8
L. Song et al. / Bioorganic & Medicinal Chemistry xxx (2018) xxx–xxx
1
3
50:1 ? 100:1 (v/v) gradient elution of CHCl /MeOH, then the resi-
1
.21 (br, 4H, CO(CH
2
)
2
CH
), 2.47 (t, J = 7.5 Hz, 2H, COCH
), 3.86 (br, 4H, ArOCH and NCH
), 4.44 (br, 4H, ArOCH
(br, 1H, NCH CH ), 6.94 (s, 1H, ArH), 7.07 (s, 1H, ArH), 7.56 (d, J
2
CH
2
CH
3
), 1.58 (br, 2H, COCH
(CH CH ), 3.15 (br, 1H, NCH
CH ), 4.01 (s, 3H, ArOCH
and NCH CH ), 5.98
2
CH
2
(CH
2
)
2
-
due of the eluate was recrystallized using acetone or a 3:1 (v/v)
solvent of acetone/ethyl acetate as crystallizing solvent to yield 3a–e.
CH
CH
3
2
2
)
3
3
2
-
2
3
2
2
3
),
4
.08 (s, 3H, ArOCH
3
3
2
2
4.1.3.1. Quaternary 13-acetylpalmatine chloride (3a). Yellow amor-
1
2
2
3
phous powder from acetone; yield, 8.7%; H NMR (500 MHz, CDCl )
=
9.0 Hz, 1H, ArH), 7.82 (d, J = 9.0 Hz, 1H, ArH), 10.48 (s, 1H,
d: 2.36 (s, 3H, COCH
4
3
), 3.50 (br, 2H, NCH
), 4.08 (s, 3H, ArOCH
CH
2
CH
2
), 3.87 (s, 3H, ArOCH
3
3
),
),
1
3
ArCH@N); C NMR (100 MHz, CDCl
3
) d: 13.8, 22.3, 23.4, 27.4,
.01 (s, 3H, ArOCH
3
3
), 4.44 (s, 3H, ArOCH
3
1
1
0.9, 45.1, 56.2, 56.4, 56.8, 57.0, 63.3, 111.1, 111.3, 118.0, 119.6,
22.0, 126.4, 129.6, 131.1, 133.0, 134.3, 146.5, 147.7, 148.9,
5
.19 (br, 2H, NCH
2
2
), 6.96 (s, 1H, ArH), 7.10 (s, 1H, ArH), 7.62
(
d, J = 9.5 Hz, 1H, ArH), 7.84 (d, J = 9.0 Hz, 1H, ArH), 10.46 (s, 1H,
50.9, 152.3, 205.8; positive-ion mode HRESIMS m/z 450.22714
1
3
ArCH@N); C NMR (100 MHz, CDCl
5
1
3
) d: 27.4, 32.8, 56.3, 56.4,
6.8, 57.0, 63.3, 111.2, 111.3, 117.8, 119.6, 122.1, 126.4, 129.3,
31.3, 132.8, 134.3, 146.5, 147.9, 149.0, 151.0, 152.5, 203.1; posi-
+
[
MÀCl] (calcd for C27
5
H32NO , 450.22750).
4.1.4. Procedure for the synthesis of dihydropalmatine (4)
+
tive-ion mode HRESIMS m/z 394.16489 [MÀCl] (calcd for
To a stirred methanol solution (250 ml) containing 1 (10 g,
23 5
C H24NO
, 394.16490).
2
5
5.78 mmol) and K
2
CO
3
(10.69 g, 41.25 mmol) was added aqueous
(1.56 g, 41.25 mmol)
% NaOH solution (15 ml) containing NaBH
4
4.1.3.2. Quaternary 13-propionylpalmatine chloride (3b). Yellow
dropwise. The reaction mixture was stirred at rt. for 3 h and then
filtered to obtain the precipitated product. This product was
washed sequentially with water (100 ml) and then 80% ethanol
(100 ml), and dried under high vacuum to yield 4 (7.38 g, 81.1%)
as yellow powder. H NMR (500 MHz, C
amorphous powder from acetone/ethyl acetate (3:1); yield:
1
1
1.3%; H NMR (500 MHz, CDCl
CH ), 2.52 (q, J = 5.6 Hz, 2H, COCH
.86 (s, 4H, ArOCH and NCH CH ), 4.01 (s, 3H, ArOCH
H, ArOCH ), 4.43 (br, 4H, ArOCH and NCH CH ), 5.89 (br, 1H,
CH ), 6.97 (s, 1H, ArH), 7.05 (s, 1H, ArH), 7.55 (d, J = 9.5 Hz,
H, ArH), 7.83 (d, J = 9.0 Hz, 1H, ArH), 10.46 (s, 1H, ArCH = N);
3
) d: 1.13 (t, J = 5.6 Hz, 3H, COCH
CH ), 3.29 (br, 1H, NCH CH
), 4.08 (s,
2
-
3
2
3
2
2
),
1
5
D
5
N) d: 2.86 (t, J = 5.5
CH ), 3.74 (s, 3H,
), 3.85 (s, 3H, ArOCH ), 3.87 (s, 3H,
N), 6.48 (s, 1H, ArCH@C), 6.74 (s, 1H,
3
3
3
2
2
3
Hz, 2H, NCH
ArOCH
ArOCH
2
CH
), 3.78 (s, 3H, ArOCH
), 4.52 (br, 2H, ArCH
2
), 3.09 (t, J = 5.5 Hz, 2H, NCH
2
2
3
3
2
2
3
3
3
NCH
2
2
3
2
1
1
3
ArH), 6.86 (d, J = 8.5 Hz, 1H, ArH), 6.93 (d, J = 8.5 Hz, 1H, ArH),
.56 (s, 1H, ArH).
