Substituent effect of fluorine atoms in the 2,4-difluorophenyl group on antifungal activity of CS-758

Article abstract of DOI:10.1016/j.jfluchem.2005.12.008

CS-758 is a novel triazole antifungal agent. To ascertain the effect of the fluorine atoms in the 2,4-difluorophenyl group, a series of compounds, 12a-12d, which have fluorine atom(s) in different positions on the benzene ring, were synthesized, and the minimum inhibitory concentrations (MICs) of this series of compounds were determined. All the compounds, including CS-758, exhibited excellent MICs against Candida, Aspergillus, and Cryptococcus species. Among them, the compounds having a fluorine atom in the 2-position on the benzene ring (12a, 12c, 12d, and CS-758) showed stronger antifungal activity particularly against Aspergillus species. The MICs of these compounds surpassed those of fluconazole and itraconazole against Candida, Aspergillus, and Cryptococcus species.

Full text of DOI:10.1016/j.jfluchem.2005.12.008

Journal of Fluorine Chemistry 127 (2006) 643–650
www.elsevier.com/locate/fluor
Substituent effect of fluorine atoms in the 2,4-difluorophenyl
group on antifungal activity of CS-758
*
Yoshiko Kagoshima , Toshiyuki Konosu
Medicinal Chemistry Research Laboratories, Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan
Received 12 December 2005; accepted 16 December 2005
Available online 9 February 2006
Abstract
CS-758 is a novel triazole antifungal agent. To ascertain the effect of the fluorine atoms in the 2,4-difluorophenyl group, a series of compounds,
12a–12d, which have fluorine atom(s) in different positions on the benzene ring, were synthesized, and the minimum inhibitory concentrations
(MICs) of this series of compounds were determined. All the compounds, including CS-758, exhibited excellent MICs against Candida,
Aspergillus, and Cryptococcus species. Among them, the compounds having a fluorine atom in the 2-position on the benzene ring (12a, 12c, 12d,
and CS-758) showed stronger antifungal activity particularly against Aspergillus species. The MICs of these compounds surpassed those of
fluconazole and itraconazole against Candida, Aspergillus, and Cryptococcus species.
# 2005 Elsevier B.V. All rights reserved.
Keywords: Antifungal; Triazole; CS-758; Fluorine atom; Synthesis; Lanosterol 14-demethylase
1. Introduction
Attention has been focused on triazole derivatives [16] as
potential candidates because of their generally broad antifungal
spectrum and low toxity. Triazole derivatives displace
lanosterol from lanosterol 14a-demethylase (14DM), a
cytochrome P450-dependent enzyme, and block the biosynthe-
sis of an essential component of fungal cell membrane,
ergosterol [17]. In Japan, fluconazole [18] and itraconazole [19]
have been the only triazole agents used clinically against
systemic mycoses, and recently, voriconazole [20] has been
launched on the market. Moreover, newer triazole agents, such
as ravuconazole [21] and posaconazole [22] are reported to be
under development (Fig. 1).
Antifungal agents effective against deep-seated mycoses are
highly in demand [1–3]. We are surrounded by fungi, and once
our immune system becomes deficient or suppressed, as it does
in AIDS patients and in those that have received anticancer
chemotherapy or an organ transplant, then we become
susceptible to fungal infection. Candida albicans is the
organism most often associated both with mucosal and
hematogenously disseminated infections [4–6]. Recently other
Candida species such as Candida glabrata, Candida tropicalis,
and Candida krusei have emerged as clinically important
pathogens [5,7,8]. Aspergillus species such as Aspergillus
fumigatus and Aspergillus flavas are also important pathogens,
which cause serious respiratory infections [9,10]. The increase
in invasive aspergillosis has led to a great need for new
antifungal agents because this infection is particularly
problematic as response to existing agents is insufficient
[10–13]. Cryptococcus neoformans is also an important
pathogen, which causes lethal meningitis in a significant
number of persons with AIDS [14,15].
In our program aimed at finding new triazole agents, we
focused our attention on triazole derivatives possessing a
dioxane ring, and we finally found CS-758 (Fig. 2), which
exhibited excellent antifungal activities against a wide variety
of pathogenic fungi [23,24]. CS-758 has good oral absorption,
and possesses desirable pharmacokinetic properties [25–31].
In the course of such a search, we fixed the substituent on the
left-side of the benzene ring as a 2,4-F2 group because most of
the known triazole antifungal agents have a 2,4-halogenated
phenyl ring, presumably in order to give them good antifungal
activity. For example, in a study aimed at developing
fluconazole derivatives, it was revealed that the compound
with a 2,4-F2 phenyl group (fluconazole) showed the best in
* Corresponding author. Tel.: +81 3 3492 3131; fax: +81 3 5436 8563.
E-mail address: yharada@sankyo.co.jp (Y. Kagoshima).
