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V. Cere et al. / Tetrahedron 56 (2000) 1225–1231
1229
(c1.58, CHCl3). Anal. Calcd for C23H28O6S: C, 63.87; H,
6.53. Found: C, 63.84; H, 6.57. m/z (EI): 432 (Ͻ1), 417 (2),
341 (12), 91 (100). IR (CCl4) nmax/cmϪ12926, 1312, 1124.
[a]2D5Ϫ26.9 (c1.14, CHCl3). Anal. Calcd for
C23H28O4S: C, 68.97; H, 7.99. Found: C, 69.04; H, 7.93.
m/z: 400 (Ͻ1), 385 (1), 292 (13), 126 (23), 91 (100). IR
(CCl4) nmax/cmϪ13060, 2900, 1450, 1370, 1220, 1080,
700.
(Ϫ)-(1R,2R.3R,4R)-1,4-di-O-Benzyl-2,3-O-isopropyli-
denecyclohex-5-ene-1,2,3,4-tetrol (7a). The same method-
ology described for 3a was followed starting from the
(Ϫ)-1,6-dideoxy-2,5-di-O-benzyl-3,4-O-isopropylidene-
1,6-thio-d-mannitol-S,S-dioxide (6a). The reaction was
carried out in 1.45 h and after the usual work-up the title
compound was obtained, in 77% yield, as a solid which
could be used as such for the following reaction. Neverthe-
less the title compound, purified by flash chromatography
(SiO2; Et2O/light-petroleum, 7:1), gave a white solid at mp
(Ϫ)-1,6-Dideoxy-2,5-di-O-benzyl-3,4-O-isopropylidene-
1,6-thio-d-sorbitol-S,S-dioxide (6b). The reaction was
carried out using the same methodology described for the
synthesis of 6a starting from the (Ϫ)-1,6-dideoxy-2,5-di-O-
benzyl-3,4-O-isopropylidene-1,6-thio-d-sorbitol (5b). The
title compound was obtained in 87% yield as a white solid
(mp 120–122ЊC). 1H NMR d: 7.40–7.25 (m, 10H,
10CHAr), 4.85 (d, 1H; CHHPh, J11.9 Hz), 4.75 (d, 1H;
CHHPh, J11.8 Hz), 4.67 (d, 1H, CHHPh, J12.0 Hz),
4.66 (d, 1H; CHHPh, J11.8 Hz), 4.54 (t, 1H, CHO,
J9.0 Hz), 4.27–4.22 (m, 1H, CHOBn), 4.20 (dd, 1H,
CHO, J9.1, 1.4 Hz), 4.00 (ddd, 1H, CHOBn, J9.1, 9.1,
3.9 Hz), 3.47–3.24 (m, 4H, 2CH2S), 1.51 (s, 3H, CH3), 1.46
(s, 3H, CH3). 13C NMR d: 137.6 (CAr), 137.1 (CAr), 128.6
(2CHAr), 128.5 (2CHAr), 128.2 (2CHAr), 127.9 (2CHAr),
127.8 (2CHAr), 109.1 (C(CH3)2), 78.3 (CHO), 76.9 (CHO),
74.9 (CHO), 73.7 (CH2Ph), 72.9 (CH2Ph), 70.4 (CHO), 59.5
(CH2S), 56.1 (CH2S), 27.1 (CH3), 26.8 (CH3). [a]2D5Ϫ35.5
(c1.16, CHCl3). Anal. Calcd for C23H28O6S: C, 63.87;
H, 6.53. Found: C, 63.81; H, 6.57. m/z: 432 (Ͻ1),
417(2), 341 (8), 91 (100). IR (Nujol) nmax/cmϪ12900,
1320, 1130.
1
66–68ЊC. H NMR d: 7.35–7.15 (m, 10H, 10CHAr), 5.81
(dd, 2H, 2CHy, J1.4, 3.2 Hz), 4.89 (d, 2H, 2CHHPh,
J11.7 Hz), 4.55 (d, 2H, 2CHHPh, J11.7 Hz), 4.30–
4.20 (m, 2H, 2CHO), 4.15–4.05 (m, 2H, 2CHO), 1.45 (s,
6H, 2CH3). 13C NMR d: 138.8 (2CAr), 129.6 (4CHAr),
128.5 (4CHAr), 127.8 (2CHAr), 127.7 (2CHy), 110.2
(C(CH3)2), 75.0 (2CHO), 73.6 (2CH2), 72.1 (2CHO), 27.1
(2CH3). [a]2D5Ϫ192.3 (c0.87, CHCl3). Anal. Calcd for
C23H26O4: C, 75.37; H, 7.16. Found: C, 75.40; H, 7.20.
m/z (EI): 366 (Ͻ1), 351 (1), 308 (4), 91 (100). IR (CCl4)
nmax/cmϪ12986, 1234, 1000.
