The application of dimethyldioxirane for the selective oxidation of polyfunctional steroids

Article abstract of DOI:10.1016/S0009-3084(00)00209-7

Oxidation and epoxidation reactions of a series of structurally different steroids related to methyl 5β-cholanoates having hydroxyl groups and/or double bonds by treatment with dimethyldioxirane (DMDO) are described. Steroidal alcohols, olefines, and unsaturated alcohols and conjugated enones with DMDO were transformed into ketones, epoxides, and epoxy-ketones, respectively, in good isolated yields. The regio- and stereoselectivities for DMDO reaction differing from those observed for organic peracids, tert-butyl hydroperoxide and alkaline hydrogen peroxide are also discussed.

Full text of DOI:10.1016/S0009-3084(00)00209-7

Chemistry and Physics of Lipids
109 (2001) 135–143
www.elsevier.com/locate/chemphyslip
The application of dimethyldioxirane for the selective
oxidation of polyfunctional steroids
Tomoaki Sasaki a, Ryusei Nakamori a, Takeru Yamaguchi a, Yuka Kasuga a,
Takashi Iida a,*, Toshio Nambara b
a Department of Chemistry, College of Humanities and Sciences, Nihon Uni6ersity, Setagaya, Sakurajousui,
Tokyo 156-8550, Japan
b Hoshi Uni6ersity, Shinagawa, Ebara, Tokyo 147-8501, Japan
Received 12 May 2000; received in revised form 19 September 2000; accepted 19 September 2000
Abstract
Oxidation and epoxidation reactions of a series of structurally different steroids related to methyl 5b-cholanoates
having hydroxyl groups and/or double bonds by treatment with dimethyldioxirane (DMDO) are described. Steroidal
alcohols, olefines, and unsaturated alcohols and conjugated enones with DMDO were transformed into ketones,
epoxides, and epoxy-ketones, respectively, in good isolated yields. The regio- and stereoselectivities for DMDO
reaction differing from those observed for organic peracids, tert-butyl hydroperoxide and alkaline hydrogen peroxide
are also discussed. © 2001 Elsevier Science Ireland Ltd. All rights reserved.
Keywords: Dimethyldioxirane; Oxidation; Epoxidation; Steroidal alcohol; Unsaturated steroid; Steroidal conjugated enone; Regiose-
lectivity; Stereoselectivity
secondary alcohols to ketones, alkenes to epox-
ides, amines to nitro compounds, sulfides to sul-
fones or sulfoxides, and tertiary carbon atoms to
tertiary alcohols have been known (Murray and
Jeyaraman, 1985; Adam et al., 1991; Singh and
Murray, 1992), a further detailed and potential
abilities of DMDO in organic syntheses remain
still unclear. The major reason may be ascribed to
its treatment and commercial unavailability, since
the generation and stability of DMDO are some-
what troublesome which limits the wide applica-
tion of the reagent for routine synthetic work.
However, DMDO as an oxidant on various sub-
strates appears to be also attractive from the
1. Introduction
Recently, two groups of investigators (Curci et
al., 1995; Murray, 1989) have reviewed the char-
acteristics and usefulness of a new class of power-
ful oxidants and/or oxygen-transfer reagents,
dimethyldioxirane (DMDO) and its some analogs,
in organic syntheses. Despite a variety of versatile
reactivities and chemical transformations such re-
actions as primary alcohols to carboxylic acids,
* Corresponding author. Tel.: +81-3-33291151; fax: +81-
3-33039899.
E-mail address: takaiida@chem.chs.nihon-u.ac.jp (T. Iida).
0009-3084/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved.
PII: S0009-3084(00)00209-7

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T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
viewpoint of so-called ‘green chemistry’ (Fernan-
dez-Escobar et al., 1998), because it consists of
only carbon, hydrogen and oxygen atoms, and
without any toxic and hazardous heavy metals
such as chromium (VI) or lead, and decomposed
to methyl acetate in a relatively short period of
time at room temperature (Singh and Murray,
1992).
Table 1 (Continued)
As part of our ongoing programme of synthesis
of biologically and physiologically important
steroids and related compounds, we were inter-
ested in efficient utilization and development of
the unique oxidant for a convenient preparation
of synthetically useful key intermediates. To our
knowledge, reaction of polyfunctional steroids
with DMDO has not yet been reported systemati-
cally. We describe here the reactivity and chemical
Table 1
Reactions of polyfunctional methyl 5b-cholonates with
DMDO
transformations of DMDO towards a wide vari-
ety of structurally different steroids related to
methyl 5b-cholanoates having hydroxyl and/or
oxo functions as well as double bonds in the
steroid nucleus.
