Regioselective synthesis of fatty acid esters of glycosides containing cis-diol and biological test against bacterial staphylococcus aureus and salmonella agona

Article abstract of DOI:10.1002/jccs.201100743

Regioselectivity of glycoside containing cis-diol esterification with fatty acid using dibutyltin dimeth-oxide as stannylating agent was probed, the results showed the equatorial position of cis-diol has some advantage of being acylated, although the orie

Full text of DOI:10.1002/jccs.201100743

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Regioselective Synthesis of Fatty Acid Esters of Glycosides Containing Cis-diol and
Biological Test against Bacterial Staphylococcus aureus and Salmonella agona
Xin Loua,b* and Jin Zhaoa
aSchool of Life Sciences, Nanjing University, Nanjing 210093, P. R. China
bMaterial and Chemical Engineering College, Chuzhou Uniersity, Chuzhou, Anhui Province, 23900, P. R. China
(Received: Dec. 20, 2011; Accepted: Apr. 3, 2012; Published Online: ??; DOI: 10.1002/jccs.201100743)
Regioselectivity of glycoside containing cis-diol esterification with fatty acid using dibutyltin dimeth-
oxide as stannylating agent was probed, the results showed the equatorial position of cis-diol has some ad-
vantage of being acylated, although the orientation of adjacent groups could affected the regioselectivity.
The glycoside fatty acid esters were regioselectively synthesized on optimized condition with this stannyl
method, the biological tests against bacterial as Staphylococcus aureus and Salmonella agona were car-
ried out with these fatty acid esters, the testing results showed that glycoside esters with 12 or 14 carbon
long chain fatty acid have some obvious inhibition against Staphylococcus aureus.
Keywords: Sugar fatty acid esters; Regioselectivity; Cis-diol glycosides; Stannyl acetal.
INTRODUCTION
The carbohydrate fatty acid esters, as non-ionic sur-
ters of methyl a-D-glucopyranoside dioxane was found to
be the most suitable solvent for regioselectivity, while
added nucleophiles decreased the regioselectivity.11 We
were interested in extending our method to other glycoside
with varying structure. Herein we investigated the regio-
selectivity of glycosides acylation containing cis-diol sys-
tem as methyl b-D-galactopyranoside and methyl a-D-
mannopyranoside.
factants, are wildly used in pharmaceutical, detergent, cos-
metic, food and agricultural industries. This type of esters
were reported as effective inhibitors of Bacillus stearo-
thermophilus, Bacillus coagulans, Desulfotomaculm ni-
grificans, and some typical anaerobic spore forming bacte-
ria including Clostridia.1 Recently fatty acid esters of su-
crose, maltose and maltriose were found by Kumari S.
Devulapalle to be used as inhibitors of the glucosyltrans-
ferases of Streptococcus sobrinus.2 Usually the fatty acid
esters of sugars were regioselectively synthesized with en-
zyme method and the 6-hydroxyl group on sugar was
acylated.3-5
Synthesis of Fatty Acid Esters of Methyl b-D-galacto-
pyranoside using DBDM as Stannylating Reagent
The synthesis of fatty acid esters of galactopyrano-
side using DBDM as stannylating reagent was carried out
in dioxane at room temperature and the results are shown in
Fig. 1.
Carbohydrate stannyl ethers and stannylene acetals
have proven to be useful intermediates in the regioselective
synthesis of carbohydrate derivatives.6-8 This method can
be used to regioselectively introduce long chained fatty
acid on sugars as sucrose,9 a-D-glucuronide.10 In this work
the regioselective synthesis of fatty acid esters of glycoside
containing cis-diol (methyl b-D-galactopyranoside and
methyl a-D-mannopyranoside) using dibutyltin dimeth-
oxide (DBDM) as stannylating agent was investigated and
the synthesized glycoside esters were assessed as antibac-
terial agent against common bacterial as Staphylococcus
aureus and Salmonella agona.
The fatty acid esters of galactoside was isolated with
flash chromatography, the major product was found to be
methyl 3-O-acyl-b-D-galactoside (the structure was deter-
mined with NMR spectrum, The 13C data shows that C-2
and C-4 of all these esters have a shift of 2-2.5 ppm upfield,
Fig. 1. Regioselective synthesis of methyl 3-O-acyl-
b-D-galactopyranoside using DBDM as stan-
nylating agent.
RESULTS AND DISCUSSION
During the regioselective synthesis of fatty acid es-
* Corresponding author. E-mail: franklinee@hotmail.com
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Article
Lou and Zhao
Table 1. The effect of temperature on the regioselectivity of
while C-3 has a 2.2-2.5 ppm shift downfield. In addition
H-3 has a downfield shift of 1.2-1.3 ppm).
acylation of methyl b-D-galactoside
Temp
Ratio of 4-O-acyl:3-O-acyl:
3,4-O-diacyl isomers
Yield of overall
monoester (%)
Factors that Influence Reaction Regioselectivity on
galactoside
(°C)
60
40
25
5
1: 3.3: 0
1: 4.1: 0
83.3
81.7
79.8
51.2
(1) The Effect of Reaction Temperature on Regioselectivity
The effect of temperature on region selectivity of
acylation of methyl b-D-galactopyranoside was investi-
gated using palmitoyl chloride as acylating agent. Table 1
showed that the result of esterification of methyl b-D-
galactopyranoside during various temperature.
