Looking glass inhibitors: both enantiomeric N-benzyl derivatives of 1,4-dideoxy-1,4-imino-d-lyxitol [a potent competitive inhibitor of α-d-galactosidase] and of 1,4-dideoxy-1,4-imino-l-lyxitol [a weak competitive inhibitor of α-d-galactosidase] inhibit na

Article abstract of DOI:10.1016/j.tetasy.2009.10.004

Benzhydryl protection by diphenyldiazomethane of an alcohol in enantiomeric base-sensitive ribonolactones allows short efficient syntheses of 1,4-dideoxy-1,4-imino-d-lyxitol (DIL) and of 1,4-dideoxy-1,4-imino-l-lyxitol (LIL). DIL showed potent [K_i

Full text of DOI:10.1016/j.tetasy.2009.10.004

Tetrahedron: Asymmetry 20 (2009) 2368–2373
Contents lists available at ScienceDirect
Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Looking glass inhibitors: both enantiomeric N-benzyl derivatives
of 1,4-dideoxy-1,4-imino-D-lyxitol [a potent competitive inhibitor
of
competitive inhibitor of
an -L-rhamnosidase competitively
a
-D-galactosidase] and of 1,4-dideoxy-1,4-imino-L-lyxitol [a weak
a-D-galactosidase] inhibit naringinase,
a
Thomas B. Mercer a, Sarah F. Jenkinson a, Barbara Bartholomew b, Robert J. Nash b, Saori Miyauchi c,
Atsushi Kato c, George W. J. Fleet a,
*
a Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
b Phytoquest Limited, IBERS, Plas Gogerddan, Aberystwyth SY23 3EB, Ceredigion, Wales, UK
c Department of Hospital Pharmacy, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Benzhydryl protection by diphenyldiazomethane of an alcohol in enantiomeric base-sensitive
Received 18 August 2009
Accepted 6 October 2009
Available online 29 October 2009
ribonolactones allows short efficient syntheses of 1,4-dideoxy-1,4-imino-
oxy-1,4-imino- -lyxitol (LIL). DIL showed potent [Ki = 0.13 M]—and LIL showed weak [Ki = 113
petitive inhibition of -galactosidase. Both enantiomers N-benzyl-DIL [Ki = 64 M] and N-benzyl-LIL
[Ki = 13 M] were moderate competitive inhibitors of naringinase, an -rhamnosidase.
D
-lyxitol (DIL) and of 1,4-dide-
L
l
l
M]—com-
a
-
D
l
l
a-L
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
DIM 7D10 is an inhibitor of
mer
dase, and shows no inhibition of
product swainsonine 8D12 and many other mannofuranose
analogues13 are powerful inhibitors of
-mannosidase, but do not
affect naringinase;
-swainsonine 8L14 is a highly potent and specific
a
-mannosidases; in contrast, its enantio-
L
-DIM 7L11 is a potent inhibitor of nariginase, an
a
-L
-rhamnosi-
Herein, we report short syntheses of the enantiomers of 1,4-
dideoxy-1,4-imino- -lyxitol, DIL 1D and LIL 1L, in which the high
yielding benzhydryl protection of the hydroxyl group by diphenyl-
diazomethane of enantiomeric base-sensitive ribonolactone aceto-
nides 3D and 3L is a crucial step (Scheme 1). Both enantiomers 1D
and 1L are competitive inhibitors of the coffee bean of
sidase, whereas the corresponding N-benzyl derivatives 2D and 2L
are competitive inhibitors of naringinase, an -rhamnosidase.
a-mannosidase. The natural
D
a
L
inhibitor of naringinase with no inhibition of mannosidases.15 DAB-
NAc 9D, the N-acetylamino analogue of DAB 4D, showed no inhibi-
tion of any glycosidase; in contrast LABNAc 9L is the most potent
pyrrolidine inhibitor of b-hexosaminidases yet described.16
a-D-galacto-
a
-L
Iminosugars, carbohydrate mimics in which the ring oxygen of a
sugar is replaced by nitrogen, have considerable therapeutic poten-
tial.1 Both the enantiomers of iminosugars frequently show potent
inhibition of the same glycosidases.2 Among the examples of inhibi-
tion by pyrrolidines as furanose analogues of hexoses,3 the natural
2. Synthesis of DIL 1D and LIL 1L
Both enantiomers LIL 1L and DIL 1D have previously been made
from carbohydrates,17 amino acids,18 or by asymmetric
synthesis.19 Although lactones are very powerful chirons, their
base lability due to the acidic proton at C2 means that standard
methods for O-benzyl protection do not reliably give good yields;
although silyl ethers may easily be formed in sequences that
require hydride reduction of the lactone, migration of the silyl
ethers to the hydroxyl groups frequently causes complications.
Protection of carbohydrate alcohols as the corresponding benzhy-
dryl ethers by reaction with diazomethane,20 a procedure that does
not require any acid or base catalyst, is particularly suitable for
lactones with an acidic proton at C2.21 The present six-step synthe-
ses of LIL 1L and DIL 1D from the readily available acetonides of
products DAB 4D and DMDP 5D are potent inhibitors of some a-glu-
cosidases although both are moderate inhibitors of other
glycosidases4 (Scheme 2); however, their enantiomers LAB 4L5,6 and
L
-DMDP 5L7 are more specific and more potent inhibitors of
a
-gluco-
sidases. Both the natural product casuarine 6D8 with six adjacent
stereogenic centers and its enantiomer
-casuarine 6L9 display
potent -glucosidase inhibition with no significant inhibition of
L
a
any other glycosidases. The synthetic mannofuranose mimic
* Corresponding author.
E-mail address: george.fleet@chem.ox.ac.uk (G.W.J. Fleet).