2. Results and discussion
The experimental procedure is very simple.
Thus a mixture of steroid (1.0 mmol) and a
concentrated DMDO (2.0 mmol) solution in
CHCl3 (see Experimental section) was allowed to
stand at room temperature for a certain period of
time (0.5–6 h), until completion of the reaction
(monitored by TLC). The subsequent work-up
procedure was also especially easy: after the reac-
tion, an excess amount of DMDO and the solvent
were evaporated and the residue was purified by a
direct crystallization or by passing through a
column of silica gel.
Our preliminary experiment revealed that vari-

T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
137
ous alkali- and acid-sensitive functional and pro-
tecting groups are essentially inert under the mild
and neutral experimental conditions used in this
study. So far examined, formyl, acetyl, methane-
sulfonyl, p-toluenesulfonyl, and carbethoxy
groups, tetrahydropyranyl and t-butyldimethylsi-
lyl ethers, dimethylacetal, and methyl ester proved
to be completely stable on exposure to a DMDO
solution.
monooxidized a-hydroxy-ketones (30 and 31) in
good isolated yields (69–73%) without oxidative
glycol cleavage of the C1–C2 bond.
In contrast to the conventionally employed
epoxidizing reagents of simple alkenes with or-
ganic peracids (e.g. m-chloroperbenzoic acid)
(Matthews and Hassner, 1972), allylic alcohols
with tert-butyl hydroperoxide (TBHP) (Sharpless
and Michaelson, 1973) or conjugated enones with
alkaline hydrogen peroxide (e.g. H2O2–NaOH)
(Matthews and Hassner, 1972), DMDO epoxi-
dized all of the three variants of the double bonds
regio- and stereoselectively without any difficulty.
The observations show that uncojugated and con-
jugated carbon–carbon double bonds as well as
homoallylic and allylic alcohols succeed to react
with DMDO. Thus, DMDO reaction of unsatu-
rated steroidal alcohols caused simultaneous oxi-
dation–epoxidation of both the hydroxyl group
and double bond in the same molecules, resulting
in the formation of the corresponding epoxy-ke-
tones in one-step. Assignment of the stereochem-
istry to the epoxides was determined on the basis
The results are shown in Table 1, together with
the structures of compounds examined and their
major isolated reaction products. Irrespective of
the position and stereochemical configuration of
secondary hydroxyl groups in the 5b-steroid nu-
cleus, DMDO oxidized rapidly (0.5–1 h) isolated
hydroxyls at the 3a-, 3b-, 6a-, 6b-, 7a-, and
7b-positions in saturated methyl 5b-cholanoates
(1–6) to afford the corresponding ketones (24–
26) in excellent isolated yields (80–90%). On the
other hand, when 12a-hydroxylated compounds
(7 and 8) were subjected to the DMDO reaction
for 0.5 h, the sole isolated products were the
corresponding 12a-hydroxy-ketones (27 and 29);
the prolonged exposure (6 h) of 7 to a DMDO
solution resulted in the formation of the com-
pletely oxidized ketones (28). Since the regiospe-
cificity of DMDO on steroid molecules differs
from those observed for other oxidizing agents
such as chromic acid, chromium VI oxide–pyri-
dine complexes (e.g. pyridinium chlorochromate),
manganese IV oxide or silver carbonate (Car-
ruthers, 1986; Tserng, 1978), DMDO is, therefore,
usefully utilized as an alternative site-selective oxi-
dizing agent in steroid syntheses.
Of further interest was that under a strictly
neutral experimental condition, treatment of
methyl 3,6-dihydroxy-5b-cholanoates (3 and 4)
with DMDO brought about the formation of
allomerized 3,6-dioxo 5a-compound (25), as evi-
denced by 13C-NMR (see Experimental section).
The unexpected observation can be interpreted as
a result of enolization from C-5 of intermediary
6-oxo-5b-steroids (A/B-cis) to the more stable
5a-isomers (A/B-trans) (Haslewood, 1967). In ad-
dition, when methyl 5b-cholanoates having a vici-
nal cis glycol structure (9 and 10) were subjected
to the DMDO reaction, only an axially-oriented
hydroxyl group was oxidized preferentially to give
1
of the H- and/or 13C-NMR signals in compari-
son with those of analogous steroids reported
previously (Cross, 1962; Tori et al., 1964; Mi-
hailovic et al., 1969; Glotter et al., 1970; Holland
et al., 1982).
