD Ring Catabolite and FadD3 Substrate
chromatography (silica gel; ethyl acetate/hexanes, 1:19 as eluent) to
and the organic layer removed. The aqueous layer was further ex-
tracted with dichloromethane (2ϫ 100 mL), and the combined or-
25
give 15 (229 mg, 47%) as a pale yellow oil. [α]
D
= +29.3 (c = 0.32
1
in CHCl
3
). H NMR (400 MHz, CDCl
0.3 Hz, 1 H), 3.56 (t, J = 6.4 Hz, 2 H), 2.61–2.34 (m, 4 H), 2.20– MgSO
.16 (m, 2 H), 2.01–1.94 (m, 2 H), 1.81–1.63 (m, 2 H), 1.56–1.49
3
): δ = 3.71 (dd, J = 7.4, ganic extracts were washed with brine (200 mL), dried with
1
2
4
, and concentrated under reduced pressure to give the crude
product as a pale yellow oil. The crude product was purified by
flash column chromatography (silica gel; ethyl acetate/hexanes, 1:19
(
0
=
3
(
–
1
m, 2 H), 1.07 (s, 3 H), 0.90 (s, 9 H), 0.89 (s, 9 H), 0.06 (s, 3 H),
.05 (s, 3 H), 0.04 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl
198.4 (C), 168.3 (C), 133.0 (C), 81.1 (CH), 62.7 (CH
4.2 (CH ), 33.6 (CH ), 31.6 (CH ), 29.9 (CH ), 25.9 (3 CH
3 CH ), 25.2 (CH ), 21.8 (CH ), 18.3 (C), 18.0 (C), 15.5 (CH
4.5 (2 CH ), –4.9 (2 CH ) ppm. IR (neat): ν˜ = 2954, 2929, 2858,
1
3
): δ as eluent) to give 20 (2.29 g, 49%) as a colourless oil. H NMR
), 45.5 (C), (500 MHz, CDCl
2
3
): δ = 4.20–4.15 (m, 1 H), 4.08 (dd, J = 6.1,
2
2
2
2
3
), 25.8 8.2 Hz, 1 H), 3.57 (dd, J = 6.3, 8.1 Hz, 1 H), 3.30–3.20 (m, 2 H),
1
3
3
2
2
3
), 2.14–2.00 (m, 2 H), 1.41 (s, 3 H), 1.36 (s, 3 H) ppm. C NMR
(125 MHz, CDCl ): δ = 109.2, 75.7, 68.6, 37.9, 27.0, 25.5, 1.2 ppm.
3
3
3
–1
+
[43]
722, 1666, 1472, 1360, 1252, 1121, 836, 776 cm . HRMS (ESI ):
Spectral data are in agreement with literature values.
+
+
calcd. for C25
for C25
H
49
O
3
+
Si
2
[M + H] 453.3215, found 453.3201; calcd.
+
(1S,7aS)-Enone 21: Prepared according to general procedure A
from enone 11 (1.00 g, 3.57 mmol) and iodide 20 (1.10 g,
4.28 mmol). The crude product was purified by flash column
chromatography (silica gel; ethyl acetate/hexanes, 1:19 Ǟ 1:9 as elu-
ent) to give 21 (738 mg, 51%) as a pale yellow oil and an insepa-
H
48
O
3
Si
2
Na [M + Na] 475.3034, found 475.3026.
General Procedure B. Conjugate Reduction of Enones Using NiCl
2
/
NaBH : Sodium borohydride (15 equiv.) was added to a solution of
4
the enone (1 equiv.) and nickel(II) chloride hexahydrate (5 equiv.) in
methanol (50 mL/mmol enone) at –35 °C. The resulting dark blue
suspension was stirred at –35 °C for 1 h, then quenched with satd.
2
4
rable (1:1) mixture of diastereomers. [α]
D
= +37.1 (c = 0.48 in
1
CHCl ). H NMR (500 MHz, CDCl , * denotes the diastereomer):
3
3
aq. NH
with ethyl acetate three times, and the combined organic extracts
were washed with brine, dried with MgSO , and concentrated un-
der reduced pressure to afford the crude products. The crude prod-
ucts were purified by flash column chromatography.
