F. P. Bymaster et al. / Bioorg. Med. Chem. Lett. 13 (2003) 4477–4480
4479
Figure 1.
Scheme 3. (a) Paraformaldehyde, (CH3)2NH–HCl, 12N HCl, EtOH;
(b) K2CO3, H2O, NaBH4, MeOH; (c) 1-fluoronaphthalene, NaH,
DMA; (d) PhOCOCl, toluene; (e) NaOH, propylene glycol.
From Table 4 it can also be seen that by comparison to
the SSRI fluoxetine (27) and the selective NE reuptake
inhibitor atomoxetine (28) (Fig. 1), that 25 is a potent
dual inhibitor of 5-HT and NE.
Further in vivo evaluation of 25 was also made, thus in
microdialysis experiments to determine the increase in
synaptic concentration of NE and 5-HT in rat, follow-
ing administration of 25, at 10 mg/kg po increases in
basal levels of NE and 5-HT by 208Æ31% and
353Æ62%, respectively, were found. Full microdialysis
results will be published elsewhere.
Scheme 4. Synthesis of 25. Reagents and conditions: Route A (a) R-1-
methyl-3,3-diphenyl-tetrahydro-pyrrolo[1,2-c][1,3,2]oxazaborole, BH3,
THF: (b) NaI, acetone; (c) methylamine, THF; (d) 1-fluoro-
naphthalene, NaH, DMA; Route B (e) S-1-methyl-3,3-diphenyl-tetra-
hydro-pyrrolo[1,2-c][1,3,2]oxazaborole, BH3, THF: (f) 1-naphthol,
DEAD, Ph3P.
In summary 25 inhibits binding to human cell lines
expressing NE and 5-HT transporters, inhibits the re-
uptake of NE and 5-HT in rat synaptosomes of 5-HT
and NE and increases NE and 5-HT in rat pre-frontal
cortex. Compound 25 has been progressed to the clinic
(as duloxetine hydrochloride, CymbaltaTM) and has been
shown to be effective in the treatment of depression.3
Table 4. Inhibition of norepinephrine and serotonin uptake into rat
synaptosomes for the enantiomers of compound 2110
Acknowledgements
The authors would like to thank Dr. John Schaus for
helpful advice in compiling this manuscript.
Compd
Compd
5-HTa
NEa
DAa
25
26
27
28
S-21
R-21
Fluoxetine
Atomoxetine
4.6
8.8
48
1500
16
16
2000
4
370
660
6000
2000
References and Notes
aKi, nM.
was converted to S-methyl-[3-(naphthalen-1-yloxy)-3-
thiophen-2-yl-propyl]-amine 25 with methylamine in
THF.6,8,9
1. Murray, C. J. L.; Lopez, A. D., eds. The Global Burden of
Disease: A comprehensive Assessment of Mortality an Dis-
ability from Diseases, Injuries and Risk Factors in 1990 and
Projected to 2020; Cambridge Mass: Harvard University Press,
1996.
Compounds 25 and 26 were then assessed for their
ability to inhibit synaptosomal uptake into rat synapto-
somes (Table 4).10 Inhibition of monoamine uptake into
rat synaptosomes has been used to assess the functional
ability of a compound to block re-uptake of mono-
amines. The resolved enantiomers 25 and 26 proved to
be equipotent at the NE transporters, however com-
pound 25 was shown to be more active at the 5-HT
transporter and was selected for further study.10
2. Thase, E. A.; Entsuah, A. R.; Rudolph, R. L. Br. J. Psy-
chiatry 2001, 178, 234.
3. Detke, M. J.; Lu, Y.; Goldstein, D. J.; Hayes, J. R.; Demi-
track, M. A. Journal of Clinical Psychiatry 2002, 63, 308.
4. The ligands for determining the Ki values at the NE, 5-HT
and Dopamine transporters were [3H]-nisoxetine, [3H]-citalo-
pram and [3H]-WIN35,428, respectively.
The method for determining the Ki is the same for each trans-
porter, thus at the NE transporter the following protocol was
followed.
Compound 25 was also evaluated for its ability to inhi-
bit the reuptake of 5-HT, NE and dopamine at the
respective human transporters. Thus compound 25 was
shown to inhibit monoamine uptake with Ki’s (nM) of
0.8, 7.5 and 240 at the 5-HT, NE and dopamine uptake
transporters, respectively.
[3H]-Nisoxetine binding assay: Each well of a 96-well micro-
titre plate was set up to contain the following:
50 mL 2nM-[N-methyl-3H]-Nisoxetine hydrochloride (70–87
Ci/mmol) (NEN)
75 mL Assay buffer (50mM Tris HCl pH 7.4 containing 300
mM NaCl and 5 mM KCl)
.