Oxidation of 5b-steroidal 3-ene (11) and 14-ene
(12) with DMDO afforded exclusively the corre-
sponding 3b,4b- and 14a,15a-epoxides (32 and
33), respectively, indicating that the reagent at-
tacks the less hindered b-face of the ring A and
the a-face of the rings B, C and D in the cis-fused
5b-steroid molecules, in analogy with those ob-
served for organic peracid epoxidation (Matthews
and Hassner, 1972). Treatment of 6-en-3b-ol (13)
with DMDO lead to the formation of the 6a,7a-
epoxy-3-ketone (34) in one-step and in a good
yield (72%), while that of homoallylic 5-en-3b-ol
(14) produced a mixture of the 5a,6a- and 5b,6b-
epoxy-3-ketones (35 and 36) in the ratio of ca. 3:1
1
(evidenced by H-NMR). Furthermore, allylic 4-
en-3a-ol (15) was transformed directly into the
4a,5a-epoxy-3-ketone (37) in 58% isolated yield.
According to the previous findings with organic
peracids or TBHP (Henbest and Wilson, 1957;
Sharpless and Michaelson, 1973), epoxidation of

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T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
cyclic allylic alcohols occurs principally cis to
the hydroxyl and yields the corresponding syn-
epoxy-alcohols via a hydrogen-bonded transition
state. This generalization was consistent with the
present result with DMDO, though the hydroxyl
function was oxidized simultaneously. A similar
result was also obtained in the epoxidation of
4b-hydroxycholesterol by the dioxirane interme-
diate generated in the reaction of potassium
caroate with acetone to give a ca. 3:1 mixture of
the 5b,6b-and 5a,6a-epoxides (Cicala et al.,
1982).
unsaturated monoepoxy-ketones site-selectively.
In the case of 1,4-diene-3-ketones (19 and 20),
epoxidation with DMDO for 2 h gave only the
corresponding unsaturated 4a,5a-epoxy-3-ke-
tones (40 and 41) in good yields (71–76%); on
the other hand, prolonged treatment of
analogous cholest-1,4-dien-3-one with perbenzoic
acid in refluxing benzene yielded the 4b,5b-
epoxycholest-1-en-3-one (Burgess, 1962) in a low
yield; in addition, 21-acetoxy-17a-hydroxy-1,4-
pregnadiene-3,11,12-trione with DMDO has
been converted to the corresponding 1a,2a-epox-
ide, probably owing to the steric effect of 19-
methyl and a dipole interaction with the C-11
carbonyl (Bovicelli, et al., 1992).
It has been also previously found that oxida-
tion of methyl 3-oxochola-1,4,6-trien-24-oate
(22) with alkaline hydrogen peroxide yields
methyl 1a,2a-epoxy-3-oxochola-4,6-dien-24-oate
as the major product, in which the double bond
nearest to the C-3 carbonyl function is epoxi-
dized (Herz and Ocampo, 1982). With DMDO,
however, the 6,7-double bond of analogous 12a-
formyloxy-3-oxochola-4,6-dien-24-oic acid (21)
and compound 22, which is more remote from
the C-3 carbonyl function than the other double
bonds, was epoxidized first, to give the respec-
tive unsaturated 6a,7a-epoxy-3-ketones (42 and
43) preferentially. The observed difference be-
tween DMDO and alkaline hydrogen peroxide
epoxidations can be rationally interpreted in
terms of the electrophilicity of DMDO, in anal-
ogy with organic peracids (Matthews and Hass-
ner, 1972), since the 6,7-double bond should be
more electron rich than the 1,2- or 4,6-double
bond and therefore susceptible to electrophilic
attack of DMDO (Cicala et al., 1982). An an-
other interesting result observed was that when
methyl 3-methoxychola-3,5-dien-24-oate (23) was
subjected to the DMDO reaction, the 4a,5a-ep-
oxy-3-ketone (37) is isolated in a reasonable
yield (44%).
Traditionally, alkaline hydrogen peroxide has
long been used as a sole epoxidizing agent of
a,b-unsaturated ketones to the corresponding
epoxy-ketones, which involves nucleophilic at-
tack of hydroperoxide ion on the conjugated
double bond, as opposed to the electrophilic ad-
dition mechanism of organic peracids on an iso-
lated carbon–carbon double bond (Matthews
and Hassner, 1972); recently, TBHP in the pres-
ence of lithium hydroxide has also been em-
ployed for the purpose (Holland et al., 1982).
