S. V. Naidu et al. / Tetrahedron Letters 46 (2005) 2129–2131
2131
analysis (Chiralcel OD, petroleum ether–i-PrOH (98:2),
1 mL/min, 240 mm. Spectral data of compound 7: colour-
References and notes
25
less oil, ½aꢀD ꢁ8.8 (c 0.9, CHCl3); IR (neat): mmax 3400,
1. (a) Davies-Coleman, M. T.; Rivett, D. E. A. Fortschr.
Chem. Org. Naturst. 1989, 55, 1–35; (b) Adityachaudhury,
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ston: Edinburgh, 1962; p 516.
3133, 3018, 2926, 2854, 1732, 1460, 1401, 1215, 760,
667 cmꢁ1 1H NMR (200 MHz, CDCl3): d 0.88 (t, J =
;
7.3 Hz, 3H), 1.24–1.37 (m, 6H), 1.59 (t, J = 6.8 Hz, 3H),
3.20 (br s, 2H), 3.85 (dt, J = 6.8, 2.4 Hz, 1H), 4.06 (d,
J = 2.4 Hz, 1H), 4.25 (q, J = 7.2 Hz, 2H); 13C NMR
(50 MHz, CDCl3): d 13.7, 13.8, 22.3, 27.6, 32.8, 61.4, 72.4,
73.2, 173.5. Anal. Calcd for C9H18O4 (190.24): C, 56.82;
H, 9.54. Found C, 56.61; H, 9.68.
11. For reviews on the Swern oxidation, see: (a) Tidwell, T. T.
Synthesis 1990, 857–870; (b) Tidwell, T. T. Org. React.
1990, 39, 297–572.
4. (a) Van Puyvelde, L.; Dube, S.; Uwimana, E.; Uwera, C.;
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followed by 1,3-dihydroxy protection as the benzylidene
derivative. The required isomer 11a could easily be
separated by silica gel column chromatography. The
stereochemistry of compound 11 was unambiguously
assigned based on NOE studies. Strong NOE correlations
were observed between the 1,3-diaxial protons of the cyclic
derivative 11a. Reagents and conditions: (i) HCl, MeOH,
5. Kjaer, A.; Norrestan, R.; Polonsky, J. Acta Chem. Scand.
Ser. B 1985, 39, 745–750.
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Ph
H
H
O
OH
O
H
O
H
H
a
C H9
H4
O
O
Ph
C4H9
C4H9
O
OH
11a
OH
11
rt, 12 h; (ii) PhCH(OMe)2, p-TSA, CH2Cl2, rt, overnight;
(b) Even after protection of the hydroxy group of 11 with
the different protecting groups such as TBS, MOM, Ac
and PMB, we were unable to separate the diastereomers
by flash chromatography.
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converted into its dibenzoate. The enantiomeric purity of
the dibenzoate was estimated to be >97% by chiral HPLC
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99, 1191–1223.
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25
15. Spectral data of compound 12: colourless oil, ½aꢀD ꢁ3.7 (c
0.9, CHCl3); IR (neat): mmax 3453, 2956, 2931, 2893, 2859,
1379, 1254, 1192 cmꢁ1 1H NMR (200 MHz, CDCl3): d
;
0.91 (t, J = 7.1 Hz, 3H), 1.26–1.36 (m, 3H), 1.39 (s, 3H),
1.42 (s, 3H), 1.46–1.66 (m, 3H), 2.09 (s, 1H), 2.77–2.89 (m,
2H), 3.22–3.28 (m, 1H), 3.68 (t, J = 7.1 Hz, 1H), 3.83–3.90
(m, 1H), 3.97–4.09 (m, 1H); 13C NMR (50 MHz, CDCl3):
d 13.9, 22.6, 27.0, 27.4, 28.2, 33.8, 44.4, 52.3, 71.5, 79.5,
81.3, 108.8. Anal. Calcd for C12H22O4 (230.30): C, 62.58;
H, 9.63. Found C, 62.71; H, 9.59.
16. For reviews on ring-closing metathesis see: (a) Grubbs, R.
H.; Chang, S. Tetrahedron 1998, 54, 4413–4450; (b)
Prunet, J. Angew. Chem., Int. Ed. 2003, 42, 2826–2830.