Synthesis and SAR of amino acid-derived heterocyclic progesterone receptor full and partial agonists

Article abstract of DOI:10.1016/j.bmcl.2009.03.146

Two classes of amino acid-derived heterocyclic progesterone receptor ligands were developed to address the metabolic issues posed by the dimethyl amide functionality of the lead compound (1). The tetrazole-derived ligands behaved as potent partial agonist

Full text of DOI:10.1016/j.bmcl.2009.03.146

Bioorganic & Medicinal Chemistry Letters 19 (2009) 2637–2641
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and SAR of amino acid-derived heterocyclic progesterone receptor
full and partial agonists
a
a
a
a
Marlys Hammond a, , Jaclyn R. Patterson , Sharada Manns , Tram H. Hoang , David G. Washburn ,
Walter Trizna b, Lindsay Glace b, Eugene T. Grygielko b, Rakesh Nagilla c, Melanie Nord c, Harvey E. Fries c,
Douglas J. Minick d, Nicholas J. Laping b, Jeffrey D. Bray b, Scott K. Thompson a
*
a Department of Chemistry, Metabolic Pathways Centre for Excellence in Drug Discovery, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA
b Department of Biology, Metabolic Pathways Centre for Excellence in Drug Discovery, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA
c Department of Drug Metabolism and Pharmacokinetics, Metabolic Pathways Centre for Excellence in Drug Discovery, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road,
King of Prussia, PA 19406, USA
d Department of Analytical Chemistry, Molecular Discovery Research, GlaxoSmithKline Pharmaceuticals, Research Triangle Park, NC 27709, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Two classes of amino acid-derived heterocyclic progesterone receptor ligands were developed to address
the metabolic issues posed by the dimethyl amide functionality of the lead compound (1). The tetrazole-
derived ligands behaved as potent partial agonists, while the 1,2,4-triazole ligands behaved as potent full
agonists.
Received 9 February 2009
Revised 28 March 2009
Accepted 31 March 2009
Available online 5 April 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Progesterone
Partial agonist
Full agonist
Triazole
Tetrazole
The steroid hormones progesterone (P4) and estrogen (E2) play
an important role in the female reproductive process. In the uterus,
E2 stimulates the proliferation of the endometrium, while P4
blocks this growth in an E2-dependent manner.1 While the exact
mechanism of this effect is not fully understood, in vitro and
in vivo studies have demonstrated that this antagonism requires
complexation of P4 with the progesterone receptor (PR)2 and can
operate through two general pathways: (1) an autocrine mecha-
nism in which liganded PR interferes with the ability of E2-bound
estrogen receptor (ER) to stimulate gene expression,3 and (2) a par-
acrine mechanism whereby P4-bound PR in one cell type, through
its gene products, suppresses E2-stimulated gene expression in an-
other cell type.4
In addition to regulating the female reproductive cycle, P4 and
E2 also play a role in modulating endometriosis, a condition char-
acterized by growth of endometrial tissue outside of the uterus
that is associated with dysmenorrhea, chronic pelvic pain, fatigue
and a host of other symptoms. As with endometrial tissue within
the uterus, proliferation of endometrial lesions is stimulated by
E2 and blocked by P4.5 Consequently, treatments for endometriosis
include the use of P4 and other progestins to moderate growth of
the offending lesions. Progestin therapies have been found to be
efficacious, but not without unpleasant side effects that include
depression, breakthrough bleeding and breast tenderness, some
of which are mediated through PR agonism.6 Additional adverse ef-
fects may be attributed to the poor nuclear hormone receptor
(NHR) selectivity of most progestins, including P4 itself.7
In the search for improved endometriosis treatments, opportu-
nity exists for exploitation of the diverse pathways involved in E2
opposition by PR agonism, including the development of small
molecule PR modulators, PR partial agonists, and highly selective
PR full agonists. A PR modulator strategy would, via selective
recruitment of cofactors by the liganded PR, be dependent upon
selective expression of proteins responsible for mediating E2 oppo-
sition while avoiding expression of proteins that mediate adverse
effects.8 Alternatively, a PR partial agonist approach would not rely
on differential cofactor recruitment, but on reducing the level of
PR-regulated gene expression such that enough gene products
are obtained to oppose E2 but not to induce side effects. Finally,
a highly selective PR full agonist would offer E2 antagonism with-
out the side effects brought about by activity at other NHRs. The
work disclosed herein is the result of efforts applied to the latter
two approaches.
