Enantioselective preparation and enzymatic cleavage of spiroisoxazoline amides

Article abstract of DOI:10.1016/S0040-4020(00)00342-2

Several enantiopure spiroisoxazoline amides were prepared from tert- butylester 22, which is obtained via an enantiotopic groups differentiating high pressure Diels-Alder cycloaddition. Treatment of these amides with an isoxazoline-splitting enzyme, which

Full text of DOI:10.1016/S0040-4020(00)00342-2

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 4173±4185
Enantioselective Preparation and Enzymatic Cleavage of
Spiroisoxazoline Amides
Kim Goldenstein,a Thomas Fendert,b Peter Prokschc and Ekkehard Winterfeldta,
*
aDepartment of Organic Chemistry, University of Hannover, Schneiderberg 1B, D-30167 Hannover, Germany
b
È
Julius-von-Sachs-Institute of Biological Sciences, University of Wurzburg, Julius-von-Sachs-Platz 2, D-97082 Wurzburg, Germany
Institute of Pharmaceutical Biology, University of Dusseldorf, Universitatsstraûe1, Building 26.23, D-40225 Dusseldorf, Germany
È
c
È
È
È
Dedicated to Professor Rolf Huisgen on the occasion of his 80th birthday
Received 24 March 2000; accepted 18 April 2000
AbstractÐSeveral enantiopure spiroisoxazoline amides were prepared from tert-butylester 22, which is obtained via an enantiotopic groups
differentiating high pressure Diels±Alder cycloaddition. Treatment of these amides with an isoxazoline-splitting enzyme, which is involved
in an injury induced defense reaction of the sponge Aplysina cauliformis, proves the bromoatoms in the cyclohexenone moiety to be
important for enzyme binding, while the presence of the N±H bond of a monoalkylamide turned out to be mandatory for ring ®ssion.
The pertinence of these results to the ring splitting mechanism is discussed. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
proven to show remarkable antibiotic and cytotoxic
activity.11
The unusual spiroisoxazoline ring systems present in the
Starting from these results and having a reliable retro-
Diels±Alder approach to key intermediates like 11 and 13
or their corresponding enantiomers at our disposal, we set
out to prepare the relevant spiroamides. It was our aim to
test the substrate speci®city of the enzyme as well as the
active site requirements and to elaborate the mechanism of
the nitrile forming ring ®ssion.
agelorins (e.g. 1aˆagelorin A, Scheme 1) and the ®stularins
È
(e.g. 2ˆ11-epi-®stularin 3) which were isolated by Konig
and Wright1 from the Barrier Reef sponge Agelas oroides
and which proved to be active against Bacillus subtilis and
Micrococcus luteus2 initiated synthetic work in various
research groups.3±7
In our laboratory the pure enantiomers 9±14 were prepared
from cycloadducts 7a and 7b which result from an
enantiotopic double bonds differentiating high pressure
Diels±Alder cycloaddition (Scheme 2).8
This could in principle be based either on nucleophilic
attack at the carboxylic group (see 15, Scheme 3) or on a
deprotonation step at the N±H group of the amide (see 16).
As communicated already,9 these simple spiro compounds
did easily match or even surpass the natural products in
biological activity, but this comparison could easily
become questionable in the light of the observation that
the ®stularins for instance are just at the starting point of
an enzymatically catalyzed defense mechanism of sponges
at least from the genus Aplysina,10 which involves an
isoxazoline splitting enzyme.
Results and Discussion
Although the most simple looking pyridone catalyzed ester
aminolysis12 worked quite well with our general inter-
mediate 17 and pyrrolidine or piperidine to provide the
disubstituted amides 18a and 18b (Scheme 4), the same
process proved to be extremly unreliable with the much
more important (see 16) primary amines like benzylamine
and cyclohexylamine.
This enzymatic degradation of the ®stularins and of related
spiroisoxazoline amides gives rise to the b-hydroxynitrile
aeroplysinine-1 3 and to the dienone 4, which obviously
results from 3 via enolether hydrolysis and hydration of
the nitrile group, and it were these metabolites that were
Since NMR data on crude reaction products in these cases
indicated conjugate addition to the cyclohexenone moiety to
compete with amide formation, we decided to switch from
methylester 17 to the corresponding acid derivatives and to
generate the desired amides along Staab's well established
carbonyl-diimidazole route.13
* Corresponding author. Tel.: 149-511-762-4649; fax: 149-511-762-
3011; e-mail: winterfeldt@mbox.oci.uni-hannover.de
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00342-2

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K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
Scheme 1.
This called for an investigation of acid and base catalyzed
hydrolysis of the intermediates in question and while proton
catalyzed acetal splitting worked very well to provide diols
13 and 19 all our efforts to achieve base catalyzed ester
hydrolysis met with failure.
It should be mentioned at this stage, however, that the corre-
sponding epoxide 26 although its preparation from 21 with
tert-butylhydroperoxide and DBU15 was achieved in 80%
yield, gave only a disappointingly meager 13% of the retro-
product 27 on thermolysis (Scheme 6).
A possible way to solve this problem would be to start
with a tert-butylester right from the beginning and to
prepare ester 22 via our Diels±Alder-retro-diene
sequence. We were well aware of the additional risks of
course, that come along with this special ester groupÐpar-
ticularly in the retro stepÐwe noticed on the other hand
with some curiosity, however, that in our previous enantio-
topic group differentiations we never had employed a
tert-butylester.
This means that 27, which is needed for regioselective and
stereoselective introduction of the bromoatoms present in
the natural products, would have to be synthesized from diol
24.
Although the corresponding bromohydrin 28 looked like the
most promising intermediate for this transformation, its
preparation turned out to be by no means straightforward.
A number of well-established methods for the bromination
of alcohols, including the Appel technique16 did either leave
13 unchanged or led to complete destruction of the molecule.
To ®ll this gap and to gather some experience with this
functional group too, we prepared ester 20 (Scheme 5)
and were pleased to arrive at the enantiopure adduct 21 in
an uneventfully high yield cycloaddition process.
As preceding in situ formation of a tosylate at the hydroxy
group to be substituted was considered an obvious way out
of this dilemma we treated the esters 13 and 24 with tosyl
chloride, HuÈnig's base and the triphenylphosphine±bromine
complex in dichloromethane in the temperature range from
08C to room temperature and were pleased to isolate 72% of
the bromo epimers 14b (Scheme 7) from methylester 13 and
also 44% of the corresponding tert-butylester 28.
As expected hydroxylation14 and diol protection with
p-methoxy-benzaldehyde dimethylacetal operated nicely
and even the retro-step could reliably be run with 50%
yield, if the reaction ¯ask was rinsed with triethylamine
prior to the thermal process.

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4175
Scheme 2. (i) 6.5 kbar, CH2Cl2, 21 d (7a 88%, 7b 78%); (ii) KOH, H2O2, THF, 08C (96%); (iii) 3008C, 1022 mbar (83%); (iv) Br2, Et3N, CH2Cl2 (48%);
(v) PPh3Br2, CH2Cl2, 08C to rt (79%).
While on the ®rst glance this seemed to con®rm our assump-
tion, a few disturbing observations made in the sequel cast
serious doubt on the tosylate intermediate. First of all to be
successful one had very much to stick to just one special
mode of addition. It had to be treatment of triphenyl-
phosphine with bromine in dichloromethane at 08C ®rst,
after 5 min the HuÈnig's base had to be added, followed by
a substoichiometric amount of tosyl chloride. Finally and
still at 08C one had to drop in the corresponding alcohol.
surprising in the presence of base, we ®rst of all, using the
procedure described above, prepared the con®gurational
stable bromides 34, 35a and 35b (Scheme 8) from the
conformational rigid secondary alcohols menthol,
androsterone and 3-epi-androsterone, which proved the
bromination to be a clean inversion process, accompanied
by the formation of triphenylphosphine oxide.
As far as the stereochemical outcome goes this indicates that
one deals with a special route to the well-known Mitsunobu
intermediate and although this still leaves open questions on
details of this substitution reaction it turned out to be the
only way to make the bromohydrins 14b and 28 which on
base treatment led to the epoxides 30a and 27 as expected.
Since this sequence rather speaks against preformation of a
tosylate, we checked the reaction with the independently
prepared tert-butyl-cyclohexyl-p-toluenetosylate 33,17 to
®nd that it was absolutely stable under reaction conditions,
that led to quick bromination of the free alcohol.
A very high yield Johnson bromination18 followed by the
again quantitative splitting of the tert-butylester provided
acid 29c, ready for amide formation.
As bromohydrine formation in this cyclohexenone series
additionally led to mixtures of epimers, which is not
Using benzylamine under Staab's conditions cleanly led to
amide 31 which on epoxide opening19 provided dibromo-
amide 32 having the agelorin type substitution pattern.
To have a comparable dibromomethylester available as a
testsubstrate for the enzymatic ring ®ssion (nucleophilic
attack, see 15) we started from acetal 17 described
earlier and prepared bromodiol 36 again using Johnson's
protocol, followed by acid catalyzed acetal hydrolysis
(Scheme 9).
Scheme 3.

4176
K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
Scheme 4. (i) a-Pyridone, dioxane, rt, 10 min (18a 75%, 18b 48%); (ii) H2SO4, acetone, rt, 30 min (74%).
Scheme 5.
Scheme 6. (i) tert-butylhydroperoxide, DBU (80%); (ii) 3008C, 1.5£1022 mbar (13%).