The alkaline peroxide epoxidations are, however,
unsuitable for conjugated enones possessing al-
kali-sensitive functional and protecting groups
such as esters or ketols in the same molecules.
The use of DMDO eliminates such a drawback,
because those groups are insensitive to a neutral
DMDO epoxidizing condition. In fact, epoxida-
tion of conjugated 4-en-3-one (17) and 3b-ace-
toxy-5-en-7-one esters (18) with DMDO
produced the corresponding a-epoxides (37 and
39) stereoselectively without simultaneous hy-
drolysis of C-24 ester and C-3 acetoxy group,
whereas that of 1-en-3-one ester (16) in the nor-
mal cis 5b-series afforded the b-epoxide (38)
predominantly. It is also worth noting here to
compare the stereoselectivity of the DMDO with
that of alkaline peroxides: thus, 17 and its
analogous steroidal 4-en-3-ones are usually oxi-
dized to the corresponding 3-oxo-4b,5b-epoxides
predominantly with alkaline peroxides (Holland,
et al., 1982; Henbest and Jackson, 1967); the
reverse was true with DMDO.
Since the regio- and stereoselectivities of
DMDO often differ from those of organic
peracids, TBHP, and/or alkaline hydrogen per-
oxide, DMDO is of particular importance for
preparing useful key intermediates and may en-
try a new class of versatile oxidizing and/or
When serial conjugated double bonds are
present in steroidal ketones, a specific double
bond was oxidized first by DMDO to afford

T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
139
oxygen-transfer reagents in the synthesis of bioac-
tive steroids.
methoxychola-3,5-dien-24-oate (23). Almost all of
the steroid samples were from our laboratory
collection.
3. Materials and methods
3.1. Preparation of DMDO in CHCl3 solution
Melting points (m.p.) were determined on an
electric micro hot stage and are uncorrected. In-
frared (IR) spectra were obtained on a Bio Rad
FTS-7 FT-IR spectrometer (Philadelphia) as KBr
tablets. Proton nuclear magnetic resonance (1H-
NMR) spectra were obtained on a JEOL JNM-
EX270 FT NMR instrument (Tokyo, Japan) with
CDCl3 containing 0.1% Me4Si as the solvent;
chemical shifts are expressed in d ppm relative to
Me4Si. Mass spectra (MS) were recorded on a
JEOL JMC-Automass 150 gas chromatograph-
mass spectrometer at 70 eV. Thin-layer chro-
DMDO was generated by the reaction of ox-
one® and acetone in the presence of sodium hy-
drogen carbonate and recovered as an acetone
solution, according to the literature method de-
scribed in detail (Murray, 1989; Adam et al.,
1991; Singh and Murray, 1992). The DMDO so-
lution in acetone was then concentrated by ex-
tracting with an approximate amount of CHCl3
(Cerre et al., 1997). The concentration of the
resulting DMDO solution in CHCl3 thus obtained
was determined by iodometric titration (Adam et
al., 1987).
matography (TLC) was performed on
a
pre-coated silica gel 60 plate (Merck, Darmstadt,
Germany) using hexane-ethyl acetate (EtOAc) or
hexane-EtOAc-acetic acid mixtures as the devel-
oping solvents.
3.2. General procedure for the oxidation by
DMDO
Monopersulfate compound (2KHSO5·KHSO4
·K2SO4; oxone®) was available from Aldrich, Mil-
waukee, WI. The following 23 bile acid methyl
esters or free acids were used as substrates: methyl
3a-hydroxy-5b-cholan-24-oate (1); methyl 3b-hy-
droxy-5b-cholan-24-oate (2); methyl 3a,6a-dihy-
droxy-5b-cholan-24-oate (3); methyl 3a,6b-dihyd-
roxy-5b-cholan-24-oate (4); methyl 3a,7a-dihy-
droxy-5b-cholan-24-oate (5); methyl 3a,7b-dihy-
droxy-5b-cholan-24-oate (6); methyl 3a,12a-dihy-
droxy-5b-cholan-24-oate (7); methyl 3a,7a,12a-
trihydroxy-5b-cholan-24-oate (8); methyl 3b,4b,-
dihydroxy-5b-cholan-24-oate (9); methyl 3a,6a,
7a-trihydroxy-5b-cholan-24-oate (10); methyl 5b-
chol-3-en-24-oate (11); methyl 3a-cathyloxy-5b-
chol-14-en-24-oate (12); methyl 3b-hydroxy-5b-
chol-6-en-24-oate (13); methyl 3b-hydroxychol-5-
en-24-oate (14); methyl 3a-hydroxychol-4-en-24-
oate (15); methyl 3-oxo-5b-chol-1-en-24-oate (16);
methyl 3-oxochol-4-en-24-oate (17); methyl 3b-
acetoxy-7-oxochol-5-en-24-oate (18); methyl 3-ox-
ochola-1,4-dien-24-oate (19); methyl 7a,12a-diace-
toxy-3-oxochola-1,4-dien-24-oate (20); 12a-formy-
loxy-3-oxochola-4,6-dien-24-oic acid (21); methyl
3-oxochola-1,4,6-trien-24-oate (22); methyl 3-
To a solution of steroid (1 mmol) in CH2Cl2 (10
ml) was added a freshly prepared solution of
DMDO (0.20 M, 10 ml; 2 mmol) in CHCl3, and
the mixture was allowed to stand at room temper-
ature for a certain period of times, until comple-
tion of the reaction (monitored by TLC). After
the reaction, an excess amount of DMDO and
solvents were evaporated under a reduced pres-
sure and the residue was crystallized directly from
an appropriate solvent. Otherwise, the reaction
product was purified by passing through a column
of silica gel eluting with toluene-EtOAc mixtures.
