72
S. Carbonnel et al. / Carbohydrate Research 319 (1999) 63–73
(b) Preparation of 18 from 17. Compound
CH3). 13C NMR (CDCl3): l 172.9–173.7
(CꢀO ester), 169.1–170.4 (OAc), 112.2, 112.3
(C-8), 100.0, 100.7 (C-7,7%), 92.5, 92.8 (C-1,1%),
60.4–62.1 (C-6,6%, COOCH2CH3), 36.4, 34.9,
34.5, 29.1, 27.9, 25.9 (CH2ꢁCꢁacetal), 25.9,
25.1, 24.6, 18.1 (CH3ꢁacetal), 20.4–20.7
(CO2CH2CH3).
17 (300 mg, 0.58 mmol) was dissolved in 10
mL of 1:1 DMF–CH3CN, B (510 mg, 4 mol
equiv, 2.32 mmol) and a catalytic amount of
camphorsulfonic acid were added and the so-
lution was kept under stirring at rt. After 1 h,
1 mol equiv of B was added, and the mixture
was heated at 70 °C. After 2 h, usual workup
and purification by column chromatography
(3:1 EtOAc–hexane) led to 18 as a white
powder (222 mg, 50%). Data for 18: mp 60–
Methyl 4,6-O-[(R)-3-carboxybutylidene]-h-
D-glucopyranoside (22).—Compound 4 (512
mg) was dissolved in 16 mL of 0.2 M KOH.
EtOH was distilled as it was formed. The
solution was maintained at 40 °C for 35 min
and then cooled to rt. Neutralization of the
mixture by adding Amberlite IR-120 (H+)
ion-exchange resin, followed by filtration and
lyophilisation, afforded compound 22 (480
mg, 94%). Data for 22: [h]2D0 +45° (c 1.0
1
61 °C; [h]2D0 +89° (c 1.0 CHCl3). For H and
13C NMR data, see Tables 4 and 5. Anal.
Calcd for C34H50O19: C, 53.50; H, 6.60.
Found: C, 53.80; H, 6.78.
(c) Transacetalation of h,h-trehalose 19. A
solution containing 1.00 g (2.92 mmol) of
trehalose in DMF (10 mL), 2 or 6 mol equiv
of B and camphorsulfonic acid, was heated to
70 °C. Progress of the reaction was monitored
by TLC (12:3:2 EtOAc–EtOH–H2O). After
1.5 h, the solution was neutralized with NEt3,
and the solvent was evaporated. Acetylation
under the usual conditions, followed by purifi-
cation on silica gel column (1:1 EtOAc–hex-
ane), afforded first the diacetal 18, and then
the monoacetal 16 (Table 7).
1
H2O). For 13C NMR and H NMR data, see
Tables 1 and 2.
1%,2,3,3%,4%,6%-Hexa-O-acetyl-4,6-O-(3-car-
boxybutylidene)sucrose (23).—Deacetylation
of 12 according to the Zemple´n procedure was
carried out as follows. Compound 12 was
dissolved in anhyd MeOH (7 mL), and a
catalytic amount of a freshly prepared 0.2 M
solution of MeONa was slowly added. After 2
h under stirring at rt, the starting material was
entirely transformed. The solvent was evapo-
rated under reduced pressure, and the residue
was dissolved in 0.2 M KOH (10 mL). The
solution was maintained under stirring at
40 °C and neutralised after 1 h with Amberlite
IR-120 (H+). Lyophilization and subsequent
acetylation gave a crude mixture which was
purified by column chromatography to afford
23 as a colourless oil. Data for 23: [h]2D0 +15°
2,3:4,6:4%,6%-Tri-O-(3-ethoxycarbonylbutyli-
dene)-h,h-trehalose (20) and 2%,3%-di-O-acetyl-
2,3:4,6:4%,6%-tri-O-(3-ethoxycarbonylbutylidene)
-h,h-trehalose (21).—To a solution containing
1.00 g (2.92 mmol) of 19 in 10 mL of anhyd
DMF were added 6.60 g (10 mol equiv) of
ethyl 4,4-diethoxybutanoate B and 20 mg of
camphorsulfonic acid. The mixture was stirred
at 70 °C for 4 h, then neutralized by NEt3 (1
mL), and the solvent evaporated under re-
duced pressure. The crude residue was purified
by chromatography (2:1 EtOAc–hexane). A
further purification was necessary to separate
20 from reagent B. Thus, 486 mg (23%) of 20
were obtained. Acetylation of 20 (200 mg)
with Ac2O–pyridine led after chromato-
graphic purification (1:3 EtOAc–hexane) to
compound 21 (134 mg, 60%).
1
(c 1.0, H2O). For 13C NMR and H NMR
data, see Tables 4 and 5.
References
[1] (a) S.J. Angyal, Ad6. Carbohydr. Chem. Biochem., 47
(1989) 1–43. (b) D.A. Rees, E.R. Morris, D. Thom, J.K.
Madden, in G.O. Aspinall (Ed.), The Polysaccharides,
Vol. 1, Academic Press, New York, 1982, pp. 195–290.
[2] A.S. Davidson, in B. Milwidsky (Ed.), Synthetic Deter-
gents, 7th ed., Longman, Essex, 1987.
1
Data for 21: [h]2D0 +83° (c 1.0, CHCl3). H
NMR (CDCl3): l 5.35 (t, 1 H, H-3%, J2%,3%
=
J3%,4%=9.5), 5.25 (m, 2 H, H-1,1%, J1%,2%=4.4),
4.87 (dd, 1 H, H-2%), 4.10 (m, 4 H, H-4,4%,5,5%),
3.70 (m, 10 H, H-6,6%,6%%,6%%%, COOCH2CH3),
2.50–1.80 (m, 18 H, OAc, ꢁCH2ꢁCH2ꢁ),
1.50–1.10 (m, 18 H, CH3ꢁacetal, CO2CH2-
[3] (a) R.W. Binkley, Modern Carbohydrate Chemistry,
Marcel Dekker, New York, 1988, pp. 94–98 and 223–
233. (b) J.W. Green, Methods Carbohydr. Chem., 3
(1963) 322–327. (c) K. Heyns, H. Paulsen, Ad6. Carbo-
hydr. Chem., 17 (1962) 169–221, and references cited
therein.