4
Cl and warmed to room temp. The mixture was extracted
δ = 4.03–3.99 (m, 2 H), 3.72 (ddd, J = 2.4, 7.3, 7.3 Hz, 1 H), 3.54–
3.49 (m, 1 H), 2.66–2.35 (m, 4 H), 2.32–2.12 (m, 2 H), 2.02–1.93
(m, 2 H), 1.84–1.76 (m, 1 H), 1.72–1.64 (m, 1 H), 1.61–1.52 (m, 2
H), 1.40 (s, 3 H), 1.33 (s, 3 H), 1.08 (s, 1.5 H, 7a-Me), 1.07* (s, 1.5
H, 7a-Me), 0.90 (s, 9 H), 0.06 (s, 3 H), 0.05 (s, 3 H) ppm. 1 C NMR
4
3
(
1
1
125 MHz, CDCl
3
, * denotes the diastereomer): δ = 198.4 (C),
98.3* (C), 168.7 (C), 168.6* (C), 132.5 (C), 132.4* (C), 108.7 (C),
08.6* (C), 81.0 (CH), 80.9* (CH), 75.7 (CH), 75.6* (CH), 69.33
(
1S,3aS,4S,7aS)-Ketone 14: Prepared according to general pro-
cedure B from enone 15 (91 mg, 0.20 mmol). The crude product
was purified by flash column chromatography (silica gel; ethyl acet-
ate/hexanes, 1:19 as eluent) to give 14 (32 mg, 35%) as a colourless
(
(
(
(
CH
2
2
2
2
), 69.32* (CH
), 33.53 (CH ), 33.49* (CH
), 29.85* (CH ), 27.0 (CH
), 25.1* (CH ), 21.83 (CH ), 21.77* (CH
), 15.4* (CH ), –4.5 (CH ) –4.9 (CH
2954, 2931, 2884, 1719, 1664, 1462, 1377, 1250, 1117, 1047, 836,
2
), 45.50 (C), 45.48* (C), 34.15 (CH
), 32.2 (CH ), 32.1* (CH
), 25.7 (3 CH ), 25.6 (CH
), 18.0 (C), 18.0* (C),
) ppm. IR (neat): ν˜
2
), 34.10*
), 29.87
), 25.2
CH
CH
CH
2
2
2
2
oil. [α]2
CDCl
.50–2.41 (m, 1 H), 2.37–2.27 (m, 2 H), 2.02–1.96 (m, 1 H), 1.91
ddd, J = 2.0, 6.9, 12.8 Hz, 1 H), 1.68–1.36 (m, 9 H), 1.02 (s, 3 H),
5
= +13.4 (c = 0.29 in CHCl
1
D
3
). H NMR (400 MHz,
2
3
3
3
3
): δ = 3.63 (t, J = 8.2 Hz, 1 H), 3.58 (t, J = 6.1 Hz, 2 H),
2
2
2
2
1
=
7
4
5.5 (CH
3
3
3
3
(
0
(
(
3
.89 (s, 18 H), 0.04 (s, 6 H), 0.01 (s, 6 H) ppm. 1 C NMR
100 MHz, CDCl ): δ = 212.7 (C), 80.5 (CH), 63.5 (CH ), 50.4
CH), 49.3 (CH), 43.5 (C), 38.0 (CH ), 35.8 (CH ), 31.5 (CH
), 24.3 (CH ), 22.8 (CH
), –4.9 (CH
3
–1
+
SiNa+ [M + Na]
Na+ [2 M +
Si
+
75 cm . HRMS (ESI ): calcd. for C23
40 4
H O
3
2
31.2588, found 431.2590; calcd. for C46
H
80
O
8
2
2
2
2
),
),
+
Na] 839.5284, found 839.5250.
0.3 (CH
8.3 (C), 18.0 (C), 10.9 (CH
2
), 26.0 (3 CH
3
), 25.8 (3 CH
), –4.5 (CH
3
2
2
1
3
3
3
), –5.3 (2 CH
3
)
(1S,3aS,4S,7aS)-Ketone 19: Prepared according to general pro-
cedure B from enone 21 (160 mg, 0.39 mmol) to give the crude
product as a pale yellow oil. The crude product was purified by
flash column chromatography (silica gel; ethyl acetate/hexanes, 1:19
Ǟ 1:4 as eluent) to give 19 (105 mg, 63%) as a colourless oil con-
ppm. IR (neat): ν˜ = 2961, 2926, 2860, 1710, 1462, 1360, 1252, 1100,
–
1
+
+
+
8
4
4
36 cm . HRMS (ESI ): calcd. for C25
H
51
O
3
Si
2
[M + H]
55.3371, found 455.3377; calcd. for C25
77.3191, found 477.3208.