* Corresponding author. Fax: +1 610 270 6609.
E-mail address: marlys.2.hammond@gsk.com (M. Hammond).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.03.146

2638
M. Hammond et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2637–2641
Table 1
Specifically, the goal of this program has been to identify small
Selected in vitro data for compounds 3–10.a
molecules having a profile that includes potent binding at the pro-
gesterone receptor (ideally <20 nM), P100-fold selectivity over
other NHRs, including the androgen receptor (AR), glucocorticoid
receptor (GR), mineralocorticoid receptor (MR) and ER, and par-
tial-to-full PR agonism. Chemistry initiated with the lead dimethyl
amide 1 (Fig. 1). Compound 1 demonstrated a PR binding IC50 of
32 nM9 and sub-nanomolar activity in a T47D-based alkaline phos-
phatase PR agonist assay.10,11 With respect to NHR selectivity,
compound 1 was 50-fold selective over AR and >100-fold selective
over GR, MR and ER, indicating that AR selectivity required
improvement. Early in the team’s efforts to optimize the
pharmacological properties of 1, it became apparent that the dim-
ethylamide group was metabolically unstable, and isosteric
replacement of this moiety might offer a means of discharging this
liability.
Applying the strategy of utilizing five-membered ring heterocy-
cles as amide surrogates, a survey of heterocyclic amide replace-
ments was conducted. A number of ligands were identified as
having good to excellent PR binding potency and agonist activity
in the T47D PR agonist assay (Table 1). Across all heterocycles
examined, P450 inhibition profiles (represented by inhibition at
the 2C19 isoform in Table 1), would require optimization and of-
fered no means of differentiation. Examination of the binding
and functional parameters, however, did allow for differentiation,
as those ligands with a methyl substituent in the 2-position rela-
tive to the point of core attachment, (exemplified by entries 4, 7,
9 and 10) were found to be both more selective over AR and signif-
icantly more potent in the agonist assay. The reduced cell poten-
cies of compounds 3, 5, 6, and 8 coupled with the lower AR
selectivity of compounds 3, 5, and 6 rendered them less appealing.
Based on their exceptional potencies and selectivities, tetrazole 9
and triazole 10 were selected for further SAR activities.
Cl
N
Het
Cl
N
Compd Het
PR
binding
IC50 (nM) fold)
AR binding
selectivity (- EC50 (nM)
PR T47D
P450 2C19
inhibition
IC50 (lM)
(% P4)
S
3
4
13b
25
15
380 (19)
0.067
N
N
N
318
6.0 (102)
606 (32)
272 (22)
0.60 (99)
14 (80)
<0.033
N
N
5
40
16
0.040
N
N
O
6
20
10
<0.033
<0.033
0.091
N
7
20
500
163
>770
>770
N
N
O
N
N
N
8
32
Analogs of 9 were prepared as shown in Scheme 1.12 Reaction of
2-chloro-4-fluorobenzonitrile with an amino acid followed by
Fischer esterification produced ester 11. Treatment with an alumi-
num amide was followed by reaction with TMS azide under Mits-
unobu-like conditions13 to afford tetrazole 12, which was then
alkylated to provide target tetrazoles 9 and 13–22. In most cases,
the syntheses began with single amino acid enantiomers, however
it was later determined that scrambling of the stereocenter bearing
the R2 substituent occurred during alkylation of the aniline nitro-
gen. In the cases examined, the racemization was not complete,
and with the exception of the example in which the enantiomers
were separated (vide infra), compounds were tested as mixtures
of undetermined ee and are shown without indication of absolute
stereochemistry.
