524 Letters in Organic Chemistry, 2011, Vol. 8, No. 7
Ye et al.
The corresponding lactone is (S)-ethyl 6-hydroxy-4-(4-
methoxyphenyl)-3,4-dihydro-2H-pyran-5-carboxylate. HPLC
(CHIRALPAK AS, Hexane:i-PrOH = 85:15, flow rate 1.0
mL/min, ꢀ = 246nm), tR = 5.45 (major), 6.46 (minor) min.
97% ee.
(R)-Diethyl 2-(1-(4-chlorophenyl)-2-formylethyl)-malonate
(4f) [6]
20
1
Viscous oil; [ꢁ]D = -26.5º(c = 0.19, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.74 (s, 1H), 7.41 (d, J=8.8 Hz, 2H),
7.34 (d, J=8.0 Hz, 2H), 4.34 (q, J=7.2 Hz, 2H), 4.17-4.09
(m, 3H), 3.81 (d, J=10.0 Hz, 1H), 3.12-2.98 (m, 2H), 1.40 (t,
J=7.2 Hz, 3H), 1.19 (t, J=7.2 Hz, 3H).
(R)-Dmiethyl 2-(2-formyl-1-(4-methoxyphenyl)-ethyl)-
malonate (4b) [4]
20
1
Viscous oil; [ꢁ]D = -28.1º(c = 0.39, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.58 (d, J=1.6 Hz, 1H), 7.16 (d, J=6.8
Hz, 2H), 6.82 (d, J=6.8 Hz, 2H), 3.99-3.97 (m, 1H), 3.77-
3.74 (m, 6H), 3.71 (d, J=10.0 Hz, 1H), 3.52 (s, 3H), 2.90-
2.86 (m, 2H).
The corresponding lactone is (S)-ethyl 4-(4-chlo-
rophenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate.
HPLC (CHIRALPAK AS, Hexane:i-PrOH = 85:15, flow
rate 1.0 mL/min, ꢀ = 246nm), tR = 6.06 (minor), 6.66 (major)
min. 90% ee.
The corresponding lactone is (S)-methyl 6-hydroxy-4-(4-
methoxyphenyl)-3,4-dihydro-2H-pyran-5-carboxylate. HPLC
(CHIRALPAK AS, Hexane:i-PrOH = 85:15, flow rate 0.8
mL/min, ꢀ = 246nm), tR = 9.00 (major), 10.22 (minor) min.
92% ee.
(R)-Dimethyl 2-(1-(3-chlorophenyl)-2-formylethyl)-malo-
nate (4g) [6]
20
1
Viscous oil; [ꢁ]D = -11.4º(c = 0.09, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.61 (s, 1H), 7.26-7.14 (m, 4H), 4.04-
4.00 (m, 1H), 3.75 (s, 3H), 3.75 (d, J=8.0 Hz, 1H), 3.55 (s,
3H), 2.96-2.91 (m, 2H).
(R)-Dimethyl 2-(1-(4-fluorophenyl)-2-formylethyl)- malo-
nate (4c) [4]
The corresponding lactone is (S)-methyl 4-(3-chlo-
rophenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate.
HPLC (CHIRALPAK AS, Hexane:i-PrOH = 83:17, flow
rate 1.0 mL/min, ꢀ = 246nm), tR = 5.78(minor), 6.11 (major)
min. 88% ee.
20
1
Viscous oil; [ꢁ]D = -25.1º(c = 0.27, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.69 (s, 1H), 7.38-7.34 (m 2H), 7.09 (t,
J=8.8 Hz, 2H), 4.18-4.12 (m, 1H), 3.86 (d, J=10.0 Hz, 1H),
3.84 (s, 3H), 3.61 (s, 3H), 3.09-3.02 (m, 2H).
The corresponding lactone is (S)-methyl 4-(4-fluo-
rophenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate.
HPLC (CHIRALPAK AS, Hexane:i-PrOH = 82:18, flow
rate 1.0 mL/min, ꢀ = 246nm), tR = 6.09 (minor), 6.39 (major)
min. 91% ee.
(R)-Diethyl 2-(1-(3-chlorophenyl)-2-formylethyl)-malonate
(4h) [6]
20
1
Viscous oil; [ꢁ]D = -25.4º(c = 0.13, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.75 (s, 1H), 7.41-7.28 (m, 4H), 4.34
(q, J=7.2 Hz, 2H), 4.17-4.10 (m, 3H), 3.82 (d, J=10.0 Hz,
1H), 3.13-2.99 (m, 2H), 1.40 (t, J=7.2 Hz, 3H), 1.18 (t,
J=7.2 Hz, 3H).
(R)-Diethyl 2-(1-(4-fluorophenyl)-2-formylethyl)-malonate
(4d) [6]
o
20
White solid; mp 52.8-53.4 C; [ꢁ]D = -32.7º(c = 0.13,
The corresponding lactone is (S)-ethyl 4-(3-chlo-
rophenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate.