50 3 2
H O Si
Na+ [M + Na]+
2
5
sisting of an inseparable (1:1) mixture of diastereomers. [α]
D
=
Acetonide-Iodide 20: Prepared in two steps from 1,2,4-butanetriol:
,2,4-Butanetriol (1.64 mL, 18.9 mmol) was added to a stirred solu-
1
+
21.8 (c = 0.31 in CHCl
diastereomer): δ = 4.07–4.01 (m, 2 H), 3.65–3.60 (m, 1 H), 3.57–
.50 (m, 1 H), 2.51–2.41 (m, 1 H), 2.38–2.27 (m, 2 H), 2.04–1.89
m, 2 H), 1.72–1.41 (m, 8 H), 1.40–1.35 (m, 1 H), 1.40 (s, 1.5 H),
3 3
). H NMR (400 MHz, CDCl , * denotes
1
tion of PTSA (93 mg, 0.49 mmol) in acetone (13.3 mL, 181 mmol)
and the mixture stirred at room temp. for 20 h. Triethylamine
(
under reduced pressure (Ͼ80 mbar) to give the crude product as a
yellow oil. The crude product was purified by flash column
chromatography (silica gel; dichloromethane/diethyl ether, 4:1 as
eluent) to give 27 (2.66 g, 97%) as a pale yellow oil. 1H NMR
3
(
0.30 mL, 1.9 mmol) was added, and the volatiles were removed
1
0
*
1
.39* (s, 1.5 H), 1.34 (s, 3 H), 1.027 (s, 1.5 H), 1.021* (s, 1.5 H),
.89 (s, 9 H), 0.01 (s, 6 H) ppm. C NMR (100 MHz, CDCl ,
3
denotes diastereomer): δ = 212.5 (C), 212.4* (C), 108.63 (C),
08.61* (C), 80.43 (CH), 80.39* (CH), 76.4 (CH), 76.2* (CH), 69.4
13
(
CH
2
), 69.3* (CH
2
), 50.6 (CH), 50.3 (CH), 49.4 (CH), 48.7* (C),
), 37.9* (CH ), 35.9 (CH ), 35.7*
), 30.9 (CH ), 30.7* (CH ), 26.9
), 25.71 (CH ), 25.67* (CH ), 24.3
), 22.2* (CH ), 18.0 (2ϫC), 10.9
), –4.9 (CH ) ppm. IR (neat): ν˜ =
(
500 MHz, CDCl
3
): δ = 4.30–4.25 (m, 1 H), 4.09 (dd, J = 6.1,
.0 Hz, 1 H), 3.82–3.79 (m, 2 H), 3.60 (t, J = 7.6 Hz, 1 H), 2.21–
.18 (m, 1 H), 1.85–1.81 (m, 2 H), 1.43 (s, 3 H), 1.37 (s, 3 H) ppm.
4
3.6 (C), 43.5* (C), 38.0 (CH
2
2
2
8
2
(
(
(
(
CH
2
3
2
3
), 31.5 (CH
), 26.9* (CH
), 24.2* (CH
), 10.8* (CH
2
), 31.4* (CH
), 25.8 (6 CH
), 22.8 (CH
), –4.5 (CH
2
2
2
CH
CH
CH
3
3
3
3
1
3
C NMR (125 MHz, CDCl
3
): δ = 109.1, 75.1, 69.4, 60.6, 35.6,
2
2
2
2
ues.
