934
2a
N. Muramoto et al.
PAPER
2 H), 7.44–7.48 (m, 5 H), 7.55 (t, J = 6.8 Hz, 1 H), 7.62–7.66 (m, 5
H), 7.69–7.74 (m, 2 H), 8.02 (dd, J = 8.2, 2.76 Hz, 2 H).
13C NMR (600 MHz, CDCl3): δ = 19.6, 20.4, 42.9, 70.0, 70.1, 71.6,
127.5, 127.7, 128.3, 128.6, 128.7, 129.3, 132.02, 132.05, 132.08,
132.1, 132.2, 138.5, 165.1.
As p-nitrobenzoate: Daicel OD column, elution with hexane–
i-PrOH (80:20), flow rate 1.0 mL/min. tR: 6.45 min for S and 9.65
min for R.
2b
HRMS (ESI): m/z [M + Na]+ calcd for C31H31O4P + Na: 521.1858;
Daicel OD column, elution with hexane–i-PrOH (95:5), flow rate 1
mL/min. tR: 9.4 min for S and 7.9 for R.
found: 521.1849.
2c
(2R,4R)-2-(Benzyloxy)pentan-4-ol [(2R,4R)-2g]
From (2R,4R)-pentane-2,4-diol (540 mg), (2R,4R)-2g was obtained
by a treatment with NaH and benzyl bromide in THF at 80 °C (20
min); yield: 860 mg (86%); colorless oil; [α]D20 –5.8 (c 0.95,
CHCl3).
Daicel OD column, elution with hexane–i-PrOH (95:5), flow rate 1
mL/min. tR: 6.25 min for S and 3.25 min for R.
2d
Daicel OD column (monitored at 210 nm), elution with hexane–
i-PrOH (97:3), flow rate 1 mL/min. tR: 4.85 min for S and 4.31 min
for R.
IR (KBr): 3423, 3030, 2966, 2930, 1454, 1374, 1119, 1066, 958,
916, 830, 735, 697 cm–1.
1H NMR (600 MHz, CDCl3): δ = 0.97 (d, J = 6.2 Hz, 3 H), 1.17 (d,
J = 6.2 Hz, 3 H), 1.38–1.95 (m, 2 H), 3.74–3.79 (m, 1 H), 3.99–4.06
(m, 1 H), 4.36 (d, J = 11.7 Hz, 1 H), 4.53 (d, J = 11.7 Hz, 1 H),
7.15–7.26 (m, 5 H).
13C NMR (600 MHz, CDCl3): δ = 19.6, 23.5, 45.6, 67.9, 70.3, 76.1,
127.7, 127.8, 128.5, 138.0.
2e, 2f, and 2g
The diastereomeric excess values of these products were deter-
mined by 1H NMR analysis.
See Supporting Information (SI) for [α]D values. Characterization of
intermediate products (2R)-3a, (1R)-3b, and (2R,4S)-3g are given
below (see also SI).
HRMS (ESI): m/z [M + Na]+ calcd for C12H18O2 + Na: 217.1204;
found: 217.1210.
(2R)-Octyl 4-(Diphenylphosphoryl)benzoate [(2R)-3a]
Yield: 64.9 mg (87%); colorless oil; [α]D20 +0.74 (c 0.4, MeOH).
IR (neat): 2928, 1717, 1437, 1273, 1104 cm–1.
(2R,4S)-2-(Benzyloxy)pentan-4-ol [(2R,4S)-2h]
Following the general procedure, product (2R,4S)-2h was obtained
by the Mitsunobu inversion of (2R,4R)-2g.
Yield: 160 mg (83%); colorless oil; [α]D20 –2.9 (c 0.73, CHCl3).
1H NMR (600 MHz, CDCl3): δ = 8.09 (d like, J = 7.6 Hz, 2 H), 7.74
(dd like, J = 11.0, 8.2 Hz, 2 H), 7.64 (dd like, J = 11.7, 7.6 Hz, 4 H),
7.55 (dd like, J = 7.6, 6.9 Hz, 2 H), 7.46 (dd like, J = 6.9, 6.2 Hz, 4
H), 5.14 (dd like, J = 12.7, 6.5 Hz, 1 H), 1.70 (m, 1 H), 1.56 (m, 1
H), 1.37–1.23 (m, 8 H), 1.31 (d, J = 6.1 Hz, 3 H), 0.85 (t, J = 6.9 Hz,
3 H).
13C NMR (150 MHz, CDCl3): δ = 165.29, 137.36, 136.69, 134.01,
133.99, 132.26, 132.24, 132.10, 132.05, 132.03, 132.00, 131.98,
131.31, 129.36, 129.28, 128.67, 128.59, 77.21, 77.00, 76.79, 72.42,
35.93, 31.66, 29.07, 25.33, 22.53, 19.98, 14.01.
