Synthesis and acid-catalyzed hydrolysis of some 3-(4-methoxyphenyl)propyl glucuronates

Article abstract of DOI:10.1135/cccc20001609

3-(4-Methoxyphenyl)propyl D-glucuronate, 3-(4-methoxyphenyl)propyl methyl 4-O-methyl-α-Dglucopyranosiduronate, 3-(4-methoxyphenyl)propyl 1,2,3,4-tetra-O-acetyl-α-D-glucopyranuronate and 3-(4-methoxyphenyl)propyl 1,2-(S):3,5-di-O-benzylidene-α-D-glucofuranuronate were prepared as a model substances for the ester lignin-saccharide bonds. Rates of acid-catalyzed hydrolysis of the prepared compounds in 1 M HCl in acetonitrile-water 3 : 1 at 20 °C have been measured by LC-DAD analysis and it showed the low stability of the ester bonds towards acid hydrolysis.

Full text of DOI:10.1135/cccc20001609

3-(4-Methoxyphenyl)propyl Glucuronates
1609
SYNTHESIS AND ACID-CATALYZED HYDROLYSIS
OF SOME 3-(4-METHOXYPHENYL)PROPYL GLUCURONATES
a2
b
Monika POLÁKOVÁa1,*, Dušan JONIAK and Miloslav ĎURIŠ
a
Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 842 38 Bratislava,
1
2
Slovakia; e-mail: chemonca@nic.savba.sk, chemdjon@post.sk
Water Research Institute, Hydroanalytical Laboratories, Nábrežie L. Svobodu 5,
812 49 Bratislava, Slovakia
b
Received April 17, 2000
Accepted Septem ber 14, 2000
3-(4-Meth oxyph en yl)propyl D-glucuron ate, 3-(4-m eth oxyph en yl)propyl m eth yl 4-O-m eth yl-
α-Dglucopyran osiduron ate, 3-(4-m eth oxyph en yl)propyl 1,2,3,4-tetra-O-acetyl-α-D-gluco-
pyran uron ate an d 3-(4-m eth oxyph en yl)propyl 1,2-(S):3,5-di-O-ben zyliden e-α-D-glucofuran -
uron ate were prepared as a m odel substan ces for th e ester lign in –sacch aride bon ds. Rates of
acid-catalyzed h ydrolysis of th e prepared com poun ds in 1 M HCl in aceton itrile–water 3 : 1
at 20 °C h ave been m easured by LC-DAD an alysis an d it sh owed th e low stability of th e
ester bon ds towards acid h ydrolysis.
Key w ord s: Carboh ydrates; Glucuron ates; Esters; Hydrolysis; Reaction kin etics; Lign in s;
Uron ates; Uron ic acids.
Th e form ation an d stability of ben zyl esters between lign in an d polysacch a-
rides durin g lign in biosyn th esis was in vestigated by exam in in g th e reaction
between D-glucuron ic acid an d quin on e m eth ide1 an d th e first lign in –
carboh ydrate com plex (LCC) ben zyl ester m odel was syn th esized2. Oth er
studies dem on strated th at a part of glucuron ic acid residues is esterified in
th e lign ified wood cell walls3–7. To th e m odel com poun ds con tain in g
ben zyl-type esters of D-glucuron ic acid an d som e ben zylalcoh ols an d bin d-
in g site an alysis of ester lin kages between lign in an d glucuron oxylan 3 th e
con jugate acid oxidation with 2,3-dich loro-5,6-dicyan o-1,4-ben zoquin on e
an d trifluoroacetic acid was applied.
As gen erally kn own , som e alkyl an d ben zyl esters of glucuron ic acid are
sen sitive to alkalin e h ydrolysis, but con siderably resistan t towards
acid-catalyzed h ydrolysis4–7. Stability of oth er esters of glucuron ic acid with
respect to th e rate of h ydrolysis h as n ot been studied so far.
In con n ection with th e study of th e ch aracter an d properties of th e ester
bon ds between lign in an d polysacch arides in wood an d m odel com poun ds
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1610
Poláková, Joniak, Ďuriš:
we prepared (4-alkoxyph en yl)propyl esters of D-glucuron ic acid, th e aro-
m atic com pon en t of wh ich represen ts on e of structural types of th e lign in
un its. It was, th erefore, con ven ien t to in vestigate th e stability of th e syn -
th esized 3-(4-m eth oxyph en yl)propyl esters of D-glucuron ic acid towards
acid catalyzed h ydrolysis.