6.9, 25.7 ppm. Spectral data are in agreement with literature val-
3
3
3
[
42]
Iodine (5.08 g, 20.0 mmol) was added to a suspension of
–1
2
954, 2924, 2860, 1708, 1472, 1367, 1250, 1128, 1062, 836 cm .
triphenylphosphine (5.25 g, 20.0 mmol) and imidazole (3.72 g,
4.6 mmol) in dichloromethane (60 mL) at 0 °C, and the mixture
+
+
+
HRMS (ESI ): calcd. for C23
4
4
H
43
O
4
Si [M + H] 411.2925, found
SiNa+ [M + Na]+ 433.2745, found
42 4
H O
5
11.2924; calcd. for C23
33.2754.
stirred at this temperature for 15 min. A solution of the above
alcohol (2.66 g, 18.2 mmol) was added dropwise, and the resulting
mixture removed from the cooling bath, wrapped in foil, and stirred
(1S,3aS,4R,7aS)-Ketone 24: [α]2
4
1
D
3
= +11.3 (c = 0.44 in CHCl ). H
at room temp. overnight. Satd. aq. Na
2
S
2
O
3
(150 mL) was added,
NMR (400 MHz, CDCl , * denotes diastereomer): δ = 4.09–3.97
3
Eur. J. Org. Chem. 2015, 6075–6083
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
6081

L. A. Stubbing, J. S. Lott, S. S. Dawes, D. P. Furkert, M. A. Brimble
FULL PAPER
–
1
+
+
(m, 2 H), 3.57 (t, 1 H, J = 8.5 Hz), 3.51–3.44 (m, 1 H), 2.66–2.67
1044, 999, 917 cm . HRMS (ESI ): calcd. for C17
H
26
O
4
Na [M +
+
(m, 1 H), 2.35–2.29 (m, 1 H), 2.25–2.21 (m, 1 H), 2.05–1.97 (m, 1
Na] 317.1723, found 317.1724.
H), 1.94–1.67 (m, 4 H), 1.61–1.37 (m, 6 H), 1.40 (s, 1.5 H), 1.38*
s, 1.5 H), 1.34 (s, 1.5 H), 1.33* (s, 1.5 H), 1.03 (s, 1.5 H), 1.04* (s,
1
(
3aS,4S,7aS)-Aldehyde 18: Periodic acid (14 mg, 0.061 mmol) was
(
added to a solution of acetonide 23 (9 mg, 0.03 mmol) in ethyl
acetate (3 mL), and the resulting suspension stirred at room temp.
for 2 h. Solid crushed Na S O ·5H O was added, and the mixture
2 2 3 2
stirred for 10 min, then filtered through a plug of Celite . The filter
cake was washed with ethyl acetate (2ϫ 3 mL), and the combined
filtrates were concentrated under reduced pressure to give the crude
product as a brown oil. The crude product was purified by flash
column chromatography (silica gel; ethyl acetate/hexanes, 0:1 Ǟ 3:7
.5 H), 0.88 (s, 9 H), 0.01 (s, 6 H) ppm. 1 C NMR (100 MHz,
CDCl , * denotes diastereomer): δ = 215.1 (C), 215.0* (C), 108.9
C), 108.8* (C), 80.8 (CH), 80.8* (CH), 75.8 (CH), 75.3* (CH),
3
3
(
®
2 2
69.3 (CH ), 69.2* (CH ), 53.6 (CH), 53.2* (CH), 47.3 (CH), 47.3*
(
CH), 42.3 (C), 42.3* (C), 36.1 (CH
2
), 35.0 (CH
), 26.9* (CH
), 25.7* (3 CH ), 23.9 (CH
), 21.55* (CH ), 18.0 (C), 18.0* (C), 12.4 (CH
), –4.5* (CH ), –4.9 (CH ), –4.9* (CH ) ppm. IR
neat): ν˜ = 2954, 2926, 2856, 1706, 1470, 1369, 1249, 1133, 1091,
2
), 33.3 (CH
), 25.8 (CH
2
), 23.4* (CH
2
3
2
),
),
),
3
2
2
2.8* (CH
2
), 31.1 (CH
2 3
), 26.9 (CH
3
5.8* (CH
1.58 (CH
3
), 25.7 (3 CH
3
3
2
2
3
), 12.4*
1
as eluent) to give 18 (4 mg, 59%) as a yellow oil. H NMR
(CH
3
), –4.5 (CH
3
3
3
3
(
400 MHz, CDCl
3
): δ = 9.79 (t, J = 1.0 Hz, 1 H), 2.74–2.44 (m, 6
(
1
H), 2.28–2.18 (m, 1 H), 2.10–1.98 (m, 2 H), 1.86–1.63 (m, 5 H),
–1
068, 837 cm .