0957-4166/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2009.10.004

T. B. Mercer et al. / Tetrahedron: Asymmetry 20 (2009) 2368–2373
2369
D
-sugars in blue
L
-sugars in red
OH
O
O
O
O
OH
OH
OH
CH2OH
HO
HO
HO
HO
H2, Pd
steps
CH2OH
steps
H2, Pd
CH2OH
CH2OH
CH2OH
CH2OH
O
O
N
H
N
O
O
N
N
H
Bn
Bn
1D
2D
3L
3D
2L
1L
α-
D
-galactosidase
α-
L
-rhamnosidase
inhibitor
α-L
-rhamnosidase
α-
D
-galactosidase
L
-ribonolactone
acetonide
D
-ribonolactone
potent inhibitor
acetonide
inhibitor
weak inhibitor
Scheme 1. Synthesis of enantiomeric 1,4-dideoxy-1,4-imino-lyxitols 1D and 1L.
OH
CH2OH
OH
CH2OH
OH
OH
OH
OH
HO
HO
HOH2C
HO
HOH2C
HO
HO
AcHN
OH
OH
OH
OH
CH2OH
N
N
H
N
H
N
N
H
N
H
OH
D-casuarine 6D
α- -glucosidase
potent inhibitor
DAB 4D
α- -glucosidase
potent inhibitor
OH
CH2OH
DMDP 5D
α- -glucosidase
potent inhibitor
OH
CH2OH
DIM 7D
D-swainsonine 8D
DABNAc 9D
D
D
D
α-
D
-mannosidase
potent inhibitor
α-
D-mannosidase
potent inhibitor
No glycosidase
inhibition
OH
OH
OH
OH
CH2OH
HO
HO
HOH2C
HO
HOH2C
HO
HO
AcHN
OH
OH
OH
OH
N
H
N
H
N
N
H
N
N
H
OH
L-casuarine 6L
LAB 4L
L-DMDP 5L
L-DIM 7L
L-swainsonine 8L
LABNAc 9L
α-
D
-glucosidase
α-
L
-rhamnosidase
α-
L
-rhamnosidase β-
D
-hexosaminidase
α-
D-glucosidase
α-
D-glucosidase
potent inhibitor
potent inhibitor
potent inhibitor
potent inhibitor
potent inhibitor
potent inhibitor
Scheme 2. Enantiomeric pyrrolidine glycosidase inhibition—potent inhibition implies lM Ki.
D
-3D22 and -3L23 ribonolactones, in overall yields of 22% and 19%,
L
which the benzyl group was removed by hydrogenolysis in the
presence of palladium on carbon to give LIL 1L, isolated as its crys-
respectively, rely on the initial protection of the primary alcohol as
the benzhydryl ether under neutral conditions.
talline hydrochloride in 76% yield [22% overall yield from the
onolactone 3D]. Enantiomer DIL 1D was prepared by an identical
sequence from -ribonolactone 3L in an overall yield of 19%.
D-rib-
For the synthesis of LIL 1L, the acetonide of D-ribonolactone 3D
was heated at reflux with diphenyldiazomethane in acetonitrile to
give the benzhydryl ether 10D in 82% yield (Scheme 3). The reduc-
tion of the fully protected lactone 10D with sodium borohydride in
methanol afforded the diol 11D (81% yield), which was esterified
with mesyl chloride in pyridine to form the dimesylate 12D in
93% yield. Treatment of dimesylate 12D with benzylamine caused
the initial displacement of the primary mesylate followed by intra-
molecular displacement of the secondary mesylate to give cycliza-
L
3. Glycosidase inhibition
DIL 1DandLIL1L, andtheirN-benzylanalogues2Dand2Lwereas-
sayed as glycosidase inhibitors against a range of enzymes (Table 1).
This work confirms the original claim5 that DIL 1D is a potent
a
-
D
-galactosidase inhibitor, but is a much weaker inhibitor of a-D
-
tion to the fully protected L
-iminolyxitol 13L. DowexÒ 50WX8-100
mannosidase than DIM 7D. The pyranose analogue of galactose,
(H+ resin) in water caused hydrolysis of both the benzhydryl- and
DGJ 14D, with IC50 0.003
potent that its enantiomer
lM (Fig. 1) is around 1000 times more
L
-DGJ 14L (IC50 13
l
M);2c DIL 1D, the
acetonide-protecting groups to give N-benzyl-LIL 2L (55%) from
O
O
O
O
OH
CH2OH
HO
OH
HO
(vi)
O
O
(v)
RO
CH2OCHPh2
R = H
CH2OCHPh2
CH2OH
N
N
CH2OR
RO
11D
N
O
O
Bn
Bn
H
3D R = H
13L
2L
1L
(ii)
(iv)
(i)
(iii)
12D
10D R = CHPh2
R = OSO2Me
Scheme 3. Reagents and conditions: (i) Ph2CN2, MeCN, 82% [81%*]; (ii) NaBH4, MeOH, 81% [78%*]; (iii) MeSO2Cl, pyridine, 93% [100%*]; (iv) PhCH2NH2, 86% [95%*]; (v) 1,4-
dioxane:H2O. 1:1, Dowex, 55% [43%*]; (vi) H2, Pd, 1,4-dioxane;and then aq HCl, 76% [75%*]. [*] are yields obtained for the enantiomeric series starting from 3L to give 1D.