IR (KBr): 3431, 3030, 2967, 2929, 1454, 1375, 1207, 1066, 1027,
953, 919, 834, 736, 698 cm–1.
1H NMR (600 MHz, CDCl3): δ = 1.05 (d, J = 6.2 Hz, 3 H), 1.14 (d,
J = 6.2 Hz, 3 H), 1.33–1.63 (m, 2 H), 3.76–3.75 (m, 1 H), 3.86–3.92
(m, 1 H), 4.33 (d, J = 11.0 Hz, 1 H), 4.53 (d, J = 11.0 Hz, 1 H),
7.16–7.27 (m, 5 H).
13C NMR (600 MHz, CDCl3): δ = 19.1, 23.4, 44.3, 64.6, 70.5, 72.7,
127.7, 127.8, 128.4, 138.3.
HRMS (ESI): m/z [M + Na]+ calcd for C27H31O3P + Na: 457.1903;
found: 457.1899.
HRMS (ESI): m/z [M + Na]+ calcd for C12H18O2 + Na: 217.1204;
found: 217.1207.
(1R)-1-Phenylethyl 4-(Diphenylphosphoryl)]benzoate [(1R)-3b]
Yield: 81.5 mg (91%); colorless oil; [α]D20 +0.067 (c 0.9, MeOH).
IR (neat): 2979, 1718, 1436, 1267, 1197, 1102 cm–1.
Reaction of (2S)-2a with Twice the Amount of 1; (2R)-Octyl
4-(Diphenylphosphino)]benzoate [(2R)-6]
The reaction was performed with (2S)-2a (10 mg), 1 (50 mg), and
DIAD (1.9 M in toluene, 42 μL) in THF (0.3 mL). Among the four
components isolated using a silica gel column, three of them were
identical to the authentic samples; the remaining component (2R)-6
exhibited a 16 units smaller mass than (2R)-3a and was gradually
changed to (2R)-3a under air.
1H NMR (600 MHz, CDCl3): δ = 7.95 (d, J = 7.6 Hz, 2 H), 7.35–
7.27 (m, 12 H), 5.12 (m, 1 H), 1.70 (m, 1 H), 1.58 (m, 1 H), 1.35–
1.20 (8 H), 1.30 (d, J = 6.2 Hz, 3 H).
1H NMR (600 MHz, CDCl3): δ = 8.07 (dd, J = 7.6, 2.1 Hz, 2 H),
7.68 (dd, J = 11.0, 8.2 Hz, 2 H), 7.57 (dd like, J = 11.7, 7.6 Hz, 4
H), 7.47 (dd like, J = 6.9, 6.9 Hz, 2 H), 7.38 (dd like, J = 7.6, 5.5 Hz,
4 H), 7.34 (d like, J = 7.6 Hz, 2 H), 7.28 (dd like, J = 7.6, 7.6 Hz, 2
H), 7.21 (dd, J = 6.9, 6.9 Hz, 1 H), 6.05 (q, J = 6.7 Hz, 1 H), 1.59
(d, J = 6.7 Hz, 3 H).
13C NMR (150 MHz, CDCl3): δ = 164.87, 141.29, 132.15, 132.11,
132.05, 132.01, 131.94, 129.42, 129.35, 128.62, 128.53, 127.99,
125.99, 73.48, 22.18.
HRMS (ESI): m/z [M + Na]+ calcd for C27H31O2P + Na: 446.1959;
found: 446.1985.
HRMS (ESI): m/z [M + Na]+ calcd for C27H23O3P + Na: 449.1277;
found: 449.1272.
(2R)-2-(Benzyloxy)butyl (4S)-4-(Diphenylphosphoryl)benzoate
[(2R,4S)-3g]
Acknowledgment
Yield: 91 mg (90%); colorless oil; [α]D20 +0.94 (c 0.87, CHCl3).
Di-2-methoxyethyl azodicarboxylate (DMEAD) was supplied by
the TOYOBO Co.
IR (KBr): 3058, 2975, 1715, 1562, 1437, 1393, 1272, 1197, 1102,
1018, 912, 857, 732, 696 cm–1.
1H NMR (600 MHz, CDCl3): δ = 1.23 (d, J = 6.2 Hz, 3 H), 1.31 (d,
J = 6.2 Hz, 3 H), 1.65–1.70 (m, 1 H), 2.11–1.17 (m, 1 H), 3.62 (q,
J = 6.3 Hz, 1 H), 4.39 (d, J = 11.7 Hz, 1 H), 4.56 (d, J = 11.7 Hz, 1
H), 3.94 (q, J = 6.3 Hz, 1 H), 7.18 (t, J = 6.8 Hz, 1 H), 7.22–7.28 (m,
Supporting Information for this article is available online at
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Synthesis 2013, 45, 931–935
© Georg Thieme Verlag Stuttgart · New York