0022-1139/$ – see front matter # 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.12.008

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Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
Fig. 1. Structural formulas of triazole antifungal agents.
vivo antifungal activity; on the other hand, 3-substitution
caused a major loss of activity [32]. In the present work, we
synthesized a series of compounds, 12a–d, possessing an F-(or
F2-)substituted phenyl ring, and evaluated their in vitro
antifungal activities to ascertain the substituent effect of the
fluorine atoms in the 2,4-difluorophenyl group of CS-758.
derivatives 2a–d were treated with (dimethylisopropoxysilyl)-
methylmagnesium chloride, prepared from chloromethyldi-
methylisopropoxysilane and magnesium, in diethyl ether at
0 8C to give silyl alcohol derivatives 3a–d. Oxidative
desilylation of 3a–d with hydrogen peroxide and sodium
hydrogen carbonate in THF-MeOH afforded diol derivatives
4a–d, whose tetrahydropyranyl group was removed by acid
treatment in MeOH at room temperature to give butantriol
derivatives 5a–d. The derivatives 5a–d were converted to the
corresponding dimesylates 6a–d, which were then treated with
an excess amount of sodium triazole, prepared from sodium
hydride and 1H-1,2,4-triazole, in N,N-dimethylformami-
de(DMF) at 65–70 8C for 2 h to give epoxides 7a–d. Treatment
of epoxides 7a–d with S-(trans-2-phenyl-1,3-dioxane-5-yl)
thioacetate 8 [23] (in the case of 7b, S-(cis-2-phenyl-1,3-
dioxane-5-yl) thioacetate 80 was used) in the presence of a
catalytic amount of sodium methoxide afforded thioesters 9a–
d. The benzylidene protection group was removed by acid
treatment in toluene at 50 8C to furnish triols 10a–d. The
acetalization reaction between 10a–d and aldehyde 11 [24]
afforded 12a–d, respectively. The trans isomers 12a–d, were
predominantly produced and easily separated from the cis
isomer by silica gel chromatography. The stereochemistry of
the 1,3-dioxane ring was elucidated by the coupling constants
2. Results and discussion
Compounds 12a–d were prepared in good yields in a similar
manner as that used for the synthesis of CS-758 [23,24]. The
synthetic route is shown in Scheme 1.
The Grignard reaction of morpholine amide 1 [33], derived
from methyl (R)-lactate, with 2-F-, 4-F-, 2,3-F2-, and 2,5-F2-
phenylmagnesium bromide in tetrahydrofuran (THF) at
ꢀ30 8C, proceeded smoothly to afford (R)-2-(3,4,5,6-tetrahy-
dro-2H-pyran-2-yl)oxypropiophenone derivatives 2a–d. The
1
in the H NMR spectra; that is, the trans isomers showed
characteristic signals of the axial methylene protons in the C4
and C6 positions in the 1,3-dioxane ring with large coupling
constants (triplet, J = ca. 11 Hz). In contrast, the corresponding
signals of the cis isomers appeared as multiplets.
Fig. 2. Structural formula of CS-758.

Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
645
Scheme 1. Reagents and conditions: (a) (substituted-phenyl)magnesium bromide, THF, ꢀ20 8C; (b) iPrOSiMe2CH2MgCl, ether, 0 8C; (c) NaHCO3, H2O2, THF/
MeOH = 1/1, 60 8C; (d) TsOH, MeOH, r.t.; (e) MsCl, pyridine, 0 8C; (f) NaH, 1H-1,2,4-triazole, DMF, 65 8C; (g) NaOMe; (h) 1N HCl aq. toluene, 50 8C; and (i)
TsOH, CH2Cl2, r.t.
Minimum inhibitory concentrations (MICs) of the test
compounds were determined against Candida, Cryptococcus,
and Aspergillus species by the broth microdilution
methods in accordance with the guidelines of the National
Committee for Clinical Laboratory Standards (NCCLS)
documents [34].
(MICs) of these compounds, CS-758, fluconazole, and
itraconazole are shown in Table 2.
Compounds 12c and 12d had good in vitro antifungal
activity almost equivalent to that of CS-758. These results
revealed that the fluorine atom in the 2-position on the benzene
ring is important to in vitro antifungal activity particularly
against Aspergillus species. The difference in MICs between
the derivatives with and without the fluorine atom at the 2-
position might possibly be due to the buttressing effect of the
fluorine atom that controls the benzene ring plane at a favorable
angle in the binding site in the target enzyme 14DM [35].
The MICs of all of the compounds with a fluorine atom at the
2-position on the benzene ring (CS-758, 12a, 12c, and 12d)
surpassed those of fluconazole and itraconazole in these
species.
At first, we compared the in vitro antifungal activity (MICs)
of CS-758 (2,4-F2 phenyl analog), 12a (2-F phenyl analog), and
12b (4-F phenyl analog) against various fungi (Table 1).
The results revealed that the compounds 12a, 12b as well as
CS-758 showed excellent MICs against Candida and Crypto-
coccus species. A difference in MICs was seen in the activity
against the Aspergillus species. Then, we evaluated the activity
of di-fluorinated compounds 12c (2,3-F2 phenyl analog) and
12d (2,5-F2 phenyl analog). The in vitro antifungal activity

646
Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
Table 1
3. Experimental
Minimum inhibitory concentrations (MICs) of compounds CS-758, 12a and
12b
3.1. General
Melting points were determined with a Yanagimoto micro
melting point apparatus and are corrected. IR spectra were
recorded either on a JASCO A-102 or on a Nic 5SCX
spectrometer. 1H NMR spectra were recorded either on a Varian
Mercury 400 (400 MHz) or on a JEOL GX-270 (270 MHz)
spectrometer using tetramethylsilane as an internal standard.
Chemical shifts are expressed in ppm downfield from the
tetramethylsilane, and the abbreviations are as follows: s,
singlet; d, doublet; dd, doublet of doublets; ddd, doublet of
doublets of doublets; t, triplet; dt, doublet of triplets; td, doublet
of triplets; tt, triplet of triplets; q, quartet; m, multiplets; br,
broad. Mass spectra (MS) were recorded either on a JEOL JMS
D300, on a JEOL BU30, or on a JEOL JMS-700 spectrometer.
Column chromatography was carried out on silica gel
(Kieselgel 60, 0.040–0.063 mm, Merck). The amounts of
silica gel used are shown in parentheses. Reactions were
followed by thin layer chromatography (TLC) on silica gel 60
F254 precoated TLC plates (Merck).
MIC (mg/mL)
CS-758
12a
X = 2-F
12b
X = 4-F
Strain
X = 2,4-F2
C. albicans ATCC24433
C. albicans SANK51486
C. albicans TIMM3164
C. albicans ATCC64550
C. parapsilosis ATCC90018
C. glabrata ATCC90030
C. krusei ATCC6285
0.016
ꢁ0.008
0.063
0.5
ꢁ0.008
ꢁ0.008
0.031
0.25
0.016
ꢁ0.008
0.125
1
0.016
1
0.016
0.5
0.031
1
0.25
0.25
1
C. tropicalis ATCC750
0.25
0.031
0.125
C. neoformans TIMM1855
0.016
0.016
0.031
A. fumigatus ATCC26430
A. fumigatus SANK10569
A. flavus SANK18497
0.063
0.063
0.25
0.063
0.063
0.125
0.5
0.5
2
3.2. Substituted-(2R)-2-[(3,4,5,6-tetrahydro-2H-pyran-2-
yl)oxy]propiophenone (2a–d)
In conclusion, we synthesized and evaluated compounds
having fluorine atom(s) at different positions on the benzene
ring, and have shown that the fluorine atom in the 2-position is
important for MICs, especially against the Aspergillus species.
CS-758 was ascertained to be one of the compounds that
showed the most effective MICs.
Compounds 2a and 2b were prepared following the
literature procedure [33].
Compounds 2c and 2d were prepared in a similar manner. As
a typical example of the Grignard reaction, the preparation of
2c is described. A suspension of a small amount of magnesium
turnings activated with methyl iodide in diethyl ether was added
Table 2
Minimum inhibitory concentrations (MICs) of compounds CS-758, 12c, 12d, fluconazole, and itraconazole
MIC (mg/mL)
CS-758
12c
12d
Fluconazole
Itraconazole
Strain
X = 2,4-F2
X = 2,3-F2
X = 2,5-F2
C. albicans ATCC24433
C. albicans SANK51486
C. albicans TIMM3164
C. albicans ATCC64550
C. parapsilosis ATCC90018
C. glabrata ATCC90030
C. krusei ATCC6285
0.016
ꢁ0.008
0.063
0.5
0.031
0.016
ꢁ0.008
0.063
1
0.5
0.25
>4
>4
0.5
>4
>4
2
0.125
0.031
0.25
1
ꢁ0.008
0.125
1
0.016
1
0.063
0.031
1
0.125
1
2
1
1
0.25
0.25
0.25
0.5
C. tropicalis ATCC750
0.25
0.5
C. neoformans TIMM1855
0.016
0.031
0.016
>4
0.25
A. fumigatus ATCC26430
A. fumigatus SANK10569
A. flavus SANK18497
0.063
0.063
0.25
0.125
0.125
0.25
0.125
0.125
0.25
>4
>4
>4
0.25
0.25
0.5

Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
647
to a mixture of 1-bromo-2,3-difluorobenzene (0.5 g, 2.6 mmol),
magnesium turnings (0.68 g, 28 mmol), and THF (40 mL) at
room temperature, and then heated. When the reaction started, a
solution of 1-bromo-2,3-difluorobenzene (4.5 g, 23 mmol) in
THF (30 mL) was added over a period of 30 min at 0 8C. The
mixture was stirred for 1.5 h at room temperature to obtain an
essentially clear solution. The solution was cooled to ꢀ30 8C,
and a solution of 4-[(2R)-2-(3,4,5,6-tetrahydro-2H-pyran-2-
yloxy)propionyl]morpholine 1 (4.87 g, 20 mmol) in THF
(30 mL) was added to it over a period of 20 min. A saturated
aqueous solution of NH4Cl was added, and products were
extracted with EtOAc. The concentrated organic layer was
purified by column chromatography on silica gel (75 g, EtOAc/
(2,3-difluorophenyl)-3-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)-
butan-1,2-diol 4c (10 g). The crude product 4c thus-obtained
was treated with p-toluenesulfonic acid monohydrate (0.20 g,
1.05 mmol) in MeOH at room temperature for 1 h. The mixture
was concentrated under reduced pressure to give an oily
product, which was chromatographed on silica gel (125 g,
EtOAc) to afford 5c (3.74 g, quantitative overall yield from 2c)
1
as a viscous colorless oil. H NMR (400 MHz, CDCl3) d 0.96
(3H, d, J = 6 Hz), 3.80 (1H, d, J = 12 Hz), 3.94 (1H, s), 4.32
(1H, dd, J = 12, 2 Hz), 4.53 (1H, qd, J = 6, 3 Hz), 7.09-7.13
(2H, m), 7.46-7.50 (1H, m); IR (KBr) 3402, 3174, 1481, 1272,
1104 cmꢀ1; MS m/z (FAB) 219 (M+ + 1).
5a: Yield 88% (overall yield from 2a). Colorless needles;
1
1
hexane = 1/9) to afford 2c (4.80 g, 89%) as a colorless oil. H
m.p. 77–79 8C; H NMR (270 MHz, CDCl3) d 0.94 (3H, d,
NMR (400 MHz, CDCl3) d 1.44 ((3/2)H, dd, J = 7, 1 Hz), 1.49
((3/2)H, dd, J = 7, 1 Hz), 1.49–1.90 (6H, m), 3.33–3.38 ((1/2)H,
m), 3.50–3.55 ((1/2)H, m), 3.68–3.74 ((1/2)H, m), 3.87–3.93
((1/2)H, m), 4.66 ((1/2)H, t, J = 4 Hz), 4.75 ((1/2)H, t,
J = 4 Hz), 4.85 ((1/2)H, qd, J = 7, 2 Hz), 5.10 ((1/2)H, qd,
J = 7, 2 Hz), 7.14–7.21 (1H, m), 7.30–7.39 (1H, m), 7.54–7.58
(1H, m); IR (CHCl3) 1700, 1481, 1273 cmꢀ1; MS m/z (FAB)
271 (M+ + 1).