3.3. Methyl 3-oxo-5i-cholan-24-oate (24)
Obtained from 1 and 2 in 90 and 83% yields,
respectively; m.p., 113–116°C (aq. methanol),
(Hill et al., 1991), m.p., 119–120°C). IR nmax
1
cm−1: 1715, 1735 (C=O). H-NMR: 0.68 (3H, s,
18-CH3), 0.92 (3H, d, J=6.2 Hz, 21-CH3), 1.02
(3H, s, 19-CH3), 3.67 (3H, s, COOCH3). MS m/z
(relative intensity); 388 (M+, 97%), 356 (M+-32,
85%), 273 (M+-side chain (S.C.; 115), 100%), 231
(M+-115–ring D (42), 30%).

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T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
3.4. Methyl 3,6-dioxo-5h-cholan-24-oate (25)
18-CH3), 1.11 (3H, s, 19-CH3), 3.66 (3H, s,
COOCH3). MS m/z (relative intensity): 402 (M+,
100%), 384 (M+-18, 23%), 287 (M+-115, 13%),
269 (M+-115-18, 13%).
Obtained from 3 and 4 in 87 and 84% yields,
respectively; m.p., 147–149°C (EtOAc-hexane)
(Hill et al., 1991, m.p., 149–151°C). IR nmax
1
cm−1: 1705, 1743 (C=O). H-NMR d: 0.69 (3H,
3.8. Methyl 12h-hydroxy-3,7-dioxo-5i-cholan-
24-oate (29)
s, 18-H), 0.93 (3H, d, J=6.5 Hz, 21-H), 0.96 (3H,
s, 19-H), 3.67 (3H, s, COOCH3). 13C-NMR d ;
12.0 (C-18), 12.5 (C-19), 18.2 (C-21), 21.6 (C-11),
23.9 (C-15), 27.9 (C-16), 30.8 (C-23), 31.0 (C-22),
35.2 (C-20), 36.9 and 37.3 (C-2,7), 37.9 (C-8), 38.0
(C-1), 39.3 (C-12), 41.2 (C-10), 43.0 (C-13), 46.5
(C-4), 51.5 (C-25), 53.4 (C-9), 55.7 (C-17), 56.5
(C-14), 57.5 (C-5), 174.6 (C-24), 209.0 (C-6), 211.2
(C-3). MS m/z (relative intensity); 402 (M+, 86%),
384 (M+-H2O (18), 85%), 329 (100%), 287 (M+-
115, 35%), 245 (M+-115-42, 42%).
Obtained from 8 in 72% yield; m.p., 190–192°C
(aq. methanol) (Hill, et al., 1991, m.p., 194.5°C).
IR wmax cm−1: 1703, 1735 (C=O), 3502 (OH).
1H-NMR: 0.72 (3H, s, 18-CH3), 0.84 (3H, d,
J=6.2 Hz, 21-CH3), 1.28 (3H, s, 19-CH3), 3.66
(3H, s, COOCH3), 4.05 (1H, m, 12b-H). MS m/z
(relative intensity): 418 (M+, 2%), 400 (M+-18,
13%), 286 (100%), 285 (M+-115-18, 89%).
