Novel C-acylated triazole derivatives of ravuconazole, an azole antifungal agent

Article abstract of DOI:10.1002/jhet.5570450245

(Chemical Equation Presented) Novel C-acylated triazoles were synthesized from ravuconazole via bicyclic triazole lactone. The synthesis and antifungal activity of these C-acylated derivatives are described.

Full text of DOI:10.1002/jhet.5570450245

Mar-Apr 2008
583
Novel C-Acylated Triazole Derivatives of Ravuconazole,
an Azole Antifungal Agent
Oak Kim,§ Yunhui Zhang, John Wichtowski,⊥ Stella Huang, Joan Fung-Tomc, Joanne
Bronson, and Yasutsugu Ueda*
Bristol-Myers Squibb Company, Pharmaceutical Research Institute, Wallingford, CT 06492-7660, USA
Received March 16, 2007
O
R
HO
O
N
N
N
N
N
F
N
F
CN
CN
N
N
S
S
F
F
1, Ravuconazole (R = H)
3, C-Acylated triazoles (R = COXR')
2, Lactone
Novel C-acylated triazoles were synthesized from ravuconazole via bicyclic triazole lactone. The
synthesis and antifungal activity of these C-acylated derivatives are described.
J. Heterocyclic Chem., 45, 583 (2008).
the thiazole and the triazole ring, respectively, with a loss
of one triazole proton. Its IR spectrum indicated the
presence of a carbonyl absorption at 1770 cm-1, which is
typical of a γ-lactone. Its low resolution mass spectrum
indicated an M+H ion at 464.
INTRODUCTION
Ravuconazole 1 (BMS-207147, ER-30346) is a potent and
broad spectrum antifungal agent [1], which was licensed to
Bristol-Myers Squibb Co. from Eisai Co. and was under-
going clinical evaluation at BMS as an oral agent. Although
an intravenous formulation is highly desirable for treatment
of serious systemic fungal infections, ravuconazole’s poor
aqueous solubility makes it nearly impractical for the
development as an intravenous agent.
Scheme 1. Preparation of C-acylated triazoles 3 via lactone 2.
HO
N
N
N
N
CN
F
S
During our investigation to functionalize the hydroxy
group of 1, leading to a potential water-soluble prodrug,
useful for the development as an iv drug [2], we found
unusual chemistry, resulting in formation of a bicyclic
triazole lactone. This lactone served as a synthetic
intermediate for a variety of novel C-acylated triazole
derivatives of ravuconazole.
F
1, Ravuconazole
ClCOCl / pyridine / CH2Cl2
O
5
O
N
2
N
RESULTS AND DISCUSSION
3
N
CN
N
F
S
4
We had previously encountered difficulty in
derivatizing the hydroxyl group present in ravuconazole
under the traditional acylating conditions, presumably
because of the sterically hindered nature of this tertiary
hydroxyl group. For example, O-acetate or O-phenyl-
carbamate could not be obtained by conventional methods
(e.g. AcCl/pyr or phenylisocyanate [3]).
In contrast to the above observation, reaction of
ravuconazole with phosgene in the presence of excess
pyridine in CH2Cl2 proceeded with exceptional ease,
5
F
2, Lactone
R-XH / pyr-CH2Cl2
R
O
X
HO
N
N
S
N
CN
N
F
producing
a white amorphous powder which was
1
characterized as a bicyclic triazole-lactone 2 [4]. Its H
NMR spectrum (CDCl3) showed two singlets (7.60 and
7.90 ppm) which were assigned to the protons attached to
F
3, C-Acylated triazoles (see Table 1)

584
O. Kim, Y. Zhang, J. Wichtowski, S. Huang, J. Fung-Tomc, J. Bronson, and Y. Ueda
Vol 45
phase silica column resulted in a material contaminated
with more of 2, indicating the chloromethyl ester 4
cyclized during the column purification. Although C-
acylated chloromethyl ester 4 was not isolated as a pure
material, spectroscopic data of the crude material were
consistent with the structure 4. This indicates more
activated acylating agents such as phosgene and
chloromethyl chloroformate reacted with this 1,2,4-
triazole to form acylated triazoles, but not non-activated
methyl chloroformate. In a separate experiment, the
reaction of ravuconazole with chloromethyl chloro-
formate, after generating the oxy-anion by potassium
hydride in THF at room temperature provided O-acylated
chloromethyl carbonate 5, contaminated with ravucon-
azole (Scheme 2). Compound 5 was found to be unstable
in methanol solution, being hydrolyzed to ravuconazole.
These spectroscopic data, including other NMR data
(H-COSY, 13C, DEPT, HMQC and HMBC [6]), and its
elemental analysis were consistent with the lactone
structure shown in 2 (Scheme 1).
The lactone 2 reacted readily with various amines, and
methanol to produce novel triazole C-acylated amide
derivatives, and methyl ester of ravuconazole, 3,
respectively in good to modest yield, as illustrated in
Scheme 1. This lactone was also readily hydrolyzed with
aqueous sodium bicarbonate in CH3CN to provide triazole-
5-carboxylate 3 (XR = O- Na+). However, treatment of the
sodium salt with dilute HCl to isolate the acid form caused
decarboxylation, resulting in formation of ravuconazole.
Although C-acyaltion of N-substituted 1,2,4-triazoles
via lithiation [7] or enol acylate rearrangement [8] are well
documented, we believe the facile formation of C-
acylated amides and esters via cyclic lactone 2 described
here is unique.
Scheme 3. Proposed mechanism to lactone 2.
The formation of the lactone 2 was not totally
unexpected, since similar cyclic lactones were reported in
a patent literature [9].
