Total synthesis and antiproliferative/cytotoxic profiling of 2-epi-jaspine B

Article abstract of DOI:10.1016/j.carres.2016.01.011

A straightforward access to 2-epi-jaspine B (4.HCl) has been developed. Key to the approach was the use of Overman rearrangement for the instalment of a stereocentre bearing a nitrogen atom. Subsequent rational execution of the stereoselective transformat

Full text of DOI:10.1016/j.carres.2016.01.011

Carbohydrate Research 423 (2016) 70–81
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Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Total synthesis and antiproliferative/cytotoxic profiling
of 2-epi-jaspine B
Eva Mezeiová a, Miroslava Martinková a,*, Kvetoslava Stanková a, Milica Fabišíková a,
Jozef Gonda a, Martina Pilátová b, Gabriela Gönciová b
a Institute of Chemical Sciences, Department of Organic Chemistry, P.J. Šafárik University, Moyzesova 11, 040 01 Košice, Slovak Republic
b Department of Pharmacology, Faculty of Medicine, P.J. Šafárik University, SNP 1, 040 66 Košice, Slovak Republic
A R T I C L E
I N F O
A B S T R A C T
Article history:
Received 11 December 2015
Received in revised form 15 January 2016
Accepted 21 January 2016
Available online 2 February 2016
A straightforward access to 2-epi-jaspine B (4.HCl) has been developed. Key to the approach was the use
of Overman rearrangement for the instalment of a stereocentre bearing a nitrogen atom. Subsequent ra-
tional execution of the stereoselective transformations furnished the functionalized scaffold 38, whose
coupling with a lipophilic segment under Wittig conditions, followed by deprotection and a THF core
construction, completed the convergent synthesis of 2-epimer of 1. The final anhydrophytosphingosine
4.HCl was screened for its antiproliferative/cytotoxic activity employing multiple human cancer cell lines.
In vitro evaluation revealed that 2-epi-jaspine B exhibited significant antitumour growth inhibitory ac-
tivity against all used cells.
Keywords:
Anhydrophytosphingosines
Jaspine B
© 2016 Elsevier Ltd. All rights reserved.
2-epi-Jaspine B
Overman rearrangement
Antiproliferative/cytotoxic activity
1. Introduction
Although the first synthesis18 of anhydrophytosphingosine mol-
ecule prior to isolation of jaspine B led ultimately to the production
Over the past 10 years, anhydrophytosphingosines have emerged
on the scene as an attractive and timely target for the total syn-
thesis due to their significant biological activity as well as the
architecturally interesting structures. Jaspine B (1, also referred as
pachastrissamine, Fig. 1) represents such structural archetype that
has been isolated independently from two marine sponges1,2 to-
gether with its oxazolidine analogue, jaspine A (2, Fig. 1).2 From the
biosynthetic standpoint is highly likely that pachastrissamine would
be derived from d-ribo-phytosphingosine 33,4 considering the same
number of carbon atoms in the backbone as well as the same ste-
reochemical C-2/C-3 amino alcohol motif (used phytosphingosine
numbering, see Fig. 1) for both 1 and 3. Jaspine B has been re-
ported to exhibit significant in vitro cytotoxicity against multiple
human cancer cell lines such as A-549,1,2,5–7 HT-29,1 MeL-28,1,8
MCF-7,6,9–11 KB,6 HCT-116,7,11–13 U2OS,12 MDA-231,11,13,14 HeLa,11,14 CNE,14
MGC-803,10 EC-9706,10 PC-3,7,13 A-375,15 WM-115,15 Caco-2,11 Jurkat,11
SNU-63813 and Caki-113 with IC50 in the micromolar to sub-
micromolar ranges. En passant, this conformationally constrained
sphingolipid and all its stereocongeners inhibit both forms of sphin-
gosine kinase (SphK1 and SphK2) with moderate to high activities.16,17
of 2-epi-jaspine B (4), its structure including relative stereochem-
istry was confirmed later through the asymmetric synthesis of the
truncated derivative 4a19–21 (Fig. 1), this compound has attracted less
attention. To date, 18 total syntheses of 4 have been reported em-
ploying especially chiral-pool approaches, which commenced from
d-ribo-phytosphingosine 3,5,22–25 (S)-Garner’s aldehyde,17,26–29
l-serine,30 diethyl d-tartrate,31 d-ribose,32 d-glucose33 and d-galactal.34
Further, two specific methods involving the highly diastereoselective
conjugate addition of chiral lithium amide to methyl (E)-4-
(triisopropylsilyloxy)but-2-enoate35,36 and an enantioselective
palladium-catalyzed allylic amination of the racemic 2-vinyloxirane37
have been used as the key transformations for the construction of
2-epi-jaspine B (Fig. 2). On the other hand, a minor synthetic
interest in comparison with 4 has been devoted towards
ent-4 and only five independent strategies utilizing (R)-Garner’s
aldehyde,16 d-serine methyl ester,38 d-mannose,39 d-glucose33 and
3-amino-3-deoxy-α-d-ribofuranose40 have been performed (Fig. 3).
2-epi-Jaspine B (4) was evaluated for in vitro cytotoxicity against
several human cancer cell lines A-549,5,34 MCF-7,9,34 DU-145,34
A-172,34 PLC/PRF/5,34 786-O34 and DLD-1,34 its antipode ent-4 (in the
form of HCl salt) was assessed for the aforementioned activity on
MDA-MB-231,11 MCF-7,11 HCT-116,11 Caco-2,11 Jurkat11 and HeLa11
and compound ent-4.HCl was found to be less active than jaspine
B (1). Recently, we have accomplished a stereoconvergent synthe-
sis of jaspine B and its five stereoisomers11,39,41 and revealed
that four members of anhydrophytosphingosine family exhibit
*
Corresponding author. Institute of Chemical Sciences, Department of Organic
Chemistry, P.J. Šafárik University, Moyzesova 11, 040 01 Košice, Slovak Republic. Tel.:
+421 55 2342329; fax: +421 55 6222124.
E-mail address: miroslava.martinkova@upjs.sk (M. Martinková).
http://dx.doi.org/10.1016/j.carres.2016.01.011
0008-6215/© 2016 Elsevier Ltd. All rights reserved.