1
3
1
2
3
.18 (s, 3 H) ppm. C NMR (100 MHz, CDCl
10.5 (C), 201.9 (CH), 49.5 (CH), 49.0 (CH), 47.5 (C), 41.8 (CH
7.4 (CH ), 36.0 (CH ), 30.4 (CH ), 22.3 (CH ), 18.5 (CH ), 13.5
) ppm. HRMS (ESI ): calcd. for C13
Na [M + Na]+
45.1148, found 245.1147.
3
): δ = 217.7 (C),
2
),
(1S,3aS,4S,7aS)-Alcohol 22: TBAF (1.0 m in THF, 200 μL,
2
2
2
2
2
0
0
.20 mmol) was added to a solution of acetonide 19 (54 mg,
.13 mmol) in THF (4 mL), and the resulting pale yellow solution
+
+
(
CH
3
18 3
H O
2
stirred at room temp. for 18 h. The volatiles were removed under
reduced pressure to give the crude product as an orange oil. The
crude product was purified by flash column chromatography (silica
gel; ethyl acetate/hexanes, 1:1 as eluent) to give the first fraction
(
3aS,4S,7aS)-Carboxylic Acid 2 (DOHNAA): Sodium chlorite
(
80% purity, 3 mg, 0.03 mmol) was added to a solution of aldehyde
1
2
8 (4.7 mg, 0.021 mmol), NaH
2 4 2
PO ·2H O (7 mg, 0.05 mmol), and
(26 mg, 48%) as the recovered starting material, and the second
-methyl-2-butene (10 μL, 0.094 mmol) in tert-butyl alcohol/water
fraction as 22 (20 mg, 51%) as a colourless oil and an inseparable
(
1
5:1, 0.6 mL), and the resulting mixture stirred at room temp. for
8 h. The volatiles were removed under reduced pressure, and the
residue was partitioned between water (5 mL) and ethyl acetate
5 mL). The organic layer was removed, and the aqueous layer fur-
ther extracted with ethyl acetate (2ϫ 5 mL). The combined organic
extracts were washed with brine (20 mL), dried with MgSO , and
(
1:1) mixture of diastereomers. [α]2
D
3
= +17.1 (c = 0.18 in CHCl
, * denotes diastereomer): δ = 4.08–
.02 (m, 2 H), 3.73 (td, J = 1.6, 9.7 Hz, 1 H), 3.57–3.50 (m, 1 H),
.52–2.40 (m, 1 H), 2.38–2.31 (m, 2 H), 2.22–2.13 (m, 1 H), 2.00
3
).
1
H NMR (400 MHz, CDCl
3
4
2
(
(
ddd, J = 2.0, 6.8, 12.9 Hz, 1 H), 1.73–1.43 (m, 9 H), 1.40 (s, 1.5
H), 1.39* (s, 1.5 H), 1.34 (s, 3 H), 1.07 (s, 1.5 H), 1.06* (s, 1.5 H)
ppm. 13C NMR (100 MHz, CDCl
, * denotes diastereomer): δ =
12.1 (C), 211.9* (C), 108.67 (C), 108.64* (C), 80.43 (CH), 80.40*
CH), 76.4 (CH), 76.2* (CH), 69.4 (CH ), 69.2* (CH ), 50.5 (CH),
0.2* (CH), 49.8 (CH), 49.2* (CH), 43.22 (C), 43.15* (C), 37.84
4
concentrated under reduced pressure to give the crude product as
a pale yellow oil. The crude product was purified by flash column
chromatography (silica gel; ethyl acetate/hexanes, 1:1 as eluent) to
give 2 (2 mg, 40%) as a white solid. [α]
CHCl
3
2
(
5
24
2
2
D
= +100.8 (c = 0.02,
[36a]
24
[36b]
24
1
3
) {ref.
[α]
D
= +121, ref.