Cl
O
OH
N
However, we were curious about how the lactone 2 was
formed, and investigated other acylating agents under
similar conditions. Methyl chloroformate [10] did not
react to form the C-acylated ravuconazole, recovering
only the starting ravuconazole. Although C-acylation was
reported in the reaction of N-substituted 1,2,4-triazoles
with alkyl chloroformate with TEA [10], these authors
revised the condition in the later publication [7a], using
lithiation followed by reaction with alkyl chloroformate to
produce 5-acylated esters of N-substituted triazoles.
N
F
Z
N
F
ClCOCl
Pyridine
6
, Acid chloride
Intermediate
1
2
Cl
?
O
O
N
N
F
Z
N
Scheme 2. Related reaction
N
Z =
CN
O
S
Cl
O
Cl
O
Cl
F
OH
N
N
F
Z
7
, Chloroformate
Intermediate
O
N
2
+
1
pyridine / CH2Cl2
Based on these results, we believe the lactone 2 was
formed via the intermediacy of acid chloride 6, followed
by the participation of the neighboring hydroxyl group,
rather than via chloroformate 7, followed by C-acylation
(Scheme 3).
Cl
O
Cl
F
4
O
KH / THF
O
Cl
O
O
F
N
N
Z
F
These novel C-acylated triazole derivatives were tested
for their antifungal activity. As summarized in Table 1,
none of these derivatives (3a-3c, 3f) displayed any
significant antifungal activity against Candida albicans,
with MIC values being 4 - >16 µg/mL. For comparison,
the reference compound ravuconazole (1) had an MIC of
0.015 µg/mL [12].
N
N
Z =
CN
S
5
Interestingly, when we used more activated chloro-
methyl chloroformate [11], C-acylated chloromethyl ester
4 was isolated as a crude product contaminated with the
lactone 2, as shown in the Scheme 2. Attempted
purification of 4 by silica gel column or C-18 reverse
The table also lists isolated yields of C-acylated
triazoles 3 from lactone 2, and the chemical shifts of their
1
hydroxy proton and heteroaromatic protons in their H
NMR spectra.

Mar-Apr 2008
C-Acylated Triazole Derivatives of Ravuconazole
585
Table 1
C-Acylated triazole derivatives of ravuconazole.
MICsb
Candida albicans
(µg/mL)
Compound
-XR
in 3
Yieldsa
(%)
-
1H NMR
(CDCl3, ppm)
5.72 (OH)
1
Ravuconazole
0.015
7.63 (thiazole-5)
7.66 (triazole-3)
7.83 (triazole-5)
7.60 (thiazole-5)
7.90 (triazole-3)
6.03 (OH)
2
lactone
22
(from 1)
65
ND
4
3a
-NHCH2CH2NHAc
7.51 (triazole-3)
7.63 (thiazole-5)
6.04 (OH)
7.49 (triazole-3)
7.63 (thiazole-5)
6.17 (OH)
7.50 (triazole-3)
7.63 (thiazole-5)
6.26 (OH)
7.57 (triazole-3)
7.62 (thiazole-5)
5.88 (OH)
7.63 (triazole-3)
7.63 (thiazole-5)
~7.34 (triazole-3)
7.95 (thiazole-5)
(CD3OD)
3b
3c
3d
3e
3f
-NHCH2CH2OH
-NHCH2CH2NMe2
-N(CH3)2
61
89
92
45
67
>16
>16
ND
ND
16
-OCH3
-O- Na+
(carboxylate)
a
Yields are not optimized; b MIC: minimum inhibitory concentration [11], ND: not determined.
4-(2-((R)-1-((R)-6-(2,4-Difluorophenyl)-8-oxo-6,8-dihydro-
5H-[1,2,4]triazolo[5,1-c][1,4]oxazin-6-yl)ethyl)thiazol-4-yl)-
benzonitrile (2). To a cold solution of ravuconazole (1) (1.09 g,
2.5 mmol) in CH2Cl2 (40 mL) was added under anhydrous
nitrogen atmosphere anhydrous pyridine (1.98 g, 25 mmol, 10
eq.). The mixture was stirred under ice cooling for 10 minutes.
To this was added dropwise 20% phosgene solution in toluene
(6.18 g, 12.5 mmol, 5 eq.). The mixture was stirred at ambient
temperature overnight. The mixture was washed with water
three times, dried over anhydrous sodium sulfate, and
concentrated in vacuo to give 1.02 g (2.2 mmol, crude yield,
88%) of a dark brown powder. A portion of the crude product
was purified by column chromatography (silica, 10%
EtOAc/CH2Cl2) to obtain 2 in about 22 % yield as a white
amorphous powder after trituration in hexanes, 1H NMR
(CDCl3) δppm 1.46 (3H, d, J = 7.3 Hz, CH3), 4.23 (1H, q, J = 7.0
Hz, CH-Me), 5.09 (1H, d, J = 14.7 Hz, NCH2), 5.33 (1H, d, J =
14.7 Hz, NCH2), 6.83-6.96 (2H, m, F/Ph-3,5-H), 7.41-7.52 (1H,
m, F/Ph-6-H), 7.60 (1H, s, thiazole-5-H), 7.71 (2H, d, J = 7.9
Hz, CN/Ph-3,5-H), 7.90 (1H, s, triazole-3-H), 7.98 (2H, d, J =
8.2 Hz, CN/Ph-2,6-H); 13C NMR (CDCl3) δppm 16.3 (CH3),
45.3 (d, J = 2.9 Hz, CH-Me), 51.2 (d, J = 8.6 Hz, NCH2), 85.9
(d, J = 4.8 Hz, OC), 105.9 (t, J = 26.5 Hz, F/Ph-3-CH), 111.9
(CN), 112.8 (dd, J = 21.1, 2.9 Hz, F/Ph-5-CH), 116.8 (thiazole-
5-CH), 118.8 (CN/Ph-1-C), 121.1 (dd, J = 10.6, 3.8 Hz, F/Ph-1-
C), 126.9 (CN/Ph-2,6-CH), 129.9 (dd, J = 9.6, 3.8 Hz, F/Ph-6-
CH), 132.8 (CN/Ph-3,5-CH), 137.9 (thiazole-4-C), 141.3
(triazole-5-C), 153.0 (lactone-C=O), 153.2 (triazole-3-CH),
153.3 (CN/Ph-4-C), 158.8 (dd, J = 249.5, 12.5 Hz, F/Ph-2-C),
163.6 (dd, J = 253.4, 12.5 Hz, F/Ph-4-C), 169.2 (thiazole-2-C);
MS (ES) m/z 464 [M+H]+; IR (KBr) νmax 2226, 1770 cm-1;
In summary, novel C-acylated triazole derivatives were
prepared by the reaction of ravuconazole with phosgene
to form bicyclic lactone 2, followed by addition of
substituted amines, methanol, or sodium bicarbonate.