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4177
Scheme 7.
Bromination of this diol 36 under the conditions described
above gave only a moderate yield of bromohydrin 38, but
since this compound is obtained in 96% yield from the
corresponding epoxide 37, this line was not investigated
any further.
from Aplysina cauliformis, a sponge that had been collected
in summer 1995 on Long Island (Bahamas) at a depth of
3 m.10
To check the general possibility to cleave spiroisoxazolines
enzymatically,20 numerous spiroisoxazoline derivatives
were treated with the cell free extract, the most important
ones were 19 (Scheme 4), 32 (Scheme 7), 38 (Scheme 9), 39
and 40 (Scheme 10).
The Staab procedure did also work very satisfactorily with
acid 25 to provide amide 39. With acid 30b we even
succeeded in the preparation of bisamide 40, which was,
however, according to its polarity and low solubility not
easily puri®ed and had to be characterized by its IR- and
MS-data along with some very characteristic NMR
signals.
We observed that the non-brominated amides 19 and 40 as
well as methylester 38 were not attacked by the enzyme at
all, diolamide 39 was cleaved partly (30%) and dibromo-
amide 32 was split quantitatively. This result indicates the
N±H bond, the hydroxy function and the two bromoatoms
to play an important role for the enzymatic cleavage and
points at cleaving mechanism 16 (Scheme 3).23
Having thus differently substituted brominated and not
brominated amides as well as their ester analogues at our
disposal we could start investigations with a cell free extract
Scheme 8.

4178
K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
Scheme 9.
Scheme 10.
Because of its agelorin type substitution pattern in the cyclo-
hexenone ring, bromohydrine 38 was additionally tested on
its ability to inhibit competitively the active site of the
enzyme against iso®stularin.23 However, dibromomethyl-
ester 38 showed no tendency to lower the enzyme activity,
so that the N±H functionality seems to have some signi®ca-
tion for the enzyme binding, too.
Experimental
General procedures
Melting points were determined on a BuÈchi melting point
microscope and are uncorrected. UV spectra were measured
on a Shimadzu 1601 instrument and IR spectra on a Perkin±
1
Elmer 581 spectrometer. H NMR and 13C NMR spectra
Our examinations demonstrate that the enzyme is highly
speci®c and its only function is the ring ®ssion reaction of
the brominated spiroisoxazoline amides to form the toxic
metabolite aeroplysinin-1 3 (Scheme 1).
were recorded on a Bruker WP 200, Bruker AM 400 and
Bruker AVS 400. dH Values are given relative to TMSˆ0;
CDCl3ˆ77.05; multiplicities of 13C NMR were determined
J
values in Hz, dC values are given relative to

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4179
by DEPT (908/1358) or by APT. MS were determined with a
Finnigan MAT 312 instrument and VG Autospec at 70 eV.
Elemental analyses were recorded on a Heraeus CHN rapid
analyzer. For ¯ash chromatography silica gel (30±60 mesh;
Baker) was used at 0.3 bar. The high pressure reactions were
performed in a Hofer apparatus. For retro-Diels±Alder
reactions a special ¯ash vacuum pyrolysis apparatus was
used. All solvents were dried by standard methods. Cyclo-
pentadiene 5 was prepared according to the procedure
described by Winterfeldt et al.,21 spiroisoxazolines 6 and
20 were prepared as described.22
Diolepyrrolidineamide 19. To a solution of 18a (21 mg,
0.053 mmol) in aq. acetone (3 ml) was added a catalytic
amount of 2 N aq. H2SO4 at room temperature. After
30 min the reaction was stopped with NaHCO3. The reac-
tion mixture was concentrated and afterwards water was
added. The aqueous phase was extracted with ethyl acetate.
The combined organic layers were dried (MgSO4) and
concentrated. Chromatographic puri®cation yielded 11 mg
(74%) of 19 as a white foam; [a]2D0ˆ79.58 (cˆ0.64, CHCl3);
IR (CHCl3): nˆ3496 cm21 (w), 3400 (w), 3004 (m), 2980
(m), 2956 (w), 1700 (s), 1624 (s), 1596 (m), 1452 (m), 1380
1
(w), 1264 (s), 1112 (m), 908 (m); H NMR (400 MHz,
CDCl3): dˆ1.88±2.03 (m, symmetric, 4H, 11-H, 110-H),
3.30 (d, Jˆ18 Hz, 1H, 7-H), 3.50 (s, 1H, OH), 3.59 (tr,
Jˆ7 Hz, 2H, 10-H, 100-H), 3.75±3.83 (m, 3H, 10-H,
100-H, OH), 3.94 (d, Jˆ18 Hz, 1H, 7-H), 4.21 (dbr,
Jˆ2 Hz, 1H, 1-H), 4.68 (d, Jˆ2.5 Hz, 1H, 2-H), 6.23 (d,
Jˆ10 Hz, 1H, 4-H), 6.62 (d, Jˆ2/10 Hz, 1H, 5-H); 13C
NMR (100 MHz, CDCl3): nˆ23.82 (C-110), 26.23 (C-11),
44.86 (C-7), 47.21 (C-100), 48.85 (C-10), 73.17 (C-1), 73.19
(C-2), 85.73 (C-6), 129.10 (C-4), 143.81 (C-5), 155.18
(C-8), 158.27 (C-9), 197.43 (C-3); MS (1508C): m/z
(%)ˆ281 (M11, 2), 280 (M1, 14), 251 (6), 220 (9), 193
(8), 149 (6), 139 (11), 136 (25), 135 (36), 125 (9), 98 (54),
86 (20), 70 (100); HRMS: m/z for C13H16N2O5 calcd:
280.1059, found: 280.1060.
Experimental procedures
Protected pyrrolidineamide 18a. To a solution of acetal 17
(25 mg, 0.065 mmol) in dry dioxane (2 ml) were added
a-pyridone (28 mg, 0.288 mmol, 4 equiv.) and afterwards
pyrrolidine (35 mg, 0.478 mmol, 7 equiv.) at room tempera-
ture. After stirring the reaction mixture for 10 min it was
quenched with water, extracted with ethyl acetate, dried
(MgSO4) and concentrated. Puri®cation by ¯ash chromato-
graphy yielded 21 mg (75%) of 18a as a white foam; IR
(CHCl3): nˆ2984 cm21 (w), 2956 (m), 2928 (w), 1696
(m), 1628 (s), 1592 (m), 1452 (m), 1400 (m), 1264 (s),
1
1092 (m), 908 (s); H NMR (400 MHz, CDCl3): dˆ1.86±
2.02 (m, 4H, 11-H, 110-H), 3.38 (d, Jˆ18 Hz, 1H, 7-H),
3.55±3.62 (m, 2H, 10-H, 100-H), 3.71±3.85 (m, 5H, 10-H,
100-H, 17-H), 3.95 (d, Jˆ18 Hz, 1H, 7-H), 4.58 (dd, Jˆ2/
6 Hz, 1H, 1-H), 4.64 (d, Jˆ6 Hz, 1H, 2-H), 5.93 (s, 1H,
12-H), 6.28 (d, Jˆ10 Hz, 1H, 4-H), 6.75 (dd, Jˆ2/10 Hz,
1H, 5-H), 6.87 (d, Jˆ9 Hz, 2H, 15-H, 150-H), 7.27 (d,
Jˆ9 Hz, 2H, 14-H, 140-H); 13C NMR (100 MHz, CDCl3):
dˆ23.82 (C-11), 26.24 (C-110), 45.08 (C-7), 47.14 (C-10),
48.75 (C-100), 55.30 (C-17), 73.94 (C-1), 78.43 (C-2), 82.63
(C-6), 105.05 (C-12), 113.87 (C-15, C-150), 127.72 (C-13),
128.24 (C-14, C-140), 130.87 (C-4), 144.09 (C-5), 155.38
(C-16), 157.91 (C-8), 160.81 (C-9), 193.05 (C-3); MS
(1808C): m/z (%)ˆ399 (M11, 1), 398 (M1, 6), 371 (1),
300 (11), 245 (13), 152 (9), 137 (22), 135 (100), 122 (14),
98 (65), 92 (9), 77 (19), 70 (29); HRMS m/z for C21H22N2O6
calcd: 398.1478, found: 398.1478.
Spiroisoxazoline adduct 21. A solution of diene 5 (2.66 g,
11.08 mmol) and spiroisoxazoline 20 (2.3 g, 9.24 mmol) in
dichloromethane (7.5 ml) was introduced into a Te¯on hose
and submitted to 6.5 kbar in a high pressure autoclave for
14 days. Puri®cation of the raw material by ¯ash chromato-
graphy yielded 3.70 g (82%) of 21 as white foam;
[a]2D0ˆ123.68 (cˆ1.35, CHCl3); IR (CHCl3): nˆ
2984 cm21 (m), 2934 (m), 2864 (m), 1711 (s), 1669 (s),
1637 (w), 1612 (m), 1593 (m), 1515 (s), 1443 (w), 1371
(m), 1252 (s), 1180 (m), 1140 (s), 910 (m); 1H NMR
(400 MHz, CDCl3): dˆ0.45 (dbr, Jˆ13 Hz, 1H, 2-Heq),
0.80 (s, 3H, 28-H), 1.06±1.64 (m, 5H), 1.57 (s, 9H, 20-H,
21-H, 22-H), 1.86 (dtr, Jˆ3/13 Hz, 1H), 2.42 (dd, Jˆ2.5/
8.5 Hz, 1H), 2.86 (d, Jˆ8 Hz, 1H, 11-H), 3.20 (d, Jˆ18 Hz,
1H, 16-H), 3.26 (d, Jˆ18 Hz, 1H, 16-H), 3.80±3.84 (m, 4H,
10-H, 27-H), 5.84 (d, Jˆ10 Hz, 1H, 14-H), 5.88 (d,
Jˆ5.5 Hz, 1H, 7-H), 6.17 (d, Jˆ5.5 Hz, 1H, 8-H), 6.51
(dd, Jˆ1/10 Hz, 1H, 13-H), 6.87 (d, Jˆ9 Hz, 2H, 25-H,
250-H), 7.29 (d, Jˆ9 Hz, 2H, 24-H, 240-H); 13C NMR
(100 MHz, CDCl3): dˆ15.40 (C-28), 21.13 (C-4), 23.81
(C-3), 27.13 (C-5), 28.03 (C-20, C-21, C-22), 28.57 (C-2),
50.26 (C-11), 51.67 (C-16), 51.68 (C-10), 55.17 (C-27),
61.31 (C-6), 62.36 (C-1), 70.87 (C-9), 83.84 (C-19), 87.66
(C-12), 113.10 (C-25, C-250), 128.94 (C-23), 129.03 (C-24,
C-240), 130.99 (C-7), 135.62 (C-14), 138.62 (C-8), 147.29
(C-13), 151.64 (C-26), 158.31 (C-17), 159.38 (C-18),
198.09 (C-15); MS (808C): m/z (%)ˆ489 (M1, 4), 372
(7), 371 (6), 305 (6), 240 (30), 234 (14), 211 (11), 210
(9), 193 (12), 176 (100), 153 (16), 119 (29); FAB-MS:
m/z (%)ˆ512 (M123, 81), 490 (M11, 100), 460 (25),
434 (94).
Protected piperidineamide 18b. To a solution of acetal 17
(20 mg, 0.056 mmol) in dry dioxane (2 ml) were added
piperidine (70 mg, 0.882 mmol, 15 equiv.) and a-pyridone
(20 mg, 0.206 mmol, 3.7 equiv.) at room temperature. After
stirring the reaction mixture for 6 h it was quenched with
water, extracted with ethyl acetate, dried (MgSO4) and
concentrated. Puri®cation by ¯ash chromatography yielded
11 mg (48%) of 18b as a white foam; IR (CHCl3):
nˆ3029 cm21 (w), 2942 (m), 2860 (w), 1696 (m), 1630
(s), 1518 (m), 1480 (m), 1399 (w), 1254 (s), 1093 (m),
1
1002 (m); H NMR (200 MHz, CDCl3): dˆ1.45±1.58 (m,
6H, 11-H, 110-H, 12-H), 3.38 (d, Jˆ18 Hz, 1H, 7-H), 3.58±
3.97 (m, 8H, 10-H, 100-H, 18-H, 7-H), 4.58±4.68 (m, 2H,
1-H, 2-H), 5.95 (s, 1H, 13-H), 6.28 (d, Jˆ10 Hz, 1H, 4-H),
6.77 (dd, Jˆ2/10 Hz, 1H, 5-H), 6.87 (d, Jˆ9 Hz, 2H, 16-H,
160-H), 7.29 (d, Jˆ9 Hz, 2H, 15-H, 150-H); MS (180 8C):
m/z (%)ˆ413 (M11, 2), 412 (M1, 9), 387 (21), 301 (25),
259 (26), 199 (3), 149 (9), 135 (79), 121 (13), 112 (100), 84
(59), 77 (16), 69 (43); HRMS: m/z for C22H24N2O6 calcd:
412.1634, found: 412.1635.
Spiroisoxazoline diol adduct. To a solution of 21 (4.30 g,
8.81 mmol) and CH3CN (50 ml) and EtOAc (50 ml) was
added with vigorous stirring a solution of RuCl3´xH2O
(461 mg, 2.23 mmol, 0.25 equiv.) and NaIO4 (3.58 g,