): δ = 2.65–2.40 (m, 6 H), 2.23 (dt, J =
.2, 19.5 Hz, 1 H), 2.09–1.98 (m, 2 H), 1.95–1.62 (m, 5 H), 1.18 (s,
D
[α] = +109 (c = 0.99)}. H
(
(
(
(
1
C
CH
2
2
3
3
), 37.78* (CH
), 31.1 (CH ), 30.6* (CH
), 24.0* (CH
2
), 35.5 (CH
2
), 35.4* (CH
), 26.9 (CH
), 22.8 (CH
) ppm. IR (neat): ν˜ = 3486 (br.), 2953, 2874,
2
), 31.4 (CH
), 25.7 (CH
), 22.2* (CH
2
), 31.1*
), 25.6*
), 10.63
NMR (400 MHz, CDCl
3
CH
CH
CH
2
2
3
3
9
3
2
1
), 24.1 (CH
2
2
2
2
1
3
H) ppm. H NMR (500 MHz, CD OD): δ = 2.67–2.46 (m, 5 H),
), 10.58* (CH
3
.36–2.27 (m, 2 H), 2.25–2.19 (m, 1 H), 2.08–2.03 (m, 1 H), 1.95–
.75 (m, 4 H), 1.64 (ddd, J = 5.5, 13.3, 13.3 Hz, 1 H), 1.19 (s, 3 H)
–1
+
706, 1470, 1371, 1215, 1060 cm . HRMS (ESI ): calcd. for
+
+
H
28
O
4
Na [M + Na] 319.1880, found 319.1885.
13
17
ppm. C NMR (100 MHz, CDCl
): δ = 217.7 (C), 210.5 (C), 177.4
), 36.1 (CH ), 30.4
), 13.5 (CH ) ppm.
Na [M + Na]+ 261.1097,
18 4
H O
3
(
(
C), 49.5 (CH), 49.0 (CH), 47.5 (C), 37.4 (CH
CH ), 29.7 (CH ), 22.3 (CH ), 21.2 (CH
2
2
(3aS,4S,7aS)-Dione 23: IBX (15 mg, 0.052 mmol) was added to a
2
2
2
2
3
solution of alcohol 22 (14 mg, 0.047 mmol) in DMSO (2 mL), and
the resulting solution stirred at room temp. for 18 h. Water (10 mL)
was added, and the mixture extracted with diethyl ether (3ϫ
+
+
HRMS (ESI ): calcd. for C13
found 261.1104.
1
0 mL). The combined organic extracts were dried with MgSO
4
[
[
[
[
1] World Health Organisation Global Tuberculosis Report, 2014.
2] C. Humphries, Nature 2013, 502, S14–S15.
3] R. Koch, Berliner Klinische Wochenschrift. 1882, 18, 221–238.
4] a) H. Ouellet, J. B. Johnston, P. R. Ortiz de Montellano, Trends
Microbiol. 2011, 19, 530–539; b) M. F. Wipperman, N. S.
Sampson, S. T. Thomas, Crit. Rev. Biochem. Mol. Biol. 2014,
and concentrated under reduced pressure to give the crude product
as a pale yellow oil. The crude product was purified by flash col-
umn chromatography (silica gel; ethyl acetate/hexanes, 3:7 as elu-
ent) to give 23 (10 mg, 71%) as a colourless oil and an inseparable
2
3
(
1:1) mixture of diastereomers. [α]
H NMR (400 MHz, CDCl
D
= +70.9 (c = 0.18 in CHCl
, * denotes diastereomer): δ = 4.13–
.03 (m, 2 H), 3.59–3.52 (m, 1 H), 2.61–2.40 (m, 4 H), 2.22 (dt, J
3
).
1
3
4
9, 269–293; c) C. E. Baer, E. J. Rubin, C. M. Sassetti, Immu-
4
nol. Rev. 2015, 264, 327–343.
=
9.2, 18.3 Hz, 1 H), 2.09–1.97 (m, 2 H), 1.90–1.47 (m, 7 H), 1.41 [5] A. K. Pandey, C. M. Sassetti, Proc. Natl. Acad. Sci. USA 2008,
(
1
s, 1.5 H), 1.40* (s, 1.5 H), 1.35 (s, 3 H), 1.17 (s, 1.5 H), 1.16* (s,
105, 4376–4380.
.5 H) ppm. 13C NMR (100 MHz, CDCl
[6] P. Mehrotra, S. V. Jamwal, N. Saquib, N. Sinha, Z. Siddiqui, V.
