J.-J. Jiang, M. Shi / Tetrahedron: Asymmetry 18 (2007) 1376–1382
1381
0
0
4
.2.6. (R)-(+)-1-((2-(Diphenylphosphino)-1,1 -binaphthyl-2 -
4.3. Typical reaction procedure
ylimino)methyl)naphthalen-2-ol L6. Yield: (210 mg, 69%).
A brown solid. Mp: 100–102 ꢁC; IR (CH Cl ) m 3052, 1712,
˚
Chiral ligand L4 (11.4 mg, 0.02 mmol), 4 A molecular
sieves (10 mg), and (CuOTf) ÆC H (5.0 mg, 0.01 mmol)
2
2
ꢀ1
1
1
622, 1605, 1563, 1323, 1180, 980, 820 cm ; H NMR
2
6
6
(
6
7
(
CDCl , TMS, 300 MHz) d 6.60 (t, J = 7.2 Hz, 1H, Ar),
.75 (t, J = 7.2 Hz, 2H, Ar), 6.89 (d, J = 9 Hz, 1H, Ar),
.00–7.31 (m, 12H, Ar), 7.43–7.53 (m, 4H, Ar), 7.62–7.73
were added to methanol (0.8 mL) at room temperature.
The reaction mixture was stirred for 30 min and then 4-
nitrobenzaldehyde 1c (30.2 mg, 0.2 mmol) and nitrometh-
ane (0.6 mL) were added to the resulting purple solution.
The mixture was stirred for 48 h at room temperature
and then concentrated in vacuo to give a glutinous phase
residue. Next, CH Cl (2.0 mL) and aqueous HCl solution
3
m, 4H, Ar), 7.97–8.10 (m, 3H, Ar), 8.12 (d, J = 9 Hz,
3
1
1
H, Ar), 8.95 (s, 1H, CH@N), 13.93 (s, 1H, OH);
P
NMR (CDCl , 121 MHz, 85% H PO ) d ꢀ12.74; MS
3
3
4
+
(
ESI) m/e 608 (M +1, 100); HRMS (ESI) calcd for
2
2
+
C H NOP (M+H ): 608.2143, found: 608.2151;
(1.0 M, 5 mL) were added into the residue and the mixture
stirred until the green color disappeared. After extraction
with CH Cl (3 · 10 mL), the combined organic layers
4
3
30
2
0
½
aꢁ ¼ þ309 (c 0.2, CHCl3).
D
2
2
were washed with brine, dried over anhydrous Na SO ,
2
4
0
4
.2.7. (R)-(+)-N-Benzylidene-2-(diphenylphosphino)-1,1 -bi-
and evaporated in vacuo. The residue was purified by flash
chromatography on silica gel (eluent: PE/EtOAc = 8/1) to
furnish adduct 2c as an off-white solid.
0
naphthyl-2 -amine L7. Yield: (108 mg, 20%). A yellow
solid. Mp: 88–90 ꢁC; IR (CH Cl ) m 3378, 3053, 1712,
1
2
2
ꢀ
1 1
620, 1433, 1359, 1220, 815, 743 cm ; H NMR (CDCl ,
3
TMS, 300 MHz) d 6.67 (d, J = 8.1 Hz, 1H, Ar), 6.93–7.56
m, 21H, Ar), 7.74 (d, J = 7.8 Hz, 1H, Ar), 7.80 (d,
J = 8.7 Hz, 1H, Ar), 7.87–7.90 (m, 3H, Ar), 8.16 (s, 1H,
4.3.1. (S)-2-Nitro-1-phenylethanol 2a. Yield: (21 mg,
1
(
63%). A yellow oil. H NMR (CDCl , TMS, 300 MHz) d
3
2.68 (br, 1H, OH), 4.52 (dd, J = 13.2, 3.3 Hz, 1H, CH),
4.62 (dd, J = 13.2, 9.3 Hz, 1H, CH), 5.48 (dd, J = 9.3,
3.3 Hz, 1H, CH), 7.36–7.42 (m, 5H, Ar); Enantiomeric
excess was determined by HPLC with a Chiralcel OD-H
column (hexane/i-PrOH = 95/5, 0.5 mL/min, 230 nm,
3
1
CH@N); P NMR (CDCl , 121 MHz, 85% H PO ) d
3
3
4
+
ꢀ
12.81; MS (ESI) m/e 542 (M +1, 100); HRMS (ESI)
+
calcd for C H NP (M+H ): 542.2038, found: 542.2032;
3
9
28
2
D
0
½
aꢁ ¼ þ191 (c 0.25, CHCl3).
2
0
tminor = 65.38 min, tmajor = 83.53 min; ½aꢁ ¼ þ28:0 (c
D
0
.95, CH Cl ), 80% ee.
2 2
4
phino)-1,1 -binaphthyl-2 -amine
.2.8.
(R)-(+)-N-(2-Chlorobenzylidene)-2-(diphenylphos-
(160 mg,
0
0
L8. Yield:
4.3.2. (+)-2-Nitro-1-(3-nitrophenyl)ethanol 2b. Yield:
(37 mg, 87%). An off-white solid. H NMR (CDCl3,
TMS, 300 MHz) d 3.13 (s, 1H, OH), 4.57–4.68 (m, 2H,
1
56%). A yellow solid. Mp: 100–102 ꢁC; IR (CH Cl ) m
3052, 1712, 1612, 1586, 1433, 814, 743 cm ; H NMR
2
2
ꢀ1
1
(
CDCl , TMS, 300 MHz) d 6.90–7.53 (m, 21H, Ar), 7.72–
CH ), 5.59–5.63 (m, 1H, CH), 7.62 (t, J = 8.1 Hz, 1H,
3
2
7
.91 (m, 4H, Ar), 8.02 (d, J = 8.7 Hz, 1H, Ar), 8.52 (s,
Ar), 7.78 (d, J = 7.8 Hz, 1H, Ar), 8.24 (d, J = 9.6 Hz,
1H, Ar), 8.34 (s, 1H, Ar); Enantiomeric excess was deter-
mined by HPLC with a Chiralcel OD-H column (hexane/
3
1
1
H, CH@N); P NMR (CDCl , 121 MHz, 85% H PO )
3
3
4
+
d ꢀ12.89; MS (ESI) m/e 576 (M +1, 100); HRMS (ESI)
+
calcd for C H ClNP (M+H ): 576.1648, found:
i-PrOH = 90/10, 1 mL/min, 230 nm, t
tmajor = 29.54 min; ½aꢁD ¼ þ24:0 (c 1.65, CH Cl ), 67% ee.
= 26.04 min,
3
9
27
minor
20
20
5
76.1631; ½aꢁD ¼ þ335 (c 0.25, CHCl3).
2
2
4
.3.3. (S)-2-Nitro-1-(4-nitrophenyl)ethanol 2c. Yield:
1
4
.2.9. (R)-(+)-N-(2,3-Dichlorobenzylidene)-2-(diphenylphos-
(37 mg, 87%). An off-white solid. H NMR (CDCl3,
0
0
phino)-1,1 -binaphthyl-2 -amine L9. Yield: (100 mg, 41%).
A yellow solid. Mp: 105–107 ꢁC; IR (CH Cl ) m 3053, 1713,
1
TMS, 300 MHz) d 3.20 (d, J = 4.2 Hz, 1H, OH), 4.57–
4.60 (m, 2H, CH ), 5.58–5.64 (m, 1H, CH), 7.63 (d,
2
2
2
ꢀ
1
1
608, 1433, 1414, 1220, 1181 cm
;
H NMR (CDCl ,
J = 8.4 Hz, 2H, Ar), 8.28 (d, J = 8.4 Hz, 2H, Ar); Enantio-
3
TMS, 300 MHz) d 6.92–7.51 (m, 19H, Ar), 7.69–7.93 (m,
meric excess was determined by HPLC with a Chiralcel
5
H, Ar), 8.04 (d, J = 8.7 Hz, 1H, Ar), 8.50 (s, 1H, CH@N);
AD-H column (hexane/i-PrOH = 65/35, 0.7 mL/min,
3
1
20
P NMR (CDCl , 121 MHz, 85% H PO ) d ꢀ12.95; MS
230 nm, tminor = 5.98 min, tmajor = 7.38 min; ½aꢁD ¼ þ25:8
3
3
4
+
(
ESI) m/e 610 (M +1, 100); HRMS (ESI) calcd for
(c 1.3, CH Cl ), 73% ee.
2
2
+
C H Cl NP (M+H ): 610.1258, found: 610.1226;
3
9
26
2
2
0
½
aꢁ ¼ þ392 (c 0.2, CHCl3).
4.3.4. (S)-1-(2-Chlorophenyl)-2-nitroethanol (2d). Yield:
D
1
(
28 mg, 70%). A yellow oil. H NMR (CDCl , TMS,
3
300 MHz) d 3.03 (d, J = 3.6 Hz, 1H, OH), 4.45 (dd,
4
.2.10. (R)-(+)-2-(Diphenylphosphino)-N-(quinolin-2-ylmethyl-
J = 13.8, 9.6 Hz, 1H, CH), 4.68 (dd, J = 13.8, 2.1 Hz,
1H, CH), 5.85 (d, J = 9.6 Hz, 1H, CH), 7.28–7.40 (m,
3H, Ar), 7.67 (d, J = 7.2 Hz, 1H, Ar); Enantiomeric excess
was determined by HPLC with a Chiralcel OD-H column
0
0
ene)-1,1 -binaphthyl-2 -amine L10. Yield: (156 mg, 53%).
A yellow solid. Mp: 95–97 ꢁC; IR (CH Cl ) m 3052, 2925,
1
2
2
ꢀ1 1
595, 1503, 1433, 1197, 1145, 1090, 964 cm ; H NMR
(
(
1
CDCl , TMS, 300 MHz) d 6.85 (s, 2H, Ar), 7.01–8.09
(hexane/i-PrOH = 98/2, 0.7 mL/min, 215 nm, tminor =
3
3
1
20
m, 26H, Ar), 8.60 (s, 1H, CH@N); P NMR (CDCl3,
28.96, tmajor = 31.54 min; ½aꢁD ¼ þ33:9 (c 0.9, CH Cl ),
2
2
21 MHz, 85% H PO ) d ꢀ12.84; MS (ESI) m/e 593
75% ee.
3
4
+
(
(
M +1, 100); HRMS (ESI) calcd for C H N P
42 29 2
20
+
M+H ): 593.2147, found: 593.2140; ½aꢁ ¼ þ230 (c 0.25,
4.3.5. (S)-1-(4-Chlorophenyl)-2-nitroethanol 2e. Yield:
D
1
CHCl ).
(33 mg, 82%). A yellow oil. H NMR (CDCl , TMS,
3
3