2370
T. B. Mercer et al. / Tetrahedron: Asymmetry 20 (2009) 2368–2373
Table 1
Concentration of iminosugars giving 50% inhibition of glycosidases [with Ki of potent inhibitors]
IC50
Enzyme
(lM)
OH
CH2OH
OH
CH2OH
OH
OH
HO
HO
HO
HO
CH2OH
CH2OH
N
H
N
H
N
N
Bn
Bn
2D
2L
1D
1L
a-Glucosidase
Rice
Yeast
845
302
331
NI (45.4%)
NI (19.7%)
NI (0%)
NI (3.1%)
NIa (12.3%)b
b-Glucosidase
Almond
Bovine liver
329
NI (22.1%)
443
NI (18.3%)
NI (10.5%)
NI (1.0%)
NI (9.5%)
NI (37.3%)
NI (11.6%)
NI (22.6%)
NI (0%)
a-Galactosidase
Coffee beans
0.5 Ki = 0.13
NI (3.0%)
39
lM
209 Ki = 113
NI (28.9%)
677
l
M
125
b-Galactosidase
Bovine liver
NI (0%)
a-Mannosidase
Jack bean
NI (15.0%)
NI (0%)
b-Mannosidase
Snail
NI (1.3%)
98
NI (19.6%)
80
NI (1.6%)
NI (38.1%)
21 Ki = 13
a-
L
-Fucosidase
Bovine epididymis
NI (31.1%)
83 Ki = 64
a-
L
-Rhamnosidase
P. decumbens
NI (10.9%)
340
l
M
lM
b-Glucuronidase
E. coli
Bovine liver
NI (0%)
NI (26.1%)
NI (43.6%)
NI (43.6%)
NI (0%)
NI (19.4%)
NI (43.8%)
NI (0%)
b-N-Acetylglucosaminidase
Jack bean
Bovine kidney
364
NI (43.9%)
NI (42.4%)
NI (29.7%)
NI (14.2%)
NI (14.3%)
NI (28.6%)
NI (21.2%)
b-Xylosidase
Aspergillus niger
NI (13.0%)
NI (3.4%)
NI (2.1%)
NI (3.3%)
a
NI: no inhibition (less than 50% inhibition at 1000
lM).
b
( ): Inhibition% at 1000
lM.
Both N-benzyl-DIL 2D [Ki = 64
[Ki = 13 M] were moderate competitive inhibitors of naringinase,
an -rhamnosidase; the structural relation between 2D and 2L
and -swainsonine 8L is shown in Figure 3. However, neither
N-benzyl derivative showed any significant inhibition of -galac-
lM] and N-benzyl-LIL 2L
OH
HO
OH
HO
l
OH
a
-L
L
CH2OH
N
H
N
H
CH2OH
a-D
tosidase. It is well established that N-alkylation of iminosugars
may have significant modifications in the potency and specificity
of the inhibition of glycosidases.1,24 This example of a change of
specificity of enzyme inhibition by N-alkylation is very rare.
DIL 1D
DGJ 14D
α-
D-galactosidase
IC50 0.5
α-D-galactosidase
IC50 0.003 μM
μM
4. Conclusion
OH
OH
OH
HO
HO
Benzhydryl protection of the readily available enantiomeric
acetonides 3L and 3D is a key step in the efficient syntheses of
the iminolyxitols DIL 1D and LIL 1L. Compound DIL 1D was shown
CH2OH
N
H
N
H
CH2OH
to be the most potent simple pyrrolidine inhibitor of
sidase. Both enantiomeric N-benzyl iminolyxitols 2D and 2L have
no significant -galactosidase inhibition but both are moderate
inhibitors of -rhamnosidase; such a change in enzyme inhibi-
a-D-galacto-
LIL 1L
D-galactosidase
L-DGJ 14L
a
-D
α-
α-
D-galactosidase
IC50 209 μM
IC50 13 μM
a-L
tion by N-alkylation is almost unprecedented.
Figure 1. Enantiomeric piperidine and pyrrolidine a-D-galactosidase inhibition.
5. Experimental
most potent furanose inhibitor yet described with IC50 0.5
much more potent than the enantiomer LIL 1L (IC50 209 M). Both
1D and 1L are competitive inhibitors of coffee bean -galactosi-
dase as shown by the Lineweaver–Burk plots (Fig. 2) and moderate
inhibitors of bovine epididymis -fucosidase [DIL 1D IC50 98 M;
LIL 1L IC50 80 M].
lM, is
All commercial reagents were used as supplied. Tetrahydrofu-
ran was purchased dry from the Aldrich chemical company in
Sure-SealTM bottles. Pyridine was purchased dry from the Aldrich
chemical company in Sure-SealTM bottles over molecular sieves.
All other solvents were used as supplied (Analytical or HPLC
l
a-D
a-
L
l
l

T. B. Mercer et al. / Tetrahedron: Asymmetry 20 (2009) 2368–2373
2371
2
1.8
1.6
1.4
1.2
1
1.8
b
a
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.00
0.10
0.20
0.30
0.40
0.50
0.00
0.20
0.40
0.60
1/[S] (mM)
0.80
1.00
1.20
-
1/[S] (mM) -1
Figure 2. Lineweaver–Burk plots showing competitive
a
-
D
-galactosidase inhibition by (a) DIL 1D and (b) LIL 2D; (a) Concd DIL 1D: 0 (j), 0.5
M.
lM (d), 1 lM (N) Ki = 0.13 lM.
(b) Concd LIL 1L: 0 (j), 250 M (d), 500 M (N) Ki = 141
l
l
l
on a Micromass LCT (ESI) spectrometer. High resolution mass spec-
tra (HRMS m/z) were carried out on a Bruker MicroTof (resolu-
tion = 10,000 FWHM). Electrospray (ESI) was used throughout.
Assays for the inhibition of glycosidases were performed as previ-
ously described.11
OH
CH2OH
HO
HO
OH
HO
N
N
Bn
N-benzyl-DIL 2D
5.1. 5-O-Benzhydryl-2,3-O-isopropylidene-D-ribono-1,4-lactone
10D
α-
L
-rhamnosidase
Ki 64 μM
Diphenyldiazomethane (1.61 g, 8.29 mmol) was added to a stir-
red solution of the acetonide of -ribonolactone 3D (1.04 g,
D
OH
HO
OH
CH2OH
HO
5.53 mmol) in acetonitrile (55 mL) and the reaction mixture was
heated at reflux for 6 h. TLC analysis (2:1, cyclohexane/ethyl ace-
tate) showed a significant residual starting material (Rf 0.2) and a
major product (Rf 0.6). An additional equivalent of diphenyldia-
zomethane (1.07 g, 5.53 mmol) was added and the reaction was
heated at reflux for a further 6 h, after which time TLC analysis
indicated that only trace starting material remained. The reaction
mixture was concentrated in vacuo and the resulting residue puri-
fied by column chromatography (cyclohexane/ethyl acetate,
20:1?5:1) to give the fully protected lactone 10D (1.60 g, 82%)
OH
N
N
Bn
N-benzyl-LIL 2L
L-swainsonine 8L
α-L
-rhamnosidase
Ki 0.45 μM
α-L
-rhamnosidase
Ki 13 μM
Figure 3. Enantiomeric pyrrolidine a-L-rhamnosidase inhibition.
as
a yellow–orange oil. HRMS (ESI+ve): found: 377.1359
[M+Na]+, C21H22NaO5 requires: 377.1365; ½a 2D3
¼ ꢀ23:5 (c 0.81,
ꢁ
grade), without prior purification. Reactions performed under an
atmosphere of argon or hydrogen gas were maintained by an in-
flated balloon. All solutions are saturated unless otherwise stated.
‘Dowex’ refers to DowexÒ 50WX8-100 (H+ resin). Thin layer chro-
matography (TLC analysis) was performed on aluminum sheets
coated with 60 F254 silica supplied by Merck. Sheets were visual-
ized using a spray of either 0.2% w/v cerium(IV) sulfate and 5%
ammonium molybdate in 2 M sulfuric acid, or potassium perman-
ganate (0.5% in 1 M NaOH). Flash chromatography was performed
either on Sorbsil C60 40/60 silica or on Merck grade 9385, 230–
400 mesh, 60 Å. Melting points were recorded on a Kofler hot block
and are uncorrected. Optical rotations were recorded on a Perkin–
Elmer 241 polarimeter with a path length of 1 dm. Concentrations
are quoted in g 100 mLꢀ1. Infrared spectra were recorded on a Bru-
ker Tensor 27 FT IR spectrophotometer using thin films on either
NaCl or Ge plates. Only the characteristic peaks are quoted. Nuclear
magnetic resonance (NMR) spectra were recorded on a Bruker
AMX500 (1H: 500 MHz and 13C: 125.7 MHz) or a Bruker AV400
(1H: 400.2 MHz and 13C: 100.6 MHz) spectrometer in the deuter-
ated solvent stated. All chemical shifts (d) are quoted in parts per
million (ppm) and coupling constants (J) in hertz (Hz). Residual
signals from the solvents were used as an internal reference. 1,
4-Dioxane was used as an internal reference where D2O is used
as the solvent. Low resolution mass spectra (m/z) were recorded
CHCl3); mmax (thin film): 1786 (s, C@O); dH (CDCl3, 400 MHz):
1.38 (3H, s, C(CH3)2), 1.49 (3H, s, C(CH3)2), 3.65 (1H, dd, H5, J5,4
1.7, Jgem 10.6), 3.76 (1H, dd, H50, J5 ,4 1.7, Jgem 10.6), 4.67 (1H, a-t,
0
H4, J 1.9), 4.76 (1H, d, H3, J3,2 5.5), 4.87 (1H, d, H2, J2,3 5.5),
5.37 (1H, s, Ph2CH), 7.22–7.42 (10H, m, Ph2CH); dC (CDCl3,
100.6 MHz): 25.7, 26.8 (C(CH3)2), 68.0 (C5), 75.8 (C2), 78.5 (C3),
81.1 (C4), 84.8 (Ph2CH), 113.2 (C(CH3)2), 126.7, 126.8, 127.9,
128.0, 128.6, 128.7 (Ph2CH), 140.6, 141.0 (ArCquat.), 174.4 (C1);
LRMS (ESI+ve): m/z (%) 372 (100) [M+NH4]+.
For the enantiomer 10L, 81%, yellow oil, ½a D21
¼ þ20:8 (c 1.0,
ꢁ
CHCl3).
5.2. 5-O-Benzhydryl-2,3-O-isopropylidene-D-ribitol 11D
Sodium borohydride (51 mg, 1.35 mmol) was added to a solu-
tion of benzhydryl lactone 10D (479 mg, 1.35 mmol) in methanol
(10 mL) at 0 °C and the reaction mixture was stirred at room tem-
perature. The reaction was monitored hourly by TLC analysis (1:1,
cyclohexane/ethyl acetate); four further additions of 1.35 mmol of
sodium borohydride were required to bring the reaction to com-
pletion, with one addition per hour. The starting material (Rf 0.8)
was no longer present, with a strong product spot clearly visible
(Rf 0.5). The reaction mixture was neutralized with ammonium

2372
T. B. Mercer et al. / Tetrahedron: Asymmetry 20 (2009) 2368–2373
chloride (satd, aq), concentrated in vacuo, and the residue was
purified by column chromatography (cyclohexane/ethyl acetate,
2:1) to yield the diol 11D (393 mg, 81%) as an off-white solid.
HRMS (ESI+ve): found: 381.1666 [M+Na]+, C21H26NaO5 requires:
81.1 (C3), 84.3 (Ph2CH), 111.2 (C(CH3)2), 126.7, 127.0, 127.1, 127.3,
127.4, 128.1, 128.3, 128.4, 128.7 (Ph2CH, PhCH2), 142.3, 142.3,
138.8 (ArCquat); LRMS (ESI+ve): m/z (%) 430 (100), [M+H]+, 452 (46)
[M+Na]+.