4180
K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
16.73 mmol, 1.9 equiv.) in deionized water at 08C. After
5 min the reaction mixture was quenched with sat. aq.
NaHSO5. The aqueous phase was extracted with ethyl
acetate. The combined organic layers were dried (MgSO4)
and concentrated. Puri®cation by ¯ash chromatography
yielded 3.92 g (85%) of the diol adduct as yellow foam;
[a]D20ˆ74.98 (cˆ0.41, CHCl3); IR (CHCl3): nˆ3587 cm21
(w), 2985 (w), 2934 (w), 1710 (s), 1595 (w), 1516 (m), 1443
Protected diol 22. A ¯ask of a ¯ash vacuum pyroysis
apparatus was rinsed with triethylamine. Then adduct 23
(500 mg, 0.780 mmol) was brought into it and heated to
1108C at 1022 mbar. This way the developed diene 5 was
sublimed and 22 remained in the reaction ¯ask. Chromato-
graphic puri®cation yielded 156 mg (50%) as a yellow
solid; melting pointˆ122.28C; IR (CHCl3): nˆ2984 cm21
(w), 2936 (w), 1714 (s), 1614 (m), 1597 (w), 1459 (w), 1371
(m), 1254 (s), 1173 (m), 1151 (m), 1126 (m), 830 (m); UV
(CHCl3): lmaxˆ261 nm; 1H NMR (200 MHz, CDCl3):
dˆ1.56 (s, 9H, 11-H, 12-H, 13-H), 3.21 (d, Jˆ18 Hz, 1H,
7-H), 3.70±3.89 (m, 4H, 7-H, 19-H), 4.58±4.77 (m, 2H,
1-H, 2-H), 5.94 (s, 1H, 14-H), 6.27 (d, Jˆ10 Hz, 1H,
4-H), 6.74 (dd, Jˆ10/1.5 Hz, 1H, 5-H), 6.87 (d, Jˆ9 Hz,
2H, 17-H, 170-H), 7.28 (d, Jˆ9 Hz, 2H, 16-H, 160-H); 13C
NMR (50 MHz, CDCl3): dˆ27.98 (C-11, C-12, C-13),
43.11 (C-7), 55.31 (C-19), 73.91 (C-1), 78.40 (C-2), 84.24
(C-10), 84.63 (C-6), 105.05 (C-14), 113.90 (C-17, C-170),
127.66 (C-15), 128.26 (C-16, C-160), 130.83 (C-4), 143.65
(C-5), 153.09 (C-18), 158.75 (C-8), 166.86 (C-9), 192.80
(C-3); FAB-MS: m/z (%)ˆ424 (M123, 7), 402 (M11, 34),
391 (7), 346 (14), 329 (18), 307 (29), 289 (20), 259 (26), 241
(12), 176 (35), 154 (100).
1
(w), 1371 (m), 1265 (s), 1127 (m), 1106 (m), 909 (m); H
NMR (400 MHz, CDCl3): dˆ0.51 (dbr, Jˆ13 Hz, 1H,
2-Heq), 0.79 (s, 3H, 28-H), 1.11±1.98 (m, 7H), 1.58 (s,
9H, 20-H, 21-H, 22-H), 2.94 (d, Jˆ9 Hz, 1H, 11-H), 3.03
(d, Jˆ18 Hz, 1H, 16-H), 3.72±3.94 (m, 6H, 27-H, 16-H,
10-H, 14-H), 4.18 (d, Jˆ2 Hz, 1H, 13-H), 5.97 (d,
Jˆ6 Hz, 1H, 7-H), 6.45 (d, Jˆ6 Hz, 1H, 8-H), 6.88 (d,
Jˆ9 Hz, 2H, 25-H, 250-H), 7.28 (d, Jˆ9 Hz, 2H, 24-H,
240-H); 13C NMR (100 MHz, CDCl3): dˆ16.08 (C-28),
21.18 (C-4), 23.60 (C-3), 26.35 (C-5), 28.04 (C-20, C-21,
C-22), 28.41 (C-2), 45,47 (C-16), 52.05 (C-10), 52.95
(C-11), 55.18 (C-27), 61.81 (C-6), 62.81 (C-1), 69.03
(C-9), 74.00 (C-13), 75.91 (C-14), 83.84 (C-19), 90.20
(C-12), 113.17 (C-25, C-250), 128.87 (C-23), 128.94
(C-24, C-240), 132.50 (C-7), 142.93 (C-8), 152.61 (C-29),
158.61 (C-17), 159.67 (C-18), 211.23 (C-15); FAB-MS: m/z
(%)ˆ546 (M123, 100), 524 (M11, 17), 523 (27), 508 (7),
495 (10), 490 (12).
Spiroisoxazoline diol 24. To a solution of 22 (550 mg,
1.38 mmol) in aq. acetone (3 ml) was added a catalytic
amount of 2 N aq. H2SO4 at room temperature. After 3 h
the reaction was stopped with NaHCO3. The reaction
mixture was concentrated and afterwards water was
added. The aqueous phase was extracted with ethyl acetate.
The combined organic layers were dried (MgSO4) and
concentrated. Chromatographic puri®cation yielded
327 mg (84%) of 24 as a white foam; [a]2D0ˆ19.68
(cˆ0.14, MeOH); IR (CHCl3): nˆ3580 cm21 (w), 3506
(w), 2984 (w), 1703 (s), 1597 (m), 1458 (w), 1371 (m),
1261 (m), 1127 (m), 909 (m); 1H NMR (400 MHz,
acetone-d6): dˆ1.53 (s, 9H, 11-H, 12-H, 13-H), 3.27 (d,
Jˆ18 Hz, 1H, 7-H), 3.73 (d, Jˆ18 Hz, 1H, 7-H), 4.17 (m,
1H, 1-H), 4.40 (d, Jˆ4 Hz, 1H, OH), 4.54 (trbr, Jˆ4 Hz, 1H,
2-H), 5.07 (d, Jˆ4 Hz, 1H, OH), 6.14 (d, Jˆ10 Hz, 1H,
4-H), 6.81 (d,Jˆ10/2 Hz, 1H, 5-H); 13C NMR (100 MHz,
acetone-d6): dˆ28.13 (C-11, C-12, C-13), 43.07 (C-7),
74.51 (C-1), 74.78 (C-2), 83.50 (C-10), 98.46 (C-6),
129.84 (C-4), 144.42 (C-5), 153.94 (C-8), 159.98 (C-9),
198.17 (C-3); MS (1508C): m/z (%)ˆ227 (M-tBu11, 211
(9), 210 (100), 181 (3), 136 (17), 123 (3), 87 (4), 83 (41);
HRMS: m/z for C9H9NO6 calcd: 227.0430, found:
227.0430.
Protected spiroisoxazoline adduct 23. To a solution of
spiroisoxazoline diol adduct (4.06 g, 7.76 mmol) in dry
CH3CN (50 ml) were added p-methoxy-benzaldehyde
acetal (4.00 g, 22.10 mmol, 2.8 equiv.) and a catalytic
amount of pTsOH at 08C. After 30 min at room temperature
the reaction mixture was quenched with sat. aq. NaHSO3.
The aqueous phase was extracted with methyl tert-butyl
ether. The combined layers were washed with brine and
dried (MgSO4). Evaporation of the solvent and puri®cation
by ¯ash chromatography yielded 3.87 g (78%) of 23 as a
white solid; melting pointˆ80.78C; IR (CHCl3):
nˆ2935 cm21 (m), 1714 (s), 1614 (m), 1594 (m), 1517
(s), 1463, 1441 (m), 1371 (m), 1252 (s), 1181 (m), 1171
(m), 1935 (m), 909 (m); 1H NMR (200 MHz, CDCl3):
dˆ0.62 (dbr, 1H, 2-Heq), 0.79 (s, 3H, 34-H), 1.12±1.73
(m, 4H), 1.54 (s, 9H, 20-H, 21-H, 22-H), 1.95±2.14 (m,
3H), 3.20 (m, 2H, 11-H, 16-H), 3.54 (d, Jˆ18 Hz, 1H,
16-H), 3.78 (s, 3H, 28-H), 3.83 (s, 3H, 33-H), 4.27 (d,
Jˆ8 Hz, 1H, 13-H), 4.29 (d, Jˆ10 Hz, 1H, 10-H), 4.48 (d,
Jˆ8 Hz, 1H, 14-H), 5.79 (s, 1H, 23-H), 6.09 (d, Jˆ6 Hz,
1H, 7-H), 6.23 (d, Jˆ6 Hz, 1H, 8-H), 6.85 (d, Jˆ9 Hz, 2H,
31-H, 310-H), 6.96 (d, Jˆ9 Hz, 2H, 26-H, 260-H), 7.16 (d,
Jˆ9 Hz, 2H, 30-H, 300-H), 7.45 (d, Jˆ9 Hz, 2H, 25-H, 250-
H); 13C NMR (100 MHz, CDCl3): dˆ15.73 (C-34), 21.03
(C-4), 23.44 (C-3), 27.66 (C-5), 28.00 (C-20, C-21, C-22),
28.55 (C-2), 43.17 (C-16), 51.75 (C-11), 52.37 (C-10),
55.21 (C-28), 55.31 (C-33), 60.50 (C-6), 63.22 (C-1),
64.92 (C-9), 78.27 (C-13), 80.81 (C-14), 80.68 (C-19),
89.84 (C-12), 104.83 (C-23), 113.52 (C-31, C-310), 114.09
(C-26, C-260), 127.13 (C-24), 128.06 (C-30, C-310),
128.09 (C-25, C-250), 129.72 (C-29), 136.25 (C-7),
138.67 (C-8), 152.76 (C-32), 158.32 (C-27), 159.34
(C-17), 160.98 (C-18), 203.78 (C-15); FAB-MS: m/z
(%)ˆ664 (M123, 25), 642 (M11, 26), 586 (8), 540
(9), 402 (100), 391 (5), 368 (8), 346 (37), 329 (9),
307 (19), 289 (11).
Diol carboxylic acid 25. To a solution of 24 (10 mg,
0.035 mmol) in dichloromethane (1 ml) was added tri¯uoro-
acetic acid (1 ml). After 1 h at room temperature the
reaction mixture was concentrated and 8 mg of acid 25
were obtained as a brown oil; [a]2D0ˆ44.48 (cˆ1.08,
MeOH); IR (CHCl3): nˆ3411 cm21 (s), 2925 (m.), 1703
(s), 1599 (m), 1514 (w), 1257 (m), 1162 (m), 1116 (m),
918 (m), 736 (w); 1H NMR (400 MHz, acetone-d6):
dˆ3.31 (d, Jˆ18 Hz, 1H, 7-H), 3.78 (d, Jˆ18 Hz, 1H,
7-H), 4.19 (dd, Jˆ2/2.5 Hz, 1H, 1-H), 4.55 (d, Jˆ2.5 Hz,
1H, 2-H), 6.15 (d, Jˆ10 Hz, 1H, 4-H), 6.85 (d, Jˆ2/10 Hz,
1H, 5-H); 13C NMR (100 MHz, acetone-d6): dˆ42.93 (C-7),
74.54 (C-1), 74.80 (C-2), 89.80 (C-6), 129.95 (C-4), 144.36
(C-5), 153.20 (C-8), 161.54 (C-9), 198.18 (C-3); MS (708C):

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4181
m/z (%)ˆ228 (M11, 3), 227 (M1, 11), 223 (17), 211 (10),
210 (100), 198 (10), 182 (13), 164 (7), 140 (12), 123 (12),
109 (7), 96 (20), 84 (9); HRMS: m/z for C9H9NO6 calcd:
227.0430, found: 227.0434.
Bromohydrinmethylester 14b. To a solution of PPh3
(240 mg, 0.916 mmol, 2.2 equiv.) in dry dichloromethane
(10 ml) was added a bromine solution (0.95 ml, 0.5 M in
dichloromethane, 0.475 mmol, 1.1 equiv.) at 08C. After-
wards HuÈnig's base (0.09 ml, 0.548 mmol, 1.3 equiv.) and
TsCl (26 mg, 0.137 mmol, 0.3 equiv.) were added and the
reaction mixture was stirred for 10 min. Then diol 13
(100 mg, 0.415 mmol) was added and the mixture was stir-
red overnight at room temperature. The reaction was
stopped with water, extracted with ethyl acetate, dried
(MgSO4) and chromatographic puri®cation yielded 71 mg
(72%) of 14b as a yellow oil; IR (CHCl3): nˆ3592 cm21
(w), 3040 (w), 2956 (w), 2928 (w), 1728 (s), 1704 (s), 1600
(m), 1444 (m), 1373 (m), 1352 (s), 1264 (m), 1124 (m), 920
(m); 13C NMR (100 MHz, CDCl3): dˆ37.46 (C-7), 53.14/
53.16 (C-10), 57.32 (C-1), 75.03 (C-2), 90.14 (C-6), 127.80
(C-4), 147.39 (C-5), 151.01/152.10 (C-8), 160.13/160.18
(C-9), 188.20 (C-3); MS (1408C): m/z (%)ˆ274 (M-31, 5),
272 (M-31, 5), 224 (89), 192 (32), 181 (30), 154 (13), 138
(28), 122 (22), 96 (100), 77 (19), 68 (36); HRMS: m/z for
C9H7NO4Br calcd: 271.9558, found: 271.9557; main
product (trans-bromohydrin): 1H NMR (400 MHz,
CDCl3): dˆ3.10 (d, Jˆ18 Hz, 1H, 7-H), 3.92 (d,
Jˆ18 Hz, 1H, 7-H), 3.96 (s, 3H, 10-H), 4.41 (dd, Jˆ3/
12 Hz, 1H, 1-H), 4.57 (d, Jˆ12 Hz, 1H, 2-H), 6.27 (d,
Jˆ10 Hz, 1H, 4-H), 7.01 (d, Jˆ10 Hz, 1H, 5-H); the spec-
troscopic data were taken from the spectra of the mixtures;
side product (cis-bromohydrin): 1H NMR (400 MHz,
CDCl3): dˆ3.24 (d, Jˆ18 Hz, 1H, 7-H), 3.97 (s, 3H, 10-
H), 4.44 (d, Jˆ18 Hz, 1H, 7-H), 4.48 (sbr, 1H, 1-H), 4.98
(sbr, 1H, 2-H), 6.25 (d, Jˆ10 Hz, 1H, 4-H), 6.76 (d,
Jˆ10 Hz, 1H, 5-H); the spectroscopic data were taken
from the spectra of the mixtures.
Epoxy adduct 26. To a solution of adduct 21 (35 mg,
0.072 mmol) in dry dichloromethane (3 ml) were added
tert-BuOOH (0.05 ml, 44 mg, 0.384 mmol, 5.5 equiv.,
80% in tert-butylperoxide) and two drops of DBU. After
stirring overnight the reaction mixture was quenched with
sat. aq. Na2S2O5, extracted with methyl-tert-butyl ether and
concentrated. Puri®cation of the raw material yielded 20 mg
(80%) of epoxide 26 as a yellow foam; [a]2D0ˆ37.28
(cˆ0.65, CHCl3); IR (CHCl3): nˆ2984 cm21 (m), 2933
(m), 1716 (s), 1594 (m), 1516 (s), 1461 (w), 1443 (w),
1385 (m), 1352 (m), 1275 (m), 1252 (s), 1181 (m), 1149
1
(m), 1130 (m), 909 (m), 822 (m); H NMR (400 MHz,
CDCl3): dˆ0.56 (dbr, Jˆ13 Hz, 1H, 2-Heq), 0.76 (s, 3H,
28-H), 1.12±1.66 (m, 5H), 1.58 (s, 9H, 20-H, 21-H, 22-
H), 1.73 (dbr, Jˆ12 Hz, 1H), 1.99 (dtr, Jˆ3.5/13 Hz, 1H),
3.04 (d, Jˆ10 Hz, 1H, 11-H), 3.35 (d, Jˆ4 Hz, 1H, 13-H),
3.37 (d, Jˆ4 Hz, 1H, 14-H), 3.39 (d, Jˆ18.5 Hz, 1H, 16-H),
3.64 (d, Jˆ18.5 Hz, 1H, 16-H), 3.79 (s, 3H, 27-H), 3.96 (d,
Jˆ10 Hz, 1H, 10-H), 6.06 (d, Jˆ5.5 Hz, 1H, 7-H), 6.14 (d,
Jˆ5.5 Hz, 1H, 8-H), 6.85 (d, Jˆ9 Hz, 2H, 25-H, 250-H),
7.12 (d, Jˆ9 Hz, 2H, 24-H, 240-H); 13C NMR (100 MHz,
CDCl3): dˆ15.77 (C-27), 21.06 (C-4), 23.34 (C-3), 26.89
(C-5), 26.92 (C-2), 28.06 (C-20, C-21, C-22), 46.35 (C-16),
52.64 (C-11), 53.07 (C-10), 55.18 (C.27), 56.00 (C-13),
60.31 (C-6), 60.58 (C-14), 61.01 (C-1), 63.86 (C-9), 84.09
(C-19), 88.55 (C-12), 113.46 (C-25, C-250), 127.71 (C.24,
C-240), 130.43 (C-23), 135.64 (C-7), 139.00 (C-8), 152.30
(C-26), 158.09 (C-17), 159.39 (C-18), 204.29 (C-15); MS
(1808C): m/z (%)ˆ266 (dienophile11, 2), 240 (diene, 100),
197 (6), 121 (3); FAB-MS: m/z (%)ˆ528 (M123, 7), 506
(M11, 4), 505 (M1, 4), 504 (M21, 4), 241 (74), 240
(100).
Bromohydrin-tert-butylester 28. To a solution of PPh3
(119 mg, 0.456 mmol, 4.3 equiv.) in dry dichloromethane
(3 ml) was added a bromine solution (0.28 ml, 0.5 M in
dichloromethane, 0.139 mmol, 1.3 equiv.) at 08C. After-
wards HuÈnig's base (3 drops) and TsCl (20 mg,
0.106 mmol, 1 equiv.) were added and the reaction mixture
was stirred for 10 min. Then diol 24 (30 mg, 0.106 mmol)
was added and the mixture was stirred for 14 h at room
temperature. No working up followed, chromatographic
puri®cation yielded 16 mg (44%) of 28 as a yellow oil; IR
(CHCl3): nˆ3590 cm21 (w), 2984 (m), 1712 (s), 1601 (w),
1264 (m), 1129 (s); FAB-MS: m/z (%)ˆ369 (M123, 7), 348
(M1, 9), 329 (18), 307 (36), 289 (23), 259 (32), 176 (27),
Spiroisoxazoline epoxide 27. Method A: Epoxyadduct 26
(15 mg, 0.030 mmol) was brought into a ¯ash vacuum
pyrolysis apparatus and sublimed at 3008C/1.51022 mbar
through a pyrolysis tube heated to 3008C. After 2 h the
whole starting material was sublimed off and a 1:1 mixture
of 27 and diene 5 was trapped on a cooling ®nger. Chroma-
tographic puri®cation yielded 1 mg (13%) of 27 as a color-
less oil.
Method B: To a solution of bromohydrine 28 (20 mg,
0.057 mmol) in dichloromethane (3 ml) was added a cata-
lytic amount of DBU. The reaction mixture was concen-
trated and chromatographic puri®cation yielded 16 mg
(95%) of 27 as a colorless oil; [a]2D0ˆ195.18 (cˆ0.50,
CHCl3); IR (CHCl3): nˆ2984 cm21 (m), 1710 (s), 1597
1
154 (100), 137 (82); main product (cis-bromohydrin): H
NMR (400 MHz, CHCl3): dˆ1,57 (s, 9H, 11-H, 12-H,
13-H), 3.01 (d, Jˆ18 Hz, 1H, 7-H), 3.83 (d, Jˆ18 Hz, 1H,
7-H), 4.38 (m, 1H, 2-H), 4.97 (sbr, 1H, 1-H), 6.20 (d,
Jˆ10 Hz, 1H, 4-H), 6.97 (d, Jˆ10 Hz, 1H, 5-H);
13C-NMR (100 MHz, CDCl3): dˆ28.01 (C-11, C-12,
C-13), 37.73 (C-7), 57.27 (C-1), 75.03 (C-2), 84.27
(C-10), 89.83 (C-6), 127.55 (C-4), 147.84 (C-5), 152.38
(C-8), 158.83 (C-9), 188.25 (C-3); the spectroscopic data
were taken from the spectra of the mixtures; side product
(trans-bromohydrin): 1H NMR (400 MHz, CDCl3): dˆ1.56
(s, 9H, 11-H, 12-H, 13-H), 3.16 (d, Jˆ18 Hz, 1H, 7-H),
3.93 (d, Jˆ18 Hz, 1H, 7-H), 4.38 (m, 1H. 1-H), 4.50
(d, Jˆ12 Hz, 1H, 2-H), 6.20 (d, Jˆ10 Hz, 1H, 4-H), 6.70
(d, Jˆ10 Hz, 1H, 5-H); 13C NMR (100 MHz, CDCl3):
dˆ28.01 (C-11, C-12, C-13), 37.73 (C-7), 57.27 (C-1),
1
(m), 1269 (s), 1140 (m); H NMR (400 MHz, CDCl3):
dˆ1.58 (s, 9H, 11-H, 12-H, 13-H), 3.33 (d, Jˆ18 Hz, 1H,
7-H), 3.58 (dd, Jˆ2/3.5 Hz, 1H, 1-H), 3.68 (d, Jˆ18 Hz,
1H, 7-H), 3.76 (dd, Jˆ2.5/3.5 Hz, 1H, 2-H), 6.09 (dd,
Jˆ10.5/2 Hz, 1H, 4-H), 6.45 (dd, Jˆ2.5/10 Hz, 1H, 5-H);
13C NMR (100 MHz, CDCl3): dˆ28.01 (C-11, C-12, C-13),
44.20 (C-7), 53.55 (C-1), 57.29 (C-2), 83.40 (C-10), 84.48
(C-6), 128.30 (C-4), 141.24 (C-5), 152.79 (C-8), 158.66
(C-9), 191.27 (C-3); MS (1508C): m/z (%)ˆ266 (M11, 3),
251 (14), 209 (59), 192 (100), 164 (16), 123 (10); HRMS:
m/z for C13H15NO5 calcd: 265.0950, found: 265.0949.