3.9. Methyl 4i-hydroxy-3-oxo-5i-cholan-
24-oate (30)
3.5. Methyl 3,7-dioxo-5i-cholan-24-oate (26)
Obtained from 5 and 6 in 80 and 84% yields,
respectively; m.p., 150–152°C (aq. methanol),
(Hill, et al., 1991), m.p., 152–155°C). IR wmax
Obtained from 9 in 69% yield; m.p., 113–116°C
(aq. methanol). IR wmax cm−1: 1721, 1741 (C=
O), 3503 (OH). H-NMR d: 0.69 (3H, s, 18-CH3),
0.92 (3H, d, J=6.2 Hz, 21-CH3), 1.02 (3H, s,
19-CH3), 3.67 (3H, s, COOCH3), 4.38 (1H, d,
J=11.3 Hz, 4a-H). MS m/z (relative intensity):
404 (M+, 41%), 389 (M+-CH3 (15), 93%), 386
(M+-18, 100%), 262 (M+-115-part of D (27),
50%), 247 (M+-115-27-15, 50%).
1
1
cm−1: 1701, 1738 (C=O). H-NMR d: 0.70 (3H,
s, 18-CH3), 0.93 (3H, d, J=6.5 Hz, 21-CH3), 1.30
(3H, s, 19-CH3), 3.67 (3H, s, COOCH3). MS m/z
(relative intensity): 402 (M+, 16%), 384 (M+-18,
8%), 370 (M+-32, 9%), 287 (M+-115, 100%), 269
(M+-115-18, 60%), 245 (M+-115-42, 18%).
3.6. Methyl 12h-hydroxy-3-oxo-5i-cholan-24-
oate (27)
3.10. Methyl 6h-hydroxy-3,7-dioxo-5i-cholan-
24-oate (31)
Obtained from 7 in 87% yield; m.p., 145–147°C
(EtOAc-hexane) (Tohma et al., 1986), m.p. , 148–
149°C). IR wmax cm−1: 1720 (C=O), 3521 (OH).
1H-NMR: 0.72 (3H, s, 18-CH3), 0.98 (3H, d,
J=5.9 Hz, 21-CH3), 1.01 (3H, s, 19-CH3), 3.67
(3H, s, COOCH3), 4.04 (1H, m, 12b-H). MS m/z
(relative intensity): 404 (M+, 3%), 386 (M+-18,
19%), 271 (M+-115-18, 100%).
Obtained from 10 in 83% yield; viscous oil. IR
1
wmax cm−1: 1711, 1741 (C=O). H-NMR d: 0.71
(3H, s, 18-CH3), 0.94 (3H, d, J=6.2 Hz, 21-CH3),
1.35 (3H, s, 19-CH3), 3.67 (3H, s, COOCH3) 4.55
(1H, m, 6b-H). MS m/z (relative intensity): 418
(M+, 25%), 400 (M+-18, 12%), 386 (M+-32,
24%), 345 (M+-73, 10%), 303 (M+-115, 14%), 285
(M+-115-18, 18%), 134 (100%).
3.7. Methyl 3,12-dioxo-5i-cholan-24-oate (28)
3.11. Methyl 3i,4i-epoxy-5i-cholan-24-oate
(32)
Obtained from 7 in 84% yield; m.p., 130–132°C
(aq. ethanol) (Hill, et al., 1991, m.p., 133–134°C).
IR wmax cm−1: 1708, 1735 (C=O). 1H-NMR:
0.86 (3H, d, J=6.5 Hz, 21-CH3), 1.06 (3H, s,
Obtained from 11 in 64% yield; m.p., 105–
107°C (methanol). IR wmax cm−1: 1732 (C=O).
1H-NMR: 0.66 (3H, s, 18-CH3), 0.87 (3H, s,

T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
141
19-CH3), 0.91 (3H, d, J=6.2 Hz, 21-CH3), 2.86
(1H, d, J=2.7 Hz, 4a-H), 3.22 (1H, m, 3a-H),
3.66 (3H, s, COOCH3). MS m/z (relative inten-
sity): 388 (M+, 86%), 355 (M+-18-15, 100%), 273
(M+-115, 16%), 231 (M+-115-42, 72%).
3.15. Methyl 4h,5h-epoxy-3-oxocholan-24-oate
(37)
Obtained from 15, 17, and 23 in 58, 80, and
44% yields, respectively; m.p., 138–140°C
(methanol). IR wmax cm−1: 1701, 1740 (C=O).