Several SAR trends were identified in this class of tetrazoles. For
example, substitution at the R2 position was important for potency
in the PR functional assay (Table 2, cf. compound 13 vs. compounds
9, 14, and 15). In addition, while all other compounds exemplified
in Table 2 were at least 100-fold selective for PR over AR, com-
pound 13 was only 40-fold selective (data not shown). Increasing
13b
13b
0.02 (92)
0.5 (107)
<0.033
<0.033
N
9
N
N
N
10
N
a
Values are the mean of P2 determinations.
b
Tight-binding limit of the assay.
O
H
F
Cl
Cl
N
Cl
Cl
a, b
OEt
R2
11
c, d
N
N
N
N
R1
N
N
N
N
N
H
N
N
N
e
N
N
Cl
R3
R3
R2
R2
O
9, 13-22
12
N
Cl
N
Scheme 1. Reagents and conditions: (a) H2NCH(R2)CO2H, K2CO3, DMF/H2O, 90 °C,
15 h; (b) EtOH, H2SO4, 80 °C, 15 h; (c) R3NH2ÁHCl, AlMe3, PhCH3, 0–60 °C, 36 h; (d)
TMSN3, PPh3, DIAD, THF, 0–23 °C, 4d; (e) R1Br, NaH, DMF, 0–23 °C, 15 h.
N
1
PR IC50 = 32 nM
T47D EC50 = 0.7 nM
the length of the R2 substituent led to an attenuation in intrinsic
agonism (and potency to a lesser extent) such that compound 15
Figure 1. Lead PR ligand 1.

M. Hammond et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2637–2641
2639
Table 2
Selected in vitro data for compounds 9 and 13–22a
R1
N
N
N
N
Cl
N
R3
R2
N
Compd
R1
R2
R3
PR IC50 (nM)
T47D EC50 (nM) (% P4)
P450 2C19 IC50 (lM)
9
2-Cl–Bn
2-Cl–Bn
2-Cl–Bn
2-Cl–Bn
2-Cl–Bn
2-Cl–Bn
2-CF3–Bn
i-Bu
Me
H
Et
i-Bu
Me
Me
Me
Me
Me
Et
i-Pr
Me
Me
Me
Me
Me
13
50
13
5
16
32
25
16
40
16
200
0.02 (93)
197 (ND)
0.04 (73)
1.3 (60)
0.6 (122)
35 (116)
139 (56)
9.5 (47)
11 (31)
6.8 (38)
ND
<0.033
<0.33
<0.033
0.30
<0.033
0.08
1.3
8.8
17
6.4
ND
13
14
15
16
17
18
19
20
21
22
Me
i-Bu
i-Bu
i-Bu
(S)-i-Bub
(R)-i-Bub
c-Bu(CH2)
c-Bu(CH2)
c-Bu(CH2)
a
Values are means of P 2 determinations.
See Ref. 15. ND = Not determined.
b
N
N
demonstrated intrinsic agonism that was 60% of P4. By contrast,
adding steric bulk directly to the tetrazole ring resulted in de-
creased agonist potency, but not intrinsic agonism (Table 2, cf.
compound 9 vs. compounds 16 and 17). The P450 inhibition (rep-
resented by 2C19 inhibition) was most influenced by modification
of the R1 aniline substituent. Compound 18, in which the 2-chloro-
benzyl substituent was replaced with a 2-(trifluoromethyl)benzyl
substituent, demonstrated markedly reduced 2C19 inhibition, but
this improvement appeared to come at the cost of agonist potency.
