4
-Bromophenylalanine 4l
organic phase was dried over anhydrous Na
2
SO
4
, and the solvent
was removed under vacuum to obtain the crude product. All
purified products gave satisfactory physical and spectroscopic
analyses by comparison with the reported literature.
Product 4l (CAS registry No: 14091-15-7) was obtained according
to the general procedures at 86% yield after purification by
◦
recrystallization in H
2
O, m.p. 260.5–262 C (dec.) (literature data:
◦
25 1
258 C (dec.)). H NMR (D
2
O, 500 MHz): d 7.52 (d, J = 8.5 Hz,
N-Isopropylcyclohexylamine 6a
2
H, ArH), 7.18 (d, J = 8.5 Hz, 2H, ArH), 3.49–3.47 (dd, J = 7.0 Hz,
J = 5.5 Hz, 1H, NCH), 2.96–2.92 (dd, J = 13.5 Hz, J = 6.0 Hz,
Product 6a (CAS registry No: 1595-42-2) was obtained according
1
3
1
H, CHH), 2.84–2.80 (dd, J = 13.5 Hz, J = 7.5 Hz, 1H, CHH); C
NMR (D O, 125 MHz) d 182.1, 137.6, 131.4(2), 131.(2), 119.8,
7.4, 40.4; HRMS (m/z): 265.9785, 267.9762 [M+Na] (calcd for
, 242.9895, 244.9874).
to the general procedures at 82% yield after purification by reduced
◦
pressure distillation, b.p. 53–55 C/1.33 kPa (literature data: 60–
2
+
◦
27 1
5
C
65 C/12 Torr). H NMR (CDCl
1H), 2.52–2.47 (m, 1H), 1.89–1.86 (m, 2H), 1.74–1.70 (m, 2H),
.63–1.59 (m, 2H), 1.28–1.13 (m, 3H), 1.05 (d, J = 4.0 Hz, 3H),
3
, 500 MHz): d 2.99–2.94 (m,
9
H
10BrNO
2
1
1
3
4-Methoxyphenylalanine 4m
1.03 (d, J = 6.5 Hz, 3H), 1.03–1.00 (m, 1H); C NMR (CDCl
25 MHz) d 53.3, 44.5, 34.1(2), 26.1, 25.1(2), 23.3(2).
3
,
1
Product 4m (CAS registry No: 7635-29-2) was obtained according
to the general procedures at 92% yield after purification by
N-n-Butylbenzylamine 6b
◦
recrystallization in H
2
O, m.p. 236–238 C (dec.) (literature data:
◦
26 1
2
8
37–241 C (dec.)). H NMR (D
.5 Hz, 2H, ArH), 6.97 (d, J = 8.5 Hz, 2H, ArH), 3.83 (s, 3H,
), 3.48–3.45 (dd, J = 7.0 Hz, J = 5.5 Hz, 1H, CHH), 2.95–
2
O, 500 MHz): d 7.22 (d, J =
Product 6b (CAS registry No: 2403-22-7) was obtained according
to the general procedures at 86% yield after purification by reduced
◦
OCH
3
pressure distillation, b.p. 105–107 C/1.33 kPa (literature data:
1
3
◦
28 1
2
.91 (dd, J = 13.5 Hz, J = 5.5 Hz, 1H, CHH); C NMR (D
2
O,
122–125 C/12 Torr). H NMR (CDCl
(d, J = 4.5 Hz, 4H, ArH), 7.26–7.24 (m, 1H, ArH), 3.79 (s, 2H,
NCH ), 2.63 (t, J = 7.5 Hz, 2H, CH ), 1.60 (br, s, 1H, NH), 1.53–
.47 (m, 2H, CH2), 1.37–1.33 (m, 2H), 0.91 (t, J = 7.5 Hz, 3H,
3
, 500 MHz): d 7.33–7.32
1
25 MHz) d 182.5, 157.5, 131.0, 130.6(2), 114.1(2), 57.5, 55.5, 40.0;
+
HRMS (m/z): 218.0778 [M+Na] (cald for C10
H
13NO
3
, 195.0895).
2
2
1
1
3
4
-Pyridinylalanine 4n
CH ); C NMR (CDCl , 125 MHz) d 140.6, 128.4(2), 128.1(2),
3
3
126.9, 54.1, 49.2, 32.3, 20.5, 14.1.