Although these triazole carboxyamides and carboxylate
were found to display no useful in vitro antifungal activity
against Candida albicans, this is a unique way of
introducing carboxyamides and carboxylates at the C-5
position of the 1,2,4-triazole in antifungal triazoles.
EXPERIMENTAL
Melting points were determined on an EZ-Melt
automated melting point apparatus (Stanford Research
1
Systems). The H and 13C NMR spectra are recorded on a
Bruker A500 spectrometer at 500 and 125.8 MHz,
respectively. Electrospray ionization (ESI) high-resolution
mass spectra (HRMS) were obtained on a Micromass
LCT mass spectrometer. The IR measurement and
elemental analysis were performed by Robertson Microlit
Laboratories, Inc., Madison, NJ. 1H-1H COSY
(Correlation Spectroscopy), DEPT (Distortionless
1
Enhancement by Polarization Transfer), H-13C HMQC
1
(Heteronuclear Multiple Quantum Coherence) and H-13C
HMBC [6] (Heteronuclear Multiple Bond Correlation)
measurements obtained for the products were consistent
with the assignments reported below.

586
O. Kim, Y. Zhang, J. Wichtowski, S. Huang, J. Fung-Tomc, J. Bronson, and Y. Ueda
Vol 45
HRMS (ESI) Calcd. for C23H16F2N5O2S (M+H) 464.0993, found
464.1013 (δ +4.4 ppm). Anal. Calcd. for C23H15F2N5O2S: C,
59.60; H, 3.26; N, 15.11. Found: C, 59.90; H, 3.53; N, 14.87.
General Procedure for the Reaction of Lactone 2 with
Amine, Methanol, or Bicarbonate. For 3a – 3d, a solution of 2
and amine (3-4 equiv.) in anhydrous pyridine at room
temperature or in THF (0.06-0.14 M solution of 2) at 50°C was
stirred for 1-3 hours. For 3e, a mixture of lactone 2 (31 mg,
0.067 mmol), methanol (1 mL), and triethylamine (202 mg, 2
mmol) in THF (10 ml) was heated at reflux for 21 hours. For the
work-up of the above reactions, the mixture was concentrated in
vacuo to dryness and the residue was purified as indicated in
each section. The sodium salt 3f was obtained by treatment with
aqueous sodium bicarbonate (1 eq.) in CH3CN overnight,
followed by concentration to dryness, and analyzed spectro-
scopically as such.
(dd, J = 20.6, 3.8 Hz, F/Ph-5-CH), 111.5 (CN), 116.1 (thiazole-
5-CH), 119.0 (CN/Ph-1-C), 124.1 (dd, J = 12.5, 3.8 Hz, F/Ph-1-
C), 127.1 (CN/Ph-2,6-CH), 130.4 (dd, J = 9.6, 5.8 Hz, F/Ph-6-
CH), 132.7 (CN/Ph-3,5-CH), 138.4 (thiazole-4-C), 147.0
(triazole-5-C), 149.1 (triazole-3-CH), 152.8 (CN/Ph-4-C), 158.3
(triazole-5-C=O), 159.2 (dd, J = 248, 11.5 Hz, F/Ph-2-CF),
162.9 (dd, J = 249, 12 Hz, F/Ph-4-CF), 172.9 (thiazole-2-C);
HRMS (ESI) Calcd. for C25H23F2N6O3S (M+H) 525.1520, found
525.1527 (δ +1.3 ppm). Anal. Calcd. for C25H22F2N6O3S• 0.18
C6H14•0.3H2O: C, 587.42; H, 4.64; N, 15.41; H2O, 0.99. Found:
C, 57.44; H, 4.74; N, 15.08; H2O, 1.28 (KF).