Ultimately, replacement of benzyl groups at R1 with aliphatic sub-
stituents led to the identification of partial agonists 19 and 20, each
having excellent PR binding, functional potency, and PR partial
agonism. Compound 20 was separated into its individual enantio-
mers 21 and 22 and all PR agonist activity was found to reside in
enantiomer 21.14
Synthesis of analogs of 10 began with the same amino acid—
aryl fluoride displacement reaction as for the tetrazole class
(Scheme 2).15 Coupling of the product acid with 4-methyl-3-thio-
semicarbazide followed by a one-pot cyclization/alkylation16 pro-
vided methylthio-substituted intermediate 23. Alkylation of the
aniline nitrogen and reductive removal of the methylthio group
afforded target triazoles 10 and 25–31. An additional set of com-
pounds in which a methyl group was incorporated at the five-posi-
tion of the triazole ring was prepared as shown in Scheme 3.17
F
Cl
N
H
a-c
N
Cl
O
R2
N
24
d, e
R1
N
N
N
Cl
N
R2
N
32-34
Scheme 3. Reagents and conditions: (a) H2NCH(R2)CO2H, K2CO3, DMF/H2O, 90 °C,
15 h; acetylhydrazide, EDC, HOBT, THF, 23 °C, 18 h; (c) POCl3, CH3CN, 75 °C, 3 h; (d)
CH3NH2, MeOH, microwave, 200 °C, 1 h; (e) NaH, DMF, R1Br, 0–23 °C, 15 h.
Amino acid—aryl fluoride displacement was followed by coupling
with acetylhydrazide and cyclization to oxadiazole 24. Conversion
of the oxadiazole to the N-methyl-1,2,4-triazole could be accom-
plished by heating in a microwave in the presence of an excess
of methylamine in methanol.18 Finally, alkylation of the aniline
nitrogen produced target triazoles 32–34. As with the tetrazole
class, some scrambling of the stereocenter adjacent to R2 occurred
during the aniline alkylation. Compounds were tested as mixtures
of undetermined ee and are shown without indication of absolute
stereochemistry.
Triazole-based PR ligands were similar in potency to their tetra-
zole-based counterparts, and several of the same SAR trends were
observed. As seen with entries 10 and 25–28 (Table 4), increasing
the size of the substituent in the R2 position attenuated intrinsic
agonism but also produced a corresponding drop in potency. As
with the tetrazole class, P450 inhibition (represented by 2C19 inhi-
bition) was observed with most analogs, and although modifica-
tions at R1 provided the same benefit, a significant drop in
progesterone-related potencies was observed (cf. 18 vs 29 and 19
vs 30). The exception to this was cyclohexylmethylene-substituted
analog 31, which had good PR binding and functional potency, full
agonism, and an acceptable P450 inhibition profile. Another strat-
egy for reducing P450 inhibition was introduction of a methyl
group to the five-position of the triazole, exemplified by com-
pounds 32–34. While compound 34, with significant bulk at R2,
N
N
F
Cl
H
N
a-c
S
Cl
N
N
R3
R2
23
N
N
d, e
R1
N
N
Cl
N
R3
R2
N
10, 25-31
Scheme 2. Reagents and conditions: (a) H2NCH(R2)CO2H, K2CO3, DMF/H2O, 90 °C,
15 h; (b) 4-methyl-3-thiosemicarbazide, EDC, i-Pr2NEt, HOBT, THF, 23 °C, 24 h; (c)
NaOMe, MeOH, 60 °C, 15 h, then MeI, 24 h; (d) RaNi, EtOH, 80 °C, 15 h; (e) NaH,
DMF, R1Br, 0–23 °C, 15 h.

2640
M. Hammond et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2637–2641
Table 3
class, when optimized for potency, selectivity and P450 inhibition,
Rat PK for compounds 19 and 10a
produced PR ligands with in vitro partial agonist profiles, while ef-
forts in the 1,2,4-triazole class allowed for the identification of po-
tent full agonists. Rat PK studies with compounds from both
classes indicated that the overall exposure of triazole 10 was more
than 15-fold greater than that for tetrazole 19. Conversely, the oral
half life of 19 was nearly fourfold longer, indicating that both com-
pounds might be suitable for in vivo pharmacology studies. Results
of these studies will be reported elsewhere.
Parameter
Compound
19b
10c
Dose (iv, po, mg/kg)
CLp (mL/min/kg)
Vdss (L/kg)
Oral Cmax (ng/mL)
Oral AUC0–t, (h ng/mL)
1.1, 2.0
1.2, 2.3
Very highe
Very largee
146 (117)
572 (67)
8.9 (0.7)
ꢀ100
4.85 (1.15)
0.54 (0.08)
2116 (583)
10085 (1779)
2.4 (0.3)
t
, po (h)
½
Oral%F
ꢀ100
Acknowledgments
a
Values are means of three experiments, standard deviation is given in
parentheses.
The authors would like to thank William Leister for the chiral
separation of compound 20 and our colleagues in the Screening
and Compound Profiling group for performing the PR and AR bind-
ing assays. We would also like to thank Dennis A. Holt for many
helpful discussions.
b
c
Discrete study.
Cassette study conducted as a mixture of four compounds.
Unable to quantitate.
e
References and notes
Table 4
Selected in vitro data for compounds 10 and 25–34a
1. Clarke, C. L.; Sutherland, R. L. Endocrinol. Rev. 1990, 11, 266–301.
2. Fang, Z.; Yang, S.; Lydon, J. P.; DeMayo, F.; Tamura, M.; Gurates, B.; Bulun, S. E.
Fertil. Steril. 2004, 82, 673–678.
3. McDonnell, D. P.; Goldman, M. E. J. Biol. Chem. 1994, 269, 11945–11949.
4. Conneely, O. M.; Mulac-Jericevic, B.; Lydon, J. P.; De Mayo, F. J. Mol. Cell.
Endocrinol. 2001, 179, 97–103.
5. Dizerega, G. S.; Barber, D. L.; Hodgen, G. D. Fertil. Steril. 1980, 33, 649–653.
6. Mihalyi, A.; Simsa, P.; Mutinda, K. C.; Meuleman, C.; Mwenda, J. M.; D’Hooghe,
T. M. Expert Opin. Emerging Drugs 2006, 11, 503–524.
R1
N
N
N
R3
Cl
N
R2
N
7. Carr, B. R.; Macdonald, P. C. Int. J. Fertil. Women’s Med. 1997, 42, 133–144.
8. Spitz, I. M. Expert Rev. Obstet. Gynecol. 2007, 2, 227–242.
9. The PR binding assay was performed according to the manufacturers protocol
(PR Competitor Assay Kit, Red—(Invitrogen–Product No. P2962)) with minor
amendments. Briefly, 40 nM PR-Ligand Binding Domain, 2 nM Fluormone PL
Red and 1 mM DTT were dissolved and mixed in Complete PR RED Buffer
Compd R1
R2
R3
PR IC50
(nM)
PR T47D EC50 (nM)
(% P4)
2C19 IC50
M)
(l
10
25
26
2-Cl–Bn
2-Cl–Bn
2-Cl–Bn
Me
Et
n-
Pr
i-
Pr
i-
Bu
H
H
H
13
16
13
0.5 (107)
0.02 (97)
0.05 (84)
<0.033
<0.33
0.11
supplemented with 2 mM CHAPS. 10 lL of the mix was dispensed to each well
of Greiner low volume plates, containing compounds at the required
concentration. The plates were spun for 1 min at 200 g, covered to protect
the reagents from light, and then incubated at room temperature for
27
28
29
30
31
2-Cl–Bn
2-Cl–Bn
H
H
H
H
H
32
4.7 (76)
157 (58)
ND
0.063
1.3
approximately 2 h. Plates were read on an Acquest using
a 530–25 nm
25
excitation and 580–10 nm emission interference filter and a 561 nm dichroic
mirror.
2-CF3–Bn i-
Bu
i-
398
500
40
1.5
10. The T47D alkaline phosphatase PR agonist assay was performed in accordance
to procedures set forth in the literature. In short, 120 lL of T47D cell
suspension was seeded into a 96-well plate and allowed to attach to the
plate overnight. On the next day, the cells were treated with compound and
i-Bu
ND
ND
Bu
Me
incubated overnight. On the following day, 100 lL of pNPP-SPAP is added and
c-
3.0 (140)
3.8
were allowed to stand in the dark for 2 h. Optical density is then measured at a
wavelength of 405 nm on a plate reader.