381.1678; mp 90–92 °C; ½a D23
ꢁ
¼ þ42:2 (c 0.39, CHCl3); mmax (thin
For the enantiomer 13D, 95%, yellow oil, ½a D20
¼ ꢀ65:6 (c 0.99,
ꢁ
film): 3416 (s, br, OH); dH (CDCl3, 400 MHz): 1.33 (3H, s,
C(CH3)2), 1.36 (3H, s, C(CH3)2), 3.58–3.63 (2H, br, s, 1-OH, 4-OH),
3.61 (1H, dd, H5, J5,4 6.5, Jgem 9.9), 3.74–3.78 (1H, dd, H1, J1,2 5.4,
CHCl3).
5.5. N-Benzyl-1,4-dideoxy-1,4-imino-L-lyxitol 2L
Jgem 11.3), 3.77–3.80 (1H, dd, H50, J5 ,4 2.7, Jgem 9.8), 3.86–3.92
0
(1H, dd, H10, J1 ,2 7.7, Jgem 11.4), 3.99–4.04 (1H, ddd, H4, J4,5 2.7,
J4,5 6.8, J4,3 9.6), 4.13 (1H, dd, H3, J3,2 5.9, J3,4 9.7), 4.37 (1H, a-dt,
A solution of the protected iminolyxitol 13L (270 mg, 0.63 mmol)
in 1,4-dioxane (1 mL) and water (1 mL) was stirred for 18 h at room
temperature with Dowex. TLC analysis (3:1, cyclohexane/ethyl ace-
tate) after this time showed that no starting material remained (Rf
0.7). The resin was filtered off and washed with methanol, and then
separately with 2 M ammonia (aq) (2 ꢂ 10 mL). The filtrate was con-
0
0
0
H2, J 5.5, J2,1 7.6), 5.44 (1H, s, Ph2CH), 7.22–7.36 (10H, m, Ph2CH);
dC (CDCl3, 100.6 MHz): 25.2, 27.8 (C(CH3)2), 60.8 (C1), 68.9 (C4),
70.6 (C5), 77.2 (C2), 77.5 (C3), 84.3 (Ph2CH), 108.6 (C(CH3)2),
126.9, 127.8, 128.5, 128.5 (Ph2CH), 141.5, 141.5 (ArCquat); LRMS
(ESI-ve): m/z (%) 358 (100), [MꢀH]ꢀ, 404 (85) [M+EtO]ꢀ.
centrated in vacuo to give N-benzyl-L-imino-lyxitol 2L (77 mg, 55%),
For the enantiomer 11L, 78%, mp 90–92 °C; ½a D21
ꢁ
¼ ꢀ27:7 (c, 1.0
orange oil. HRMS (ESI+ve): found: 224.1281 [M+H]+, C12H18NO3 re-
in CHCl3).
quires: 224.1287; ½a D22
ꢁ
¼ þ46:6 (c 1.0, H2O);
mmax (thin film): 3385
(s, br, OH); dH (D2O, 400 MHz): 2.66 (1H, dd, H1, J1,2 6.3, Jgem 11.6),
2.67 (1H, dd, H10, J1 ,2 5.3, Jgem 11.6), 2.82 (1H, ddd, H4, J4,5 4.4, J4,3
0
5.3. 5-O-Benzhydryl-2,3-O-isopropylidene-1,4-di-O-methanesul-
fonyl- -ribitol 12D
0
0
D
5.9, J4,5 7.4), 3.44 (1H, dd, H5, J5 ,4 4.3, Jgem 11.0), 3.47 (1H, d, PhCH2,
Jgem 12.8), 3.62 (1H, dd, H50, J5 ,4 7.5, Jgem 11.1), 3.75 (1H, d, PhCH2, Jgem
0
Methanesulfonyl chloride (0.36 mL, 4.64 mmol) was added to a
solution of the protected diol 11D (664 mg, 1.85 mmol) in anhy-
drous pyridine (13 mL) and cooled to 0 °C; the reaction was stirred
at room temperature for 2.5 h. TLC analysis (2:1, cyclohexane/
ethyl acetate) showed the conversion of starting material (Rf 0.24,
staining blue) to one major product (Rf 0.33, staining yellow).
Pyridine was removed in vacuo, and the resulting residue was
purified by column chromatography (cyclohexane/ethyl acetate,
3:1) to give dimesylate 12D (884 mg, 93%) as a colorless oil.
HRMS (ESI+ve): found: 537.1218 [M+Na]+, C23H30NaS2O9 requires:
12.8), 4.06 (1H, a–q, H2, J 5.6), 4.14 (1H, dd, H3, J3,2 5.0, J3,4 5.8), 7.22–
7.30 (5H, m PhCH2); dC (D2O, 100.6 MHz): 56.8 (C1), 59.45, 59.52
(PhCH2, C5), 66.4 (C4), 70.1 (C2), 71.9 (C3), 128.1, 128.9, 130.3
(PhCH2), 137.5 (ArCquat); LRMS (ESI-ve): m/z (%) 222 (100) [MꢀH]ꢀ,
282 (96) [M+AcO]ꢀ.
For the enantiomer 2D, 43%, yellow oil, ½a D21
¼ ꢀ46:2 (c 1.0,
ꢁ
H2O).