RESULTS AND DISCUSSION
Th e com poun ds exam in ed (Sch em e 1) were prepared as described in Experi-
1
m en tal. H NMR an alysis of th e product m ixture after acetalization reaction
(preparation of com poun d 1) sh owed two doublets for H-1 (δ 6.27 an d 6.23
ppm , J ≈ 4, H-1 (S)/(R)) an d two sin glets (δ 6.18 an d 5.94 ppm , 1,2-Ph CH
(S)/(R)) due to two isom ers at th e acetal cen tre of th e 1,3-dioxolan e rin g. Its
1H NMR an alysis afforded on e doublet (δ 6.27 ppm , J = 3.6, H-1) an d on e
sin glet (δ 6.18 ppm , 1,2-Ph CH), wh ich were ch aracteristic for isom er with S
con figuration of th e ph en yl group on th e 1,2-ben zyliden e rin g. Isom ers
with th e S-ph en yl an d R-ph en yl group orien tation were distin guish ed by
ch aracteristic differen t for h ydrogen s on 1,2-ben zyliden e rin g (0.24 ppm ).
Th e steric accessibility of carboxylic groups in substituted D-glucuron ic ac-
ids [acid 1, m eth yl 2,3-di-O-ben zyl-4-O-m eth yl-α-D-glucopyran osiduron ic
acid (8) an d 1,2,3,4-tetra-O-acetyl-α-D-glucopyran uron ic acid (4)] for ester
form ation were dem on strated: th e acids were con den sed with
COOR
COOCH2CH2CH2
O
OCH3
O
CH
O
(ii)
PhHC
O
OH
OH
O
HO
O
OH
CHPh
1, R = H
3
(i)
2, R = 4-CH3OC6H4(CH2)3
COOR
O
(i) N,N'-dicyclohexylcarbodiimide (DCC),
OAc
OAc
OAc
3-(4-CH3OC6H4)-CH2CH2CH2OH, pyridine, CH2Cl2, r.t., 5 h;
(ii) H2/Pd(C), EtOAc–MeOH 1 : 1, r.t., 24 h
AcO
4, R = H
(i)
5, R = 4-CH3OC6H4(CH2)3
SCHEME 1
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

3-(4-Methoxyphenyl)propyl Glucuronates
1611
3-(4-m eth oxyph en yl)propan ol an d correspon din g 3-(4-m eth oxyph en yl)-
propyl esters in appropriate yields were obtain ed. Ben zyliden e groups of
3-(4-m eth oxyph en yl)propyl 1,2-(S):3,5-di-O-ben zyliden e-α-D-glucofuran -
uron ate (2) an d ben zyl groups of 3-(4-m eth oxyph en yl)propyl m eth yl
2,3-di-O-ben zyl-4-O-m eth yl-α-D-glucopyran osiduron ate (9) were rem oved
by h ydrogen olysis at room tem perature an d atm osph eric pressure in th e
presen ce of palladium -on -carbon catalyst in EtOAc–MeOH, affordin g quan -
titative yields of 3-(4-m eth oxyph en yl)propyl D-glucuron ate (3) an d
3-(4-m eth oxyph en yl)propyl m eth yl 4-O-m eth yl-α-D-glucopyran osiduron ate
(10). Com poun d 3 was obtain ed as m ixture α an d β an om ers, wh ich was
con fim ed by 13C NMR data (94.0 C-1α an d 98.7 C-1β). Its acetylation af-
forded of th e m ixture tetraacetates in ratio th e 1 : 2.5. A key step in syn th e-
sis of m eth yl 2,3-di-O-ben zyl-4-O-m eth yl-α-D-glucopyran osiduron ic acid (8)
was oxidation of th e prim ary h ydroxyl group of com poun d 7 to carboxylic
acid (Sch em e 2). It was ach ieved by 2,2,6,6-tetram eth ylpiperidin e-oxy free
radical (TEMPO)-catalyzed oxidation (TEMPO, NaOCl, Bu4NBr, KBr,
CH2OH
O
CH2OH
O
(i)
OH
OBz
HO
OCH3
CH3O
OCH3
OBz
OH
6
7
(ii)
COOCH2CH2CH2
O
OCH3
COOH
O
(iv)
OH
OBz
OCH3
CH3O
CH3O
OCH3
OBz
OH
10
8, R = H
(iii)
9, R = 4-CH3OC6H4(CH2)3
(i) 1. PhCH(OCH3)2, 4-toluenesulfonic acid monohydrate, DMF, 60 oC, 2 h; 2. PhCH2Cl,
KOH, H2O, 90–100 oC, 2 h; 3. 1M HCl, (CH3)2CO–H2O 5 : 1, reflux; 4. Ph3CCl, pyridine,
100 oC, 5 h; MeI, Ag2O, CH2Cl2, r.t., 24 h; 5. CH3COOH, 90–100 oC, 2 h; (ii) TEMPO,
NaOCl (5% aq. solution), KBr, NaHCO3, Bu4NBr, CH2Cl2, 0 oC, 30 min; (iii) DCC,
3-(4-CH3OC6H4)-CH2CH2CH2OH, pyridine, CH2Cl2, r.t., 5 h; (iv) H2/Pd(C), EtOAc–MeOH
1 : 1, r.t., 24 h
SCHEME 2
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1612
Poláková, Joniak, Ďuriš:
NaHCO3), wh ich was very effective for selective tran sform ation of h ydroxyl
group of carboh ydrate 7 an d quickly produced acid 8 in 80% yield of pure
com poun d after extraction reaction m ixture with out furth er purification .