11. Di Lorenzo, D.; Albertini, A.; Zava, D. Cancer Res. 1991, 51, 4470–4475.
Hex(CH2)
2-Cl–Bn
2-Cl–Bn
32
33
Me Me 63
4.5 (119)
4.0 (87)
43
4.1
n-
Pr
i-
Me 50
12. Example preparation: compound 9. Step 1:
A suspension of 2-chloro-4-
fluorobenzonitrile (8 g, 51.4 mmol), -alanine (5.5 g, 67.7 mmol), and K3CO3
L
34
2-Cl–Bn
Me 398
1665 (61)
ND
(10.66 g, 77.1 mmol) in DMF (260 mL) and H2O (40 mL) were heated with
stirring at 90 °C for 15 h. Water (200 mL) was added and the reaction mixture
was acidified to pH 4 with 6 N HCl and extracted with EtOAc. The organic
extracts were dried over Na2SO4 and concentrated. The crude product was used
in the next step without purification. Step 2: The crude aniline was taken up in
a solution of EtOH (150 mL) and H2SO4 (8 mL) and the solution was stirred at
80 °C for 24 h. The solvent was removed and the residue was neutralized with
saturated NaHCO3 and extracted with Et2O. The organic layer was washed with
H2O, dried over Na2SO4 and concentrated. The residue was purified via silica
gel chromatography with 5–20% EtOAc/hexane to yield the ester (8.42 g, 65%)
as a light yellow oil. Step 3: Trimethylaluminum (2 M in toluene, 9.6 mL,
19.2 mmol) was added slowly to a suspension of methylamine hydrochloride
(1.3 g, 19.2 mmol) in toluene (19 mL) at 0 °C. After warming to rt, a solution of
the ester (907 mg, 3.84 mmol) in toluene (6 mL) was added and the reaction
solution was stirred at 60 °C for 16 h. After cooling to 0 °C, 1 N HCl (20 mL) was
added. After stirring for 15 min, saturated NaHCO3 and brine were added and
the mixture was extracted with EtOAc. The organic extracts were dried over
Na2SO4 and concentrated. The solid residue was suspended in Et2O and
collected by filtration to afford the amide as a beige solid (490 mg, 54%). Step 4:
DIAD (0.77 mL, 3.95 mmol) and TMSN3 (1.05 mL, 7.92 mmol) were added
alternatingly to a solution of the amide (470 mg, 1.98 mmol) and PPh3 (1.04 g,
3.95 mmol) in a mixture of THF (10 mL) and acetonitrile (10 mL) at 0 °C. After
3 days at rt, the reaction mixture was diluted with H2O and extracted with
EtOAc. The organics were dried over Na2SO4 and concentrated. The residue was
purified using silica gel chromatography with 20–50% EtOAc/hexane to give
the tetrazole (630 mg, 120% (contaminated with PPh3O)) as a light yellow solid.
Step 5: Sodium Hydride (60% in mineral oil, 23 mg, 0.57 mmol) was added to a
solution of the tetrazole (100 mg, 0.38 mmol) in DMF (4 mL) at 0 °C. After
Pr
a
Values are the means of P2 determinations. ND = not determined.
suffered from markedly reduced PR binding and functional po-
tency, analogs 32 and 33 were free of potent P450 inhibition and
were found to be single-digit nanomolar full agonists of PR.
The pharmacokinetic parameters of tetrazole 19 and triazole 10
were evaluated in rats (Table 3). Plasma clearance for 19 was found
to be too high to quantitate, likely driven by a large volume of dis-
tribution that was likewise too large to quantitate. By comparison,
triazole 10 demonstrated low plasma clearance and a smaller vol-
ume of distribution. In addition, the oral AUC of 10 was approxi-
mately 18-fold higher than that of tetrazole 19. The oral half-life
of tetrazole 19, perhaps due to its large volume of distribution,
was nearly 9 h, while that of triazole 10 was 2.4 h, suggesting that,
even though the overall exposure of 10 was greater, both com-
pounds would be suitable for in vivo studies.