HPLC (CHIRALPAK AS, Hexane:i-PrOH = 80:20, flow
rate 1.0 mL/min, ꢀ = 246nm), tR = 4.98 (major), 5.61 (minor)
min. 99% ee.
1
CHCl3); H NMR (400 MHz, CDCl3): ꢂ 9.60 (s, 1H), 7.27-
7.21 (m, 2H), 6.98 (t, J=4.4 Hz, 2H), 4.21 (q, J=7.2 Hz, 2H),
4.05-3.94 (m, 3H), 3.67 (d, J=9.6 Hz, 1H), 2.98-2.83 (m,
2H), 1.26 (t, J=7.2 Hz, 3H), 1.04 (t, J=6.8 Hz, 3H).
The corresponding lactone is (S)-ethyl 4-(4-fluoro-
phenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate. Vis-
cous oil; HPLC (CHIRALPAK AS, Hexane:i-PrOH = 80:20,
flow rate 1.0 mL/min, ꢀ = 246nm), tR = 4.96 (major), 5.59
(minor) min. 98% ee; 1H NMR (400 MHz, CDCl3): ꢂ 7.84 (s,
1H), 7.18-7.15 (m, 2H), 7.01-6.96 (m, 2H), 4.15-4.05 (m,
3H), 3.90 (d, J=4.8 Hz, 1H), 3.81-3.77 (m, 1H), 2.21-2.13
(m, 1H), 1.83-1.79 (m, 1H), 1.15 (t, J=7.2 Hz, 3H); 13C
NMR (100 MHz, CDCl3): ꢂ 167.1, 162.7, 160.3, 156.4,
140.3, 129.1, 129.0, 115.2, 115.0, 62.5, 59.8, 34.2, 29.8,
14.2.
(R)-Dimethyl 2-(2-formyl-1-(4-methylphenyl)-ethyl)-malo-
nate (4i) [6]
20
1
Viscous oil; [ꢁ]D = -24.8º(c = 0.23, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.58 (t, J=2.0 Hz, 1H), 7.13-7.08 (m,
4H), 4.03-3.95 (m, 1H), 3.74 (s, 3H), 3.71 (d, J=8.0 Hz, 1H),
3.51 (s, 3H), 2.91-2.87 (m, 2H), 2.29 (s, 3H).
The corresponding lactone is (S)-methyl 6-hydroxy-4-p-
tolyl-3,4-dihydro-2H-pyran-5-carboxylate. HPLC (CHIRA
LPAK AS, Hexane:i-PrOH = 83:17, flow rate 1.0 mL/min, ꢀ
= 246nm), tR = 5.04 (minor), 5.36 (major) min. 93% ee.
(R)-Dimethyl 2-(1-(4-chlorophenyl)-2-formylethyl)- malo-
nate (4e) [6]
(R)-Diethyl 2-(2-formyl-1-(3-methylphenyl)ethyl)-malonate
(4j) [6]
20
1
20
Viscous oil; [ꢁ]D = -37.3º(c = 0.13, CHCl3); 1H NMR
Viscous oil; [ꢁ]D = -19.2º(c = 0.16, CHCl3); H NMR
(400 MHz, CDCl3): ꢂ 9.60 (s, 1H), 7.28-7.18 (m, 4H), 4.02-
3.98 (m, 1H), 3.74 (s, 3H), 3.72 (d, J=9.6 Hz, 1H), 3.53 (s,
3H), 2.95-2.90 (m, 2H).
(400 MHz, CDCl3): ꢂ 9.60 (s, 1H), 7.17 (t, J=7.6 Hz, 1H),
7.03 (d, J=9.6 Hz, 3H), 4.21 (q, J=7.2 Hz, 2H), 4.01-3.93
(m, 3H), 3.69 (d, J=10.0 Hz, 1H), 2.90-2.86 (m, 2H), 2.31 (s,
3H), 1.26 (t, J=7.2 Hz, 3H), 1.01 (t, J=7.2 Hz, 3H).
The corresponding lactone is (S)-methyl 4-(4-chlo-
rophenyl)-6-hydroxy-3,4-dihydro-2H-pyran-5-carboxylate.
HPLC (CHIRALPAK AS, Hexane:i-PrOH = 85:15, flow
rate 1.0 mL/min, ꢀ = 246nm), tR = 5.78(minor), 6.36 (major)
min. 90% ee.
The corresponding lactone is (S)-ethyl 6-hydroxy-4-m-
tolyl-3,4-dihydro-2H-pyran-5-carboxylate. HPLC (CHIRA
LPAK AS, Hexane:i-PrOH = 80:20, flow rate 1.0 mL/min, ꢀ
= 246nm), tR = 5.06 (major), 5.86 (minor) min. 98% ee.