1: 6.3: 0
1: 30.3: 10
Note: The ratio of isomer esters was determined by HPLC
Method H (mobile phase: methanol: acetonitrile: water = 70: 20:
10; flow rate = 1.0 mL/min; Refractive index detector) after
analyzing the crude reaction mixture. Reaction conditions: methyl
b-D-galacto pyranside: DBDM: palmitoyl chloride (1: 1.1: 1.1),
dioxane.
From temp. experiments it can be seen that the reac-
tions between 20-60 °C only produced monoester products,
and that the regioselectivity increased with the decrease of
temperature, however at lower temp. of 5 °C a kinetic prod-
uct diester (3,4-O-diacyl-b-D-galactoside) was formed.
(2) The Effect of Acylating Agent on Regioselectivity
The fatty acid chlorides as acylating agent, become
inactive with the increase of chain length of fatty acid, Ta-
ble 2 showed the effect of fatty acid chain length on the
yield and regioselectivity of the DBDM mediated acylation
of methyl b-D-galactoside.
Table 2. The effect of acylating agent on regioselectivity of
reaction
Ratio of 4-O-acyl:3-O- Overall yield of
Acylating agent
acyl isomers
monoesters (%)
C7H15COCl
C9H19COCl
C11H23COCl
C13H27COCl
C15H31COCl
C17H35COCl
1:17.3
1:14.4
1:13.4
1:8.3
79
72
80
78
86
83
1:6.3
The data in Table 2 showed that the regioselectivity of
acylation decreased with the increase of chain length, that
means more active the acylating agent is, better the regio-
selectivity is, while the yield was not substantially affected.
Synthesis of Fatty Acid Esters of Methyl a-D-manno-
pyranoside Using DBDM as Stannylating Reagent
The synthesis of fatty acid esters of methyl a-D-ma-
nopyranoside using DBDM as stannylating reagent was
carried out as galactoside esters. After separation with
flash chromatography, a mixture of 2-O and 3-O isomers
was given (Figure 2). The ratio of isomers varied with reac-
1:5.2
Note: The ratio of monoester isomers was determined by HPLC
method H. Reaction conditions: methyl b-D-galactopyranside:
DBDM: acyl chloride (1: 1.1: 1.1), r. t., dioxane.
tion conditions.
Factors that Influence Reaction Regioselectivity on
manopyranoside esterification
(1) The Effect of Temperature on the Regioselectivity
The effect of temperature on regioselectivity of acyl-
ation of methyl a-D-mannopyranoside was investigated,
herein plamitoyl chloride was chosen as acylating agent,
dioxane as solvent, the result was seen in Table 3.
Table 3 shows that at higher temperatures, diesters
were formed along with monoesters. The diesters were
identified by their longer migration on TLC plates and lon-
ger retention time by HPLC analysis (method H). The
amount of diester increases with the rise in temperature.
Worthy of notice the change in temperature has affected the
regioselectivity of monoester formation: O-2 position is fa-
voured for substitution at 40-60 ºC, while at ambient or
lower temperature the 3-O isomer is the major product.
(2) The Effect of Solvent on Regioselectivity
Fig. 2. Regioselective synthesis of fatty acid esters of
methyl a-D-mannopyranoside using DBDM as
stannylating agent.
Due to not so satisfactory as galactopyranoside es-
terification was observed in the solvent of dioxane, mean-
2
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Cis-diol Glycosides Esters as Antibacterial
Table 3. Temp. effect on regioselectivity of acylation of methyl-a-D-mannopyranoside in
dioxane
Ratio of 2-palmitoyl:3-
palmitoyl mannoside
(%)
Ratio of 2,6-palmitoyl:
Yield of
Temp.
Yield of overall
monoester (%)
3,6-palmitoyl mannoside overall diester
(°C)
(%)
(%)
60
40
25
10
0
4: 1
1.5: 1
0.9: 1
0.6: 1
0.25: 1
31
42
59
61
53
1.5: 1
0.9: 1
1.1: 1
N/A
35
31
18
N/A
N/A
N/A
Note: The ratio of mono and diester isomers was determined by HPLC method H; Reaction
conditions: methyl a-D-mannopyranoside: DBDM: palmitoyl chloride (1: 1.1: 1.1).
while the previous work has proven solvent to be important
factor to affect the regioselectivity, In order to improve the
regioselectivity on mannopyranoside esterfication, differ-
ent solvents were investigated. The results are given in
Table 4.
Table 4. The effect of solvent on regioselective acylation of
methyl-a-D-mannopyranoside with palmitoyl chloride
Ratio of isomer 2-:3-
palmitoyl galactoside
Yield of overall
monoester (%)
Solvent
Toluene
Dioxane
DMP
0.8: 1
0.9: 1
3.2: 1
4.2: 1
67
63
59
72
The ratio of isomers 2b and 2b’ from the reaction in
dioxane is nearly equal to 1:1, which suggests that the
stannylene complex dimer of methyl a-D-mannopyrano-
side is a 1,2-dimer, rather than 1,1-dimer (Fig. 3). The re-
sult of dimerization is to activate both hydroxyls on 2 and 3
position. Substitution occurs equally on the 2 and 3 posi-
tion, while with other solvents the stannylene complex pre-
fer to be 1,1-dimer or 2,2-dimer.