2d: Yield 98%. A colorless oil; 1H NMR (400 MHz, CDCl3)
d 1.43 ((3/2)H, dd, J = 6, 1 Hz),1.48 ((3/2)H, dd, J = 7, 1 Hz),
1.50–1.89 (6H, m), 3.36 ((1/2)H, dt, J = 12, 4 Hz), 3.53 ((1/2)H,
dt, J = 12, 4 Hz), 3.73 ((1/2)H, dt, J = 12, 4 Hz), 3.90 ((1/2)H,
J = 11, 4 Hz), 4.66 ((1/2)H, t, J = 4 Hz), 4.75 ((1/2)H, t,
J = 4 Hz), 4.87 ((1/2)H, qd, J = 7, 1 Hz), 5.12 ((1/2)H, qd,
J = 7, 2 Hz), 7.08–7.15 (1H, m), 7.17–7.25 (1H, m), 7.50–7.54
(1H, m); IR (CHCl3) 1698, 1491, 1417, 1257 cmꢀ1; MS m/z
(FAB) 271 (M+ + 1).
J = 6 Hz), 2.45 (1H, dd, J = 7, 6 Hz), 2.59 (1H, d, J = 6 Hz),
3.63 (1H, s), 3.78 (1H, dd, J = 11, 7 Hz), 4.33 (1H, ddd, J = 11,
6, 2 Hz), 4.53 (1H, qd, J = 6, 3 Hz), 7.01 (1H, ddd, J = 12, 8,
1 Hz), 7.18 (1H, td, J = 8, 1 Hz), 7.28 (1H, tdd, J = 8, 5, 2 Hz),
7.74 (1H, td, J = 8, 2 Hz); IR (KBr) 3464, 3277, 1484, 1453,
1208 cmꢀ1; MS m/z (EI) 200 (M+); Anal. Calcd for C10H13FO3:
C, 59.99; H, 6.55. Found: C, 59.49; H, 6.28.
5b: Yield 22% (overall yield from 2b). A colorless powder;
1
m.p. 91–93 8C; H NMR (270 MHz, CD3OD) d 0.93 (3H, d,
J = 6 Hz), 2.50 (1H, d, J = 6 Hz), 2.55 (1H, dd, J = 7, 5 Hz),
3.34 (1H, s), 3.71 (1H, dd, J = 11, 7 Hz), 4.12 (1H, dd, J = 11,
5 Hz), 4.21 (1H, quint, J = 6 Hz), 7.05 (2H, t, J = 9 Hz), 7.38
(2H, dd, J = 9, 5 Hz); IR (KBr) 3404, 1509, 1221, 1158 cmꢀ1
;
MS m/z (FAB) 223 (M+ + Na); Anal. Calcd for C10H13FO3: C,
59.99; H, 6.55. Found: C, 60.02; H, 6.51.
5d: Yield 95% (overall yield from 2d). A colorless viscous
oil; 1H NMR (400 MHz, CDCl3) d 0.95 (3H, d, J = 6 Hz), 3.77
(1H, d, J = 11 Hz), 4.31 (1H, dd, J = 11, 2 Hz), 4.52 (1H, qd,
J = 6, 3 Hz), 6.94-7.00 (2H, m), 7.44–7.48 (1H, m); IR (KBr)
3422, 1487, 1142, 1065 cmꢀ1; MS m/z (FAB) 219 (M+ + 1).
3.3. (2R,3R)-2-(Substituted-phenyl)-butan-1,2,3-triol
(5a–d)
As a typical example of the Grignard reaction, followed by
oxidative desilylation and deprotection, the preparation of 5c is
described. To a solution of (dimethylisopropoxysilyl)methyl
magnesium chloride, prepared from chloromethyldimethyliso-
propoxysilane (5.74 g, 34.4 mmol) and magnesium (0.84 g,
34.4 mmol) in diethyl ether, was added dropwise a solution of
2c (4.65 g, 17.2 mmol) in THF (20 mL) over 10 min, while
stirring at 0 8C. The mixture was then warmed to room
temperature. After 30 min, the mixture was cooled to 0 8C and a
saturated aqueous solution of NH4Cl was added to the mixture,
which was extracted with EtOAc. The extract was washed with
brine, and the solvent was evaporated in vacuo to give crude
product (2S,3R)-2-(2,3-difluorophenyl)-1-(dimethylisoprop-
oxysilyl)-3-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)-butan-2-ol
(3c) as an oil (8.1 g), which was used without further
purification for the next step. To a solution of the thus-obtained
3c in a 1:1 mixture of THF (40 mL) and MeOH (40 mL) were
added NaHCO3 (1.4 g, 17 mmol) and 31% H2O2 (16 mL), and
the mixture was stirred at 70 8C for 40 min. After cooling to
room temperature, the mixture was diluted with EtOAc
and washed with brine. The solvent was distilled off under
reduced pressure to give the crude oily product (2R,3S)-2-
3.4. (2R,3R)-2-(Substituted-phenyl)-1,3-
bis(methylsulfonyloxy)-butan-2-ol (6a–d)
As a typical example of mesylation, the preparation of 6c is
described. Methanesufonyl chloride (5.71 g, 50 mmol) was
added, while stirring at 0 8C, to a solution of 5c (3.51 g,
16.1 mmol)in pyridine (18 mL), and then themixturewas stirred
at the same temperature for30 min. The mixturewas diluted with
EtOAc and washed with a saturated NaHCO3 solution and brine
successively. The concentrated organic layer was purified by
column chromatography on silica gel (100 g, EtOAc/hexane = 1/
1)toafford6c (5.04 g, 84%) asaviscousoil. 1H NMR(400 MHz,
CDCl3) d 1.28 (3H, d, J = 7 Hz), 2.99 (3H, s), 3.10 (3H, s), 3.41
(1H, s), 4,75 (2H, d, J = 1 Hz), 5.31 (1H, q, J = 7 Hz), 7.16–7.23
(2H, m), 7.46–7.50 (1H, m); IR (KBr) 3486, 1485, 1350, 1344,
1171 cmꢀ1; MS m/z (FAB) 375 (M+ + 1).
6a: Yield 90%. Colorless needles; m.p. 94–95 8C; 1H NMR
(400 MHz, CDCl3) d 1.26 (3H, d, J = 6 Hz), 2.95 (3H, s), 3.09
(3H, s), 3.24 (1H, s), 4.75 (2H, s), 5.35 (1H, q, J = 6 Hz), 7.08
(1H, ddd, J = 12, 8, 1 Hz), 7.24 (1H, td, J = 8, 1 Hz), 7.37 (1H,
tdd, J = 8, 5, 2 Hz), 7.72 (1H, td, J = 8, 2 Hz); IR (KBr) 3098,
1489, 1448, 1275, 760 cmꢀ1; MS m/z (FAB) 357 (M+ + 1);

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Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
Anal. Calcd for C12H17FO7S2: C, 40.44; H, 4.81. Found: C,
40.52; H, 4.52.
diluted with EtOAc and washed with brine. The organic layer
was dried with MgSO4 and concentrated by rotary evaporator to
give a crude oil, which was purified by column chromatography
(75 g, EtOAc/hexane = 3/2) as a colorless amorphous solid. 1H
NMR (400 MHz, CDCl3) d 1.21 (3H, d, J = 7 Hz), 3.42 (1H, q,
J = 7 Hz), 3.49 (1H, tt, J = 11, 5 Hz), 3.75 (2H, t, J = 11 Hz),
3.72 (2H, t, J = 11 Hz), 4.41 (1H, ddd, J = 11, 5, 2 Hz), 4.52
(1H, ddd, J = 11, 5, 2 Hz), 4.89 (1H, d, J = 14 Hz), 4.92 (1H, d,
J = 1 Hz), 5.07 (1H, d, J = 14 Hz), 5.49 (1H, s), 6.94–7.03 (2H,
m), 7.17–7.23 (1H, m), 7.33–7.41 (3H, m), 7.49 (2H, dd, J = 7,
2 Hz), 7.75 (1H, s), 7.77 (1H, s); IR (KBr) 3131, 1732, 1376,
1140 cmꢀ1; MS m/z (FAB) 430 (M+ + 1).
1
6b: Yield 97%. A colorless solid; m.p. 121–122 8C; H
NMR (400 MHz, CDCl3) d 1.27 (3H, d, J = 6 Hz), 2.98 (3H, s),
3.01 (1H, s), 3.06 (3H, s), 4.53 (1H, dd, J = 11 Hz), 4.55 (1H,
dd, J = 11 Hz), 5.08 (1H, q, J = 7 Hz), 7.11 (2H, t, J = 9 Hz),
7.45 (2H, dd, J = 9, 5 Hz); IR (KBr) 3484, 1492, 1346,
1169 cmꢀ1; MS m/z (FAB) 375 (M+ + 1); Anal. Calcd for
C12H17FO7S2: C, 40.44; H, 4.81. Found: C, 40.52; H, 4.69.
6d: Yield 92%. A colorless viscous oil; 1H NMR (400 MHz,
CDCl3) d 1.27 (3H, d, J = 6 Hz), 2.99 (3H, s), 3.11 (3H, s), 3.36
(1H, s), 4.73 (2H, s), 5.32 (1H, q, J = 7 Hz), 7.03-7.26 (2H, m),
7.43–7.47 (1H, m); IR (KBr) 3484, 1492, 1346, 1169 cmꢀ1; MS
m/z (FAB) 375 (M+ + 1).
In the case of 9b, S-(cis-2-phenyl-1,3-dioxane-5-yl)
thioacetate 80 was used in place of S-(trans-2-phenyl-1,3-
dioxane-5-yl) thioacetate 8.
3.5. (2R,3S)-2-(Substituted-phenyl)-3-methyl-2-[(1H-1,2,4-
triazol-1-yl)-methyl]oxirane (7a–d)
9b: Yield 72%. A colorless oil; 1H NMR (270 MHz, CDCl3)
d 1.29 (3H, d, J = 7 Hz), 2.97 (1H, m), 3.50 (1H, q, J = 7 Hz),
4.26 (1H, d-like, J = 12 Hz), 4.36 (1H, dd, J = 12, 3 Hz), 4.36
(1H, dd, J = 12, 2 Hz), 4.42 (1H, dd, J = 12, 3 Hz), 4.56 (1H, s),
4.57 (1H, d, J = 14 Hz), 5.10 (1H, d, J = 14 Hz), 5.61 (1H, s),
6.89 (2H, t, J = 9 Hz), 7.16 (1H, dd, J = 9, 5 Hz), 7.3-7.5 (3H,
m), 7.4-7.6 (2H, m), 7.69 (1H, s), 7.80 (1H, s); IR (KBr) 1732,
1605, 1509, 1278, 1135 cmꢀ1; MS m/z (FAB) 430 (M+ + 1).