2-((2R,3R)-3-(4-(4-Cyanophenyl)thiazol-2-yl)-2-(2,4-di-
fluorophenyl)-2-hydroxybutyl)-N-(2-(dimethylamino)ethyl)-
2H-1,2,4-triazole-3-carboxamide (3c). This compound was
obtained as a beige amorphous powder after trituration of the
1
crude in hexanes, H NMR (CDCl3) δ ppm 1.19 (3H, d, J = 7.0
2-[3-[4-(4-Cyanophenyl)-thiazol-2-yl]-2-(2,4-difluoro-
phenyl)-2-hydroxy-butyl]-2H-[1,2,4]triazole-3-carboxylic
acid (2-acetylamino-ethyl)-amide (3a). This compound was
obtained as pinkish crystals after purification by silica gel
column (eluant: 10-60% EtOAc/CH2Cl2), followed by crystal-
lization from a mixture of diethyl ether and 95% EtOH (10:1),
Hz, CH3), 2.21 (6H, s, NCH3), 2.36 - 2.49 (2H, m, NCH2), 3.36
(2H, d, J = 4.9 Hz, NCH2), 4.23 (1H, q, J = 7.0 Hz, CH-Me),
4.97 (1H, d, J = 14.0 Hz, NCH2), 5.19 (1H, d, J = 14.0 Hz,
NCH2), 6.17 (1H, br.s, OH), 6.73 (1H, dt, J = 8.3, 2.4 Hz, F/Ph-
5-CH), 6.83 (1H, ddd, J = 12, 8.5, 2.5 Hz, F/Ph-3-CH), 7.36 –
7.45 (1H, m, F/Ph-6-CH), 7.51 (1H, s, triazole-3-CH), 7.64 (1H,
s, thiazole-5-CH), 7.71 (1H, br, CONH), 7.71 (2H, d, J = 8.2 Hz,
CN/Ph-3,5-CH), 8.09 (2H, d, J = 8.2 Hz, CN/Ph-2,6-CH),
presence of a few amount of hexanes was detected; 13C NMR
(CDCl3) δppm 17.6 (CH3), 37.0 (NCH2), 44.6 (d, J = 5.8 Hz,
CH), 45.2 (NCH3), 57.0 (d, J = 4.8 Hz, NCH2), 57.3 (NCH2),
77.4 (OC), 104.0 (t, J = 27 Hz, F/Ph-3-CH), 111.1 (dd, J = 20.6,
3.4 Hz, F/Ph-5-CH), 111.4 (CN), 116.1 (thiazole-5-CH), 119.0
(CN/Ph-1-C), 124.2 (dd, J = 12.5, 3.8 Hz, F/Ph-1-C), 127.1
(CN/Ph-2,6-CH), 130.4 (dd, J = 9.6, 5.8 Hz, F/Ph-6-CH), 132.7
(CN/Ph-3,5-CH), 138.5 (thiazole-4-C), 147.2 (triazole-5-C),
149.3 (triazole-3-CH), 152.7 (CN/Ph-4-C), 157.8 (triazole-5-
C=O), 159.3 (dd, J = 248.1, 12.0 Hz, F/Ph-2-CF), 162.9 (dd, J =
248.6, 12.5 Hz, F/Ph-4-CF), 172.8 (thiazole-2-C); HRMS (ESI)
Calcd. for C27H28F2N7O2S (M+H) 552.1993, found 552.1979 (δ -
2.6 ppm). Anal. Calcd. for C27H27F2N7O2S•0.28 C6H14: C, 59.89;
H, 5.32; N, 17.05. Found: C, 59.51; H, 5.24; N, 16.72.
2-((2R,3R)-3-(4-(4-Cyanophenyl)thiazol-2-yl)-2-(2,4-di-
fluorophenyl)-2-hydroxybutyl)-N,N-dimethyl-2H-1,2,4-tri-
azole-3-carboxamide (3d). This compound was obtained as off-
white crystals after crystallization from diethyl ether, mp 202°C;
1H NMR (CDCl3) δ ppm 1.18 (3H, d, J = 7.0 Hz, CH3), 2.99
(3H, s, NCH3), 3.09 (3H, s, NCH3), 4.15 (1H, q, J = 7.0 Hz, CH-
Me), 4.70 (1H, d, J = 14.3 Hz, NCH2), 5.10 (1H, d, J = 14.3 Hz,
NCH2), 6.26 (1H, br.s, OH), 6.75 (1H, t, J = 8.2 Hz, F/Ph-5-CH),
6.84 (1H, t, J = 10.2 Hz, F/Ph-3-CH), 7.39 (1H, q, J = 8.2 Hz,
F/Ph-6-CH), 7.57 (1H, s, triazole-3-CH), 7.62 (1H, s, thiazole-5-
CH), 7.73 (2H, d, J = 7.6 Hz, CN/Ph-3,5-CH), 8.08 (2H, d, J =
7.3 Hz, CN/Ph-2,6-CH); 13C NMR (CDCl3) δppm 17.7 (CH3),
35.8 (NCH3), 39.0 (NCH3), 44.0 (d, J = 4.8 Hz, CH), 56.5 (d, J =
4.8 Hz, NCH2), 77.7 (OC), 104.0 (t, J = 26.4 Hz, F/Ph-3-CH),
111.2 (d, J = 20.2 Hz, F/Ph-5- CH), 111.6 (CN), 116.0 (thiazole-
5-CH), 119.0 (CN/Ph-1-C), 124.1 (dd, J = 12.5, 3.8 Hz, F/Ph-1-
C), 127.1 (CN/Ph-2,6-CH), 130.4 (dd, J = 8.6, 5.8 Hz, F/Ph-6-
CH), 132.7 (CN/Ph-3,5-CH), 138.4 (thiazole-4-C), 148.2
(triazole-5-C), 149.1 (triazole-3-CH), 152.8 (CN/Ph-4-C), 159.2
(dd, J = 247.6, 11.5 Hz, F/Ph-2-CF), 159.9 (triazole-5-C=O),
162.9 (dd, J = 249.5, 12.5 Hz, F/Ph-4-CF), 173.1 (thiazole-2-C);
HRMS (ESI) Calcd. for C25H23F2N6O2S (M+H) 509.1571, found
509.1588 (δ +3.3 ppm). Anal. Calcd. for C25H22F2N6O2S: C,
59.04; H, 4.36; N, 16.52. Found: C, 59.11; H, 4.42; N, 16.41.