DMF
Note: The ratio of monoester isomers was determined by HPLC
method H; Reaction conditions: methyl a-D-mannopyranoside:
DBDM: palmitoyl chloride (1: 1: 1) at r. t.
antibacterial testing.
The bacteria were grown as described in the experi-
mental section and were added to the sugar esters solution
(final concentration of 100 ppm). Figure 4 shows the re-
sults of screening of fatty acid esters of methyl b-D-galac-
topyranoside, varying in chain length from 8 to 18 carbons,
as inhibitors of the growth of Staphylococcus aureus. Fig-
ure 5 shows a similar screening result for Salmonella
agona. Fig. 6 and Fig. 7 show the screening results of
Antibacterial Screening of Methyl b-D-galactopyrano-
side and Methyl a-D-mannopyranoside Esters
The series of regioselectively synthesized fatty acid
esters: methyl 3-acyl b-D-galactopyranoside (Figure 1)
were screened for antibacterial activity against Staphylo-
coccus aureus and Salmonella agona, however the corre-
sponding pure manopyranoside ester isomers could not
separated with flash chromatography hence the mixture of
2-isomer and 3-isomer as the ratio of 1:1 were screed for
Fig. 4. Influence of chain length of fatty acid esters of
methyl b-D-galactopyranoside on the growth
of Staphylococcus aureus in culture.
Fig. 3. The structure of a 1,2-dimer (a) and a 1,1-dimer
(b) which account for different regioselectiv-
ities.
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mannopyrano side esters against Staphylococcus aureus
and Salmonella agona respectively.
tors of Staphylococcus aureus, the population of S. aureus
was reduced from 5.322 (water control) to 3.441 (1c) and
3.563 Log10 CFU/mL (1d, Figure 4). The same two esters
are mild inhibitors of Salmonella agona, the population of
S. agona was reduced from 6.094 (water control) to 3.813
(1c) and 3.830 Log10 CFU/mL (1d, Fig. 5). It is of interest,
for this compound, (1d) that it is almost as effective against
Salmonella agona as it is against Staphylococcus aureus.
The screening results of antibacterial test on manno-
pyranside esters showed: myristate (C14) and laurate (C12)
are comparatively rather effective agents. The population
of S. aureus was reduced from 5.348 (water control) to
3.319 (1c) and 2.924 Log10 CFU/mL (1d, Fig. 6). The
same two esters are mild inhibitors of Salmonella agona,
the population of S. agona was reduced from 5.964 (water
control) to 4.113 (1c) and 3.911 Log10 CFU/mL (1d, Fig.
7).
Preliminary screening shows that esters 1c (myristate
C14), 1d (laurate C12) are moderately effective as inhibi-
Fig. 5. Influence of chain length of fatty acid esters of
methyl b-D-galactopyranoside on the growth
of Salmonella agona in culture.
EXPERIMENTAL
Optical rotations were determined with a AA-5 Series
Polarimeter at the sodium D line at 23 °C. 1H and 13C spec-
tra were recorded with Varian Inova 300 and 500 spectrom-
eters. 1H chemical shifts in DMSO-d6 or CD3OD were ref-
erenced to DMSO-d6 (2.50 ppm), CHD2OD (3.30 ppm);
13C chemical shifts in DMSO-d6 or CD3OD were refer-
enced to DMSO-d6 (39.5 ppm), or CHD2OD (49.0 ppm).
Coupling constants are reported in hertz, FTIR spectra
were recorded with a Nicolet FTIR 3000 using KBr discs,
as specified. Melting points were measured on a STUART
melting point apparatus. Elemental analysis was performed
on an Exeter Analytical CE 440 elemental analyser. Low
and high-resolution mass spectra were acquired on a
Quattro Micro (Micromass, Waters Corp., USA) and on
liquid chromatography-time of flight (LCT) (Micromass,
Waters Corp., USA) mass spectrometers respectively. TLC
was performed on aluminium sheets precoated with Silica
Gel 60 (HF254, E. Merck) and spots visualized by UV and
charring with H2SO4-EtOH (1:20). Flash Column Chroma-
tography was carried out with Silica Gel 60 (0.040-0.630
mm, E. Merck) using a solvent mixture system correlated
with TLC mobility. Chromatography solvents used were
CHCl3 and MeOH. The Waters Assoc. HPLC system con-
sisted of a M 6000 Pump, a U6K injector and a R401 refrac-
tive index detector. The column used was a 15 cm ´ 4.6 mm
Luna C18 (analytic column), 25 cm ´ 10 mm Luna C18
(preparative column) stainless-steel column. Columns
were equilibrated and developed isocratically with metha-
Fig. 6. Influence of chain length of fatty acid esters of
methyl a-D-manopyranoside on the growth of
Staphylococcus aureus in culture.
Fig. 7. Influence of chain length of fatty acid esters of
methyl a-D-manopyranoside on the growth of
Salmonella agona in culture.
4
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Cis-diol Glycosides Esters as Antibacterial
nol: acetonitrile: water (70: 20: 10) at a flow rate of 1
mL/min (method H). HPLC-grade methanol, acetonitrile
and water were filtered through a 0.45 µm nylon filter
(millipore) and degassed prior to chromatography.