1H-NMR d: 0.70 (3H, s, 18-CH3), 0.92 (3H, d,
J=6.2 Hz, 21-CH3), 1.06 (3H, s, 19-CH3), 3.03
(1H, s, 4b-H), 3.67 (3H, s, COOCH3). 13C-NMR
d: 12.0 (C-18), 16.5 (C-19), 18.2 (C-21), 21.4 (C-
11), 24.2 (C-15), 28.0 (C-16), 28.9 and 29.1 (C-
6,7), 29.7 (C-1), 30.9 (C-23), 31.0 (C-22), 33.1
(C-2), 35.3 and 35.4 (C-8,20), 36.7 (C-10), 39.6
(C-12), 42.5 (C-13), 50.6 (C-9), 51.5 (C-25), 55.6
(C-14), 55.8 (C-17), 62.9 (C-4), 70.2 (C-5), 174.7
(C-24), 207.1 (C-3). MS m/z (relative intensity):
402 (M+, 9%), 384 (M+-18, 16%), 287 (M+-115,
40%), 269 (M+-115-18, 27%), 245 (M+-115-42,
9%).
3.12. Methyl 3h-cathyloxy-14h,15h-epoxy-5i-
cholan-24-oate (33)
Obtained from 12 in 72% yield; m.p., 143–
146°C (methanol). IR wmax cm−1: 1737 (C=O).
1H-NMR: 0.84 (3H, s, 18-CH3), 0.85 (3H, d,
J=6.2 Hz, 21-CH3), 0.95 (3H, s, 19-CH3),
1.29(3H, t, J=7.0 Hz, CH3CH2OCO), 3.32 (H, s,
15b-H), 3.66 (3H, s, COOCH3), 4.16 (2H, q,
J=7.0 Hz, CH3CH2OCO), 4.55 (1H, brm, 3b-H).
MS m/z (relative intensity): 460 (M+, 1%), 386
(M+-C2H5COOH (74), 33%), 368 (M+-74-18,
100%).
3.16. 1i,2i-epoxy-3-oxo-5i-cholan-24-oate (38)
3.13. Methyl 6h,7h-epoxy-3-oxo-5i-cholan-24-
oate (34)
Obtained from 16 in 84% yield; m.p., 120–
122°C (methanol) (Tohma, et al., 1986, m.p. ,
123–124°C). IR wmax cm−1: 1713, 1737 (C=O).
1H-NMR d: 0.67 (3H, s, 18-CH3), 0.91 (3H, d,
J=6.2 Hz, 21-CH3), 1.30 (3H, s, 19-CH3), 3.28
(1H, d, J=4.1 Hz, 1a-H), 3.42 (1H, d, J=4.1 Hz,
2a-H), 3.66 (3H, s, COOCH3). MS m/z (relative
intensity): 402 (M+, 2%), 316 (M+-86, 14%), 287
(M+-115, 8%), 260 (M+-115-27, 6%), 245 (M+-
115-42, 8%), 227 (M+-115-42-18, 7%), 201
(100%).
Obtained from 13 in 55% yield; m.p., 133–
135°C (EtOAc-hexane). IR wmax cm−1: 1716, 1743
1
(C=O). H-NMR d: 0.73 (3H, s, 18-CH3), 0.93
(3H, d, J=5.4 Hz, 21-CH3), 0.95 (3H, s, 19-CH3),
3.13 (2H, m, 6b- and 7b-H), 3.67 (3H, s,
COOCH3). MS m/z (relative intensity): 402 (M+,
3%), 384 (M+-18, 5%), 369 (M+-18-15, 13%), 287
(M+-115, 21%), 269 (M+-115-18, 91%).
3.14. Methyl 5x,6x-epoxy-3-oxo-5i-cholan-24-
oate (35 and 36)
3.17. Methyl 3i-acetoxy-5h,6h-epoxy-7-
oxocholan-24-oate (39)
Obtained from 14 in 83% yield as a mixture of
the a- and b- epoxides (ratio, 3:1); m.p., 108–
110°C (aq. methanol). IR wmax cm−1: 1669, 1743
Obtained from 18 in 72% yield; m.p., 133–
135°C (methanol). IR wmax cm−1: 1694, 1731
1
1
(C=O). H-NMR d: (5a,6a-epoxide), 0.61 (3H, s,
(C=O). H-NMR d: 0.66 (3H, s, 18-CH3), 0.91
18-CH3), 0.74 (3H, s, 19-CH3), 2.90 (1H, d, J=
4.3 Hz, 6b-H), 3.66 (3H, s, COOCH3); (5b,6b-
epoxide), 0.64 (3H, s, 18-CH3), 0.74 (3H, s,
19-CH3), 3.09 (H, d, J=4.3 Hz, 6a-H), 3.66 (3H,
s, COOCH3). MS m/z (relative intensity): 402
(M+, 35%), 387 (M+-15, 11%), 269 (M+-115-18,
6%), 227 (M+-115-27-18-15, 19%).