(Ϫ)-Conduritol E (8a). To 168 mg (0.46 mmol) of
(Ϫ)-(1R,2R,3R,4R)-1,4-di-O-benzyl-2,3-O-isopropylidene-
cyclohex-5-ene-1,2,3,4-tetrol (7a) dissolved in 4 mL of
CH2Cl2 0.2 mL of SnCl4 were added. After 1 h the reaction
mixture was neutralized with a saturated solution of
NaHCO3 and extracted with CH2Cl2. By evaporation of
the aqueous layer was recovered a residue which was
extracted with 10 mL of CH3OH. The organic layer was
dried on MgSO4, filtered on celite and by evaporation of
the solvent gave 54 mg (0.354 mmol, 77%) of the expected
(1S,2R,3R,4R)-(Ϫ)-1,4-di-O-Benzyl-2,3-O-isopropylidene-
cyclohex-5-ene-1,2,3,4-tetrol (7b). The reaction was
carried out using the same methodology described for the
synthesis of 7a starting from the (Ϫ)-1,6-dideoxy-2,5-di-O-
benzyl-3,4-O-isopropylidene-1,6-thio-d-sorbitol-S,S-dioxide
(6a). The reaction was carried in 2 h and, after usual workup
7b was obtained as a yellow oil in 79% yield. The title
compound was purified by flash chromatography (SiO2;
light-petroleum/Et2O, 8:1). 1H NMR d: 7.75–7.50 (m,
10H, 10CHAr), 6.18–6.04 (m, 2H, 2CHy), 5.24 (d, 1H,
CHHPh, J12.0 Hz), 5.15 (d, 1H, CHHPh, J12.0 Hz),
4.99 (d, 1H, CHHPh, J11.9 Hz), 4.96 (d, 1H, CHHPh,
J11.9 Hz), 4.60–4.38 (m, 3H, 3CHO), 3.81 (dd, 1H,
CHO, J3.4, 9.8 Hz), 1.80 (s, 6H, 2CH3). 13C NMR d:
138.9 (CAr), 138.6 (CAr), 131.9 (CHy), 128.4 (2CHAr),
128.3 (2CHAr), 127.9 (2CHAr), 127.8 (2CHAr), 127.7
(2CHAr), 127.0 (CHy), 110.6 (C(CH3)2) 78.3 (CHO),
78.0 (CHO), 76.6 (CHO), 73.2 (CH2Ph), 71.5 (CH2Ph),
71.1 (CHO), 27.4 (CH3), 26.9 (CH3). [a]2D5Ϫ88.6
(c1.46, CHCl3). Anal. Calcd for C23H26O4: C, 75.37; H,
7.16. Found: C, 75.41; H, 7.12. m/z: 366 (Ͻ1), 351 (1), 202
(8), 149 (16), 91 (100). IR (CCl4) nmax/cmϪ12987, 1371,
1089.
1
(Ϫ)-conduritol E16 as a white solid at mp 191–193ЊC. H
NMR (D2O) d: 5.72 (m, 2H, 2CH), 4.15 (m, 2H, 2CHO),
3.76 (m, 2H, 2CHO). 13C NMR (D2O) d: 127.3 (2CHy),
66.7 (2CHO), 64.2 (2CHO). [a]2D5Ϫ330.0 (c1.90, H2O).
Anal. Calcd for C6H10O4: C, 49.30; H, 6.90. Found: C,
49.25; H, 6.97. m/z (EI): 146 (Ͻ1), 110 (100), 82 (8). IR
(Nujol) nmax/cmϪ13520, 3000, 1092, 1030.
(Ϫ)-1,6-Dideoxy-2,5-di-O-benzyl-3,4-O-isopropylidene-
1,6-thio-d-sorbitol (5b). The reaction was carried out using
the same methodology described for the synthesis of 5a
starting
from the
3,4-O-isopropylidene-1,6-thio-d-
sorbitol.12 The reaction was quantitative and the product,
obtained as yellow oil, could be used for the following
reaction as such. Nevertheless the title compound, purified
by flash chromatography (SiO2; light-petroleum/Et2O, 5:1)
gave a yellow solid (mp55–58ЊC). 1H NMR d: 7.50–7.15
(m, 10H, 10CHAr), 4.90–4.73 (m, 4H, 2CH2Ph), 4.67 (dd,
1H, CHO, J12.2, 2.3 Hz), 4.17–4.08 (m, 1H, CHOBn),
3.97 (dd, 1H, CHO, J9.1, 2.2 Hz), 3.78–3.67 (m, 1H,
CHOBn), 2.84 (dd, 1H, CHHS, J15.5, 4.3 Hz), 2.73–
2.54 (m, 3H, 2CHHS and CHHS), 1.49 (s, 3H, CH3), 1.42
(s, 3H, CH3). 13C NMR d: 138.7 (CAr), 138.6 (CAr), 128.4
(2CHAr), 128.3 (2CHAr), 128.2 (2CHAr), 127.7 (2CHAr),
127.6 (2CHAr), 109.1 (C(CH3)2), 79.8 (2CHO), 79.0
(CHO), 74.5 (CHO), 73.0 (CH2Ph), 71.5 (CH2Ph), 36.8
(CH2S), 36.6 (CH2S), 27.2 (CH3), 26.7 (CH3).
(Ϫ)-Conduritol
F (8b). The title compound was
synthesized analogously to 8a starting from the
(1S,2R,3R,4R)-(Ϫ)-1,4-di-O-benzyl-2,3-O-isopropylidene-
cyclohex-5-ene-1,2,3,4-tetrol (7b). After 70 min, by usual
workup, the title compound16 was obtained in 79% yield as a
pale yellow solid at mp 128–130ЊC. 1H NMR d: 5.79 (ddd,
1H, CH, J10.0, 4.7, 1.9 Hz), 5.71 (dd, 1H, CHy,
J10.0, 1.9 Hz), 4.15 (t, 1H, CHO, J4.3 Hz), 3.92 (dt,
1H, CHO, J7.5, 1.6 Hz), 3.61 (dd, 1H, CHO, J10.4,
7.7 Hz), 3.41 (dd, 1H, CHO, J10.4, 4.2 Hz). 13C NMR