General Procedure for the Tin-mediated Acylation of
Methyl b-D-galactopyranoside and Methyl a-D-
mannopyranoside
Data for fatty acid esters of methyl-b-D-galactopyr-
anoside and methyl-a-D-manopyranoside
Methyl 3-O-stearoyl-b-D-galactoside (1a)
Yield 69.6%; Mp 135-137 °C; [a]D +19.98° (C 0.786,
CHCl3); 1H NMR (300 MHz, CD3OD): d 4.70 (dd, 1H, J2,3
= 10.2 Hz, J3,4 = 3.3 Hz, H-3), 4.22 (d, 1H, J1,2 = 7.9 Hz,
H-1), 4.01 (broad d, 1H, J3,4 = 3.3 Hz, H-4), 3.75 (dd, 1H,
J5,6b = 6.8 Hz, J6a,6b = 11.3 Hz, H-6b), 3.73-3.67 (m, 2H,
H-2, H-6a), 3.57 (ddd, 1H, J4,5 = 1.0 Hz, J5,6b = 6.8 Hz, J5,6a
= 5.7 Hz, H-5), 3.54 (s, 3H, OCH3), 2.40 (apt t, 2H, J = 7.5
Hz, COCH2), 1.63 (broad t, 2H, J = 7.2 Hz, COCH2CH2),
1.29 (m, 28H, -CH2CH2-), 0.89 (apt t, 3H, J = 6.6 Hz, CH3);
13C NMR (300 MHz, CD3OD): d 175.4 (CO), 106.2 (C-1),
77.5 (C-3), 76.6 (C-5), 70.2 (C-2), 68.1 (C-4), 62.4 (C-6),
57.6 (OCH3), 35.2 (COCH2), 33.3 (COCH2CH2), 31.0, 30.8,
30.8, 30.8, 30.8, 30.8, 30.7, 30.7, 30.6, 30.5, 30.5, 30.3 (m,
-CH2CH2-), 26.1 (CH2CH2CH3), 23.9 (-CH2CH2CH3),
14.7 (-CH2CH2CH3); FTIR (KBr): 3517, 3323 (OH), 2926,
2849, 1719 (CO), 1468, 1375, 1144, 1036, 893, 780, 723,
590 cm-1; Anal. Calcd. for C25H48O7: C, 65.22; H, 10.43;
Found: C, 65.06; H, 10.53; ES-LRMS: Found 477.4; re-
quired 477.3 [M.H2O-H]-.
Methyl b-D-galactopyranoside or methyl a-D-manno-
pyranoside (0.97 g, 5 mmol) was dissolved in dioxane or
other solvent (40 mL). DBDM (1.47 mL, 5.5 mmol) was
added into the solution, causing effervescence. The reac-
tion mixture was kept at r.t. and a solution of fatty acid
chloride in dioxane (10 mL) was added dropwise over one
hour. The reaction was monitored using TLC and termi-
nated when all the starting material had been converted (24
h). The mixture was evaporated under vacuum to give a
syrup. This was fractionated by flash chromatography us-
ing a solvent mixture of chloroform: methanol = 15: 1 to
give the desired monoester.
Microbiological Experimental
(1) Incubate the bacteria
3L BHI solution Made up (37 g/L) was sterilized in
the autoclave at the temperature of 110 °C for 15 min. the
Salmonella agona and Staphylococcus aureus were incu-
bated respectively into 30 mL BHI broth solution (in dupli-
cate), left at 37 °C overnight.
Methyl 3-O-palmitoyl-b-D-galactoside (1b)
Yield 74.2%; Mp 136-138 °C, [a]D +24.84° (C 0.801,
CHCl3); 1H NMR (500 MHz, CD3OD): d 4.71 (ddd, 1H, J2,3
= 10.1 Hz, J3,4 = 3.4 Hz, J = 1.0 Hz, H-3), 4.22 (d, 1H, J1,2
=
(2) Dilution of bacterial solution (1:100)
7.5 Hz, H-1), 4.01 (broad d, 1H, J3,4 = 3.4 Hz, H-4), 3.75
(dd, 1H, J5,6b = 6.7 Hz, J6a,6b = 11.3 Hz, H-6b), 3.72 (dd, 1H,
J1,2 = 7.3 Hz, J2,3 = 10.3 Hz, H-2), 3.71 (dd, 1H, J5,6a = 5.7
Hz, J6a,6b = 11.3 Hz, H-6a), 3.57 (ddd, 1H, J4,5 = 1.0 Hz, J5,6b
= 6.8 Hz, J5,6a = 5.7 Hz, H-5), 3.54 (s, 3H, OCH3), 2.40 (apt
t, 2H, J = 7.5 Hz, COCH2), 1.63 (m, 2H, COCH2-CH2),
1.29 (m, 24H, -CH2H2-), 0.90 (apt t, 3H, J = 7.0 Hz, CH3);
13C NMR (500 MHz, CD3OD) d: 175.6 (CO), 106.0 (C-1),
77.3 (C-3), 76.4 (C-5), 70.0 (C-2), 68.0 (C-4), 62.3 (C-6),
57.4 (OCH3), 35.1 (COCH2), 33.1 (COCH2CH2), 30.8,
30.8, 30.8, 30.8, 30.8, 30.7, 30.5, 30.5, 30.5, 30.3
(-CH2CH2-), 25.9 (CH2CH2CH3), 23.8 (CH2CH2CH3),
14.5 (CH2CH2CH3); FTIR (KBr): 3522 (OH), 2921, 2844,
1719 (CO), 1468, 1375, 1041, 898, 780, 718, 600 cm-1;
Anal. Calcd. for C23H44O7:C, 63.89; H, 10.19; Found: C,
63.78; H, 10.34; ES-LRMS: Found 455.3; required 455.2
[M-H]-.