1
mp 113°C; H NMR (CDCl3) δ ppm 1.20 (3H, d, J = 6.9 Hz,
CH3), 1.96 (3H, s, COCH3), 3.38 – 3.46 (4H, m, NCH2), 4.24
(1H, q, J = 7.0 Hz, CH-Me), 4.98 (1H, d, J = 14.0 Hz, NCH2),
5.21 (1H, d, J = 14.0 Hz, NCH2), 5.92 (1H, br.s, OH), 6.71 –
6.77 (1H, m, F/Ph-5-H), 6.80 – 6.88 (1H, m, F/Ph-3-H), 7.34 –
7.43 (1H, m, F/Ph-6-H), 7.56 (1H, s, triazole-3-H), 7.64 (1H, s,
thiazole-5-H), 7.73 (2H, d, J = 8.5 Hz, CN/Ph-3,5-H), 7.94 (1H,
br.s, CONH), 8.09 (2H, d, J = 8.5 Hz, CN/Ph-2,6-H); presence
of a few amount of EtOH was detected; 13C NMR (CDCl3) δppm
17.6 (CH3), 23.2 (CO-CH3), 39.6 (NCH2), 40.3 (NCH2), 44.5 (d,
J = 5.8 Hz, CH), 57.0 (d, J = 4.8 Hz, NCH2), 77.5 (OC), 104.1 (t,
J = 26.9 Hz, F/Ph-3-CH), 111.1 (dd, J = 20.6, 2.4 Hz, F/Ph-5-
CH), 111.5 (CN), 116.1 (thiazole-5-CH), 119.0 (CN/Ph-1-C),
124.1 (dd, J = 12.0, 3.4 Hz, F/Ph-1-C), 127.1 (CN/Ph-2,6-CH),
130.4 (dd, J = 8.6, 5.8 Hz, F/Ph-6-CH), 132.7 (CN/Ph-3,5-CH),
138.5 (thiazole-4-C), 147.0 (triazole-5-C), 149.4 (triazole-3-
CH), 152.7 (CN/Ph-4-C), 158.5 (triazole-5-C=O), 159.2 (dd, J =
247.1, 12.0 Hz, F/Ph-2-CF), 162.9 (dd, J = 249.0, 12.0 Hz, F/Ph-
4-CF), 171.3 (CH3-C=O), 172.8 (thiazole-2-C); HRMS (ESI)
Calcd. for C27H26F2N7O3S (M+H) 566.1786, found 566.1803 (δ
+3.0 ppm). Anal. Calcd. for C27H25F2N7O3S •0.6 C2H5OH: C,
57.09; H, 4.86; N, 16.53. Found: C, 57.26; H, 4.65; N, 16.35.
2-((2R,3R)-3-(4-(4-Cyanophenyl)thiazol-2-yl)-2-(2,4-di-
fluorophenyl)-2-hydroxybutyl)-N-(2-hydroxyethyl)-2H-1,2,4-
triazole-3-carboxamide (3b). This compound was obtained as a
white foam after purification by silica gel column (eluant: 10-
60% EtOAc/CH2Cl2), followed by trituration in hexanes, 1H
NMR (CDCl3) δ ppm 1.19 (3H, d, J = 7.0 Hz, CH3), 2.20 (1H,
br, OH), 3.40 - 3.53 (2H, m, NCH2), 3.70 - 3.80 (2H, m, NCH2),
4.24 (1H, q, J = 7.2 Hz, CH-Me), 5.01 (1H, d, J = 14.0 Hz,
NCH2), 5.18 (1H, d, J = 14.0 Hz, NCH2), 6.72 (1H, dt, J = 8.3,
2.5 Hz, F/Ph-5-CH), 6.83 (1H, ddd, J = 11.5, 8.5, 2.5 Hz, F/Ph-
3-CH), 7.35 – 7.04 (1H, m, F/Ph-6-CH), 7.52 (1H, s, triazole-3-
CH), 7.63 (1H, s, thiazole-5-CH), 7.66 (1H, t, J = 5.3 Hz,
CONH), 7.72 (2H, d, J = 8.5 Hz, CN/Ph-3,5-CH), 8.09 (2H, d, J
= 8.5 Hz, CN/Ph-2,6-CH), presence of a few amount of hexanes
was detected; 13C NMR (CDCl3) δ ppm 17.6 (CH3), 42.2
(NCH2), 44.3 (d, J = 4.8 Hz, CH), 57.0 (d, J = 3.8 Hz, NCH2),
61.3 (OCH2), 77.5 (OC), 104.1 (t, J = 28 Hz, F/Ph-3-CH), 111.1

Mar-Apr 2008
C-Acylated Triazole Derivatives of Ravuconazole
587
Methyl 2-((2R,3R)-3-(4-(4-Cyanophenyl)thiazol-2-yl)-2-(2,4-
difluorophenyl)-2-hydroxybutyl)-2H-1,2,4-triazole-3-carbox-
ylate (3e). This compound was obtained as beige crystals after
crystallization from a mixture of diethyl ether and methanol
3-CH or thiazole-5-CH), 7.63 (1H, s, thiazole-5-CH or triazole-
3-CH), 7.76 (2H, d, J = 8.5 Hz, CN/Ph-3,5-CH), 8.11 (2H, d, J =
8.5 Hz, CN/Ph-2,6-CH). The presence of about 40 mol % of the
lactone 2 was observed; 13C NMR (CDCl3) δppm 18.0 (CH3),
42.7 (d, J = 5.8 Hz, CH), 57.3 (d, J = 3.8 Hz, NCH2), 69.5
(OCH2), 77.9 (d, J = 4.8 Hz, OC), 104.1 (t, J = 26.5 Hz, F/Ph-3-
CH), 111.5 (dd, J = 20.6, 3.4 Hz, F/Ph-5-CH), 111.9 (CN), 115.3
(thiazole-5-CH), 118.9 (CN/Ph-1-C), 123.2 (dd, J = 11.5, 3.8
Hz, F/Ph-1-C), 127.2 (CN/Ph-2,6-CH), 130.3 (dd, J = 9.1, 5.3
Hz, F/Ph-6-CH), 132.8 (CN/Ph-3,5-CH), 137.8 (thiazole-4-C),
144.3 (triazole-5-C), 150.3 (triazole-3-CH), 153.5 (CN/Ph-4-C),
156.9 (triazole-5-C=O), 159.1 (dd, J = 247.6, 11.5 Hz, F/Ph-2-
CF), 163.0 (dd, J = 250.5, 12.5 Hz, F/Ph-4-CF), 172.9 (thiazole-
2-C), Peaks corresponding to the lactone 2 were also observed;
HRMS (ESI) Calcd. for C24H19F2N5O3S (M+H) 530.0865, found
530.0847 (δ - 3.4 ppm).