Product 4n (CAS registry No: 1956-21-4) was obtained according
to the general procedures at 84% yield after purification by
N-Ethylbenzylamine 6c
◦
1
recrystallization in H
2
O, m.p. 251.5–253 C (dec.). H NMR (D
2
O,
5
2
3
00 MHz): d 8.43 (d, J = 6.0 Hz, 2H, ArH), 7.32 (d, J = 6.0 Hz,
Product 6c (CAS registry No: 14321-27-8) was obtained according
H, ArH), 3.57–3.54 (dd, J = 7.5 Hz, J = 6.0 Hz, 1H, NCH),
.03–2.99 (dd, J = 13.5 Hz, J = 6.0 Hz, 1H, CHH), 2.91–2.87 (dd,
to the general procedures at 87% yield after purification by reduced
◦
pressure distillation, b.p. 75–77 C/1.33 kPa (literature data: 82–
1
3
◦
29 1
J = 13.3 Hz, J = 6.0 Hz, 1H, CHH); C NMR (D
d 180.1, 148.6(2), 125.2(2), 56.6, 39.6. HRMS (m/z): 189.0628
2
O, 125 MHz)
85 C/11 Torr) H NMR (CDCl
4.5 Hz, 4H, ArH), 7.26–7.23 (m, 1H), 3.79 (s, 2H, CH
(q, J = 7.0 Hz, 2H), 1.62 (br, s, 1H), 1.14 (t, J = 7.0, 3H, CH
3
, 500 MHz): d 7.32–7.31 (t, J =
2
), 2.70–2.67
+
13
[M+Na] (calcd for C
8
H
10
N
2
O
2
, 166.0742).
3
);
C
NMR (CDCl
3
, 125 MHz) d 140.5, 128.4(2), 128.2(2), 126.9, 53.9,
2
-Naphthylalanine 4o
43.6, 15.3.
Product 4o (CAS registry No: 14108-60-2) was obtained according
N-Benzylphenylamine 6d
to the general procedures at 86% yield after purification by
◦
recrystallization in H
2
O and EtOH (13 : 3), m.p. 240.5–243 C.
Product 6d (CAS registry No: 103-32-2) was obtained according
to the general procedures at 80% yield after purification by flash
1
H NMR (D
2
O, 500 MHz): d 7.83–7.79 (m, 3H, ArH), 7.66 (s,
1
3
5
H, ArH), 7.45–7.42 (m, 2H, ArH), 7.34(d, J = 9.0 Hz, 1H, ArH),
.50 (t, J = 5.5 Hz, 1H, NCH), 3.08–3.05 (dd, J = 7.5 Hz, J =
.5 Hz, 1H, CHH), 2.93–2.88 (dd, J = 7.5 Hz, J = 6.0 Hz, 1H,
chromatography with neutral aluminum oxide (7/1 PE/Et as
1
eluent). H NMR (CDCl
3
, 500 MHz): d 7.36–7.32 (m, 4H, ArH),
7.28–7.23 (m, 1H, ArH), 7.18–7.15 (m, 2H, ArH), 6.71 (t, J =
7.5 Hz, 1H, ArH), 6.63 (d, J = 7.5 Hz, 2H, ArH), 4.32 (s, 2H,
1
3
CHH); C NMR (D
2
O, 125 MHz) d 182.0, 166.1, 136.0, 133.2,
1
3
132.0, 128.0, 127.9, 127.6, 127.5, 126.4, 125.8, 57.3, 40.8; HRMS
CH
2
), 4.04 (br, s, 1H, NH); C NMR (CDCl , 125 MHz) d 148.3,
3
+
(
m/z): 216.1014 [M+H] (cald for C13
H
13NO , 215.0946).
2
139.6, 129.3(2), 128.7(2), 127.6(2), 127.3, 117.7, 113.0(2), 48.4;
+
HRMS (m/z): 184.1120 [M+H] (cald for C13H13N, 183.1048).
General procedures of reduction of imines and hydrazones
Dibenzylamine 6e
To stirred mixture of amorphous nickel (9–11 mmol%) and
solution of substrate (25 mmol) dissolved in methanol (20 mL) an
aqueous solution of sodium hydroxide (50 mL, 5.0 M), methanol
Product 6e (CAS registry No: 103-49-1) was obtained according
to the general procedures at 89% yield after purification by flash
(
15 mL) and sodium borohydride (3.0 g, 79 mmol) was added
chromatography with neutral aluminum oxide (6/1 PE/Et as
◦
1
dropwise at 20–40 C for 2–4 h. Then, the reaction was kept at 30–
6
eluent). H NMR (CDCl
3
, 500 MHz): d 7.35–7.31 (m, 8H, ArH),
◦
13
0 C for another 0.5–3 h, and monitored by TLC. The mixture
7.27–7.24 (m, 2H, ArH), 3.82 (s, 4H, 2CH2), 1.59 (br, s, 1H);
C
was filtered and the solution was neutralized to pH 9–10 with 2 M
aqueous HCl. The aqueous phase was extracted with ethyl acetate
and the organic phase was washed with brine. The combined
NMR (CDCl , 125 MHz) d 140.6, 128.6(4), 128.4(4), 127.1(2),
3
+
53.4(2); HRMS (m/z): 198.1269 [M+H] (cald for C14
H15N,
197.1204).
6
68 | Org. Biomol. Chem., 2012, 10, 663–670
This journal is © The Royal Society of Chemistry 2012