4182
K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
75.03 (C-2), 84.33 (C-10), 88.36 (C-6), 127.55 (C-4),
147.84 (C-5), 153.44 (C-8), 158.71 (C-9), 188.84 (C-3);
the spectroscopic data were taken from the spectra of the
mixtures.
(61), 162 (32), 146 (50), 93 (100), 77 (36), 66 (83); HRMS:
m/z for C10H8NO5 calcd: 222.0402, found: 222.0406.
Bromoepoxide-tert-butylester 29b. To a solution of 27
(15 mg, 0.057 mmol) in dry dichloromethane (2 ml) was
added a solution of bromine in dry dichloromethane
(0.11 ml, 0.5 M, 0.057 mmol, 1 equiv.) at 08C. After 3 h
stirring at room temperature HuÈnig's base (4 drops) was
added. The solution was stirred for 30 min at room tempera-
ture and then the reaction was stopped by ¯ash chromato-
graphy. The yield was 18 mg (93%) of 29b as a yellow oil;
[a]D20ˆ172.18 (cˆ0.82, CHCl3); IR (CHCl3): nˆ2984 cm21
Epoxymethylester 30a. To a solution of bromohydrin 14
(50 mg, 0.165 mmol) in dichloromethane (5 ml) was added
a catalytic amount of DBU. The reaction mixture was
concentrated and chromatographic puri®cation yielded
33 mg (90%) of 30a as a white solid; [a]2D0ˆ275.58
(cˆ0.79CHCl3); melting pointˆ77.48C; IR (CHCl3):
nˆ3040 cm21 (w), 2956 (w), 2928 (w), 1728 (s), 1692
(s), 1596 (m), 1444 (m), 1372 (m), 1260 (s), 1228 (m),
1
(w), 1710 (s), 1599 (m), 1260 (m), 1142 (m); H NMR
1
1124 (m), 912 (m); H NMR (400 MHz, CDCl3): dˆ3.37
(400 MHz, CDCl3): dˆ1.58 (s, 9H, 11-H, 12-H, 13-H),
3.38 (d, Jˆ18 Hz, 1H, 7-H), 3.69 (d, Jˆ18 Hz, 1H, 7-H),
3.72 (d, Jˆ3.5 Hz, 1H, 2-H), 3.80 (dd, Jˆ3.5/2.5 Hz, 1H,
1-H), 6.39 (d, Jˆ2.5 Hz, 1H, 5-H); 13C NMR (100 MHz,
CDCl3): dˆ31.15 (C-11, C-12, C-13), 46.27 (C-7), 55.78
(C-1), 86.86 (C-10), 87.14 (C-6), 127.15 (C-4), 143.57
(C-5), 154.90 (C-8), 160.56 (C-9), 186.85 (C-3); MS
(1208C): m/z (%)ˆ364 (M119, 10), 362 (M119, 9), 345
(M1, 5), 343 (M1, 4), 330 (10), 328 (11), 289 (3), 287 (24),
272 (57), 270 (60), 244 (27), 242 (27), 149 (21), 84 (100);
HRMS: m/z for C9H14BrNO5 calcd: 269.9402, found:
269.9402.
(d, Jˆ18 Hz, 1H, 7-H), 3.59 (dd, Jˆ2/4 Hz, 1H, 1-H), 3.70±
3.77 (m, 2H, 2-H, 7-H), 3.95 (s, 3H, 10-H), 6.12 (dd, Jˆ2/
10 Hz, 1H, 4-H), 6.46 (dd, Jˆ3/10 Hz, 1H, 5-H); 13C NMR
(100 MHz, CDCl3): dˆ43.88 (C-7), 53.23 (C-10), 53.51
(C-1), 57.14 (C-2), 83.81 (C-6), 128.53 (C-4), 140.87
(C-5), 151.46 (C-8), 160.02 (C-9), 191.14 (C-3); MS
(908C): m/z (%)ˆ223 (M1, 49), 206 (10), 194 (29), 174
(11), 164 (17), 146 (37), 136 (24), 119 (20), 94 (100), 77
(26), 66 (53); HRMS: m/z for C10H9NO5 calcd: 223.0481,
found: 223.0484.
Epoxy carboxylic acid 30b. To a solution of 27 (16 mg,
0.060 mmol) in dichloromethane (0.75 ml) was added
tri¯uoroacetic acid (0.75 ml). After 2 h at room temperature
the reaction mixture was concentrated and 13 mg (quant.) of
acid 30b were obtained as a brown oil; [a]2D0ˆ199.78
(cˆ0.34, MeOH); IR (CHCl3): dˆ3494 cm21 (w), 2927
Bromoepoxy carboxylic acid 29c. To a solution of 29b
(18 mg, 0.052 mmol) in dichloromethane (1 ml) was
added tri¯uoroacetic acid (1 ml). After 2 h at room tempera-
ture the reaction mixture was concentrated and 15 mg
(quant.) of acid 29c were obtained as a brown oil;
[a]2D0ˆ171.48 (cˆ0.69, MeOH); 1H NMR (400 MHz,
acetone-d6): dˆ3.68 (d, Jˆ18 Hz, 1H, 7-H), 3.79 (d,
Jˆ18 Hz, 1H, 7-H), 3.89 (d, Jˆ3.5 Hz, 1H, 2-H), 4.14
(dd, Jˆ2.5/3.5 Hz, 1H, 1-H), 7.41 (d, Jˆ2.5 Hz, 1H, 5-H);
13C NMR (100 MHz, acetone-d6): dˆ44.22 (C-7), 54.18
(C-1), 58.04 (C-2), 86.17 (C-6), 124.37 (C-4), 143.82
(C-5), 153.51 (C-8), 160.93 (C-9), 186.23 (C-3); MS
(1508C): m/z (%): 289 (M1, 4), 287 (4), 205 (92), 177
(15), 175 (18), 123 (25), 121 (26); HRMS: m/z for
C9H6BrNO5 calcd: 286.9429, found: 286.9416.
1
(m), 1694 (s), 1599 (m), 1263 (m); H NMR (400 MHz,
acetone-d6): dˆ3.56 (d, Jˆ18 Hz, 1H, 7-H), 3.61 (dd,
Jˆ3.5/2 Hz, 1H, 2-H), 3.73 (d, Jˆ18 Hz, 1H, 7-H), 4.02
(dd, Jˆ2.5/3.5 Hz, 1H, 1-H), 6.10 (dd, Jˆ2/10 Hz, 1H, 4-
H), 6.80 (dd, Jˆ2.5/10 Hz, 1H, 5-H); 13C NMR (100 MHz,
acetone-d6): dˆ45.45 (C-7), 55.27 (C-1), 59.09 (C-2), 85.61
(C-6), 129.42 (C-4), 144.35 (C-5), 154.50 (C-8), 162.22 (C-
9), 193.85 (C-3); MS (1408C): m/z (%): 210 (M11, 2), 209
(M1, 13), 180 (7), 165 (10), 149 (16), 125 (38), 97 (100);
HRMS: m/z for C9H7NO5 calcd: 209.0324, found: 209.0324.
Bromoepoxymethylester 29a. To a solution of 30a (20 mg,
0.090) in dry dichloromethane (3 ml) was added a solution
of bromine in dry dichloromethane (0.21 ml, 0.5 M,
0.108 mmol, 1.2 equiv.) at 08C. After 1 h HuÈnig's base
(0.03 ml, 0.179 mmol, 2 equiv.) was added at 08C. The solu-
tion was stirred for 5 h at room temperature and then
extracted with methyl-tert-butyl ether. The organic layer
was washed with water, dried (MgSO4) and concentrated.
Puri®cation by ¯ash chromatography yielded 22 mg (83%)
of 29a as a yellow solid; [a]2D0ˆ202.88 (cˆ0.64, CHCl3);
melting pointˆ158.08C; IR (CHCl3): dˆ3040 cm21 (w),
2956 (w), 1728 (s), 1708 (s), 1596 (m), 1444 (m), 1376
Bromoepoxyamide 31. To a solution of acid 29c (25 mg,
0.087 mmol) in dry THF (2 ml) was added Staab's reagent
(14 mg, 0.087 mmol, 1 equiv.) at room temperature. The
solution was stirred for 10 min, then benzylamine (9 mg,
0.087 mmol, 1 equiv.) was added at room temperature.
After stirring the reaction mixture for 10 min, it was worked
up by puri®cation by ¯ash chromatography. In this way
19 mg (58%) of 31 were obtained as a yellow solid;
[a]2D0ˆ146.18 (cˆ0.64, CHCl3); melting pointˆ158.08C;
IR (CHCl3): dˆ3417 cm21 (m), 3043 (w), 2929 (w), 1707
(s), 1681 (s), 1602 (m), 1530 (s), 1340 (w), 1252 (m), 910
(m); UV (CHCl3): lmaxˆ280 nm; 1H NMR (400 MHz,
CDCl3): dˆ3.45 (d, Jˆ18 Hz, 7-H), 3.78 (m, 3H, 7-H,
2-H, 1-H), 4.55 (d, Jˆ6 Hz, 2H, 10-H), 6.91 (d, Jˆ2.5 Hz,
1H, 5-H), 6.94 (trbr, Jˆ7 Hz, 1H, NH), 7.35 (m, 5H, 11-H,
12-H, 13-H, 110-H, 120-H); 13C NMR (100 MHz, CDCl3):
dˆ43.46 (C-7), 43.79 (C-10), 53.37 (C-1), 57.16 (C-2),
85.05 (C-6), 125.04 (C-4), 127.97 (C-13, C-130), 128.04
(C-14), 128.95 (C-12, C-120), 136.94 (C-11), 141.35
(C-5), 153.98 (C-8), 158.14 (C-9), 184.80 (C-3); MS
(1608C): m/z (%): 378 (M1, 3), 376 (M1, 3), 344 (3), 341
1
(w), 1260 (s), 1140 (m), 908 (m); H NMR (200 MHz,
CDCl3): dˆ3.41 (d, Jˆ18 Hz, 1H, 7-H), 3.68±3.82 (m,
3H, 1-H, 2-H, 7-H), 3.95 (s, 3H, 10-H), 6.92 (dbr, Jˆ2 Hz,
1H, 5-H); 13C NMR (100 MHz, CDCl3): dˆ44.78 (C-7),
54.35 (C-10), 54.37 (C-1), 58.10 (C-2), 86.37 (C-6),
126.30 (C-4), 142.01 (C-5), 152.41 (C-8), 160.78 (C-9),
185.59 (C-3); MS (1108C): m/z (%)ˆ304 (M11, 5), 303
(M1, 35), 302 (M11, 6), 301 (M1, 41), 286 (14), 284
(12), 272 (32), 242 (43), 222 (48), 203 (45), 194 (75), 172