5.6. 1,4-Dideoxy-1,4-imino-L-lyxitol 1L
537.1229; ½a 2D3
ꢁ
¼ ꢀ21:7 (c 1.0, CHCl3); dH (CDCl3, 400 MHz): 1.36
A solution of N-benzyl- -imino-lyxitol 2L (65 mg, 0.29 mmol) in
L
(3H, s, C(CH3)2), 1.44 (3H, s, C(CH3)2), 3.03 (6H, s, 2 ꢂ –OSO2CH3),
1,4-dioxane (1 mL) in the presence of 10% palladium on carbon
(6 mg, 10% by weight) was stirred at room temperature under a
hydrogen atmosphere for 18 h. TLC analysis (9:1, ethyl acetate/
methanol) showed the complete consumption of starting material
(Rf 0.3) and a single product (Rf 0.0). The reaction mixture was fil-
tered through CeliteÒ, the filtrate was concentrated in vacuo, and
treated with aqueous 2 M hydrochloric acid (aq). Concentration in
3.77 (1H, dd, H5, J5,4 5.1, Jgem 11.5), 3.88 (1H, dd, H50, J5 ,4 2.6, Jgem
0
11.4), 4.36 (1H, dd, H1, J1,2 6.8, Jgem 10.4), 4.42 (1H, dd, H3, J3,2 5.8,
J3,4 6.8), 4.48 (1H, m, H2), 4.53 (1H, dd, H10, J1 ,2 3.4, Jgem 10.5),
0
0
4.97–5.01 (1H, ddd, H4, J4,5 2.4, J4,5 4.9, J4,3 7.0), 5.43 (1H, s, Ph2CH),
7.22–7.36 (10H, m, Ph2CH); dC (CDCl3, 100.6 MHz): 25.4, 27.5
(C(CH3)2), 37.4, 39.2 (2 ꢂ –OSO2CH3), 68.2 (C1), 68.4 (C5), 74.6
(C2), 75.1 (C3), 78.2 (C4), 84.6 (Ph2CH), 109.6 (C(CH3)2), 126.9,
127.0, 127.9, 127.9, 128.6, 128.6 (Ph2CH), 133.8, 133.8 (ArCquat);
LRMS (ESI+ve): m/z (%) 532 (100), [M+NH4]+, 537 (80) [M+Na]+.
vacuo yielded the hydrochloride of L-imino-lyxitol 1L.HCl salt
(30 mg, 76%) as a white crystalline solid. HRMS (ESI+ve): found:
134.0812 [M+H]+, C5H12NO3 requires: 134.0817; mp 153–154 °C;
For the enantiomer 12L, 100%, colorless oil, ½a D23
ꢁ
¼ þ20:2 (c
½
a 2D4
ꢁ
¼ ꢀ20:7 (c 0.60, H2O) (lit.25
½
a 2D0
ꢁ
¼ ꢀ13:2 (c 0.014, H2O)); mmax
0.98, CHCl3).
(thin film): 3385 (s, br, OH); dH (D2O, 400 MHz): 2.85 (1H, dd, H1,
J1,2 7.3, Jgem 11.8), 3.18 (1H, dd, H10, J1 ,2 7.3, Jgem 11.8), 3.34–3.39
0
5.4. 5-O-Benzhydryl-N-benzyl-2,3-O-isopropylidene-1,4-dideoxy-
1,4-imino- -lyxitol 13L
(1H, m, H4), 3.63 (1H, dd, H5, J5,4 7.6, Jgem 11.7), 3.75 (1H, dd, H50,
0
L
J5 ,4 5.6, Jgem 11.7), 4.13 (1H, a-t, H3, J 4.4), 4.24 (1H, dt, H2, J2,3 4.4,
J 7.3); dC (D2O, 100.6 MHz): 48.1 (C1), 59.4 (C5), 61.8 (C4), 71.0
A stirred solution of the dimesylate 12D (179 mg, 0.35 mmol) in
benzylamine (5 mL) was heated at reflux for 18 h. After this time
TLC analysis (2:1, cyclohexane/ethyl acetate) showed conversion
of the starting material (Rf 0.3) to one major product (Rf 0.8). The
solution was concentrated in vacuo by co-evaporation with toluene;
the residue was purified by column chromatography (cyclohexane/
(C2), 71.4 (C3); LRMS (ESI+ve): m/z (%) 134 (100) [M+H]+.
For the enantiomer 1D, 75%, mp 151–154 °C, ½a D20
¼ þ18:2 (c
ꢁ
0.85, H2O) (lit.17e mp 159–161 °C, ½a 2D0
ꢁ
¼ þ19:8 (c 0.45, H2O); lit.5
mp 157–159 °C, ½a D20
¼ þ18:8 (c 0.16, H2O)).
ꢁ
References
ethyl acetate, 40:1?27:1) to give the protected 1,4-imino-L-lyxitol
1. (a) Compain, P.; Martin, O. R. Iminosugars: From Synthesis to Therapeutic
Application; John Wiley & Son, 2007. ISBN-0-470-03391-3; (b) Asano, N.; Nash,
R. J.; Molyneux, R. J.; Fleet, G. W. J. Tetrahedron: Asymmetry 2000, 11, 1645–
1680; (c) Watson, A. A.; Fleet, G. W. J.; Asano, N.; Molyneux, R. J.; Nash, R. J.
Phytochemistry 2001, 56, 265–295; (d) Winchester, B.; Fleet, G. W. J.
Glycobiology 1992, 2, 199–210.
2. (a) d’Alonzo, D.; Guaragna, A.; Palumbo, G. Curr. Med. Chem. 2009, 16, 473–505;
(b) Blériot, Y.; Gretzke, D.; Krülle, T. M.; Butters, T. D.; Dwek, R. A.; Nash, R. J.;
Asano, N.; Fleet, G. W. J. Carbohydr. Res. 2005, 340, 2713–2718; (c) Kato, A.;
Kato, N.; Kano, E.; Adachi, I.; Ikeda, K.; Yu, L.; Okamoto, T.; Banba, Y.; Ouchi, H.;
Takahata, H.; Asano, N. J. Med. Chem 2005, 48, 2036–2044; (d) Asano, N.; Ikeda,
K.; Yu, L.; Kato, A.; Takebayashi, K.; Adachi, I.; Kato, I.; Ouchi, H.; Takahata, H.;
Fleet, G. W. J. Tetrahedron: Asymmetry 2005, 16, 223–229.