1
(2:1), mp 169°C; H NMR (CDCl3) δ ppm 1.20 (3H, d, J = 7.3
Hz, CH3), 3.85 (3H, s, OCH3), 4.20 (1H, q, J = 7.0 Hz, CH-Me),
4.93 (1H, d, J = 14.0 Hz, NCH2), 5.17 (1H, d, J = 14.0 Hz,
NCH2), 6.79 – 6.87 (1H, m, F/Ph-5-CH), 6.79 – 6.87 (1H, m,
F/Ph-3-CH), 7.33 – 7.41 (1H, m, F/Ph-6-CH), 7.63 (2H, s,
triazole-3-CH and thiazole-5-CH), 7.74 (2H, d, J = 8.5 Hz,
CN/Ph-3,5-CH), 8.09 (2H, d, J = 8.5 Hz, CN/Ph-2,6-CH); 13C
NMR (CDCl3) δppm 17.9 (CH3), 44.3 (d, J = 5.8 Hz, CH), 53.0
(OCH3), 57.0 (d, J = 3.8 Hz, NCH2), 77.8 (d, J = 4.8 Hz, OC),
104.1 (t, J = 26.5 Hz, F/Ph-3-CH), 111.4 (dd, J = 20.2, 2.9 Hz,
F/Ph-5-CH), 112.0 (CN), 115.5 (thiazole-5-CH), 118.8 (CN/Ph-
1-C), 123.5 (dd, J = 12.5, 3.8 Hz, F/Ph-1-C), 127.1 (CN/Ph-2,6-
CH), 130.4 (dd, J = 9.6, 5.8 Hz, F/Ph-6-CH), 132.7 (CN/Ph-3,5-
CH), 137.9 (thiazole-4-C), 145.3 (triazole-5-C), 150.2 (triazole-
3-CH), 153.2 (CN/Ph-4-C), 158.8 (triazole-5-C=O), 159.1 (dd, J
= 247.6, 12.5 Hz, F/Ph-2-CF), 163.0 (dd, J = 249.5, 12.5 Hz,
F/Ph-4-CF), 173.1 (thiazole-2-C); HRMS (ESI) Calcd. for
C24H20F2N5O3S (M+H) 496.1255, found 496.1274 (δ +3.8 ppm).
Anal. Calcd. for C24H19F2N5O3S: C, 58.17; H, 3.86; N, 14.13.
Found: C, 58.13; H, 3.81; N, 14.15.
Carbonic acid chloromethyl ester 2-[4-(4-cyanophenyl)-
thiazol-2-yl]-1-(2,4-difluorophenyl)-1-[1,2,4]triazol-1-yl-methyl-
propyl ester (5). To a stirred solution of ravuconazole (1) (88
mg, 0.20 mmol) in anhydrous THF (1 mL) was added a
suspension of KH (35 mg, 30 % oil suspension) in THF (0.5
mL) at room temperature under anhydrous nitrogen atmosphere,
and the mixture stirred for 15 minutes. To this mixture was
added chloromethyl chloroformate (50 mg, 0.3 mmol; Fluka),
and the mixture stirred for 1.5 hours. The reaction was quenched
by addition of water, and the mixture diluted with EtOAc (~15
mL) was washed successively with water, 0.1 N HCl, and then
with brine. The organic phase was dried (sodium sulfate), and
concentrated in vacuo to obtain 75 mg (0.14 mmol, Y. 71 %) of
the title compound 5, contaminated with about 35 mol % of
Sodium 2-((2R,3R)-3-(4-(4-Cyanophenyl)thiazol-2-yl)-2-(2,4-
difluorophenyl)-2-hydroxybutyl)-2H-1,2,4-triazole-3-carbox-
ylate (3f). This compound was obtained as an off-white powder,
1H NMR (CD3OD) δ ppm 1.06 (3H, d, J = 6.7 Hz, CH3), 4.18
(1H, q, J = 7.0 Hz, CH-Me), 4.78 - 4.86 (1H, m, NCH2), 4.95
(1H, d, J = 13.4 Hz, NCH2), 6.68 (1H, br.s, F/Ph-5-CH), 6.84
(1H, t, J = 9.2 Hz, F/Ph-3-CH), 7.28 - 7.47 (2H, m, F/Ph-6-CH,
and triazole-3-CH), 7.69 (2H, d, J = 7.6 Hz, CN/Ph-3,5-CH),
7.95 (1H, s, thiazole-5-CH), 8.07 (2H, d, J = 7.0 Hz, CN/Ph-2,6-
CH); 13C NMR (CDCl3) δppm 16.9 (CH3), 46.0 (d, J = 5.8 Hz,
CH), 56.8 (NCH2), 77.0 (OC), 103.7 (t, J = 27 Hz, F/Ph-3-CH),
110.6 (dd, J = 21.1, 2.9 Hz, F/Ph-5-CH), 111.0 (CN), 118.0
(thiazole-5-CH), 118.9 (CN/Ph-1-C), 125.7 (dd, J = 13.0, 3.4
Hz, F/Ph-1-C), 127.1 (CN/Ph-2,6-CH), 130.8 (dd, J = 9.1, 6.2
Hz, F/Ph-6-CH), 132.8 (CN/Ph-3,5-CH), 139.3 (thiazole-4-C),
148.9 (triazole-3-CH), 152.1 (CN/Ph-4-C), 159.9 (dd, J = 247.1,
12.0 Hz, F/Ph-2-CF), 163.2 (dd, J = 247.1, 13.0 Hz, F/Ph-4-CF),
173.5 (thiazole-2-C); HRMS (ESI) Calcd. for C23H16F2N5O3S
(M-H) 480.0942, found 480.0935 (δ -1.4 ppm).