In summary, replacement of the dimethyl amide of lead PR li-
gand 1 with 5-membered ring heterocycles led to the discovery
of two series of selective PR partial and full agonists. The tetrazole

M. Hammond et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2637–2641
2641
stirring for 30 min, 1-(bromomethyl)-2-chlorobenzene (117 mg, 0.57 mmol)
was added and the reaction mixture was stirred at rt for 1 h, quenched with
water and extracted with EtOAc. The organic layer was washed with H2O, dried
over Na2SO4 and concentrated. The residue was purified via silica gel
chromatography with 5–50% EtOAc/hexane to give the pure tetrazole (83 mg,
53%) as a white solid. 1H NMR (CDCl3) d 7.49 (d, 1H, J = 8.8 Hz), 7.39 (d, 1H,
J = 9.2 Hz), 7.22 (t, 1H, J = 7.6 Hz), 7.15 (t, 1H, J = 7.6 Hz), 6.89 (m, 2H), 6.66 (dd,
1H, J = 8, 4 Hz), 5.46 (dd, 1H, J = 12, 8 Hz), 4.72 (d, 1H, J = 20 Hz), 4.50 (d, 1H,
J = 20 Hz), 3.97 (s, 3H), 1.88 (d, 3H, J = 4 Hz). LC–MS (ES) m/z 386.8 (M+H)+.
13. Duncia, J. V.; Pierce, M. E.; Santella, J. B., III J.Org.Chem. 1991, 56, 2395–2400.
14. The absolute configuration for compound 22 was determined by ab initio VCD
analysis. The confidence limit for this assignment was estimated to be 88%,
using linear regression analysis to correlate observed and experimental VCD
intensities for a set of thirteen marker bands. The calculated IR spectrum was
in very good overall agreement with the experimental spectrum, indicating
good modeling of the conformational space (required for reliable VCD
assignments). Based on these results, the absolute configuration assigned to
compound 22 was considered to be reliable.
a light yellow solid. Step 5: Conducted as described in Ref. 12, Step 5 to afford
triazole 10 as a light yellow solid (25 mg, 33%). 1H NMR (CD3OD) d 8.31 (s, 1H),
7.56 (d, 1H, J = 8.8 Hz), 7.35 (d, 1H, J = 7.2 Hz), 7.18 (m, 2H), 7.10 (s, 1H), 6.92
(m, 2H), 5.78 (m, 1H), 4.82 (d, 1H, J = 18.4 Hz), 4.45 (d, 1H, J = 18.4 Hz), 3.64 (s,
3H), 1.76 (d, 3H J = 6.4 Hz). LCMS (ES) m/z 386.2 (M+H)+.
16. Angibaud, P.; Saha, A. K.; Bourdrez, X.; End, D. W.; Freyne, E.; Lezouret, P.;
Mannens, G.; Mevellec, L.; Meyer, C.; Pilatte, I.; Poncelet, V.; Roux, B.; Smets, G.;
Van Dun, J.; Venet, M.; Wouters, W. Bioorg. Med. Chem. Lett. 2003, 13, 4361–
4364.