13C NMR an alysis of acid 8 sh owed presen ce n ew sign al in carboxylic region
(173.4 ppm) and C-6 primary hydroxyl carbon peak (≈62 ppm) disappeared.
Protectin g groups of 7 were in tacted durin g reaction 8. Furth er, for m on itor-
in g acid-catalyzed h ydrolysis α-an om er of 1,2,3,4-tetra-O-acetyl-
D-glucopyran uron ic acid (4) was esterified (δ 6.41 ppm , H-1). All esterified
com poun ds (2, 3, 5, 9 an d 10) were ch aracterized by m ultiplet for term in al
CH2 group of alcoh ol lin ked to carboxyl of correspon din g D-glucuron ic acid
(δ 4.12–4.30 ppm ).
Very few m easurem en ts of th e h ydrolysis rates of uron ic acid esters an d
so th e presen t work was un dertaken in an attem pt to determ in e th e effect
of various con figuration s on th e h ydrolysis of 3-(4-m eth oxyph en yl)propyl
D-glucuron ates an d in particular to com pare th e rates for differen tly substi-
tuted carboxylic part of esters.
Th e h ydrogen ion -catalyzed h ydrolysis an d form ation of esters h ave been
carefully studied9–12. Th ese reaction s are reversible, so if th e m ech an ism is
kn own for on e of th em , th at for th e reversible reaction can be in ferred by
m ean s of th e prin ciple of m icroscopic reversibility. For m ost esters in aque-
ous acid solution th e eviden ce is con sisten t with th e AAC2 path way, th e re-
action rates bein g first order in substrate an in h ydrogen ion 9,13,14. Th e
effects of steric h idran ce produced by bulky substituen ts in th e ester sh ould
h ave a serious retardin g effect for th e AAC2 m ech an ism . In gold9 h as stressed
th at th e un im olecular m ech an ism is favoured wh en th e bim olecular m ech -
an ism is retarded by steric h in dran ce.
In th e presen t work quan titative m easurem en ts h ave been m ade of th e
rates of acid-catalyzed h ydrolysis of th e ester bon d of th e D-glucuron ates (2,
3, 5 an d 10) are given in Table I.
Th e h ydrolyses were carried out at 20 °C with 1 M HCl in aceton itrile–
water 3 : 1. Th e course of h ydrolysis was ch ecked by LC-DAD an alysis. Th is
m eth od seem s to be appropriate, because th e h ydrolysis m ixture is an alysed
by direct in troducin g th e sam ple an d separation of th e com pon en ts. Th e
m eth od gives valuable in form ation about th e products of h ydrolysis an d
paren t com poun ds. Th e results obtain ed were accurate an d reproducible.
Th ese observation s h ad ability to distin guish th e h ydrolysis of acetal an d
ester bon ds in th e studied com poun ds sim ultan eously. Th e an alytical m ea-
surem en ts were treated in stan dard fash ion . Th e first-order rate con stan ts
were calculated from Eq. (1):
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

3-(4-Methoxyphenyl)propyl Glucuronates
1613
c∞ − c0
c∞ − ct
2.303
k
=
log
,
(1)
t
wh ere c0, ct an d c∞ are con cen tration s of th e reaction solution in itially, after
a tim e t an d at in fin ite tim e.
Con cen tration s of all th e com pon en ts of th e h ydrolyzed m ixture were
m easured with in th e predeterm in ed tim e scale, th e h alf-life of th e reaction
an d th e values were foun d, usin g a calibration curve. Rate con stan ts for h y-
drolysis of 3-(4-m eth oxyph en yl)propyl D-glucuron ates (2, 3, 5 an d 10) were
calculated from th e in crease in con cen tration of 3-(4-m eth oxyph en yl)-
propan ol in th e h ydrolysis m ixture as well as from th e decrease in con cen -
tration of th e startin g ester. In th e case of ben zyliden e derivative 2, th e h y-
drolysis rate of th e 3,5-ben zyliden e group was determ in ed from th e in crease
in con cen tration ben zaldeh yde. Th e h ydrolysis of each com poun d was ex-
am in ed in duplicate an d th e differen ces between th e m ean values of th e
rate con stan ts n ever differin g m ore th an 3%.