1
ravuconazole (1) as an amber foam, H NMR (CDCl3) δppm
1.53 (3H, d, J = 7.0 Hz; CH3), 4.35 (1H, q, J = 6.7 Hz; CH-Me),
5.47 (1H, d, J = 15 Hz; NCH2), 5.61 (1H, d, J = 15 Hz, NCH2),
5.69 (1H, d, J = 6.1 Hz, OCH2), 5.74 (1H, d, J = 6.5 Hz, OCH2),
6.70 (1H, t, J = 7.6 Hz, F/Ph-5-CH), 6.75-6.83 (1H, m, F/Ph-6-
CH), 6.87 (1H, m, F/Ph-3-CH), 7.52 (1H, s, thiazole-5-CH),
7.65 (2H, d, J = 8.2 Hz, CN/Ph-3,5-CH), 7.85 (2H, d, J = 7.9 Hz,
CH3
CH3
H3C
N
N
O
O
O
OH
O
OH
CH3
H
CH3
H
CH3
H
O
N
N
N
F
N
F
Z
N
F
Z
Z
H
H
H
H
H
H
H
HH
N
N
N
2-[3-[4-(4-Cyanophenyl)-thiazol-2-yl]-2-(2,4-difluoro-
phenyl)-2-hydroxy-butyl]-2H-[1,2,4]triazole-3-carbox-
ylic acid chloromethyl ester (4). To a stirred solution of
ravuconazole (1) (88 mg, 0.2 mmol) and anhydrous pyridine
(158 mg, dried over KOH) in CH2Cl2 (1 mL; Sure Seal) was
added in an ice-bath under anhydrous nitrogen atmosphere
dropwise a solution of chloromethyl chloroformate (129 mg, 1.0
mmol; Fluka) in CH2Cl2 (1 mL). The mixture was stirred at
ambient temperature overnight. The mixture diluted with CH2Cl2
(15 mL) was washed successively with water, 0.1 N HCl and
brine. This was dried (sodium sulfate), and concentrated in
vacuo to give the title compound 4 (95 mg, 0.18 mmol; Y. 90
F
F
F
2, Lactone
3d
3e
Cl
O
H
H
H
H
O
Cl
O
OH
O
H
CH3
H
CH3
H
N
O
N
N
F
Z
N
H
Z
F
H
H
N
HH
N
H
1
%), contaminated with the lactone 2 as a crude film, H NMR
(CDCl3) δppm 1.19 (3H, d, J = 7.0 Hz; CH3), 4.14 (1H, q, J =
7.1 Hz; CH-Me), 4.97 (1H, d, J = 13.7 Hz, NCH2), 5.08 (1H, d, J
= 13.7 Hz; NCH2), 5.73 (1H, d, J = 6.1 Hz, OCH2), 5.88 (1H, d,
J = 6.1 Hz, OCH2), 5.98 (1H, br.s, OH), 6.74 (1H, dt, J = 8.3, 2.3
Hz, F/Ph-5-CH), 6.83 (1H, ddd, J = 12, 8.7, 2.5 Hz, F/Ph-3-CH),
7.34 (1H, dt, J = 8.9, 6.7 Hz, F/Ph-6-CH), 7.61 (1H, s, triazole-
F
F
4
5
a: The newly formed section of the each compound is shown. Red arrows indicate
observed H-C connectivity.
Figure 1. 2D NMR Correlation of the representative compounds by HMBCa

588
O. Kim, Y. Zhang, J. Wichtowski, S. Huang, J. Fung-Tomc, J. Bronson, and Y. Ueda
Vol 45
[2] Ueda, Y.; Matiskella, J. D.; Golik, J.; Connolly, T. P.;
Hudyma, T. W.; Venkatesh, S.; Dali, M.; Kang, S. H.; Barbour, N.;
Tejwani, R.; Varia, S.; Knipe, J.; Zheng, M.; Mathew, M.; Mosure, K.;
Clark, J.; Lamb, L.; Medina, I.; Gao, Q; Huang, S.; Chen C.-P.; Bronson,
J.J. Bioorg. Med. Chem. Lett. 2003, 13, 3669.