13L (129 mg, 86%) as a yellow oil. HRMS (ESI+ve): found: 430.2377
[M+H]+, C28H32NO3 requires: 430.2382; ½a 2D3
¼ þ64:0 (c 0.75,
ꢁ
CHCl3); dH (CDCl3, 400 MHz): 1.32 (3H, s, C(CH3)2), 1.48 (3H, s,
C(CH3)2), 2.05 (1H, dd, H1, J1,2 4.6, Jgem 11.2), 2.62 (1H, a-q, H4,
J 5.2), 3.03 (1H, d, H10, Jgem 11.2), 3.26 (1H, d, PhCH2, Jgem 13.7),
3.74 (1H, dd, H5, J5,4 5.6, Jgem 9.7), 3.90 (1H, dd, H50, J5 ,4 5.4, Jgem
0
9.8), 4.28 (1H, d, PhCH02, Jgem 13.7), 4.59 (1H, dd, H2, J2,1 4.8, J2,3
6.3), 4.71 (1H, dd, H3, J3,4 5.0, J3,2 6.3), 5.42 (1H, s, Ph2CH), 7.21–
7.50 (15H, m, Ph2CH, PhCH2); dC (CDCl3, 100.6 MHz): 25.7, 26.3
(C(CH3)2), 57.8 (PhCH2), 59.6 (C1), 67.2 (C4), 68.4 (C5), 78.1 (C2),

T. B. Mercer et al. / Tetrahedron: Asymmetry 20 (2009) 2368–2373
2373
3. Clinch, K.; Evans, G. B.; Fleet, G. W. J.; Furneaux, R. H.; Johnson, S. W.; Lenz, D.;
Mee, S.; Rands, P. R.; Schramm, V. L.; Ringia, E. A. T.; Tyler, P. C. Org. Biomol.
Chem. 2006, 4, 1131–1139.
4. Scofield, A. M.; Fellows, L. E.; Nash, R. J.; Fleet, G. W. J. Life Sci. 1986, 39, 645–
651.
16. (a) Rountree, J. S. S.; Butters, T. D.; Wormald, M. R.; Dwek, R. A.; Asano, N.;
Ikeda, K.; Evinson, E. L.; Nash, R. J.; Fleet, G. W. J. Tetrahedron Lett. 2007, 48,
4287–4291; (b) Rountree, J. S. S.; Butters, T. D.; Wormald, M. R.; Boomkamp, S.
D.; Dwek, R. A.; Asano, N.; Ikeda, K.; Evinson, E. L.; Nash, R. J.; Fleet, G. W. J.
ChemMedChem 2009, 4, 378–392.
5. Fleet, G. W. J.; Nicholas, S. J.; Smith, P. W.; Evans, S. V.; Fellows, L. E.; Nash, R. J.
Tetrahedron Lett. 1985, 26, 3127–3130.
6. (a) Behling, J. R.; Campbell, A. L.; Babiak, K. A.; Ng, J. S.; Medich, J.; Farid, P.;
Fleet, G. W. J. Tetrahedron 1993, 49, 3359–3368; (b) Fleet, G. W. J.; Smith, P. W.
Tetrahedron 1986, 42, 5685–5691.
7. Yu, C. Y.; Asano, N.; Ikeda, K.; Wang, M. X.; Butters, T. D.; Wormald, M. R.;
Dwek, R. A.; Winters, A. L.; Nash, R. J.; Fleet, G. W. J. Chem. Commun. 2004,
1936–1937.
17. (a) Doddi, V. R.; Kokatla, H. Y.; Pal, A. P. Y.; Basak, Y. K.; Vankar, Y. D. Eur. J. Org.
Chem. 2008, 5731–5739; (b) Jang, K. C.; Jeong, I.-Y.; Yang, M. S.; Choi, S. U.;
Park, K. H. Heterocycles 2000, 53, 887–896; (c) Thompson, D. K.; Hubert, C. N.;
Wightman, R. H. Tetrahedron 1993, 49, 3827–3840; (d) Dureault, A.; Greck, C.;
Depezay, J. C. J. Carbohydr. Chem. 1990, 9, 121–123; (e) Bashyal, B. P.; Fleet, G.
W. J.; Gough, M. J.; Smith, P. W. Tetrahedron 1987, 43, 3083–3093; (f) Austin,
G.N.; Baird, P.D.; Fleet, G.W.J.; Peach, J.M.; Smith, P.W.; Watkin, D. J.
Tetrahedron 1987, 43, 3095–108.
8. (a) Nash, R. J.; Thomas, P. I.; Waigh, R. D.; Fleet, G. W. J.; Wormald, M. R.; Lilley,
P. M. D.; Watkin, D. J. Tetrahedron Lett. 1994, 35, 7849–7852; (b) van Ameijde,
J.; Horne, G.; Wormald, M. R.; Dwek, R. A.; Nash, R. J.; Jones, P. W.; Evinson, E. L.;
Fleet, G. W. J. Tetrahedron: Asymmetry 2006, 17, 2702–2712.
9. Nash, R. J.; van Ameijde, J.; Horne, G.; Fleet, G. W. J., in preparation.
10. (a) Fleet, G. W. J.; Smith, P. W.; Evans, S. V.; Fellows, L. E. Chem. Commun. 1984,
1240–1241; (b) Park, C.; Meng, L.; Stanton, L. H.; Collins, R. E.; Mast, S. W.; Yi, X.;
Strachan, H.; Moremen, K. W. J. Biol. Chem. 2005, 280, 37204–37216; (c) Daniel, P.