Manivel, S. Chatterjee, K. V. S. Rao, PLoS Pathog. 2014, 10,
e1004265.
3
, * denotes diastereomer):
δ = 218.0 (C), 210.4 (C), 210.3* (C), 108.8 (C), 108.7* (C), 76.3
CH), 76.0* (CH), 69.4 (CH ), 69.2* (CH ), 49.8 (CH), 49.5* (CH),
9.4 (CH), 48.8* (CH), 47.5 (C), 47.4* (C), 37.34 (CH ), 37.28*
), 30.4 (CH ), 30.3*
), 25.6* (CH ), 22.5
(
4
2
2
[
7] M. Kim, H. C. Wainwright, M. Locketz, L. Bekker, G. B. Wal-
ther, C. Dittrich, A. Visser, W. Wang, F. Hsu, U. Wiehart, L.
Tsenova, G. Kaplan, D. G. Russell, EMBO Mol. Med. 2010, 2,
2
(
(
(
(
CH
CH
CH
2
2
2
), 36.1 (CH
), 26.9 (CH
), 22.4* (CH
2
3
), 31.4 (CH
), 26.9* (CH
), 21.9 (CH ), 13.5 (CH
2
), 30.6* (CH
2
3
2
3
), 25.7 (CH
3
2
58–274.
) ppm. IR [8] B. C. VanderVen, R. J. Fahey, W. Lee, Y. Liu, R. B. Abramov-
itch, C. Memmott, A. M. Crowe, L. D. Eltis, E. Perola, D. D.
2
2
3
), 13.4* (CH
3
neat): ν˜ = 2933, 2881, 1738, 1708, 1596, 1449, 1376, 1266, 1062,
6082
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 6075–6083

DOHNAA, a Cholesterol CD Ring Catabolite and FadD3 Substrate
Deininger, T. Wang, C. P. Locher, D. G. Russell, PLoS Pathog.
[27] C. Prakash, S. Saleh, I. A. Blair, Tetrahedron Lett. 1989, 30,
2015, 11, 1–20.
19–22.
[
[
[
9] R. van der Geize, A. W. F. Grommen, G. I. Hessels, A. A. C.
[
28] E. J. Corey, J. W. Ponder, P. Ulrich, Tetrahedron Lett. 1980, 21,
Jacobs, L. Dijkhuizen, PLoS Pathog. 2011, 7, e1002181.
137–140.
10] N. M. Nesbitt, X. Yang, P. Fontán, I. Kolesnikova, I. Smith,
N. S. Sampson, E. Dubnau, Infect. Immun. 2010, 78, 275–282.
11] a) S. L. Kendall, P. Burgess, R. Balhana, M. Withers, A.
ten Bokum, J. S. Lott, C. Gao, I. Uhia-Castro, N. G. Stoker,
Microbiology 2010, 156, 1362–1371; b) S. L. Kendall, M. With-
ers, C. N. Soffair, N. J. Moreland, S. Gurcha, B. Sidders, R.
[
[
29] A. R. Vaino, W. A. Szarek, Chem. Commun. 1996, 2351–2352.
30] J. Farràs, C. Serra, J. Vilarrasa, Tetrahedron Lett. 1998, 39,
327–330.
[31] G. Kim, M. Chu-Moyer, S. J. Danishefsky, G. K. Schulte, J.
Am. Chem. Soc. 1993, 115, 30–39.
Frita, A. ten Bokum, G. S. Besra, J. S. Lott, N. G. Stoker, Mol. [32]
S. Zhang, L. Xu, M. L. Trudell, Synthesis 2005, 1757–1760.
33] M. Carda, S. Rodríguez, B. Segovia, J. A. Marco, J. Org. Chem.
Microbiol. 2007, 65, 684–699.
[
[
[
12] I. Casabon, A. M. Crowe, J. Liu, L. D. Eltis, Mol. Microbiol.
2002, 67, 6560–6563.
2013, 87, 269–283.
[34] S. Watanuki, K. Matsuura, Y. Tomura, M. Okada, T. Okazaki,
13] A. M. Crowe, P. J. Stogios, I. Casabon, E. Evdokimova, A. Sav-
chenko, L. D. Eltis, J. Biol. Chem. 2015, 290, 872–882.