CN/Ph-2,6-CH), 7.88 (1H, s, triazole-3-CH), 8.04 (1H, s,
triazole-5-CH). The presence of about 35 mol % of ravucon-
azole (1) was observed; 13C NMR (CDCl3) δppm 15.9 (CH3),
44.3 (CH), 50.3 (d, J = 11.5 Hz, NCH2), 72.4 (OCH2), 87.4 (d, J
= 5.8 Hz, OC), 105.0 (dd, J = 28.3, 25.4 Hz, F/Ph-3-CH), 111.5
(CN), 111.7 (dd, J = 20.6, 3.4 Hz, F/Ph-5-CH), 116.2 (thiazole-
5-CH), 118.9 (CN/Ph-1-C), 119.1 (dd, J = 10.6, 3.8 Hz, F/Ph-1-
C), 126.8 (CN/Ph-2,6-CH), 130.0 (dd, J = 9.1, 5.3 Hz, F/Ph-6-
CH), 132.7 (CN/Ph-3,5-CH), 138.3 (thiazole-4-C), 144.9
(triazole-5-CH), 151.1 (OC=O), 152.1 (triazole-3-CH), 152.9
(CN/Ph-4-C), 159.3 (dd, J = 249, 11.5 Hz, F/Ph-2-CF), 163.1
(dd, J = 253, 13.0 Hz, F/Ph-4-CF), 168.7 (thiazole-2-C). Peaks
corresponding to ravuconazole (1) were also observed. HRMS
(ESI) Calcd. for C24H19F2N5O3S (M+H) 530.0865, found
530.0887 (δ + 4.1 ppm).
[3] Hearon, W. M. Methods Carbohydrate Chenistry 1963, 2, 239.
[4] We originally thought O-carbonates or O-carbamates which
contain a water-soluble functionality, prepared by the reaction of
ravuconazole with phosgene followed by amines or alcohols containing
a water-soluble group could serve as potential prodrugs since those can
be hydrolyzed in vivo by esterases or carbamidases [5].
[5] Sinkula, A.A; Yalkowsky, S.H. J. Pharmaceut. Sci., 1975,
64, 181; Patt, W. C.; Reisdorph, B. R.; Repine, J. T.; Doherty, A. M.;
Haleen,S. J.; Walker, D. M.; Welch, K. M.; Flynn, M. A.; Hallak, H.;
Reyner, E. L. Bioorg. Med. Chem. Lett. 1997, 7, 297.
[6] 2D NMR correlation of the representative compounds, 2, 3d,
3e, 4, and 5 by HMBC is shown in Figure 1. It is interesting to note the
absence of connectivity between the NCH2 and the CH-Me in the C-
acylated derivatives, such as compound 3d, 3e and 4.
[7] For example (a) Dallacker, F.; Minn, K. Chem. -Ztg., 1986,
110, 275. (b) Anderson, D. K.; Sikorski, J. A.; Reitz, D. B.; Pilla, L. T. J.
Heterocycl. Chem. 1986, 23, 1257. (c) Micetich, R. G.; Spevak, P.; Hall,
T. W.; Bains, B. K. Heterocycles, 1985, 23, 1645. (d) Ohta, S.;
Kawasaki, I.; Fukuno, A.; Yamashita, M.; Tada, T.; Kawabata, T. Chem.
Pharm. Bull. 1993, 41, 1226.
Acknowledgements. We would like to thank our Discovery
Analytical Service group and the Microbiology department for
supplying analytical and microbiological data for the
compounds. We also thank Jonathan Weiss for the manuscript
preparation.
REFERENCES AND NOTES
§
[8] (a) Radul, O. M.; Krimer, M. Z.; Rebrova, O. N.; Biyushkin,
V. N.; Feofanova, I. V.; Panasenko, A. A. Izv. Akad. Nauk. Ser. Khim.
1993, 560. (b). Radul, O. M.; Krimer, M. Z. Izv. Akad. Nauk. SSSR Ser.
Khim. 1990, 1454. (c) Radul, O. M.; Krimer, M. Z. Dokl. Akad. Nauk.
SSSR 1991, 321, 538.
Present address: Paratek Pharmaceuticals Inc., 75 Kneeland
St., Boston, MA 02111.
⊥
Present address: Pfizer Inc., MS 8260-1611, Eastern Point
Road, Groton, CT 06340
*
Corresponding author. Fax: 203-677-7702, e-mail:
[9] Saito. J.; Kurahashi, Y.; Goto, T.; Yamaguchi, N. Eur. Pat.
Appl. 185987, 1986; Chem. Abstr. 1986, 105, 153072.
Yasutsugu.Ueda@bms.com
[1] (a) Hata, K.; Kimura, J.; Miki, H.; Toyosawa, T.; Nakamura,
T.; Katsu, K. Antimicrob. Agents Chemother. 1996, 40, 2237. (b) Fung-
Tomc, J. C.; Huczko, E.; Minassian, B.; Bonner, D. Antimicrob. Agents
Chemother., 1998, 42, 313. and references therein. (c) For a recent
review article on ravuconazole, see Arikan, S.; Rex, J. H. Current
Opinion in Investigational Drugs, 2002, 3, 555.
[10] Dallacker, F.; Minn, K. Chem. -Ztg., 1986, 110, 101.
[11] Available from Fluka Chemika.
[12] In vitro antifungal activity, MIC (minimum inhibitory
concentration) was determined by the microbroth dilution method,
inoculum of ~2x103 cfu/mL, and incubation time of 48 hours [1b].