(3H, d, J=6.2 Hz, 21-CH3), 1.04 (3H, s, 19-CH3),
2.03 (3H, s, 3-COCH3), 3.04 (1H, s, 6b-H), 3.66
(3H, s, COOCH3), 4.93 (1H, brm, 3a-H). MS m/z
(relative intensity): 400 (M+-CH3COOH (60),
4%), 382 (M+-60-18, 7%), 372 (25%), 345 (M+-
115, 14%), 327 (M+-115-18, 15%), 285 (M+-115-
42-18, 19%), 267 (M+-115-60-18, 22%).

142
T. Sasaki et al. / Chemistry and Physics of Lipids 109 (2001) 135–143
3.18. Methyl 4h,5h-epoxy-3-oxochol-1-en-24-oate
(40)
21-CH3), 1.20 (3H, s, 19-CH3), 3.35 (1H, m, 7b-H),
3.63 (1H, d, J=3.8 Hz, 6b-H), 3.67 (3H, s,
COOCH3), 6.22 (1H, d, J=10.3 Hz, 2-H), 6.47
(1H, s, 4-H), 7.00 (H, d, J=10.3 Hz, 1-H). MS m/z
(relative intensity): 398 (M+, 3%), 383 (M+-15,
1%), 380 (M+-18, 2%), 265 (M+-115-18, 13%), 238
(M+-115-27-18, 10%), 223 (M+-115-27-18-15,
11%), 147 (100%).
Compound 44 was obtained in 20% yield; m.p.,
203–205°C (methanol). IR wmax cm−1: 1697, 1735
(C=O). 1H-NMR: 0.76 (3H, s, 18-CH3), 0.94 (3H,
d, J=6.2 Hz, 21-CH3), 1.14 (3H, s, 19-CH3), 3.31
(1H, m, 7b-H), 3.45 (2H, m, 1b- and 6b-H), 3.51
(1H, d, J=3.5 Hz, 2b-H), 3.67 (3H, s, COOCH3),
6.11 (1H, s, 4H). MS m/z (relative intensity): 399
(M+-15, 38%), 382 (M+-32, 61%), 299 (M+-115,
12%), 281 (M+-115-18, 100%).
Obtained from 19 in 71% yield; m.p., 103–106°C
(methanol). IR wmax cm−1: 1681, 1731 (C=O).
1H-NMR d: 0.71 (3H, s, 18-CH3), 0.91 (3H, d,
J=6.2 Hz, 21-CH3), 1.31 (3H, s, 19-CH3), 3.21
(1H, s, 4b-H), 3.66 (3H, s, COOCH3), 5.85 (1H, d,
J=10.8 Hz, 2-H), 6.52 (1H, d, J=10.8 Hz, 1-H).
MS m/z (relative intensity): 400 (M+,
7%), 385 (M+-15, 16%), 327 (M+-73, 10%), 285
(M+-115, 64%), 267 (M+-115-18, 39%), 258 (M+-
115-27, 9%).
3.19. Methyl 7h,12h-diacetoxy-4h,5h-epoxy-3-
oxochol-1-en-24-oate (41)
Obtained from 20 in 76% yield; m.p., 172–175°C
(EtOAc-hexane). IR wmax cm−1: 1681,1736 (C=
O). 1H-NMR d: 0.79 (3H, s, 18-CH3), 0.80 (3H, d,
J=5.4 Hz, 21-CH3), 1.30 (3H, s, 19-CH3), 2.12
(6H, s, 7- and 12-COCH3), 3.11 (1H, s, 4b-H), 3.66
(3H, s, COOCH3), 5.06 (1H, brs, 7b-H), 5.12 (1H,
brs, 12b-H), 5.87 (1H, d, J=10.8 Hz, 2-H), 6.43
(1H, d, J=10.8 Hz, 1-H). MS m/z (relative inten-
sity): 341 (M+-115-60, 30%), 323 (M+-115-18-60,
7%), 281 (M+-115-60-27-18-15, 100%), 263 (M+-
115-60-60-18, 20%).
Acknowledgements
This work was supported in part by a Grant-in-
Aid for Scientific Research from the Ministry of
Education, Science, Sports and Culture of Japan.
Fumitoshi Abe contributed able technical
assistance.
3.20. 12h-Formyloxy-6h,7h-epoxy-3-oxochol-4-
en-24-oic acid (42)
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Obtained from 21 in 61% yield; m.p., 201–203°C
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