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
71
Fig. 1. Structures of various sphingolipids.
interesting antiproliferative/cytotoxic activities.11 These promis-
ing findings as well as our ongoing studies of how the employed
chiral allylic templates derived from the simple furanoses can in-
fluence the stereochemical outcome of the two types of aza-
Claisen rearrangement prompted us to encompass a construction
of 2-epi-jaspine B (4) from l-arabinose utilizing our approach. More-
over, compound 4 was found to show good sphingosine kinase
(SphK1) inhibitory activity (IC50 = 3.9 μM) comparable to that of the
conventional agent N,N-dimethylsphingosine (IC50 = 2.8 μM).16
Pachastrissamine 1 demonstrated lower potency of the aforemen-
tioned inhibition (IC50 = 4.6 μM).16
14 to DIBAl-H generated allylic alcohol 15 in a yield of 97%. After
we achieved the construction of the aforementioned substrate 15,
its transformation to the corresponding imidate 16 was accom-
plished. Its formation proceeded efficiently when 15 was treated
with NaH and trichloroacetonitrile. After 30 min, 1H NMR spec-
trum of the crude reaction mixture showed the complete
consumption of the starting alcohol 15. The Overman rearrange-
ment of imidate 16 was taken place in o-xylene and in the presence
of K2CO3 and furnished the desired products 17 and 18 (17:18 ≈ 50:50
ratio) in high yields (91–97%, Table 1). Column chromatography then
allowed the straightforward separation of both products. We also
prepared thiocyanate 19 and to accomplish it, the conversion of
the 15 into 19 (93%) was carried out via the known two-step
procedure11,41 (Scheme 2). The thermal aza-Claisen rearrange-
ment of 19 was realized either at 70 °C or at 90 °C to afford the
corresponding isothiocyanates 20 and 21 in 93% and 90% com-
bined yields, respectively. The stereoselectivities were similar to those
observed in the Overman reaction of 16 (20:21 ≈ 50:50 ratio,
Scheme 2). Moreover, the resultant rearranged products 20 and 21
were obtained as an inseparable mixture of diastereoisomers and
thus we converted only Overman’s derivatives 17 and 18 into the
required oxazolidinones 24 and 25, respectively (vide infra). The same
cyclic carbamates could be also built up from the isothiocyanates
20 and 21 applying our elaborated protocol.11,41 Compound 24
allowed then a direct access to the 2-epi-jaspine B (Scheme 5). 2,4-
Di-epi-jaspine B (5), which exhibits significant inhibitory activities
against SphKs and atypical protein kinase C,16 could be available from
25. Our new synthetic approach to 5 and further biological inves-
tigations are underway and will be reported in due course.
2. Chemistry
2.1. Results and discussion
As shown in Scheme 1, our investigation began with the con-
struction of the acetonide foldamer 6. Commencing with the known
1,2-O-isopropylidene-5-O-trityl-β-l-arabinofuranose 7,11 the re-
maining free hydroxyl functionality was bezylated, using standard
reaction conditions such as BnBr, NaH in DMF, to afford the fully
protected derivative 8 in 95% yield.42 Following the cleavage of the
triphenylmethyl group of 8 (CSA, CH2Cl2/MeOH), the liberated
primary hydroxyl in 943–46 (81%) was exposed to BzCl in pyridine
to provide the corresponding benzoate ester 1043,45 in 91% yield
(Scheme 1). Removal of the acetonide moiety in 10 with 80% TFA
gave a mixture of the anomeric furanoses 11 whose NaIO4-mediated
oxidative fragmentation followed by NaBH4 workup furnished diol
12 (94%). A two-step protocol involving protection (2,2-DMP, p-TsOH)/
deprotection (K2CO3, MeOH) manipulations resulted in the formation
of the requisite derivative 6 via intermediate 13 in 83% yield start-
ing from 12.
As we had already prepared amides 17 and 18, the stage was now
set for the confirmation of the newly constructed stereochemistry
in these products and for this purpose, chemical correlations of 17,
18 and the known derivative 2611 to the common products were ex-
ecuted (Scheme 4). To reach the requisite oxazolidinones 24 and 25,
a two-step procedure involving ozonolysis (O3, −78 °C) of both
trichloroacetamides 17 and 18 followed by the reductive work up
(NaBH4) was performed to furnish the corresponding alcohols 22
and 23 in 98% and 88% yields, respectively. Their DBU treatment
The next objective was the effective transformation of the alcohol
6 to suitable substrates for the rearrangement reactions. Subse-
quently realized oxidation/Wittig olefination of 6 provided
exclusively (E)-α,β-unsaturated ester 14 in 98% yield over two steps
(Scheme 2); the (E)-geometry within 14 was identified through the
vinyl proton coupling constant value (Jtrans = 15.7 Hz). Exposure of
Fig. 2. Reported syntheses of 2-epi-jaspine B (2001–2015).