3
C NMR (100 MHz, CDCl ) d: 8.0, 27.4, 38.6, 56.2, 56.4, 56.8,
7.0, 63.3, 110.9, 111.3, 118.0, 119.6, 122.0, 126.4, 129.6, 131.2,
7
5
1
33.0, 134.3, 146.5, 147.8, 149.0, 151.0, 152.3, 206.3; positive-ion
+
4.1.5. General procedure for the syntheses of compounds 5a–g
To a stirred solution of 4 (1.7 mmol) in acetonitrile (15 ml) was
added ethyl
mode HRESIMS m/z 408.18030 [MÀCl] (calcd for C24
5
H26NO ,
4
08.18055).
x-halogenated aliphatic acid ester (ClCOOEt or Br
(
CH COOEt (n > 0)) (6.8 mmol) and NaI (6.8 mmol). The reaction
2 n
)
4
.1.3.3. Quaternary 13-butanoylpalmatine chloride (3c). Yellow
mixture was refluxed overnight and filtered to obtain the filtrate.
The solvent of the filtrate was removed under evaporation. The
residue was acidified using aqueous 2 N HCl (10 ml). The solution
was stirred at rt. for 1 h, extracted with CH
organic layers were combined together and dried over anhydrous
MgSO . After filtration, the filtrate was concentrated under reduced
pressure to give a crude product, which was purified via a silica gel
CC, eluted using a 50:1 (v/v) isocratic elution of CH Cl /MeOH, then
the residue of the eluate was recrystallized using a 2:1 (v/v) sol-
vent of CH Cl /EtOAc as crystallizing solvent to yield 5a–g.
amorphous powder from acetone/ethyl acetate (3:1); yield:
1
1
1.7%; H NMR (500 MHz, CDCl
CH CH ), 1.62 (br, 2H, COCH
COCH CH CH ), 3.20 (br, 1H, NCH
NCH CH ), 4.01 (s, 3H, ArOCH
H, ArOCH and NCH CH ), 5.93 (br, 1H, NCH
ArH), 7.07 (s, 1H, ArH), 7.56 (d, J = 9.0 Hz, 1H, ArH), 7.83 (d, J =
3 2
) d: 0.89 (t, J = 7.0 Hz, 3H, COCH -
2
3
2
CH
2
3
CH ), 2.46 (t, J = 7.5 Hz, 2H,
2
Cl
(3 Â 20 ml). The
2
2
2
3
2 2 3
CH ), 3.85 (br, 4H, ArOCH and
2
2
3 3
), 4.08 (s, 3H, ArOCH ), 4.43 (br,
4
4
3
2
2
2
CH ), 6.96 (s, 1H,
2
2
2
.0 Hz, 1H, ArH), 10.47 (s, 1H, ArCH = N); 1 C NMR (100 MHz,
3
9
2
2
CDCl ) d: 13.6, 17.3, 27.4, 47.0, 56.2, 56.5, 56.9, 57.0, 63.3, 111.2,
3
1
1
11.3, 118.0, 119.6, 122.0, 126.4, 129.6, 131.2, 132.9, 134.3,
4
.1.5.1. Quaternary 13-ethoxycarbonylpalmatine chloride (5a). Yel-
46.4, 147.7, 148.9, 150.9, 152.3, 205.7; positive-ion mode HRE-
+
low amorphous powder from CH Cl /EtOAc (2:1); yield: 11.9%;
SIMS m/z 422.19580 [MÀCl] (calcd for C25
5
H28NO , 422.19620).