Th e results from th e kin etic study of h ydrolysis sh owed th at ester bon d of
all study com poun ds h ydrolyze un der relatively m ild con dition s at sim ilar
rates. Th e observed sm all differen ces are due to th e in fluen ce of th e
glucuron ic acid m oieties on ly. Th e effect of substituen ts in th e acyl m oiety
is eviden t but sm all. Th e h igh est reaction rate of n on substituted ester 3 is
on ly 1.7 tim es h igh er th an th at of th e lowest 10. Th e experim en ts in dicated
th at in th e case of ester 10 n o cleavage of th e glycosidic bon d occurred.
Moreover, th e acid-catalyzed h ydrolysis of th e 1,2-ben zyliden e acetal group
is virtually n ot observed un der th e con dition s of th e ester bon d h ydrolysis
in th e ben zyliden e derivative of α-D-glucofuran uron ate 2, wh ile ester an d
3,5-ben zyliden e acetal group were h ydrolyzed approxim ately at th e sam e
TABLE I
Rates of h ydrolysis of 3-(4-m eth oxyph en yl)propyl esters of D-glucuron ic acid at 20 ± 0.1 °C
in aceton itrile–water 3 : 1, 1 M HCl
Com poun d
106k, s–1
Relative rate
3
2
15.1 ± 0.02
9.28 ± 0.1
1.70
1.04
1.07
1
5
9.49 ± 0.04
8.90 ± 0.03
10
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1614
Poláková, Joniak, Ďuriš:
rates. Th e slower rate of h ydrolysis of 1,2-acetal group an d glycoside vs ester
in studied substan ce was caused probably slower reaction in th e gen erally
accepted m ech an ism for acetals an d glycosides, in volves a fast, pre-
equilibrium proton ation , followed by rate-determ in in g h eterolysis of th e
proton ated in term ediate to an alcoh ol an d a carbon ium ion 10,11
.
Steric effects are n egligible for th e un im olecular decom position of a
proton ated ester. Th e bim olecular reaction is ch aracterized by a sm all elec-
tron ic effect of differen t substituen ts in th e acyl group. Th e rate of
h eterolysis of th e acyl–oxygen bon d in th e AAC1 m ech an ism is very sen si-
tive to ch an ges in th e electron ic structure of th e proton ated ester. Th e AAC2
m ech an ism sh ould sh ow specific h ydrogen -ion catalyst an d n ot gen eral
acid catalysis15. Th e experim en tal eviden ce suggests th at th e bim olecular
m ech an ism is th e com m on est for th e h ydrolysis of sim ple esters in aqueous
acid solution s.
EXPERIMENTAL
Meltin g poin ts were determ in ed on a Kofler h ot-stage. Optical rotation s were m easured at
20 °C usin g a Perkin –Elm er autom atic polarim eter, m odel 141; [α]D values are given in 10–1
deg cm 2 g–1 1H NMR an d 13C NMR spectra in ch loroform -d an d aceton e-d6 were recorded
.
with a Bruker AM-300 spectrom eter (1H at 300 MHz, 13C at 75 MHz). Ch em ical sh ifts, given
in ppm (δ-scale) were distin guish ed by HETCOR. Couplin g con stan ts (J) are given in Hz.
Mass spectra: LC/PB-MS was perform ed on a HP 5989 B MS En gin e apparatus equipped with
a HP 59980B PB in terface an d a “h igh en ergy dyn ode” (HED) detector (Hewlett–Packard).
Liquid Ch rom atograph y/Particle Beam -Mass Spectrom eter was con n ected with a 50 cm × 0.12
m m i.d. stain less-steel capillary. Th e system was con trolled an d data were acquired by a HP
MS Ch em Station G1034C software run n in g on a Vectra Series 4 com puter. Th in layer ch ro-
m atograph y on silica gel (Merck PF254) coated glass plates was carried out usin g system s A
(eth yl acetate–m eth an ol 10 : 1), B (ben zen e–eth yl acetate 8 : 1), C (ben zen e–m eth an ol 40 : 1)
as eluen ts, an d colum n ch rom atograph y on colum n s of dry packed silica gel (product
No. 9385, Merck) was carried out usin g th e sam e system s. Detection was perform ed by
ch arrin g with 5% sulfuric acid in eth an ol. D-Glucuron ic acid, N,N′-dicycloh exylcarbodiim ide
an d 3-(4-m eth oxyph en yl)propan ol were com m ercial products (Fluka).
Solvents and chemicals. LiCh rosph er RP-18 an alytical colum n 250 m m lon g with 4.0 m m
i.d., packed with 5 µm octadecylsilica, was used for separation of an alytes presen t in th e
reaction m ixture. HPLC gradien t-grade aceton itrile was obtain ed from Merck (Merck,
Germ an y). Ultra-pure water was prepared by ultrafiltration with a Milli-Q system (Millipore,
U.S.A.).