9c: This crude product was used for the next reaction without
further purification. An analytical sample was obtained by
column chromatography of a small portion of crude product
(EtOAc/hexane = 2/5) as a colorless amorphous solid.
1H NMR (400 MHz, CDCl3) d 1.23 (3H, d, J = 7 Hz), 3.39
(1H, q, J = 7 Hz), 3.50 (1H, tt, J = 11, 5 Hz), 3.75 (1H, t,
J = 11 Hz), 3.77 (1H, t, J = 11 Hz), 4.40 (1H, ddd, J = 11, 5,
2 Hz), 4.52 (1H, ddd, J = 11, 5, 2 Hz), 4.87 (1H, dd, J = 14,
6 Hz), 5.08 (1H, d, J = 14 Hz), 5.12 (1H, d, J = 1 Hz), 5.49 (1H,
s), 6.92–6.98 (1H, m), 7.05 (1H, qd, J = 8, 1 Hz), 7.11–7.16
(1H, m), 7.34–7.41 (3H, m), 7.49 (2H, dd, J = 7, 3 Hz), 7.79
(1H, s), 7.82 (1H, s); IR (KBr) 3405, 1480, 1275, 1140,
1075 cmꢀ1; MS m/z (FAB); 448 (M+ + 1).
As a typical example, the preparation of 7c is described.
Triazole (3.32 g, 48.1 mmol) was slowly added to a suspension
of sodium hydride (55% mineral oil dispersion, 1.84 g,
41.1 mmol) in DMF (30 mL), while stirring at 0 8C. When
the hydrogen gas ceased to evolve at room temperature, a
solution of 6c (4.50 g, 12.0 mmol) in DMF was added
dropwise. The mixture was stirred at 70 8C for 2 h. After the
mixture was cooled to 0 8C, saturated aqueous solution of
NH4Cl was added to the mixture, which was extracted with
EtOAc. The extract was washed with H2O (ꢂ3) and brine. The
mixture was concentrated under reduced pressure to give an
oily crude product, which was chromatographed on silica gel
(100 g, EtOAc/Hexane = 1/1) to afford 7c (1.80 g, 59%) as a
colorless oil. 1H NMR (400 MHz, CDCl3) d 1.66 (3H, d,
J = 6 Hz), 3.23 (1H, q, J = 6 Hz), 4.46 (1H, d, J = 15 Hz), 4.91
(1H, d, J = 15 Hz), 6.79 (1H, ddd, J = 8, 6, 1 Hz), 6.93 (1H, tdd,
J = 8, 6, 1 Hz), 7.08 (1H, qd, J = 8, 1 Hz), 7.82 (1H, s), 7.98
(1H, s); IR (KBr) 3111, 1486, 1273, 1136 cmꢀ1; MS m/z (EI)
251 (M+), 236, 188, 153, 141, 96 (100%).
9d: This crude product was used for the next reaction
without further purification. An analytical sample was obtained
by column chromatography of a small portion of crude product
(EtOAc/hexane = 1/1) as a colorless amorphous solid.
1H NMR (400 MHz, CDCl3) d 1.22 (3H, d, J = 7 Hz), 3.38
(1H, q, J = 7 Hz), 3.49 (1H, tt, J = 12, 5 Hz), 3.75 (1H, t,
J = 12 Hz), 3.77 (1H, t, J = 12 Hz), 4.41 (1H, ddd, J = 12, 5,
2 Hz), 4.52 (1H, ddd, J = 12, 5, 2 Hz), 4.88 (1H, d, J = 14 Hz),
5.06 (1H, d, J = 14 Hz), 5.08 (1H, d, J = 1 Hz), 5.49 (1H, s),
6.85–6.91 (1H, m), 6.95 (1H, dt, J = 9, 4 Hz), 7.08–7.13 (3H,
m), 7.36–7.41 (2H, m), 7.49 (1H, dd, J = 7, 2 Hz), 7.80 (1H, s),
7.82 (1H, s); IR (KBr) 3405, 1487, 1140, 1074 cmꢀ1; MS m/z
(FAB) 448 (M+ + 1).
7d: Yield 56%. A colorless oil; 1H NMR (400 MHz, CDCl3)
d 1.64 (3H, d, J = 6 Hz), 3.20 (1H, q, J = 6 Hz), 4.42(1H, d,
J = 15 Hz), 4.97 (1H, d, J = 15 Hz), 6.76–6.81 (1H, m), 6.89–
6.96 (1H, m), 6.99 (1H, dt, J = 9, 4 Hz), 7.83 (1H, s), 7.99 (1H,
s); IR (KBr) 3110, 1500, 1490, 1184, 1135 cmꢀ1; MS m/z (EI)
251 (M+).
The spectral data of 7a and 7b were identical with those
described in the literature [33].