1 mL of 30 mL BHI solution was transferred into 100
mL BHI, kept it at 37 °C for 14 hours.
(3) Centrifugation
50 mL of superior BHI solution was centrifuged at
4,800 Rpm for 10 mins; the superior solution was decanted
and washed, re-suspended in 9 mL MRD, centrifuged once
again for 5 min. to get a 9 mL solution, diluted to a 1:100
solution.
(4) Addition of sugar ester solution
1 mL aliquot was transferred into 10 mL of 100 ppm
sugar ester solution (in duplicate), incubated for 6 h at 37
°C.
(5) Dilution
The solution was serially diluted to such concentra-
tion: 10-1N, 10-2N, 10-3N, 10-4N on PCA plate in duplicate,
incubated it at 37 °C one day.
(6) Count bacterial number
Methyl 3-O-myristoyl-b-D-galactoside (1c)
The PCA plate in which bacterial number between 25
and 500 was selected, counted the number of bacterial and
worked out the logN.
Yield 69.6%; Mp 108-110 °C; [a]D +26.00° (C 0.745,
CHCl3); 1H NMR (300 MHz, CD3OD): d 4.69 (dd, 1H, J2,3
= 10.1 Hz, J3,4 = 3.3 Hz, H-3), 4.22 (d, 1H, J1,2 = 7.7 Hz,
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Article
Lou and Zhao
H-1), 4.00 (dd, 1H, J3,4 = 3.3 Hz, J4,5 = 0.8 Hz, H-4),
(OH), 2926, 2844, 1724 (CO), 1468, 1380, 1206, 1031,
893, 785, 723 cm-1; Anal. Calcd. for C17H32O7:C, 58.62; H,
9.32; Found: C, 58.46; H, 9.32; ES-LRMS: Found 347.3;
required 347.2 [M-H]-.
3.74-3.67 (m, 3H, H-2, H-6a, H-6b), 3.57 (ddd, 1H, J4,5
=
0.8 Hz, J5,6b = 6.6 Hz, J5,6a = 5.6 Hz, H-5), 3.53 (s, 3H,
OCH3), 2.40 (apt t, 2H, J = 7.5 Hz, COCH2), 1.63 (broad t,
2H, J = 7.2 Hz, COCH2CH2), 1.29 (m, 20H, -CH2CH2-),
0.90 (apt t, 3H, J = 6.8 Hz, CH3); 13C NMR (300 MHz,
CD3OD): d 175.5 (CO), 106.2 (C-1), 77.5 (C-3), 76.6
(C-5), 70.2 (C-2), 68.2 (C-4), 62.4 (C-6), 57.6 (OCH3),
35.3 (COCH2), 33.1 (COCH2CH2), 31.0, 30.8, 30.8, 30.7,
30.6, 30.5, 30.5, 30.2 (-CH2CH2-), 26.1 (CH2CH2CH3),
23.9 (CH2CH2CH3), 14.7 (CH2CH2CH3); FTIR (KBr):
3524, 3309 (OH), 2923, 2847, 1716 (CO), 1466, 1415,
1201, 1076, 916, 758, 717, 666 cm-1; Anal.Calcd. for
C21H40O7: C, 62.38; H, 9.9; Found: C, 61.92; H, 10.00;
ES-LRMS: Found 403.3; required 403.3 [M-1]-.
Methyl 3-O-octanoyl-b-D-galactoside (1e)
Yield 74.7%; [a]D +22.76° (C 0.552, CHCl3); Mp
130-132 °C; 1H NMR (300 MHz, CD3OD): d 4.70 (dd, 1H,
J2,3 = 10.1 Hz, J3,4 = 3.4 Hz, H-3), 4.22 (d, 1H, J1,2 = 7.7 Hz,
H-1), 4.00 (dd, 1H, J3,4 = 3.4 Hz, J4,5 = 0.8 Hz, H-4), 3.75
(dd, 1H, J5,6b = 6.8 Hz, J6a,6b = 11.3 Hz, H-6b), 3.73-3.67
(m, 2H, H-2, H-6a), 3.57 (broad ddd, 1H, J4,5 = 0.8 Hz, J5,6b
= 6.8 Hz, J5,6a= 5.5 Hz, H-5), 3.53 (s, 3H, OCH3), 2.40 (apt
t, 2H, J = 7.5 Hz, COCH2), 1.63 (broad t, 2H, J = 7.3 Hz,
COCH2CH2), 1.31 (m, H, -CH2CH2-), 0.89 (apt t, 3H, J =
6.8 Hz, CH3); 13C NMR (300 MHz, CD3OD): d 175.4 (CO),
106.2 (C-1), 77.5 (C-3), 76.6 (C-5), 70.1 (C-2), 68.2 (C-4),
62.5 (C-6), 57.7 (OCH3), 35.3 (COCH2), 33.1 (COCH2CH2),
30.5, 30.41 (-CH2CH2-), 26.2 (CH2CH2CH3), 24.0
(CH2CH2CH3), 14.7 (CH2CH2CH3); FTIR (KBr): 3504
(OH), 2950, 2844, 1716 (CO), 1463, 1374, 1206, 1035,
779, 728, 704 cm-1; Anal. Calcd. for C15H28O7:C, 56.25; H,
8.75; Found: C, 56.20; H, 8.93; ES-LRMS: Found 319.3;
required 319.2 [M-H]-.