Instrumentation. Th e LC an alyses were perform ed with
a HP 1090 Series II liquid
ch rom atograph (Hewlett–Packard, Germ an y) equipped with a PV5 tern ary solven t delivery
system (SDS) an d in jection valve with a 25 µl loop an d a built-in Diode array detector
equipped with a 10 m m flow cell. For sin gle-wavelen gth m on itorin g th e DA detector was set
at 210 n m with a ban dwidth of 4 n m . Durin g recordin g absorption spectra th e optical slit of
diode width was 4 n m an d a sam plin g in terval for recordin g of th e spectra was 320 m s with
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

3-(4-Methoxyphenyl)propyl Glucuronates
1615
a peak width of 0.053 m in . Absorption spectra were recorded from 190 to 600 n m . Data
from th e DA detector were collected an d evaluated by th e Ch em Station software C.03.03
(Hewlett–Packard).
Th e m obile ph ase con sisted of water (A)–aceton itrile (B) gradien t m ixture. Th e gradien t
started at 70% A an d decreased lin early to 0% A after 12 m in , rem ain ed kept at 0% A for
6 m in an d return ed to 70% A in 1 m in . Th e total run -tim e was th us 19 m in , wh ile th e flow
rate was con stan tly set at 0.4 m l m in –1
.
Procedure for rate measurements. A solution s of th e 3-(4-m eth oxyph en yl)propyl esters of
D-glucuron ic acid (2, 3, 5 an d 10) were 8 m M in aceton itrile. From th is solution , 3 m l were
placed un der n itrogen ous atm osph ere in a th erm ostat m ain tain ed at 20 ± 0.1 °C. Wh en th e
solution h ad attain ed th erm ostat tem perature, 4 M aqueous h ydroch loric acid (1 m l) was
added (resultin g con cen tration of HCl was 1 m ol l–1). Th e portion s (25 µl) of reaction m ix-
ture were subsequen tly with drawn accordin g for suitable tim e sch edule an d added to
aceton itrile (0.950 m l). Afterwords, th e solution was im m ediately n eutralized with 1 M aque-
ous NaOH (25 µl), cooled to about 0 °C. Th e 10 µl aliquot was used for LC-DAD an alyses.
1,2-(S):3,5-Di-O-ben zyliden e-α-D-glucofuran uron ic Acid (1)
Com poun d 1 was prepared acetalization reaction of D-glucuron ic acid with ben zaldeh yde ac-
cordin g to ref.16 an d m ixture of isom eric 1,2-(RS):3,5-di-O-ben zyliden e-α-D-glucofuran uron ic
acids were obtain ed. After two recrystallization steps from ch loroform –h eptan e (5 : 1) acid 1
was obtain ed. M.p. 186–189 °C, [α]D +31.0 (c 1.0, pyridin e); ref.16 gives m .p. 195–196 °C,
[α]D +48.6 (c 1.01, pyridin e). 1H NMR (CDCl3): 6.27 d, 1 H, J(1,2) = 3.6 (H-1); 6.18 s, 1 H
(1,2-Ph CH); 5.85 s, 1 H (3,5-Ph CH); 5.06 s, 1 H (H-5); 4.82 d, 1 H, J(2,3) < 1 (H-2); 4.66 d, 1 H,
J(3,4) = 2.1 (H-3); 4.60 d, 1 H, J(4,5) = 1 (H-4). 13C NMR (CDCl3): 172.6 (COO–); 129.7,
128.4, 127.8, 126.5 (C-arom .); 106.2 (1,2-Ph CH); 105.3 (C-1); 96.3 (3,5-Ph CH); 84.4 (C-2);
77.7 (C-3); 74.3 (C-4); 73.4 (C-5). For C20H18O7 (370.4) calculated: 64.85% C, 4.90% H;
foun d: 65.00% C, 4.82% H.