3.6. (2R,3R)-2-(Substituted-phenyl)-3-[(2-phenyl-1,3-
dioxane-5-yl)sulfanyl]-1-(1H-1,2,4-triazol-1-yl)-butan-2-ol
(9a–d)
As a typical example of oxirane opening reaction, the
preparation of 9a is described. A 4.9 N solution of sodium
methoxide in MeOH (0.12 mL, 0.39 mmol) was added to a
solution of 7a (0.93 g, 4.0 mmol) and S-(trans-2-phenyl-1,3-
dioxane-5-yl) thioacetate 8 (1.14 g, 4.8 mmol) in EtOH
(20 mL) at room temperature with stirring. The whole was
heated at 87 8C for 13 h. After the mixture was cooled, it was
3.7. (2R,3R)-2-(Substituted-phenyl)-3-{[2-hydroxy-1-
(hydroxymethyl)ethyl]sulfanyl}-1-(1H-1,2,4-triazol-1-yl)-
butan-2-ol (10a–d)
As a typical example of deprotection, the preparation of 10a
is described. An aqueous solution of 1N HCl (110 mL,
110 mmol) was added to a solution of 9a (13 g, 30.3 mmol) in

Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
649
toluene (80 mL) at room temperature, and the mixture was
stirred at 50 8C for 2.5 h. After cooling to room temperature, the
aqueous layer was separated, and the product in the organic
layer was further extracted with a diluted aqueous HCl solution
(ꢂ2) and brine, successively. The aqueous layers were
combined, and solid NaHCO3 was carefully added until CO2
gas ceased to evolve. The liberated product was extracted with
EtOAc and the combined organic extracts were washed with
brine and dried. Solvents were removed in vacuo to afford crude
solid residue, which was washed with EtOAc and collected by
was poured slowly into a stirred aqueous solution of saturated
NaHCO3 at 0 8C. The product was extracted with EtOAc (ꢂ3),
and the combined organic layer was washed with brine. The
extract was dried over MgSO4, and the solvent was removed in
vacuo to afford a colorless crude residue, which was
chromatographed on silica gel (50 g, EtOAc/Hexane = 1/1)
to afford 12a (0.43 g, 55%) as a colorless amorphous solid; 1H
NMR (400 MHz, CDCl3) d 1.19 (3H, d, J = 7 Hz), 3.39 (1H, q,
J = 7 Hz), 3.38–3.45 (1H, m), 3.62 (1H, t, J = 11 Hz), 3.65 (1H,
t, J = 11 Hz), 4.31 (1H, ddd, J = 11, 5, 2 Hz), 4.44 (1H, ddd,
J = 11, 5, 2 Hz), 4.87 (1H, d, J = 14 Hz), 4.92 (1H, s), 5.04 (1H,
d, J = 14 Hz), 5.07 (1H, d, J = 4 Hz), 5.90 (1H, dd, J = 15,
4 Hz), 6.62 (1H, dd, J = 15, 11 Hz), 6.75 (1H, d, J = 15 Hz),
6.98 (1H, dd, J = 15, 11 Hz), 6.92–7.02 (2H, m), 7.18-7.23 (1H,
m), 7.32–7.36 (2H, m), 7.41 (1H, dd, J = 8, 1 Hz), 7.58 (1H, t,
J = 8 Hz), 7.75 (1H, s), 7.77 (1H, s); IR (KBr) 3426, 2852,
2231, 1141 cmꢀ1; MS m/z (FAB) 525 (M+ + 1).
1
filtration. (5.57 g, 55%, as a pale brown amorphous solid); H
NMR (400 MHz, CDCl3) d 1.21 (3H, d, J = 7 Hz), 2.47 (1H, t,
J = 6 Hz), 2.78 (1H, t, J = 6 Hz), 3.24 (1H, quint, J = 6 Hz),
3.50 (1H, q, J = 7 Hz), 3.7–4.0 (4H, m), 4.92 (1H, d, J = 14 Hz),
5.14 (1H, d, J = 14 Hz), 5.16 (1H, s), 6.97 (1H, ddd, J = 12, 8,
1 Hz), 7.02 (1H, td, J = 8, 1 Hz), 7.22 (1H, tdd, J = 8, 5, 2 Hz),
7.39 (1H, td, J = 8, 2 Hz), 7.765 (1H, s), 7.770 (1H, s); IR (KBr)
1513, 1485, 1451, 1275, 1209, 1136, 1072, 1054 cmꢀ1; MS m/z
(FAB) 342 (M+ + 1).
1
12b: Yield 27%. A colorless amorphous solid; H NMR
(400 MHz, CDCl3) d 1.21 (3H, d, J = 7 Hz), 3.13 (1H, q,
J = 7 Hz), 3.33 (1H, tt, J = 11, 5 Hz), 3.58 (1H, t, J = 11 Hz),
3.60 (1H, t, J = 11 Hz), 4.26 (1H, ddd, J = 11, 5, 2 Hz), 4.37
(1H, ddd, J = 11, 5, 2 Hz), 4.52 (1H, d, J = 14 Hz), 4.60 (1H, s),
4.98 (1H, d, J = 14 Hz), 5.04 (1H, d, J = 4 Hz), 5.89 (1H, dd,
J = 15, 4 Hz), 6.60 (1H, dd, J = 15, 10 Hz), 6.74 (1H, d,
J = 16 Hz), 6.94 (1H, dd, J = 16, 10 Hz), 6.95–6.99 (2H, m),
7.21–7.24 (2H, m), 7.34 (1H, dd, J = 10, 1 Hz), 7.40 (1H, dd,
J = 8, 1 Hz), 7.58 (1H, t, J = 8 Hz), 7.71 (1H, s), 7.83 (1H, s); IR
(KBr) 3428, 2231, 1509, 1140 cmꢀ1; MS m/z (FAB) 525
(M+ + 1).
1
10b: Yield 87%. A pale brown amorphous solid; H NMR
(270 MHz, CDCl3) d 1.26 (3H, d, J = 7 Hz), 2.6–2.8 (2H, br),
3.16 (1H, quint, J = 6 Hz), 3.27 (1H, q, J = 7 Hz), 3.6–4.0 (4H,
m), 4.66 (1H, d, J = 14 Hz), 4.92 (1H, s), 4.94 (1H, d,
J = 14 Hz), 6.99 (2H, t, J = 9 Hz), 7.25 (2H, dd, J = 9, 5 Hz),
7.75 (1H, s), 7.84 (1H, s); IR (KBr) 1605, 1510, 1277 cmꢀ1; MS
m/z (FAB) 342 (M+ + 1).