72
E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
Table 1
Overman rearrangement of imidate 16
Entry
Imidate
Conditionsa
Time (h)
Ratiob 17:18
Yieldc (%)
1
2
16
16
MW, 130 °C
MW, 150 °C
2
0.5
52:48
51:49
91
97
a
In o-xylene, in the presence of K2CO3.
b
c
Ratio in the crude reaction mixtures. Determined by 1H NMR spectroscopy.
Isolated combined yields.
The obtained derivative 33, prepared independently from two
diastereoisomers 24 and 26, had the same spectroscopic data,
melting point and specific rotation, revealing that oxazolidinone 24
is (4S)-configured. Consequently, the corresponding congener 25
must be (4R)-isomer.
Fig. 3. Published syntheses of ent-4.
caused an intramolecular cyclization to afford the aforementioned
cyclic carbamate 24 (89%) and 25 (85%, Scheme 3). To assign the
stereochemistry at the C-4 position in 24 and 25, our next task was
to modify these compounds and also derivative 2611 to the common
ketones 33 and 34, and this was effectively accomplished by using
the approach illustrated in Scheme 4.
Thus, benzylation of these three derivatives 24–26 under stan-
dard conditions (BnBr, NaH, DMF) proceeded without problem and
afforded the corresponding fully protected structures 27 (92%), 28
(96%) and 29 (91%). The chemoselectivity of the catalytic hydroge-
nation (H2, 10% Pd/C) in 27–29 secured the formation of the alcohols
30, 31 and 32 in 97%, 94% and 96% yields, respectively (Scheme 4).
Their IBX oxidation successfully led to the desired common ketone
33 (78% from 30 and 81% from 32) and 34 (89%).
Having unambiguously determined the stereochemistry in both
cycles 24 and 25, our remaining task was to complete the synthe-
sis of 4 as depicted in Scheme 5. Thus, the acetonide moiety of 24
was removed by treatment with p-TsOH in MeOH to produce the
corresponding diol 35 (92%), wherein the liberated primary hy-
droxyl group was protected as the triphenymethyl ether 36 in 95%
yield. The obtained product 36 was further benzylated (BnBr, NaH,
TBAI), furnishing the protected compound 37 in 94% yield
(Scheme 5). Exposure of 37 to p-TsOH in MeOH/CH2Cl2 resulted in
the formation of alcohol 38 (92%). To achieve the coupling between
a crude aldehyde derived from previously prepared 38 and the phos-
phonium salt, C13H27PPh3Br,39,47 the well-established Wittig
reaction was executed to afford the (Z)-olefin 39 exclusively in 71%
yield. The corresponding alkene 39 was reduced by the catalytic
Scheme 1. Reagents and conditions: (a) BnBr, NaH, TBAI, DMF, 0 °C→rt; (b) CSA, CH2Cl2/MeOH (2:1), rt; (c) BzCl, pyridine, DMAP, 0 °C→rt; (d) 80% TFA, 0 °C; (e) (i) NaIO4,
MeOH/H2O (1:1), rt; (ii) NaBH4, MeOH/CH2Cl2 (4:1), 0 °C→rt; (f) 2,2-DMP, p-TsOH, CH2Cl2, rt; (g) K2CO3, MeOH, 0 °C→rt.
Scheme 2. Reagents and conditions: (a) (i) IBX, MeCN, reflux; (ii) Ph3P
=CHCO2Et, CH2Cl2, rt; (b) DIBAL-H, CH2Cl2, −50 °C→rt; (c) NaH, CCl3CN, THF, 0 °C→rt, 16; (d) (i) MsCl,
Et3N, CH2Cl2, 0 °C→rt; (ii) KSCN, MeCN, 5 °C→rt, 19; (e) Table 1; (f) Δ, n-heptane, 70 °C (23 h, 93%) and 90 °C (15 h, 90%).