3-(4-Meth oxyph en yl)propyl 1,2-(S):3,5-Di-O-ben zyliden e-α-D-glucofuran uron ate (2)
A solution of com poun d 1 (0.18 g, 0.5 m m ol) in dich lorom eth an e (10 m l) was added gradu-
ally to 3-(4-m eth oxyph en yl)propan ol (0.08 g, 0.5 m m ol), N,N′-dicycloh exylcarbodiim ide
(0.10 g, 0.5 m m ol) an d dry pyridin e (0.1 m l) in dich lorom eth an e (10 m l), an d left stan din g
at room tem perature for 5 h . N,N′-Dicycloh exylurea was filtered off an d th e solven t was
evaporated to dryn ess. Th e residue was treated with eth er an d
a secon d crop of
N,N′-dicycloh exylurea was rem oved. Th e eth eral filtrate was evaporated an d th e residue was
crystallized from m eth an ol. Yield 0.21 g (80%) of 2, m .p. 98–100 °C, [α]D +27.0 (c 1.0, ch lo-
roform ). 1H NMR (CDCl3): 7.52–7.43 m , 10 H (H-arom . from acetals); 7.08 d, 2 H, J = 8.5
(H-arom . from ester); 6.83 d, 2 H (H-arom .); 6.26 d, 1 H, J(1,2) = 3.6 (H-1); 6.17 s, 1 H
(1,2-Ph CH); 5.87 s, 1 H (3,5-Ph CH); 4.96 s, 1 H (H-5); 4.81 d, 1 H, J(2,3) < 1 (H-2); 4.63 d,
1 H, J(3,4) = 2 (H-3); 4.53 d, 1 H, J(4,5) = 1 (H-4); 4.28 m , 2 H (COOCH2CH2CH2); 3.78 s,
3 H (OCH3); 2.67 t, 2 H (COOCH2CH2CH2); 2.03 m , 2 H (COOCH2CH2CH2). 13C NMR
(CDCl3): 168.2 (COOR); 129.7, 128.8, 126.1 (C-arom ); 106.1 (1,2-Ph CH); 105.3 (C-1); 95.9
(3,5-Ph CH); 84.4 (C-2); 76.6 (C-3); 74.8 (C-4); 73.7 (C-5); 65.3 (COOCH2CH2CH2); 55.3
(OCH3); 31.2, 30.3 (COOCH2CH2CH2). EI-MS, m/z (%): 518 (12, [M]+), 369 (20), 263 (35),
166 (15), 148 (38), 121 (29), 105 (27), 77 (18). For C30H30O8 (518.6) calculated: 69.46% C,
5.84% H; foun d: 69.58% C, 5.76% H.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1616
Poláková, Joniak, Ďuriš:
3-(4-Meth oxyph en yl)propyl D-Glucuron ate (3)
A m ixture of 2 (0.16 g, 0.3 m m ol) an d 10% Pd/C (0.1 g) in eth yl acetate–m eth an ol (1 : 1, 10
m l) was sh aken in h ydrogen un der atm osph eric pressure for 24 h . Th e catalyst was rem oved
by filtration an d wash ed with eth yl acetate. Th e solven t was rem oved an d th e crude product
was purified by colum n ch rom atograph y (system A). Yield 0.10 g (100%) of title com poun d 3
(syrup). 1H NMR ((CD3)2CO): 7.11 d, 4 H, J = 8.7 (H-arom .); 6.85 d, 4 H (H-arom .); 5.26 d,
1 H, J(1,2) = 3.9 (H-1α); 4.72 d, 1 H, J(1,2) = 8.1 (H-1β); 4.32–3.24 m , 8 H (H-2, 3, 4, 5);
4.11 m , 4 H (COOCH2CH2CH2); 3.79 s, 6 H (OCH3); 2.61 t, 4 H (COOCH2CH2CH2);
1.94–1.88 m , 4 H (COOCH2CH2CH2). 13C NMR ((CD3)2CO): 170.6 (COOR); 98.7 (C-1β); 94.0
(C-1α); 77.4–72.8 (C-2, 3, 4, 5); 64.7, 64.5 (COOCH2CH2CH2); 55.4 (OCH3); 31.5–30.1
(COOCH2CH2CH2). EI-MS, m/z (%): 342 (20, [M]+), 282 (35), 252 (27), 193 (26), 166 (27),
148 (19), 121 (30), 77 (12). For C16H22O8 (342.4) calculated: 56.11% C, 6.48% H; foun d:
55.87% C, 5.83% H.
1,2,3,4-Tetra-O-acetyl-α-glucopyran uron ic Acid (4)
Title com poun d was prepared accordin g to ref.17, m .p. 151–152 °C, [α]D +16.5 (c 0.5, ch loro-
form ); ref.17 reported m .p. 152–154 °C, [α ]2D0 +16.3 (c 0.5, ch loroform ).
3-(4-Meth oxyph en yl)propyl 1,2,3,4-Tetra-O-acetyl-α-D-glucopyran uron ate (5)
Com poun d 4 (0.18 g, 0.5 m m ol) in dich lorom eth an e (10 m l) was added gradually to
3-(4-m eth oxyph en yl)propan ol (0.08 g, 0.5 m m ol), N,N′-dicycloh exylcarbodiim ide (0.10 g,
0.5 m m ol) an d dry pyridin e (0.1 m l) in dich lorom eth an e (5 m l), an d left stan din g at room
tem perature for 5 h . N,N′-Dicycloh exylurea was filtered off an d th e solven t was evaporated
to dryn ess. Th e residue was treated with eth er an d a secon d crop of N,N′-dicycloh exylurea
was rem oved. Th e eth eral filtrate was evaporated an d th e residue was purified by colum n
ch rom atograph y (system B). Yield 0.21 g (82%) of 5 (syrup), [α]D +56.0 (c 1.0, ch loroform ).