10c: Yield 61% (overall yield from 7c). A colorless oil; 1H
NMR (400 MHz, DMSO-d6) d 1.06 (3H, d, J = 7 Hz), 2.85 (1H,
quint, J = 6 Hz), 3.55–3.68 (5H, m), 4.80 (1H, d, J = 15 Hz),
4.85 (1H, t, J = 5 Hz), 5.04 (1H, t, J = 5 Hz), 5.10 (1H, d,
J = 15 Hz), 6.01 (1H, s), 6.97–7.01 (2H, m), 7.23–7.30 (1H, m),
7.62 (1H, s), 8.31 (1H, s); IR (KBr) 3238, 1480, 1272, 1206,
1138 cmꢀ1; MS m/z (FAB) 360 (M+ + 1).
10d: Yield 83% (overall yield from 7d). A colorless oil; 1H
NMR (400 MHz, CDCl3) d 1.22 (3H, d, J = 7 Hz), 3.27 (1H,
quint, J = 6 Hz), 3.50 (1H, q, J = 7 Hz), 3.75 (1H, dd, J = 11,
6 Hz), 3.78–3.86 (2H, m), 3.96 (1H, dd, J = 11, 6 Hz), 4.89 (1H,
d, J = 14 Hz), 5.19 (1H, d, J = 14 Hz), 5.56 (1H, s), 6.87–7.00
(2H, m), 7.16–7.31 (1H, m), 7.78 (s, 1H), 7.88 (1H, s); IR (KBr)
3302, 1488, 1047 cmꢀ1; MS m/z (FAB) 360 (M+ + 1).
1
12c: Yield 55%. A colorless amorphous solid; H NMR
(400 MHz, CDCl3) d 1.21 (3H, d, J = 7 Hz), 3.36 (1H, q,
J = 7 Hz), 3.43 (1H, tt, J = 11, 5 Hz), 3.62 (1H, t, J = 11 Hz),
3.64 (1H, t, J = 11Hz), 4.32 (1H, ddd, J = 11, 5, 2 Hz), 4.43
(1H, ddd, J = 11, 5, 2 Hz), 4.85 (1H, d, J = 14 Hz), 5.06 (1H, d,
J = 14 Hz), 5.07 (1H, d, J = 4 Hz), 5.12 (1H, s), 5.90 (1H, dd,
J = 15, 4 Hz), 6.62 (1H, dd, J = 15, 10 Hz), 6.75 (d, 1H,
J = 16 Hz), 6.92–6.99 (2H, m), 7.01–7.08 (1H, m), 7.10–7.14
(1H, m), 7.34 (1H, dd, J = 10, 1 Hz), 7.41 (1H, dd, J = 8, 1 Hz),
7.58 (1H, t, J = 8 Hz), 7.79 (1H, s), 7.82 (1H, s); IR (KBr) 3406,
2231, 1480, 1275, 1140 cmꢀ1; MS m/z (FAB) 543 (M+ + 1).
1
12d: Yield 66%. A colorless amorphous solid; H NMR
3.8. 4-[(1E,3E)-4-(trans-5-{[(1R,2R)-2-(Substituted-
phenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-
yl)propyl]sulfanyl}-1,3-dioxan-2-yl)buta-1,3-dien-1-yl]-3-
fluorobenzonitrile (12a–d)
(400 MHz, CDCl3) d 1.20 (3H, d, J = 7 Hz), 3.35 (1H, q,
J = 7 Hz), 3.41 (1H, tt, J = 11, 5 Hz), 3.62 (1H, t, J = 11 Hz),
3.64 (1H, t, J = 11 Hz), 4.31 (1H, ddd, J = 11, 5, 2 Hz), 4.43
(1H, ddd, J = 11, 5, 2 Hz), 4.86 (1H, d, J = 14 Hz), 5.03 (1H, d,
J = 14 Hz), 5.06–5.08 (2H, m), 5.90 (1H, dd, J = 15, 4 Hz), 6.62
(1H, dd, J = 15, 10 Hz), 6.75 (1H, d, J = 16Hz), 6.95 (1H, dd,
J = 16, 10 Hz), 6.85–6.98 (2H, m), 7.07–7.12 (1H, m), 7.34
(1H, d, J = 10 Hz), 7.40 (1H, d, J = 8 Hz), 7.58 (1H, t,
J = 8 Hz), 7.79 (1H, s), 7.81 (1H, s); IR (KBr) 3416, 2231,
1487, 1141 cmꢀ1; MS m/z (FAB) 543 (M+ + 1).
As a typical example of acetalization, the preparation of 12a
is described. A mixture of 10a (0.51 g, 1.5 mmol), 3-fluoro-4-
[(1E,3E)-5-oxopenta-1,3-dien-1-yl]-benzonitrile
11
[24]
(0.30 g, 1.5 mmol), and p-toluenesulfonic acid monohydrate
(0.28 g, 1.64 mmol) in dry THF (10 mL) was allowed to stand
at room temperature for 30 min. Then the solvent was removed
using a rotary evaporator. The residue was suctioned using a
vacuum pump at room temperature to afford an oily residue.
Similar evaporation cycles (addition of THF, allowing the
mixture to stand, and evaporation) were repeated two more
times. To the residue, THF (15 mL) was added, and the solution
Acknowledgements
We acknowledge the contribution of Dr. Makoto Mori and
Dr. Takuya Uchida of our laboratories to this study.

650
Y. Kagoshima, T. Konosu / Journal of Fluorine Chemistry 127 (2006) 643–650
[22] Y. Kaku, A. Tsuruoka, H. Kakinuma, I. Tsukada, M. Yanagisawa, T. Naito,
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