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4183
(3), 256 (1), 254 (2), 228 (2), 174 (17), 173 (15), 132 (14),
107 (88), 91 (100); HRMS: m/z for C16H13N2O4 calcd:
376.0059, found: 376.0060.
dichloromethane, 0.897 mmol, 1.3 equiv.) at 08C. After-
wards HuÈnig's base (0.15 ml, 0.897 mmol, 1.3 equiv.) and
TsCl (26 mg, 0.137 mmol, 0.2 equiv.) were added and the
reaction mixture was stirred for 10 min. Then cis-androster-
one (200 mg, 0.690 mmol) was added and the mixture was
stirred over night at room temperature. The reaction was
stopped with water, extracted with ethyl acetate, dried
(MgSO4) and chromatographic puri®cation yielded
Bromohydrinamide 32. To a solution of PPh3 (16 mg,
0.061 mmol, 1.2 equiv.) in dry dichloromethane (2 ml)
was added a solution of bromine in dry dichloromethane
(0.10 ml, 0.5 M, 0.051 mmol, 1.0 equiv.) at 08C. After
5 min at 08C 31 (19 mg, 0.051 mmol) was added. After
2 h at room temperature the reaction was stopped by ¯ash
chromatography. In this way 16 mg (70%) of 32 were
obtained as a yellow oil (diasteromeric mixture, trans:cis-
bromohydrinˆ93:7); IR (CHCl3): nˆ3593 cm21 (w), 3417
(m), 2928 (w), 1715 (s), 1678 (s), 1605 (m), 1531 (s), 1315
(w), 1258 (m), 910 (s), 792 (s); 13C NMR (100 MHz,
CDCl3): dˆ37.37 (C-7), 43.71 (C-10), 55.87 (C-1), 74.39
(C-2), 90.51 (C-6), 122.68 (C-4), 127.94 (C-13, C-130),
128.90 (C-12, C-120), 136.99 (C-11), 147.62 (C-5), 153.64
(C-8), 158.48 (C-9), 181.82 (C-3); MS (1908C): m/z (%):
460 (M1, 1), 458 (M1, 2), 456 (M1,1), 361 (7), 359 (6), 341
(1), 291 (2), 241 (3), 175 (17), 106 (100), 91 (97); HRMS:
m/z for C16H14Br2O4N2 calcd: 455.9320, found: 455.9322;
208 mg (70%) of 35a as
a white solid; melting
pointˆ136.78C; IR (CHCl3): nˆ2936 cm21 (m), 2852 (m),
1732 (s), 1464 (w), 1452 (w), 1372 (w), 1160 (w), 908 (m);
1H NMR (400 MHz, CDCl3): dˆ0.71 (dtr, Jˆ4/12 Hz, 1H),
0.86 (s, 3H, 18-H), 0.88 (s, 3H, 19-H), 0.94 (dd, Jˆ5/12 Hz,
1H), 1.10 (dd, Jˆ5/12 Hz, 1H), 1.05 (dtr, Jˆ4/14 Hz, 1H),
1.14±2.19 (m, 13H), 2.44 (ddd, Jˆ1/10/18 Hz, 1H, 16-H),
3.98±4.05 (m, symmetric, 1H, 3-H); 13C NMR (100 MHz,
CDCl3): dˆ12.28 (C-18), 13.80 (C-19), 20.31 (CH2), 21.73
(CH2), 28.09 (CH2), 30.72 (CH2), 31.48 (CH2), 31.48 (CH2),
34.06 (CH2), 34.92 (CH), 35.51 (C), 35.80 (CH2), 35.70
(CH2), 40.47 (CH2), 47.75 (C), 47.95 (CH), 51.12 (CH),
52.12 (CH), 54.32 (CH), 221 (C); MS (RT): m/z (%)ˆ354
(M1, 13), 352 (14), 310 (4), 295 (3), 273 (3), 217 (3), 107
(6), 69 (38); HRMS: m/z for C19H29BrO calcd: 352.1402,
found: 352.1404; elemental analysis: calcd: C: 64.59, H:
8.27; found: C: 64.96, H: 8.51.
1
main product (trans-bromohydrin): H NMR (400 MHz,
CDCl3): dˆ3.16 (d, Jˆ18 Hz, 1H, 7-H), 3.38 (d, Jˆ3 Hz,
1H, OH), 3.91 (d, Jˆ18 Hz, 1H 7-H), 4.32 (ddbr, Jˆ2/12 Hz,
1H, 1-H), 4.50 (dd, Jˆ6/15 Hz, 1H, 10-H), 4.56 (dd, Jˆ6/
15 Hz, 1H, 10-H), 4.58 (d, Jˆ12 Hz, 1H, 2-H), 6.39 (trbr,
Jˆ6 Hz, 1H, NH), 7.33 (m, 6H, 5-H, 12-H, 13-H, 14-H,
120-H, 130-H); the spectroscopic data were taken from the
spectra of the mixtures; side product (cis-bromohydrine): 1H
NMR (400 MHz, CDCl3): dˆ3.28 (d, Jˆ18 Hz, 1H, 7-H),
3.98 (d, Jˆ18 Hz, 1H, 7-H), 4.37 (sbr, 1H, 1-H), 4.53 (m,
3H, 10-H, 2-H), 7.11 (d, Jˆ1 Hz, 1H, 5-H), 7.33 (m, 5H,
12-H, 13-H, 14-H, 120-H, 130-H); the spectroscopic data
were taken from the spectra of the mixtures.
a-Androsteronebromide 35b. To a solution of PPh3
(415 mg, 1.59 mmol, 2.3 equiv.) in dry dichloromethane
(10 ml) was added a bromine solution (1.79 ml, 0.5 M in
dichloromethane, 0.897 mmol, 1.3 equiv.) at 08C. After-
wards HuÈnig's base (0.15 ml, 0.897 mmol, 1.3 equiv.) and
TsCl (26 mg, 0.137 mmol, 0.2 equiv.) were added and the
reaction mixture was stirred for 10 min. Then trans-andros-
terone (200 mg, 0.690 mmol) was added and the mixture
was stirred over night at room temperature. The reaction
was stopped with water, extracted with ethyl acetate, dried
(MgSO4) and chromatographic puri®cation yielded 225 mg
(93%) of 35b as a white solid; melting pointˆ168.08C; IR
(CHCl3): nˆ2932 cm21 (m), 2860 (m), 1732 (s), 1452 (m),
1368 (w), 1252 (m), 1052 (m), 1012 (m), 908 (m); 1H NMR
(400 MHz, CDCl3): dˆ0.81 (s, 3H, 18-H), 0.86 (s, 3H,
19-H), 0.88±1.99 (m, 16H), 2.08 (dtr, Jˆ9/18 Hz, 1H,
16-H), 2.41 (dd, Jˆ8/18 Hz, 1H, 16-H), 4.73 (q, Jˆ3 Hz,
1H, 3-H); 13C NMR (100 MHz, CDCl3): dˆ12.33 (C-18),
13.83 (C-19), 20.05 (CH2), 21.73 (CH2), 27.57 (CH2), 30.63
(CH2), 30.94 (CH2), 31.51 (CH2), 32.85 (CH2), 34.99 (CH),
35.82 (CH2), 36.39 (C), 37.22 (CH2), 40.16 (CH), 47.77 (C),
51.42 (CH), 53.98 (CH), 55.59 (CH), 221.17 (C); MS
(1308C): m/z (%)ˆ355 (M11, 23), 354 M1, 95), 353
(M11, 24), 352 (M1, 100), 319 (12), 310 (30), 296 (24),
282 (20), 218 (35), 164 (10), 147 (13), 123 (20), 121 (19), 97
(26), 95 (20), 93 (30), 81 (24); HRMS: m/z for C19H29BrO
calcd: 352.1402, found: 352.1401; elemental analysis:
calcd: C: 64.59, H: 8.27; found: C: 64.83, H 8.27.
Mentholbromide 34. To a solution of PPh3 (738 mg,
2.821 mmol, 2.2 equiv.) in dry dichloromethane (10 ml)
was added a bromine solution (3.33 ml, 0.5 M in dichloro-
methane, 1.67 mmol, 1.3 equiv.) at 08C. Afterwards NEt3
(0.23 ml, 1.67 mmol, 1.3 equiv.) and TsCl (49 mg,
0.256 mmol, 0.2 equiv.) were added and the reaction
mixture was stirred for 10 min. Then menthol (200 mg,
1.282 mmol) was added and the mixture was stirred for
1.5 h at room temperature. The reaction was stopped with
water, extracted with ethyl acetate, dried (MgSO4) and chro-
matographic puri®cation yielded 479 mg (86%) of 34 as a
colorless oil; IR (CHCl3): nˆ2948 cm21 (s), 2924 (s), 2868
(m), 2844 (m), 1480 (w), 1456 (m), 1384 (w), 1368 (w),
1272 (m), 1228 (m), 1188 (m); 1H NMR (400 MHz, CDCl3):
dˆ0.78 (m, 1H), 0.89 (d, Jˆ7 Hz, 3H, 10-H), 0.92 (sbr, 3H,
8-H), 0.93 (sbr, 3H, 9-H), 1.31±1,59 (m, 3H), 1.70±1.79 (m,
symmetric, 2H), 1.90±2.02 (m, 1H), 2.16 (dq, Jˆ4/14 Hz,
1H), 4.65±4.69 (m, 1H, 1-H); 13C NMR (100 MHz, CDCl3):
dˆ20.09/20.66/27.78 (CH3), 25.08 (CH2), 26.79 (CH),
31.39 (CH), 34.85 (CH2), 43.94 (CH2), 49.27 (CH), 60.65
(C-1); MS (RT): m/z (%)ˆ139 (M-Br, 81), 123 (13), 109
(3), 95 (51), 83 (100), 81 (41), 69 (36); HRMS: m/z for
C10H19 calcd: 139.1487, found: 139.1487.
Protected bromodiolmethylester. To a solution of 17
(200 mg, 0.557 mmol) in dry dichloromethane (4 ml) was
added a solution of bromine in dry dichloromethane (1.1 ml,
0.5 M, 0.557 mmol, 1 equiv.) at 08C. After 1 h stirring at
08C Et3N (24 mg, 0.244 mmol, 4 equiv.) was added. The
solution was stirred for 3 h at room temperature and then
the reaction was stopped with water, extracted with methyl-
tert-butyl ether and dried (MgSO4). Puri®cation by ¯ash
b-Androsteronebromide 35a. To a solution of PPh3
(415 mg, 1.59 mmol, 2.3 equiv.) in dry dichloromethane
(10 ml) was added a bromine solution (1.79 ml, 0.5 M in