2
2
1
H NMR (500 MHz, DMSO d
CH ), 3.21 (t, J = 5.5 Hz, 2H, NCH
s, 3H, ArOCH ), 4.09 (s, 3H, ArOCH
(q, J = 7.0 Hz, 2H, COOCH CH ), 4.90 (t, J = 5.5 Hz, 2H, NCH CH ),
6
) d: 1.28 (t, J = 7.0 Hz, 3H, COOCH
CH ), 3.79 (s, 3H, ArOCH ), 3.90
), 4.13 (s, 3H, ArOCH ), 4.54
2
-
3
2
2
3
4.1.3.4. Quaternary 13-pentanoylpalmatine chloride (3d). Yellow
(
3
3
3
amorphous powder from acetone/ethyl acetate (3:1); yield: 9.4%;
1H NMR (400 MHz, CDCl
2
3
2
2
3
) d: 0.83 (t, J = 7.6 Hz, 3H, CO(CH
CH CH ), 1.57 (br, 2H, COCH CH
), 2.48 (t, J = 7.2 Hz, 2H, COCH (CH CH ), 3.19 (br, 1H, NCH
), 3.86 (br, 4H, ArOCH and NCH CH ), 4.01 (s, 3H, ArOCH
), 4.44 (br, 4H, ArOCH and NCH CH ), 5.96
), 6.94 (s, 1H, ArH), 7.07 (s, 1H, ArH), 7.56 (d, J
9.2 Hz, 1H, ArH), 7.82 (d, J = 9.2 Hz, 1H, ArH), 10.49 (s, 1H,
2
)
3
CH
3
),
7
.20 (s, 2H, ArH Â 2), 7.84 (d, J = 9.0 Hz, 1H, ArH), 8.25 (d, J = 9.5
1
.21–1.31 (m, 2H, CO(CH
2
)
2
2
3
2
2
CH
2
-
-
13
Hz, 1H, ArH), 10.11 (s, 1H, ArCH@N); C NMR (100 MHz, DMSO d
d: 13.7, 26.2, 55.7, 55.9, 56.2, 57.0, 62.1, 63.3, 109.7, 111.5, 117.7,
20.1, 120.9, 124.7, 127.5, 129.0, 131.5, 134.7, 144.5, 147.9,
148.0, 150.7, 151.7, 165.9; positive-ion mode HRESIMS m/z
6
)
CH
CH
3
2
2
)
2
3
2
2
3
2
2
3
),
1
4
.08 (s, 3H, ArOCH
3
3
2
2
+
4
24.17508 [MÀCl] (calcd for C24
6
H26NO , 424.17546).
(
br, 1H, NCH CH
2
2
=
1
3
4
.1.5.2. Quaternary 13-ethoxycarbonylmethylpalmatine chloride
ArCH = N); C NMR (100 MHz, CDCl
3
) d: 13.7, 21.9, 25.8, 27.4,
(5b). Yellow amorphous powder from CH
2
Cl /EtOAc (2:1); yield:
) d: 1.25 (t, J = 7.2 Hz, 3H,
), 3.13 (t, J = 5.2 Hz, 2H, NCH CH ), 3.77 (s, 3H,
), 3.90 (s, 3H, ArOCH ), 4.09 (s, 3H, ArOCH ), 4.12 (s, 3H,
), 4.23 (q, J = 7.2 Hz, 2H, COOCH CH ), 4.50 (s, 2H, @CCH
CH ), 4.86 (br, 2H, NCH CH ), 7.21 (s, 1H, ArH), 7.22 (s,
H, ArH), 8.02 (d, J = 9.2 Hz, 1H, ArH), 8.24 (d, J = 9.2 Hz, 1H,
2
4
1
1
4.8, 56.2, 56.4, 56.8, 57.0, 63.3, 111.1, 111.2, 118.0, 119.6, 122.0,
1
2
0.6%; H NMR (400 MHz, DMSO d
6
26.4, 129.6, 131.1, 133.0, 134.3, 146.5, 147.8, 148.9, 151.0,
+
52.3, 205.8; positive-ion mode HRESIMS m/z 436.21158 [MÀCl]
COOCH
ArOCH
2
CH
3
2
2
(
calcd for C26
H30NO
5
, 436.21185).
3
3
3
ArOCH
3
2
3
2
-
4.1.3.5. Quaternary 13-hexanoylpalmatine chloride (3e). Yellow
COOCH
1
2
3
2
2
amorphous powder from acetone/ethyl acetate (3:1); yield: 7.8%;
1H NMR (500 MHz, CDCl
) d: 0.84 (t, J = 5.0 Hz, 3H, CO(CH CH ),
13
3
2
)
4
3
6
ArH), 9.99 (s, 1H, ArCH@N); C NMR (100 MHz, DMSO d ) d: