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A. Maisonial et al. / Bioorg. Med. Chem. 20 (2012) 257–269
to reflux for 3 h. It was filtered over CeliteÒ, the filtrate was con-
centrated in vacuo and the reside was purified by fc (0.5 cm, ethyl
acetate/MeOH/NH3 9:1:0.2, 5 mL, Rf 0.06). Pale yellow oil, yield
83.1 mg (92%). According to the 1H NMR spectrum and the HPLC
analysis, the isolated product contained 9 and 10 in the ratio
69:31. The products were separated only after N-alkylation. 9:
(0.01%), 5 mL). In addition to the pure samples 28 mg (ca. 59%) of
the mixture was isolated.
13 (Rf (cyclohexane/ethyl acetate 7:3+NH3 (0.01%)) 0.29): color-
less oil, yield 4.2 mg (7.6%). C21H24FNO (325.4). MS (EI): m/z = 325
~
[M], 310 [M–CH3], 248 [M–Ph], 91 [CH2Ph]. IR:
m
(cmꢁ1) = 2938 (C–
H), 1601 (arom. C@C), 1052 (C–O), 756 (C–H, 1,2-disubst. arom.),
699 (C–H, monosubst. arom.). 1H NMR (CDCl3): d (ppm) = 1.42 (d,
J = 6.3 Hz, 3H, NCHArCH3), 1.66 (ddd, J = 13.5/4.7/2.5 Hz, 1H,
N(CH2CH2)2), 1.78 (ddd, J = 13.5/6.0/2.9 Hz, 1H, N(CH2CH2)2),
1.84–2.13 (m, 2H, N(CH2CH2)2), 2.31–2.50 (m, 2H, N(CH2CH2)2),
2.72 (d broad, J = 11.3 Hz, 1H, N(CH2CH2)2), 3.04 (d broad,
J = 9.8 Hz, 1H, N(CH2CH2)2), 3.45–3.52 (m, 1H, NCH(CH3)Ar),
4.45–4.66 (m, 2H, CHCH2F), 5.35 (dt, J = 20.4/4.7 Hz, 0.5H, ArCHO),
5.36 (dt, J = 20.4/4.7 Hz, 0.5H, ArCHO), 7.16–7.38 (m, 9H, arom. H).
Purity (HPLC): 95.5%, tR = 17.92 min.
14 (Rf (cyclohexane/ethyl acetate 7:3+NH3 (0.01%)) 0.37): Color-
less oil, yield 5.8 mg (11.2%). C21H25NO (307.4). MS (EI): m/z = 307
[M], 292 [M–CH3], 230 [M–Ph], 202 [M–CH3CHPh], 91 [CH2Ph]. IR:
m
(cmꢁ1) = 2969 (C–H), 1601 (arom. C@C), 1071 (C–O), 754 (C–H,
~
C
13H16FNO (221.3); 10: C13H17NO (203.3). MS (ESI): m/z = 222
(cmꢁ1) = 3298 (N–H), 2940
~
m
[MH (9)], 204 [MH (12)]. IR (9+10):
(C–H), 1604 (arom. C@C), 1072 (C–O), 754 (C–H, 1,2-disubst.
arom.). 1H NMR (CDCl3): d (ppm) = 1.50 (d, J = 6.4 Hz, 3 ꢃ 0.31H,
CHCH3), 1.68–2.04 (m, 4H, N(CH2CH2)2), 3.00–3.17 (m, 4H,
N(CH2CH2)2), 4.57 (ddd, J = 47.3/9.7/4.9 Hz, 0.69H, CHCH2F), 4.61
(ddd, J = 47.7/9.7/3.8 Hz, 0.69H, CHCH2F), 5.29 (q, J = 6.4 Hz,
0.31H, ArCHO), 5.41 (dt, J = 20.3/4.3 Hz, 0.69H, ArCHO), 7.10–7.18
(m, 1H, arom. H), 7.21–7.36 (m, 3H, arom. H). A signal for the
NH-proton is not seen in the spectrum. Purity (HPLC): 9: 66.6%,
tR = 12.01 min; 10: 30.2%, tR = 13.05 min.
4.1.7. 10-(4-Fluorobenzyl)-3-(fluoromethyl)-3H-spiro[[2]benzo-
furan-1,40-piperidine] (11) and 10-(4-fluorobenzyl)-3-methyl-
3H-spiro[[2]benzofuran-1,40-piperidine] (12)
A mixture of the secondary amines 9/10 (37.4 mg, 0.17 mmol),
4-fluorobenzyl chloride (26 lL, 0.22 mmol), K2CO3 (0.118 mg,
0.85 mmol) and CH3CN (5 mL) was heated to reflux for 8 h and sub-
sequently stirred at rt for 15 h. The mixture was filtered over Cel-
iteÒ, the solvent was removed in vacuo and the residue was
purified by fc (0.7 cm, cyclohexane/ethyl acetate 8:2, 5 mL). In
addition to the pure samples 24 mg (ca. 27%) of a mixture was
isolated.
1,2-disubst. arom.), 700 (C–H, monosubst. arom.). 1H NMR (CDCl3):
d (ppm) = 1.42 (d, J = 6.5 Hz, 3H, NCHArCH3), 1.46 (t, J = 6.3 Hz, 3H,
ArCHCH3) 1.64 (ddd, J = 13.5/4.3/2.8 Hz, 1H, N(CH2CH2)2), 1.76
(ddd, J = 13.5/4.8/2.8 Hz, 1H, N(CH2CH2)2), 1.72–1.82 (m, 0.5H,
N(CH2CH2)2), 1.91 (td, J = 13.1/4.6 Hz, 0.5H, N(CH2CH2)2), 2.02 (td,
J = 13.3/3.9 Hz, 0.5H, N(CH2CH2)2), 2.14 (td, J = 12.9/4.3 Hz, 0.5H,
N(CH2CH2)2), 2.28–2.50 (m, 2H, N(CH2CH2)2), 2.63–2.72 (m, 1H,
N(CH2CH2)2), 2.98–3.08 (m, 1H, N(CH2CH2)2), 3.48 (q, J = 6.5 Hz,
1H, NCH(CH3)Ar), 5.25 (m, 1H, ArCHO), 7.09–7.14 (m, 2H, arom.
H), 7.22–7.27 (m, 2H, arom. H), 7.30–7.37 (m, 5H, arom. H). Purity
(HPLC): 98.3%, tR = 18.44 min.
11 (Rf (cyclohexane/ethyl acetate 5:5) 0.40): colorless oil, yield
19.6 mg (22%). C20H22F2NO (329.4). MS (EI): m/z = 329 [M], 234
~
[M–PhF], 220 [M–CH2PhF], 109 [PhCH2F]. IR:
m
(cmꢁ1) = 2941 (C–
4.1.9. [(10-Benzyl-3H-spiro[[2]benzofuran-1,40-piperidin]-3-yl)-
methyl] tosylate (15)
H), 1603 (arom. C@C), 1053 (C–O), 828 (C–H, 1,4-disubst. arom.),
755 (C–H, 1,2-disubsst. arom.). 1H NMR (CDCl3): d (ppm) = 1.74
(ddd, J = 13.9/5.8/2.8 Hz, 2H, N(CH2CH2)2), 1.97 (td, J = 13.1/
4.5 Hz, 1H, N(CH2CH2)2), 2.06 (td, J = 13.1/4.4 Hz, 1H, N(CH2CH2)2),
2.45 (td, J = 11.8/2.5 Hz, 1H, N(CH2CH2)2), 2.48 (td, J = 11.8/2.5 Hz,
1H, N(CH2CH2)2), 2.81 (br d, J = 11.2 Hz, 2H, N(CH2CH2)2), 3.55 (s,
2H, NCH2Ph), 4.56 (ddd, J = 47.3/9.7/4.9 Hz, 1H, CHCH2F), 4.61
(ddd, J = 47.7/9.7/3.8 Hz, 1H, CHCH2F), 5.40 (dt, J = 20.3/4.3 Hz,
1H, ArCHO), 7.01 (t, J = 8.7 Hz, 2H, arom. H), 7.16–7.18 (m, 1H,
arom. H), 7.21–7.23 (m, 1H, arom. H), 7.28–7.35 (m, 4H, arom.
H). Purity (HPLC): 95.1%, tR = 17.74 min.
Under N2 the alcohol 8 (97 mg, 0.31 mmol), 4-(dimethyl-
amino)pyridine (DMAP, 9.7 mg, 0.08 mmol) and NEt3 (0.2 mL,
1.44 mmol) were dissolved in CH2Cl2 (8 mL) and the solution was
cooled down to ꢁ25 °C. A solution of p-toluenesulfonyl chloride
(120 mg, 0.63 mmol) in CH2Cl2 (2 mL) was added and the mixture
was stirred for 30 min at ꢁ25 °C and for 21 h at rt. Diluted NaOH
was added, the layers were separated and the aqueous layer was
extracted with CH2Cl2 (4ꢃ). The combined organic layers were
dried (Na2SO4), concentrated in vacuo and the residue was purified
by fc (1.7 cm, cyclohexane/ethyl acetate 7:3, 10 mL, Rf (cyclohex-
ane/ethyl acetate 5:5) 0.35.
12 (Rf (cyclohexane/ethyl acetate 5:5) 0.44): colorless oil, yield
8.0 mg (10%). C20H22FNO (311.4). MS (EI): m/z = 311 [M], 216
(cmꢁ1) = 2939
~
m
Colorless oil, yield 127.4 mg (88%). C27H29NO4S (463.6). MS (EI):
m/z = 463 [M], 372 [M–CH2Ph], 308 [M–SO2PhCH3], 91 [PhCH2]. IR:
(cmꢁ1) = 2925 (C–H), 1598 (arom. C@C), 1361, 1175 (O2S@O),
~
m
[M–PhF], 202 [M–CH2PhF], 109 [F PhCH2]. IR:
(C–H), 1602 (arom. C@C), 1071 (C–O), 829 (C–H, 1,4-disubst.
arom.), 754 (C-H, 1,2-disubst. arom.). 1H NMR (CDCl3):
d
813 (C–H, 1,4-disubst. arom.), 756 (C–H, 1,2-disubst. arom.), 740,
698 (C–H, monosubst. arom.). 1H NMR (CDCl3): d (ppm) = 1.56
(ddd, J = 13.6/5.2/2.5 Hz, 1H, N(CH2CH2)2), 1.65 (ddd, J = 13.4/5.2/
2.5 Hz, 1H, N(CH2CH2)2), 1.92 (td, J = 12.9/4.5 Hz, 1H, N(CH2CH2)2),
1.98 (td, J = 13.1/4.5 Hz, 1H, N(CH2CH2)2), 2.30 (td, J = 12.7/2.5 Hz,
1H, N(CH2CH2)2), 2.38 (td, J = 12.5/2.7 Hz, 1H, N(CH2CH2)2), 2.42
(s, 3H, ArCH3), 2.73 (d broad, J = 11.2 Hz, 1H, N(CH2CH2)2), 2.79 (d
broad, J = 11.3 Hz, 1H, N(CH2CH2)2), 3.56 (s, 2H, NCH2Ph), 4.15
(dd, J = 10.1/5.2 Hz, 1H, CH2OTos), 4.21 (dd, J = 10.1/4.5 Hz, 1H,
CH2OTos), 5.35 (t broad, J = 4.8 Hz, 1H, ArCHO), 7.12 (br t,
J = 7.1 Hz, 2H, arom. H), 7.22–7.37 (m, 9H, arom. H), 7.73 (br d,
J = 8.3 Hz, 2H, arom. H). Purity (HPLC): 99.2%, tR = 19.39 min.
(ppm) = 1.49 (d, J = 6.4 Hz, 3H, CHCH3), 1.72 (ddd, J = 13.8/5.4/
2.7 Hz, 2H, N(CH2CH2)2), 1.88 (td, J = 13.0/4.0 Hz, 1H, N(CH2CH2)2),
2.10 (td, J = 12.9/4.1 Hz, 1H, N(CH2CH2)2), 2.44 (td, J = 14.7/2.3 Hz,
1H, N(CH2CH2)2), 2.47 (td, J = 14.7/2.3 Hz, 1H, N(CH2CH2)2), 2.76–
2.82 (m, 2H, N(CH2CH2)2), 3.55 (s, 2H, NCH2Ph), 5.28 (q,
J = 6.3 Hz, 1H, ArCHO), 7.01 (t, J = 7.7 Hz, 2H, arom. H), 7.11–7.15
(m, 2H, arom. H), 7.24–7.28 (m, 2H, arom. H), 7.30–7.34 (m, 2H,
arom. H). Purity (HPLC): 97.6%, tR = 17.92 min.
4.1.8. 3-(Fluoromethyl)-10-(1-phenylethyl)-3H-spiro[[2]benzo-
furan-1,40-piperidine] (13) and 3-methyl-10-(1-phenylethyl)-3H-
spiro[[2]benzofuran-1,40-piperidine] (14)
A mixture of the secondary amines 9/10 (37.4 mg, 0.17 mmol),
4.2. Receptor binding studies
1-bromo-1-phenylethane (30 lL, 0.22 mmol), K2CO3 (0.117 mg,
0.85 mmol) and CH3CN (5 mL) was heated to reflux for 8 h and sub-
sequently stirred at rt for 15 h. The mixture was filtered over Cel-
iteÒ, the solvent was removed in vacuo and the residue was
purified by fc (0.7 cm, cyclohexane/ethyl acetate 7:3+NH3
Membrane preparations and r1 and r2 assays were performed
as described in Ref. 36,38–41 The protein concentration was deter-
mined according to the method of Bradford51 using bovine serum
albumin as standard. The r1 assay was performed with the