Methyl 3-O-lauroyl-b-D-galactoside (1d)
Yield 74.4%; Mp 116-118 °C; [a]D +29.40° (C 0.748,
CHCl3); 1H NMR (300 MHz, CD3OD): d 4.70 (dd, 1H, J2,3
= 10.2 Hz, J3,4 = 3.3 Hz, H-3), 4.22 (d, 1H, J1,2 = 7.8 Hz,
H-1), 4.01 (dd, 1H, J3,4 = 3.3 Hz, H-4), 3.76-3.66 (m, 3H,
H-2, H-6a, H-6b), 3.57 (dd, 1H, J5,6b = 6.8 Hz, J5,6a = 5.5
Hz, H-5), 3.53 (s, 3H, OCH3), 2.41 (apt t, 2H, J = 7.5 Hz,
COCH2), 1.63 (broad t, 2H, J = 7.0 Hz, COCH2CH2), 1.29
(m, 16H, -CH2CH2 ), 0.90 (apt t, 3H, J = 6.7 Hz, CH3); 13
C
For the compounds of mannopyranoside ester, only
stearate, palmiate, laurate isomers with small quantity were
separated with HPLC preparative column for the character-
istic work.
NMR (300 MHz, CD3OD): d 175.5, (CO), 106.3 (C-1),
77.5 (C-3), 76.6 (C-5), 70.2 (C-2), 68.2 (C-4), 62.5 (C-6),
57.6 (OCH3), 35.3 (COCH2), 33.3 (COCH2CH2), 31.0, 30.8,
30.8, 30.7, 30.6, 30.5 (-CH2CH2-), 26.2 (CH2CH2CH3),
24.0 (CH2CH2CH3), 14.7 (CH2CH2CH3); FTIR (KBr):
3512 (OH), 2916, 2849, 1724 (CO), 1468, 1380, 1206,
1041, 898, 785, 723 cm-1; Anal. Calcd. for C19H36O7: C,
60.64; H, 9.57; Found: C, 60.57; H, 9.76; ES-LRMS:
Found 375.4; required 375.5 [M-H]-.
Methyl 3-stearoyl-a-D-mannoside (2a)
Yield 52%; 1H NMR (500 MHz, CD3OD): d 4.96 (dd,
1H, J2,3 = 3.4 Hz, J3,4 = 9.5 Hz, H-3), 4.62 (d, 1H, J1,2 = 1.3
Hz, H-1), 3.93 (dd, 1H, J1,2 = 1.6 Hz, J2,3 = 3.4 Hz, H-2),
3.83 (dd, 1H, J5,6b = 2.5 Hz, J6a,6b = 11.8 Hz, H-6b), 3.74
(dd, 1H, J5,6a = 5.9 Hz, J6a,6b = 11.8 Hz, H-6a), 3.62 (apt t,
J3,4 = J4,5 = 9.5 Hz, H-4), 3.50 (ddd, 1H, J4,5 = 9.5 Hz, J5,6b
=
Methyl 3-O-decanoyl-b-D-galactoside (1d)
2.5 Hz, J5,6a = 5.9 Hz, H-5), 3.37 (s, 3H, OCH3), 2.40 (apt t,
2H, J = 7.6 Hz, COCH2), 1.69 (m, 2H, COCH2CH2), 1.29
Yield 67.3%; Mp 126-128 °C; [a]D +21.69° (C 0.869,
CHCl3); 1H NMR (300 MHz, CD3OD): d 4.70 (dd, 1H, J2,3
= 10.1 Hz, J3,4 = 3.2 Hz, H-3), 4.22 (d, 1H, J1,2 = 7.8 Hz,
H-1), 4.01 (broad d, 1H, J3,4 = 3.2 Hz, H-4), 3.78-3.67 (m,
3H, H-2, H-6a, H-6b), 3.56 (broad dd, 1H, J5,6b = 6.5 Hz,
J5,6a = 5.5 Hz, H-5), 3.54 (s, 3H, OCH3), 2.40 (apt t, 2H, J =
7.5 Hz, COCH2), 1.63 (broad t, 2H, J = 7.1 Hz, COCH2CH2),
1.29 (m, 12H, CH2CH2-), 0.90 (apt t, 3H, J = 6.6 Hz, CH3);
13C NMR (300 MHz, CD3OD): d 175.4 (CO), 106.2 (C-1),
77.5 (C-3), 76.6 (C-5), 70.2 (C-2), 68.1 (C-4), 62.4 (C-6),
57.6 (OCH3), 35.2 (COCH2), 33.3 (COCH2CH2), 30.8,
30.7, 30.7, 30.4 (-CH2CH2-), 26.1 (CH2CH2CH3), 23.9
(CH2CH2CH3), 14.7 (CH2CH2CH3); FTIR (KBr): 3512
(m, 28H, -CH2CH2-), 0.90 (apt t, 3H, J = 7.0 Hz, CH3); 13
C
NMR (500 MHz, CD3OD): d 102.9 (C-1), 75.6 (C-3), 74.8
(C-5), 69.8 (C-2), 66.1 (C-4), 63.0 (C-6), 55.5 (OCH3),
35.3 (COCH2), 33.3 (COCH2CH2), 31.0, 30.9, 30.9, 30.9,
30.8, 30.8, 30.7, 30.7, 30.6, 30.5, 30.5, 30.3 (m,
-CH2CH2-), 26.2 (CH2CH2CH3), 24.0 (-CH2CH2CH3),
14.8 (-CH2CH2CH3); FTIR (KBr): 3429 (OH), 2921, 2849,
1740 (CO), 1468, 1134, 1059, 975, 723 cm-1.