1H NMR (CDCl3): 7.09 d, 2 H, J = 8.6 (H-arom .); 6.83 d, 2 H (H-arom .); 6.41 d, 1 H, J(1,2) =
3.6 (H-1); 5.55 t, 1 H, J(3,4) = 9.9, J(2,3) = 9.8 (H-3); 5.28 t, 1 H, J(3,4) = 9.9, J(4,5) = 10.0
(H-4); 5.12 dd, 1 H, J(2,3) = 9.8 (H-2); 4.42 d, 1 H, J(4,5) = 10.0 (H-5); 4.12 m , 2 H
(COOCH2CH2CH2); 3.78 s, 3 H (OCH3); 2.62 t, 2 H (COOCH2CH2CH2); 2.18, 2.11, 2.04,
2.01 4 × s, 4 × 3 H (4 × OCOCH3); 1.93 m , 2 H (COOCH2CH2CH2). 13C NMR (CDCl3): 170.0
(COOR); 169.5–166.8 (OCOCH3); 132.7, 129.2 (C-arom .); 88.8 (C-1); 73.1 (C-5); 72.0 (C-3);
70.6 (C-2); 69.1 (COOCH2CH2CH2); 68.9 (C-4); 55.2 (OCH3); 30.9, 30.1 (COOCH2CH2CH2);
20.8, 20.6, 20.5, 20.3 (4 × OCOCH3). EI-MS, m/z (%): 510 (17, [M]+), 314 (19), 289 (40), 215
(18), 166 (29), 148 (35), 121 (21), 43 (34). For C24H30O12 (510.5) calculated: 56.44% C,
5.93% H; foun d: 56.58% C, 5.96% H.
Meth yl 2,3-Di-O-ben zyl-4-O-m eth yl-α-D-glucopyran oside (7)
Th e title com poun d was prepared accordin g refs18–21, startin g from m eth yl α-D-gluco-
pyran oside (6) in six steps in overall yield 31% (syrup), [α]D +67.0 (c 1.0, ch loroform ).
Meth yl 2,3-Di-O-ben zyl-4-O-m eth yl-α-D-glucopyran osiduron ic Acid (8)
To solution of 7 (0.39 g, 1 m m ol) in dich lorom eth an e (2 m l) con tain in g TEMPO (2,2,6,6-
tetram eth ylpiperidin -1-oxyl, 1 m g) a solution of saturated aqueous sodium h ydrogen -
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3-(4-Methoxyphenyl)propyl Glucuronates
1617
carbon ate (2 m l) con tain in g potassium brom ide (11 m g) an d tetrabutylam m on ium brom ide
(15 m g) was added. Th e m ixture was cooled to 0 °C an d solution s of 1.3 sodium
M
h ypoch lorite (3 m l) an d sodium h ydrogen carbon ate (1 m l) were added dropwise over 30
m in . Th e organ ic layer wash ed with water (5 × 10 m l). Th e com bin ed aqueous extracts were
acidified with 1 M h ydroch loric acid an d extracted with eth yl acetate (3 × 15 m l), dried an d
con cen trated. Yield 0.32 g (80%) of 13 (syrup), [α]D +39.0 (c 1.0, ch loroform ). 1H NMR
(CDCl3): 7.36–7.25 m , 10 H (H-arom .); 4.96–4.60 4 × d, 4 H, J = 10.9 (2 × Ph CH2); 4.81 d,
1 H, J(1,2) = 3.6 (H-1); 4.11 d, 1 H, J(4,5) = 10.1 (H-5); 3.90 t, 1 H, J(2.3) = 9.2, J(3,4) = 9.3
(H-3); 3.54 s, 3 H (4-OCH3); 3.51 dd, 1 H, J(2,3) = 9.2 (H-2); 3.44 dd, 1 H, J(4,5) = 9.3 (H-4);
3.39 s, 3 H (1-OCH3). 13C NMR (CDCl3): 173.4 (COOR); 137.7–127.6 (C-arom .); 98.6 (C-1);
81.2, 81.1 (C-3, 4); 78.9 (C-2); 75.3, 73.6 (2 × Ph CH2); 69.4 (C-5); 60.8 (4-OCH3); 55.7
(1-OCH3). For C22H26O7 (402.4) calculated: 65.64% C, 6.52% H; foun d: 65.85% C, 6.76% H.