F.; Newburg, D. S.; O’Neil, N. E.; Smith, P. W.; Fleet, G. W. J. Glycoconjugate J. 1989,
6, 229–240; (d) Carpenter, N. M.; Fleet, G. W. J.; Cenci di Bello, I.; Winchester, B.;
Fellows, L. E.; Nash, R. J. Tetrahedron Lett. 1989, 30, 7261–7264.
11. Hakansson, A. E.; van Ameijde, J.; Guglielmini, L.; Horne, G.; Nash, R. J.; Evinson,
E. L.; Kato, A.; Fleet, G. W. J. Tetrahedron: Asymmetry 2007, 18, 282–289.
12. (a) Costanzi, E.; Balducci, C.; Cacan, R.; Duvet, S.; Orlacchio, A.; Beccari, T.
Biochem. Biophys. Acta 2006, 1760, 1580–1586; (b) Lagana, A.; Goetz, J. G.;
Cheung, P.; Raz, A.; Dennis, J. W.; Nabi, I. R. Mol. Cell. Biol. 2006, 26, 3181–3193;
(c) Au, C. W. G.; Pyne, S. G. J. Org. Chem. 2006, 71, 7097–7099; (d) Fleet, G. W. J.;
Gough, M. J.; Smith, P. W. Tetrahedron Lett. 1984, 25, 1853–1856.
13. (a) diBello, I. C.; Fleet, G.; Namgoong, S. K.; Tadano, K.; Winchester, B. Biochem.
J. 1989, 259, 855–861; (b) Winchester, B.; Aldaher, S.; Carpenter, N. C.; di Bello,
I. C.; Choi, S. S.; Fairbanks, A. J.; Fleet, G. W. J. Biochem. J. 1993, 290, 743–749.
14. (a) Guo, H.; O’Doherty, G. A. Org. Lett. 2006, 8, 1609–1612; (b) Oishi, T.;
Iwakuma, T.; Hirama, M.; Ito, S. Synlett 1995, 404–406.
18. (a) Jeon, J.; Lee, J. H.; Kim, J.-W.; Kim, Y. G. Tetrahedron: Asymmetry 2007, 18,
2448–2453; (b) Razavi, H.; Polt, R. Tetrahedron Lett. 1998, 39, 3371–3374.
19. (a) Meyers, A. I.; Andres, C. J.; Resek, J. E.; Woodall, C. C.; McLaughlin, M. A.; Lee,
P. H.; Price, D. A. Tetrahedron 1999, 55, 8931–8952; (b) Hummer, W.; Dubois,
E.; Gracza, T.; Jager, V. Synthesis 1997, 634–642; (c) Defoin, A.; Sifferlen, T.;
Streith, T. Synlett 1997, 1294–1296; (d) Diez, D.; Beneitez, M. T.; Gil, M. J.;
Moro, R. F.; Marcos, I. S.; Garrido, N. M.; Basabe, P.; Urones, J. G. Synthesis 2005,
565–568.
20. Jackson, G.; Jones, H. F.; Petursson, S.; Webber, J. M. Carbohydr. Res. 1982, 102,
147–157.
21. Best, D.; Jenkinson, S. F.; Rule, S. D.; Higham, R.; Mercer, T. B.; Newell, R. J.;
Weymouth-Wilson, A. C.; Fleet, G. W. J.; Petursson, S. Tetrahedron Lett. 2008, 49,
2196–2199.
22. Batra, H.; Moriarty, R. M.; Penmasta, R.; Sharma, V.; Stanciuc, G.; Staszewski, J.
P.; Tuladhar, S. M.; Walsh, D. A. Org. Process Res. Dev. 2006, 10, 484–486.
23. (a) Kold, H.; Lundt, I.; Pedersen, C. Acta Chem. Scand. 1994, 48, 675–678; SEE
2(B): (b) Blériot, Y.; Gretzke, D.; Krülle, T. M.; Butters, T. D.; Dwek, R. A.; Nash,
R. J.; Asano, N.; Fleet, G. W. J. Carbohydr. Res 2005, 340, 2713–2718.
24. (a) Rawlings, A. J.; Lomas, H.; Pilling, A. W.; Lee, M. J.-R.; Alonzi, D. S.; Rountree,
J. S. S.; Jenkinson, S. F.; Fleet, G. W. J.; Dwek, R. A.; Jones, J. H.; Butters, T. D.
ChemBioChem 2009, 10, 1101–1105; (b) Mellor, H. R.; Nolan, J.; Pickering, L.;
Wormald, M. R.; Platt, F. M.; Dwek, R. A.; Fleet, G. W. J.; Butters, T. D. Biochem. J.
2002, 366, 225–233; (c) Asano, N.; Nishida, M.; Kato, A.; Kizu, H.; Matsui, K.;
Shimada, Y.; Itoh, T.; Baba, M.; Watson, A. A.; Nash, R. J.; Lilley, P. M. deQ.;
Watkin, D. J.; Fleet, G. W. J. J. Med. Chem 1998, 41, 2565–2571; (d) Daher, S. A.;
Fleet, G.; Namgoong, S. K.; Winchester, B. Biochem. J. 1989, 258, 613–615.
25. Huang, Y.; Dalton, D. R.; Carroll, P. J. J. Org. Chem. 1997, 62, 372–376.
15. (a) Davis, B.; Bell, A. A.; Nash, R. J.; Watson, A. A.; Griffiths, R. C.; Jones, M. G.;
Smith, C.; Fleet, G. W. J. Tetrahedron Lett. 1996, 37, 8565–8568; (b) Hakansson,
A. E.; van Ameijde, J.; Horne, G.; Nash, R. J.; Wormald, M. R.; Kato, A.; Besra, G.
S.; Gurcha, S.; Fleet, G. W. J. Tetrahedron Lett. 2008, 49, 179–184.