4184
K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
chromatography yielded 217 mg (89%) of the protected
bromodiolmethylester as a yellow foam; IR (CHCl3):
nˆ3040 cm21 (w), 2956 (w), 2932 (w), 2856 (w), 1728
(s), 1612 (m), 1516 (m), 1444 (m), 1376 (w), 1252 (s),
1096 (m), 908 (m); H NMR (400 MHz, CDCl3): dˆ3.30/
(100 MHz, CDCl3): dˆ37.28 (C-7), 53.27 (C-10), 55.56
(C-2), 74.45 (C-1), 90.80 (C-6), 123.01 (C-4), 147.29 (C-
5), 152.11 (C-8), 159.97 (C-9), 181.72 (C-3); the spectro-
scopic data were taken from the spectra of the mixtures;
side product (trans-bromohydrin): 1H NMR (400 MHz,
CDCl3): dˆ3.26 (d, Jˆ18 Hz, 1H, 7-H), 3.93 (s, 3H,
10-H), 3.97 (d, Jˆ18 Hz, 1H, 7-H), 4.44 (sbr, 1H, 1-H),
5.12 (d, Jˆ3 Hz, 1H, 2-H), 7.14 (d, Jˆ1 Hz, 1H, 5-H);
13C NMR (100 MHz, CDCl3): dˆ47.67 (C-7), 53.23
(C-10), 55.56 (C-2), 74.44 (C-1), 89.92 (C-6), 124.37
(C-4), 143.89 (C-5), 151.03 (C-8), 159.94 (C-9), 182.12
(C-3); the spectroscopic dates were taken from the
spectra of the mixtures.
1
3.32 (d, Jˆ18 Hz, 1H, 7-H), 3.77±3.95 (m, 7-H, 16-H,
10-H), 4.52/4.61 (dd, Jˆ2/5 Hz, 1H, 1-H), 4.82/4.97 (d,
Jˆ5 Hz, 1H, 2-H), 5.95/5.96 (s, 1H, 11-H), 6.86±6.93 (m,
2H, 14-H, 140-H), 7.19 (d, Jˆ2 Hz, 1H, 5-H), 7.24/7.35 (d,
Jˆ9 Hz, 1H, 13-H, 130-H); 13C NMR (100 MHz, CDCl3):
dˆ40.84/40.93 (C-7), 51.26 (C-16), 53.31/53.32 (C-10),
72.24/73.64 (C-1), 74.56/76.33 (C-2), 83.81/84.01 (C-6),
102.02/103.37 (C-11), 111.88/111.93 (C-14, C-140), 125.04/
126.71 (C-12), 125.63/126.17 (C-13, C-130), 141.37/142.13
(C-5), 149.60/149.71 (C-15), 157.87 (C-8), 158.70/158.92
(C-9); FAB-MS: m/z (%)ˆ462 (M123, 6), 460
(M123, 6), 429 (7), 401 (16), 355 (20), 341 (23),
325 (27), 281 (84), 267 (31), 249 (17), 221 (81), 207
(100), 191 (33), 176 (13).
Diolbenzylamide 39. To a solution of acid 25 (15 mg,
0.044 mmol) in dry THF (3 ml) was added Staab's reagent
(7 mg, 0.044 mmol, 1 equiv.) at room temperature. The
solution was stirred for 10 min, then benzylamine (5 mg,
0.047 mmol, 1.1 equiv.) was added at room temperature.
After stirring the reaction mixture for 1 h, it was worked
up by puri®cation by ¯ash chromatography. In this way
7 mg (50%) of 39 were obtained as a brown oil;
[a]D20ˆ71.58 (cˆ0.38, CHCl3); IR (CHCl3): nˆ3580 cm21
(w), 3504 (w), 3416 (m), 3064 (w), 3040 (w), 2928 (w),
1700 (s), 1680 (s), 1600 (m), 1528 (s), 1252 (m), 1128
(m), 1108 (m), 908 (m); 1H NMR (400 MHz, CDCl3):
dˆ3.23 (d, Jˆ18 Hz, 1H, 7-H), 3.89 (d, Jˆ18 Hz, 1H,
7-H), 4.21 (tr, Jˆ2.5 Hz, 1H, 1-H), 4.54 (dd, Jˆ2/6 Hz,
2H, 10-H), 4.63 (d, Jˆ3 Hz, 1H, 2-H), 6.24 (d, Jˆ10 Hz,
1H, 4-H), 6.59 (dd, Jˆ2/10 Hz, 1H, 5-H), 6.98 (tr, Jˆ6 Hz,
1H, NH), 7.27±7.39 (m, 5H, 12-H, 120-H, 13-H, 130-H,
14-H); 13C NMR (100 MHz, CDCl3): dˆ42.66 (C-10),
43.66 (C-7), 73.02 (C-1), 73.07 (C-2), 87.45 (C-6), 127.91
(C-14), 127.92 (C-13, C-130), 128.87 (C-12, C-120), 129.01
(C-4), 137.10 (C-11), 143.40 (C-5), 154.26 (C-8), 158.85
(C-9), 197.15 (C-3); MS (1508C): m/z (%)ˆ316 (M1, 6),
256 (3), 175 (15), 160 (6), 106 (71), 91 (100); HRMS: m/z
for C16H16N2O5 calcd: 316.1059, found: 316.1057.
Bromodiolmethylester 36. To a solution of protected
bromodiolmethylester (19 mg, 0.043 mmol) in aq. acetone
(3 ml) was added a catalytic amount of 2 N aq. H2SO4 at
room temperature. After 4 h the reaction was stopped with
NaHCO3. The reaction mixture was concentrated and after-
wards water was added. The aqueous phase was extracted
with ethyl acetate. The combined organic layers were dried
(MgSO4) and concentrated. Chromatographic pruri®cation
yielded 9 mg (65%) of 36 as a yellow foam; [a]2D0ˆ132.58
(cˆ0.28, CHCl3); IR (CHCl3): nˆ3576 cm21 (w), 3524 (w),
2956 (w), 2928 (w), 2856 (w), 1732 (s), 1596 (w), 1444 (m),
1376 (m), 1296 (m), 1252 (s), 1128 (m), 1112 (m); 1H NMR
(400 MHz, CDCl3): dˆ2.83 (d, Jˆ2 Hz, 1H, OH), 3.29 (d,
Jˆ18 Hz, 1H, 6-H), 3.66 (d, Jˆ2 Hz, 1H, OH), 3.90 (d,
Jˆ18 Hz, 1H, 7-H), 3.99 (s, 3H, 10-H), 4.28±4.32 (m,
1H, 1-H), 4.81±4.85 (m, 1H, 2-H), 7.08 (d, Jˆ2 Hz, 1H,
5-H); 13C NMR (100 MHz, CDCl3): dˆ42.66 (C-7), 53.22
(C-10), 73.03 (C-1), 73.57 (C-2), 88.49 (C-6), 124.77 (C-4),
143.22 (C-5), 160.56 (C-9), 191.05 (C-3); MS (1308C): m/z
(%)ˆ7.13 (M1, 6), 319 (M1, 7), 290 (13), 259 (14), 244
(12), 216 (20), 202 (19), 176 (91), 174 (100), 152 (12), 124
(12), 99 (23), 78 (19), 69 (37).
Bisamide 40. To a solution of acid 30b (20 mg,
0.096 mmol, 3 equiv.) in DMSO (0.3 ml) was added Staab's
reagent (16 mg, 0.096 mmol, 3 equiv.) at room temperature.
The solution was stirred for 5 min, then a solution of a,a0-
diamino-p-xylene (4.3 mg, 0.087 mmol, 1 equiv.) in DMSO
(0.1 ml) was added at room temperature. After stirring the
reaction mixture for 1.5 h, it was quenched with brine,
extracted with ethyl acetate and dried (MgSO4). Puri®cation
by ¯ash chromatography yielded 5 mg (30%) of 40 as a
white solid; [a]2D0ˆ151.38 (cˆ0.21, CHCl3); IR (CHCl3):
nˆ3418 cm21 (w), 2999 (w), 2928 (m), 1686 (s), 1601
Bromohydrinmethylester 38. To a solution of PPh3
(25 mg, 0.095 mmol, 1.5 equiv.) in dry dichloromethane
(2 ml) was added a solution of bromine in dry dichloro-
methane (0.13 ml, 0.5 M, 0.063 mmol, 1.0 equiv.) at 08C.
After 5 min at 08C 36 (19 mg, 0.063 mmol) was added.
After 2 h at room temperature the reaction was stopped
with water, extracted with ethyl acetate and dried
(MgSO4). Puri®cation by ¯ash chromatography yielded
23 mg (96%) of 38 as a yellow oil (diastereomeric mixture,
trans:cis-bromohydrinˆ1:2); IR (CHCl3): nˆ3584 cm21
(w), 3040 (w), 2956 (w), 2928 (w), 1728 (s), 1600 (m),
1444 (m), 1376 (m), 1260 (s), 1128 (m), 908 (s); MS (rt):
m/z (%)ˆ305 (M-78, 5), 303 (M-78, 4), 281 (4), 271 (10),
261 (3), 242 (3), 222 (8), 212 (4), 176 (3), 149 (4), 99 (10),
85 (68), 83 (100), 77 (7); HRMS: m/z for C10H10NO5Br
calcd: 302.9743, found: 302.9745; main product (cis-
1
(m), 1530 (m), 1259 (m), 1230 (m), 1015 (w), 830 (w); H
NMR (400 MHz, acetone-d6): dˆ3.55 (d, Jˆ18 Hz, 1H,
7-H), 3.59 (dd, Jˆ2/3.5 Hz, 1H, 1-H), 3.72 (d, Jˆ18 Hz,
1H, 7-H), 4.00 (d, Jˆ2.5/3.5 Hz, 1H, 2-H), 4.50 (d,
Jˆ6.5 Hz, 2H, 10-H), 6.08 (dd, Jˆ2/10.5 Hz, 1H, 4-H),
6.80 (dd, Jˆ2.5/10 Hz, 1H, 5-H), 7.34 (s, 2H, 12-H, 120-
H); 13C NMR (100 MHz, actone-d6): dˆ43.31 (C-10), 44.50
(C-7), 54.17 (C-1), 58.06 (C-2), 83.77/83.78 (C-6), 128.20
(C-4), 128.74/128.75 (C-12, C-120), 138.85/138.86 (C-11),
143.53 (C-5), 155.52 (C-8), 159.61 (C-9), 192.84 (C-3);
FAB-MS: m/z (%)ˆ541 (M123, 10), 519 (M11, 16), 460
(17), 413 (28), 392 (31), 391 (100), 329 (44), 307 (98), 289
(55), 259 (66), 241 (17).
1
bromohydrine): H NMR (400 MHz, CDCl3): dˆ3.12 (d,
Jˆ18 Hz, 1H, 7-H), 3.87 (d, Jˆ18 Hz, 1H, 7-H), 3.92 (s,
3H, 10-H), 4.37 (dd, Jˆ3/12 Hz, 1H, 1-H), 4.56 (d,
Jˆ12 Hz, 1H, 2-H), 7.41 (s, 1H, 5-H); 13C NMR