Methyl 2-stearoyl-a-D-mannoside (2a¢)
Yield 15%; 1H NMR (500 MHz, CD3OD): d 4.98 (dd,
1H, J1,2 = 1.6 Hz, J2,3 = 3.4 Hz, H-2), 4.61 (d, 1H, J1,2 = 1.3
6
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Cis-diol Glycosides Esters as Antibacterial
Hz, H-1), 3.83 (dd, 1H, J5,6b = 2.5 Hz, J6a,6b = 11.8 Hz,
H-6b), 3.74-3.62 (m, 4H, H-2, H-3, H-4, H-6a), 3.50 (m,
1H, H-5), 3.37 (s, 3H, OCH3), 2.30 (apt t, 2H, J = 7.6 Hz,
COCH2), 1.63 (m, 2H, COCH2CH2), 1.29 (m, 28H,
-CH2CH2-), 0.95 (apt t, 3H, J = 7.4 Hz, CH3); 13C NMR
(500 MHz, CD3OD): d 100.2 (C-1), 74.7 (C-5), 73.8 (C-2),
70.7 (C-3), 69.1 (C-4), 63.2 (C-6), 55.6 (OCH3), 35.2
(COCH2), 33.3 (COCH2CH2), 31.0, 31.0, 31.0, 30.9, 30.8,
30.8, 30.7, 30.7, 30.6, 30.5, 30.5, 30.5 (m, -CH2CH2-), 26.2
(CH2CH2CH3), 24.0 (CH2CH2CH3), 14.8 (CH2CH2CH3);
FTIR (KBr): 3429 (OH), 2921, 2849, 1740 (CO), 1468,
1134, 1059, 975, 723 cm-1.
1H, J2,3 = 3.4 Hz, J3,4 = 9.5 Hz, H-3), 4.62 (d, 1H, J1,2 = 1.3
Hz, H-1), 3.93 (dd, 1H, J1,2 = 1.6 Hz, J2,3 = 3.4 Hz, H-2),
3.83 (dd, 1H, J5,6b = 2.5 Hz, J6a,6b = 11.8 Hz, H-6b), 3.74
(dd, 1H, J5,6a = 5.9 Hz, J6a,6b = 11.8 Hz, H-6a), 3.62 (apt t,
J3,4 = J4,5 = 9.5 Hz, H-4), 3.50 (m, 1H, H-5), 3.37 (s, 3H,
OCH3), 2.40 (apt t, 2H, J = 7.6 Hz, COCH2), 1.69 (m, 2H,
COCH2CH2), 1.29 (m, 20H, -CH2CH2-), 0.90 (apt t, 3H, J =
7.0 Hz, CH3); 13C NMR (300 MHz, CD3OD) d: 172.5 (CO),
102.7 (C-1), 75.5 (C-3), 74.7 (C-5), 69.9 (C-2), 66.5 (C-4),
62.7 (C-6), 55.5 (OCH3), 35.4 (COCH2), 33.4 (COCH2CH2),
31.1, 31.1, 31.1, 30.7, 30.7, 30.5 (-CH2CH2-), 26.2
(CH2CH2CH3), 24.0 (CH2CH2CH3), 14.8 (CH2CH2CH3);
FTIR: 3399 (OH), 2921, 2854, 1735 (CO), 1463, 1057,
970, 810, 718 cm-1.