3-(4-Meth oxyph en yl)propyl Meth yl 2,3-Di-O-ben zyl-4-O-m eth yl-α-D-gluco-
pyran osiduron ate (9)
Com poun d
8 (0.2 g, 0.5 m m ol) in dich lorom eth an e (10 m l) was added gradually to
3-(4-m eth oxyph en yl)propan ol (0.08 g, 0.5 m m ol), N,N′-dicycloh exylcarbodiim ide (0.10 g,
0.5 m m ol) an d dry pyridin e (0.1 m l) in dich lorom eth an e (5 m l), an d left stan din g at room
tem perature for 5 h . N,N′-Dicycloh exylurea was filtered off an d th e solven t was evaporated
to dryn ess. Th e residue was treated with eth er an d a secon d crop of N,N′-dicycloh exylurea
was rem oved. Th e eth eral filtrate was evaporated an d th e residue was purified by colum n
ch rom atograph y (system B). Yield 0.22 g (78%) of 9 (syrup), [α]D +22.0 (c 1.0, ch loroform ).
1H NMR (CDCl3): 7.39–7.21 m , 10 H (2 × C6H5CH2); 7.09 d, 2 H, J = 8.6 (H-arom .); 6.83 d,
2 H (H-arom .); 4.94–4.61 4 × d, 4 H, J = 12.3 (2 × Ph CH2); 4.59 d, 1 H, J(1,2) = 3.5 (H-1);
4.19 m , 2 H (COOCH2CH2CH2); 4.07 d, 1 H, J(4,5) = 10.1 (H-5); 3.87 t, 1 H, J(2.3) = 9.2,
J(3,4) = 9.3 (H-3); 3.78 s, 3 H (H3COC6H4); 3.53 dd, 1 H, J(2,3) = 9.6 (H-2); 3.49 s, 3 H
(4-OCH3); 3.42 dd, 1 H, J(4,5) = 10.2 (H-4); 3.41 s, 3 H (1-OCH3). 13C NMR (CDCl3): 169.8
(COOR); 137.9, 129.8, 128.5, 127.7 (C-arom .); 98.8 (C-1); 81.4, 81.3 (C-3, 4); 79.1 (C-2);
75.8, 73.6 (2 × Ph CH2); 70.1 (C-5); 64.9 (COOCH2CH2CH2); 60.7 (4-OCH3); 55.7 (1-OCH3);
55.2 (H3COC6H4); 31.0, 30.3 (COOCH2CH2CH2). For C32H38O8 (550.6) calculated: 69.78% C,
6.97% H; foun d: 69.98% C, 6.84% H.
3-(4-Meth oxyph en yl)propyl Meth yl 4-O-Meth yl-α-D-glucopyran osiduron ate (10)
A m ixture of 9 (0.16 g, 0.3 m m ol) an d 10% Pd/C (0.1 g) in eth yl acetate–m eth an ol (1 : 1, 20
m l) was sh aken in h ydrogen un der atm osph eric pressure for 24 h . Th e catalyst was rem oved
by filtration an d wash ed with eth ylacetate. Th e solven t was rem oved un der reduced pressure
an d th e crude product was purified by colum n ch rom atograph y (system C). Yield 0.11 g
(100%) of 10 (syrup), [α]D +86.0 (c 0.5, ch loroform ). 1H NMR (CDCl3): 7.09 d, 2 H, J = 8.4
(H-arom .); 6.83 d,
2 H (H-arom .); 4.82 d, 1 H, J(1,2) = 3.7 (H-1); 4.25 m , 2 H
(COOCH2CH2CH2); 4.07 d, 1 H, J(4,5) = 9.8 (H-5); 3.79 s, 3 H (H3COC6H4); 3.72 t, 1 H,
J(3,4) = J(2,3) = 9.4 (H-3); 3.59 dd, 1 H, J(2,3) = 9.4 (H-2); 3.52 s, 3 H (4-OCH3); 3.46 s, 3 H
(1-OCH3); 3.40 dd, 1 H, J(3,4) = 9.2, J(4,5) = 9.5 (H-4). 13C NMR (CDCl3): 169.6 (COO–);
132.7, 130.9 (C-arom .); 99.4 (C-1); 80.8 (C-4); 74.5 (C-3); 72.1 (C-2); 70.2 (C-5); 65.0
(COOCH2CH2CH2); 60.5 (4-OCH3); 55.8 (1-OCH3); 55.3 (H3COC6H4); 31.1, 30.2
(COOCH2CH2CH2). EI-MS, m/z (%): 370 (70, [M]+), 321 (15), 251 (22), 222 (17), 166 (35),
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1618
Poláková, Joniak, Ďuriš:
148 (28), 121 (21), 77 (14). For C18H26O8 (370.4) calculated: 58.33% C, 7.15% H; foun d:
58.58% C, 6.96% H.
This work was supported by the Slovak Grant Agency (project No. 2/506098).
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