17. Example preparation: compound 34. Step 1: Conducted as described in Ref. 12,
Step 1 using
L-valine in place of
L-alanine. Step 2: EDC (9.29 g, 48.5 mmol) was
added in one portion to
a
solution of the aniline (9.8 g, 38.8 mmol),
acetylhydrazide (3.59 g, 48.5 mmol) and HOBT (5.94 g, 38.8 mmol). The
resultant mixture was stirred at rt for 18 h, diluted with water and extracted
with EtOAc. The organics were washed with brine, dried over Na2SO4 and
concentrated. The residue was purified by silica gel chromatography using 0–
10% MeOH/CH2Cl2 to afford the bis-acylhydrazide (4.84 g, 40%). Step 3: POCl3
(7.25 mL, 78 mmol) was added via syringe to
a solution of the bis-
15. Example preparation: compound 10. Step 1: Conducted as described in Ref. 12,
Step 1. Step 2: N-methylhydrazinecarbothioamide (3.38 g, 32.1 mmol), HOBT
(3.47 g, 25.7 mmol) and EDC (6.15 g, 32.1 mmol) were added to a solution of N-
acylhydrazide (4.8 g, 15.6 mmol) in CH3CN (110 mL). The reaction mixture
was heated at 75 °C for 4 h, and then concentrated to remove the CH3CN. The
residue was partitioned between ½ saturated brine and EtOAc, the layers were
separated and the aqueous layer was further extracted with EtOAc. The
combined organics were washed with brine, dried over Na2SO4 and
concentrated. Purification by ISCO chromatography using 0–10% MeOH/
(3-chloro-4-cyanophenyl)-L-alanine (5.77 g, 25.7 mmol) in DMF (20 mL) and
THF (100 mL). After stirring for 24 h, EtOAc was added and the reaction
mixture was washed with aq NaHCO3, brine and H2O. The organics were dried
over Na2SO4, concentrated, and purified via silica gel chromatography with 4–
10% MeOH/CH2Cl2 to give the product (3.19 g, 40%) as a white solid. Step 3:
Sodium methoxide (0.83 g, 15.3 mmol) was added to a mixture of the product
from Step 2 (3.19 g, 10.2 mmol) in MeOH (100 mL) and the reaction mixture
was stirred at 60 °C for 15 h. After cooling, MeI (1.27 mL, 20.4 mmol) was
added and the reaction mixture was stirred at room temperature for 24 h. The
solvent was removed and the residue was partitioned between EtOAc and H2O.
The organic layer was washed with H2O and concentrated. The resulting light
yellow solid was triturated with EtOAc to give the product (2.17 g, 69%) as a
white solid. Step 4: Raney-nickel (excess) was added to a suspension of the
(methylthio)triazole (2.17 g, 7.05 mmol) in EtOH (71 mL) and the reaction
mixture was stirred at 80 °C for 15 h. The reaction mixture was filtered through
a pad of Celite and concentrated. The residue was purified via silica gel
chromatography with 0.5–5% MeOH/CH2Cl2 to give the product (1.18 g, 64%) as
CH2Cl2 afforded the oxadiazole (1.61 g, 36%). Step 4:
A solution of the
oxadiazole (750 mg, 2.58 mmol) and methylamine (6.45 mL of a 2 M solution
in THF, 12.9 mmol) in NMP (6.5 mL) was heated to 200 °C in a microwave oven
for 1 h. The reaction mixture was diluted with EtOAc and washed with ½
saturated brine and brine. Without drying, the organics were concentrated in
vacuo and the solid residue was stirred with 5:1 EtOAc/hexane for 1 h. The
solids were collected by filtration to provide the 1,2,4-triazole (660 mg, 84%) as
a white powder. Step 5: Conducted as described in Ref. 12 to provide 34 as a
waxy yellow solid (75 mg, 53%). 1H NMR (CDCl3) d 7.46 (d, 1H, J = 8 Hz), 7.32 (d,
1H, J = 8 Hz), 7.10 (t, 1H, J = 8 Hz), 6.95 (t, 1 H, J = 8 Hz), 6.90 (m, 1H), 6.73 (m,
1H), 6.42 (d, 1H, J = 8 Hz), 4.95 (d, 1H, J = 16 Hz), 4.76 (d, 1H, J = 8 Hz), 4.52 (d,
1H, J = 20 Hz), 3.44 (s, 3H), 3.15 (br m, 1H), 2.26 (s, 3H), 1.08 (d, 3H, J = 8 Hz),
1.07 (d, 3H, J = 8 Hz). LCMS (ES) m/z 427.8 (M+H)+.
18. Carlsen, P. H. J.; Jorgensen, K. B. J. Heterocycl. Chem. 1994, 31, 805–807.