M. Ohta, S. Tsukamoto, Bioorg. Med. Chem. 2011, 19, 5628–
5638.
[
[
14] G. Stork, P. J. Franklin, Aust. J. Chem. 1992, 45, 275–284.
15] A. R. Daniewski, J. Kiegiel, E. Piotrowska, T. Warchoł, W.
Wojciechowska, Liebigs Ann. Chem. 1988, 593–594.
[35] M. Horinouchi, T. Hayashi, H. Koshino, T. Kurita, T. Kudo,
Appl. Environ. Microbiol. 2005, 71, 5275–5281.
[
16] S. G. Davies, A. J. Russell, R. L. Sheppard, A. D. Smith, J. E.
[36] a) C. J. Sih, K. C. Wang, J. Am. Chem. Soc. 1963, 85, 2135–
2137; b) T. Komeno, S. Ishihara, H. Itan, Tetrahedron 1972, 28,
4719–4736.
Thomson, Org. Biomol. Chem. 2007, 5, 3190–3200.
[
[
17] A. R. Daniewski, W. Liu, J. Org. Chem. 2001, 66, 626–628.
18] R. H. Jih, G. H. Hakimelahi, C. Chou, Tetrahedron Lett. 1992,
[37] G. Stork, D. E. Kahne, J. Am. Chem. Soc. 1983, 105, 1072–
3
3, 6469–6472.
19] Z. Chen, Z. Chen, Y. Zhang, Y. Tu, F. Zhang, J. Org. Chem.
011, 76, 10173–10186.
1073.
[
[
[38] S. G. Ouellet, J. B. Tuttle, D. W. C. MacMillan, J. Am. Chem.
Soc. 2005, 127, 32–33.
2
20] R. A. Micheli, Z. G. Hajos, N. Cohen, D. R. Parrish, L. A.
Portland, W. Sciamanna, M. A. Scott, P. A. Wehrli, J. Org.
Chem. 1975, 40, 675–681.
[39] a) B. H. Lipshutz, J. M. Servesko, B. R. Taft, J. Am. Chem. Soc.
2004, 126, 8352–8353; b) B. H. Lipshutz, J. M. Servesko, T. B.
Petersen, P. P. Papa, A. A. Lover, Org. Lett. 2004, 6, 1273–1275;
ˇ
[
[
21] G. Mehta, S. Yaragorla, Tetrahedron Lett. 2013, 54, 549–552.
22] X. Wang, S. C. Butler, J. C. Gallucci, L. A. Paquette, J. Org.
Chem. 2009, 74, 6825–6830.
23] A. Bartoszewicz, M. Kalek, J. Nilsson, R. Hiresova, J. Stawin-
ski, Synlett 2008, 1, 37–40.
24] a) Z. G. Hajos, D. R. Parrish, E. P. Oliveto, Tetrahedron 1968,
c) B. A. Baker, Z. V. Bo sˇ kovi c´ , B. H. Lipshutz, Org. Lett. 2008,
10, 289–292.
[40] Y. Tang, J. Liu, P. Chen, M. Lv, Z. Wang, Y. Huang, J. Org.
Chem. 2014, 79, 11729–11734.
[41] R. C. A. Isaacs, M. J. Di Grandi, S. J. Danishefsky, J. Org.
Chem. 1993, 58, 3938–3941.
[42] K. Suzuki, N. Suzuki, M. Yamaura, T. Yoshizawa, J. Carbo-
hydr. Chem. 2005, 24, 73–84.
[
[
2
4, 2039–2046; b) Z. Hajos, R. Micheli, D. Parrish, E. Oliveto,
J. Org. Chem. 1967, 32, 3008–3010.
[
[
25] S. Yamashita, K. Iso, K. Kitajima, M. Himuro, M. Hirama, J. [43] D. F. Taber, M. Xu, J. C. Hartnett, J. Am. Chem. Soc. 2002,
Org. Chem. 2011, 76, 2408–2425.
26] T. Hu, J. V. Schaus, K. Lam, M. G. Palfreyman, M. Wuonola,
G. Gustafson, J. S. Panek, J. Org. Chem. 1998, 63, 2401–2406.
124, 13121–13126.
Received: May 28, 2015
Published Online: August 11, 2015
Eur. J. Org. Chem. 2015, 6075–6083
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
6083