Methyl 3-palmitoyl-a-D-mannoside (2b)
Yield 35%; 1H NMR (300 MHz, CD3OD): d 4.92 (dd,
1H, J2,3 = 3.2 Hz, J3,4 = 9.5 Hz, H-3), 4.62 (d, 1H, J1,2 = 1.3
Hz, H-1), 3.93 (dd, 1H, J1,2 = 1.6 Hz, J2,3 = 3.2 Hz, H-2),
3.80 (dd, 1H, J5,6b = 2.3 Hz, J6a,6b = 11.8 Hz, H-6b), 3.74
(dd, 1H, J5,6a = 5.9 Hz, J6a,6b = 11.8 Hz, H-6a), 3.62 (apt t,
J3,4 = J4,5 = 9.5 Hz, H-4), 3.50 (m, 1H, H-5), 3.32 (s, 3H,
OCH3), 2.38 (apt t, 2H, J = 7.6 Hz, COCH2), 1.67 (m, 2H,
COCH2CH2), 1.29 (m, 24H, -CH2CH2-), 0.90 (apt t, 3H, J =
7.1 Hz, CH3); 13C NMR (300 MHz, CD3OD): d 172.5 (CO),
102.8 (C-1), 75.8 (C-3), 74.8 (C-5), 70.0 (C-2), 66.0 (C-4),
63.0 (C-6), 55.5 (OCH3), 35.3 (COCH2), 33.2 (COCH2CH2),
30.9, 30.9, 30.8, 30.8, 30.8, 30.7, 30.5, 30.5, 30.5, 30.3
(-CH2CH2-), 26.2 (CH2CH2CH3), 24.1 (CH2CH2CH3),
14.7 (CH2CH2CH3); FTIR (KBr): 3419 (OH), 2911, 2844,
1745 (CO), 1468, 1062, 965, 718 cm-1.
Methyl 2-lauroyl-a-D-mannoside (2d¢)
Yield 13%; 1H NMR (500 MHz, CD3OD): d 4.98 (dd,
1H, J1,2 = 1.6 Hz, J2,3 = 3.4 Hz, H-2), 4.61 (d, 1H, J1,2 = 1.3
Hz, H-1), 3.83 (dd, 1H, J5,6b = 2.5 Hz, J6a,6b = 11.8 Hz, H-
6b), 3.74 (dd, 1H, J5,6a = 5.9 Hz, J6a,6b = 11.8 Hz, H-6a),
3.68 (dd, 1H, J2,3 = 3.4 Hz, J3,4 = 9.5 Hz, H-3), 3.62 (apt t,
J3,4 = J4,5 = 9.5 Hz, H-4), 3.50 (m, 1H, H-5), 3.37 (s, 3H,
OCH3), 2.30 (apt t, 2H, J = 7.6 Hz,COCH2), 1.63 (m, 2H,
COCH2CH2), 1.29 (m, 20H, -CH2CH2-), 0.95 (apt t, 3H, J =
7.4 Hz, CH3); 13C NMR (300 MHz, CD3OD): d 100.1
(C-1), 74.6 (C-5), 70.7 (C-3), 74.1 (C-2), 69.0 (C-4), 63.0
(C-6), 55.6 (OCH3), 35.3 (COCH2), 33.4 (COCH2CH2),
31.0, 30.9, 30.9, 30.7, 30.6, 30.5 (-CH2CH2-), 26.2
(CH2CH2CH3), 24.0 (CH2CH2CH3), 14.7 (CH2CH2CH3);
FTIR (KBr): 3429 (OH), 2921, 2849, 1740 (CO), 1468,
1134, 1059, 975, 723 cm-1.
Methyl 2-palmitoyl-a-D-mannoside (2b¢)
Yield 35%; 1H NMR (300 MHz, CD3OD): d 4.94 (dd,
1H, J1,2 = 1.3 Hz, J2,3 = 3.4 Hz, H-2), 4.61 (d, 1H, J1,2 = 1.3
Hz, H-1), 3.81 (dd, 1H, J5,6b = 2.5 Hz, J6a,6b = 11.6 Hz,
H-6b), 3.74 (dd, 1H, J5,6a = 5.9 Hz, J6a,6b = 11.8 Hz, H-6a),
3.68 (dd, 1H, J2,3 = 3.4 Hz, J3,4 = 9.5 Hz, H-3), 3.62 (apt t,
J3,4 = J4,5 = 9.5 Hz, H-4), 3.50 (m, 1H, H-5), 3.37 (s, 3H,
OCH3), 2.30 (apt t, 2H, J = 7.6 Hz, COCH2), 1.63 (m, 2H,
COCH2CH2), 1.29 (m, 24H, -CH2CH2 -), 0.95 (apt t, 3H, J
= 7.4 Hz, CH3); 13C NMR (300 MHz, CD3OD): d 100.5
(C-1), 74.8 (C-5), 73.9 (C-2), 71.0 (C-3), 69.1 (C-4), 63.1
(C-6), 55.6 (OCH3), 35.2 (COCH2), 33.0 (COCH2CH2),
30.9, 30.9, 30.8, 30.8, 30.7, 30.7, 30.5, 30.5, 30.5, 30.4
(-CH2CH2-), 25.8 (CH2CH2CH3), 24.0 (CH2CH2CH3),
14.7 (CH2CH2CH3); FTIR (KBr): 3419 (OH), 2911, 2844,
1745 (CO), 1468, 1062, 965, 718 cm-1.
ACKNOWLEDGMENT
This work was supported by Anhui Provincial-level
University Research Projects Funding KJ2011Z275, Anhui
Provincial-level Chemical Engineering and Technology
Teaching Team 20101035 and Chuzhou University Fund-
ing 2010kj009Z, We also thank Professor Gary Henehan,
Dr Seamas Cassidy and Dr Julie Dunne in Dublin Institute
of Technology, Ireland for their suggestion on this whole
work.
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J. Chin. Chem. Soc. 2012, 59, 000-000
© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
7

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Lou and Zhao
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© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2012, 59, 000-000