86
K. Damodar, B. Das
PAPER
A soln of RuCl3·H2O (0.025 g, 0.12 mmol) in H2O (6.9 mL), was
added at r.t. NaIO4 (0.98 g, 4.6 mmol) was added in one portion with
vigorous stirring and the mixture was stirred for a further 2 h at r.t.
The progress of the reaction was monitored by TLC. After complete
consumption of the starting material, the reaction was quenched
with sat. aq Na2S2O3 soln (30 mL). The phases were separated and
the aq layer was extracted with EtOAc (3 × 50 mL). The organic
portions were combined, dried over Na2SO4 and concentrated under
reduced pressure. The crude residue was subjected to column chro-
matography (silica gel, hexane–EtOAc, 17:3) to afford pure alde-
hyde 10 (0.49 g, 65%) as a colourless liquid.
ESI-MS: m/z 392 [M + H]+, 414 [M + Na]+.
Supporting Information for this article is available online at
Acknowledgment
The authors thank CSIR, New Delhi for financial assistance and are
also grateful to K. Haribabu for HPLC analysis and the NMR, Mass,
and IR divisions of IICT for recording the spectra.
[a]D27 –26.2 (c 0.58, CHCl3).
IR (neat): 3330, 1720, 1529, 1458, 1248 cm–1.
References
1H NMR (200 MHz, CDCl3): d = 9.78 (s, 1 H), 7.20–7.12 (br s, 5
H), 5.08 (s, 2 H), 4.90 (d, J = 8.0 Hz, 1 H), 4.08–4.04 (m, 1 H),
2.64–2.55 (m, 2 H), 1.51 (d, J = 7.0 Hz, 2 H), 1.39–1.20 (m, 14 H),
0.84 (t, J = 7.0 Hz, 3 H).
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13C NMR (50 MHz, CDCl3): d = 201.2, 156.1, 135.8, 128.7, 128.3,
66.2, 49.6, 47.1, 35.0, 31.2, 29.9, 29.8, 29.7, 25.8, 23.5, 14.7.
ESI-MS: m/z 334 [M + H]+.
Benzyl [(4R,6S)-4-Hydroxy-2-oxopentadecan-6-yl]carbamate
(11) and Benzyl [(4S,6S)-4-Hydroxy-2-oxopentadecan-6-yl]car-
bamate (12)
The aldehyde 10 (0.2 g, 0.6 mmol) was dissolved in acetone (1 mL)
and H2O (5 mL). Next, sat. aq NaOH soln (0.2 mL) was added at r.t.
The mixture was stirred at r.t. for 45 min, diluted with H2O (5 mL)
and extracted with CHCl3 (3 × 25 mL). The organic portions were
combined and dried over Na2SO4. The solvent was evaporated and
the crude residue subjected to flash column chromatography (silica
gel, hexane–EtOAc, 3:7 to 3:2) to give the pure aldol products
[0.270 g, 69%; syn (12)/anti (11) = 1:1].
Benzyl [(4R,6S)-4-Hydroxy-2-oxopentadecan-6-yl]carbamate
(7) Daly, J. W.; Garraffo, H. M.; Spande, T. F. Amphibian
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(11)
Pale-yellow solid; yield: 0.082 g (35%); mp 68–70 °C; [a]D27 –8.4
(c 0.85, CHCl3).
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IR (neat): 3336, 2921, 1694, 1538, 1464, 1256 cm–1.
1023.
1H NMR (200 MHz, CDCl3): d = 7.37–7.27 (m, 5 H), 5.09 (s, 2 H),
4.82 (d, J = 9.0 Hz, 1 H), 4.10 (br s, 1 H), 3.93–3.74 (m, 2 H), 2.62
(dd, J = 12.0, 8.0 Hz, 1 H), 2.43 (dd, J = 12.0, 3.0 Hz, 1 H), 2.17 (s,
3 H), 1.64–1.51 (m, 2 H), 1.48–1.36 (m, 2 H), 1.34–1.18 (m, 14 H),
0.88 (t, J = 7.0 Hz, 3 H).
13C NMR (50 MHz, CDCl3): d = 208.7, 157.2, 136.3, 128.5, 128.1,
128.0, 66.9, 64.3, 50.2, 48.3, 42.7, 35.2, 31.8, 30.9, 29.6, 29.4, 29.3,
29.2, 26.1, 22.6, 14.1.
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ESI-MS: m/z 392 [M + H]+.
HRMS (ESI): m/z [M + H]+ calcd for C23H38NO4: 392.2800; found:
392.2806.
Benzyl [(4S,6S)-4-Hydroxy-2-oxopentadecan-6-yl]carbamate
(12)
Pale-yellow solid; yield: 0.080 g (34%); mp 67–69 °C; [a]D27 +14.5
(c 0.6, CHCl3).
IR (neat): 3336, 2921, 1694, 1538, 1464, 1256 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.33–7.26 (m, 5 H), 5.04 (s, 2 H),
4.73 (d, J = 9.0 Hz, 1 H), 4.06–4.04 (m, 1 H), 3.66–3.62 (m, 1 H),
2.73 (dd, J = 12.0, 3.0 Hz, 1 H), 2.48 (dd, J = 12.0, 8.0 Hz, 1 H),
2.14 (s, 3 H), 1.57 (t, J = 7.0 Hz, 2 H), 1.51–1.40 (m, 2 H), 1.34–
1.21 (m, 14 H), 0.88 (t, J = 7.0 Hz, 3 H).
13C NMR (50 MHz, CDCl3): d = 209.9, 156.3, 136.6, 128.5, 128.1,
128.0, 66.6, 65.7, 49.6, 49.1, 42.0, 35.9, 31.9, 30.7, 29.7, 29.6, 29.5,
29.3, 25.7, 22.7, 14.1.
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Synthesis 2012, 44, 83–86
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