K. Goldenstein et al. / Tetrahedron 56 (2000) 4173±4185
4185
New York, London, 1998; p 379. (d) Ebel, R. Dissertation,
University of WuÈrzburg, 1998.
Acknowledgements
11. Teeyapant, R.; Woerdenbag, H. J.; Kreis, P.; Hacker, L.;
Wray, V.; Witte, L.; Proksch, P. Z. Naturforsch. C 1993, 48, 939.
12. Roney, P. R. J. Am. Chem. Soc. 1969, 91, 6090.
13. Staab, A. H.; LuÈcking, M.; DuÈrr, F. H. Chem. Ber. 1962, 95,
1275.
The project described here was supported by the Graduier-
tencolleg ªChemische und technische Grundlagen der
Naturstofftransformationº (GRK 223/2-96) at Hannover
University. Thanks are due to the Deutsche Forschungs-
gemeinschaft for this grant.
14. (a) Shing, T. K. M.; Tai, V. W.-F.; Tam, E. K. W. Angew.
Chem. 1994, 106, 2408; Angew Chem. Int. Ed. Engl. 1994, 33,
2312. (b) Shing, T. K. M.; Tai, V. W.-F.; Chung, I. H. F.; Jiang,
Q. Chem. Eur. J. 1996, 2, 50.
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