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
73
Scheme 3. Reagents and conditions: (a) (i) O3, MeOH/CH2Cl2 (5:1), −78 °C; (ii) NaBH4, −78 °C→0 °C; (b) DBU, CH2Cl2, 0 °C→rt.
hydrogenation on 10% Pd/C to provide the saturated derivative 40
(89%). Finally, N-debenzylation of 40 (H2, 10% Pd/C, 35% HCl) and
subsequent treatment of the resulting protected phytosphingosine
41 {69%, [α]D23 = +7.9 (c 0.24, MeOH)} with 6 M HCl furnished 4.HCl
in 89% yield {[α]D26 = +25.0 (c 0.16, MeOH), lit.36 {[α]D21 = +15.5 (c 0.9,
MeOH)} (Scheme 5). The NMR data and also magnitude of the optical
rotation were in accord with those reported for the corresponding
enantiomers ent-41 {lit.39 [α]D25 = −5.0 (c 0.22, MeOH)} and ent-
4.HCl {lit.39 [α]D22 = −29.6 (c 0.48, MeOH)}. As a further confirmation
of structure, we converted salt 4.HCl into the acetylated products
4223,32,36 (75%). Again, the spectroscopic data and the specific rota-
tion (both sign and magnitude) for 42 {[α]D27 = −13.3 (c 0.18, CHCl3)}
nicely matched the values published in the literature for the same
product {lit.23 [α]D22 = −15.4 (c 1.0, CHCl3), lit.32 [α]D26 = −15.1 (c 1.2,
CHCl3), lit.36 [α]D21 = −14.6 (c 0.5, CHCl3)}. As an additional determi-
nation of the stereochemistry, 1H NMR NOE analyses on the N,O-
acetylated derivative 42 have been carried out. As seen in Fig. 4, NOE
experiments of 42 revealed trans relationship between protons H-2
and H-3 on the tetrahydrofuran skeleton. On the other hand, en-
hancements between H-3 and H-4 protons proved their cis
orientation on the aforementioned ring.
doxorubicin were included as positive control in the case of cell lines
Jurkat, HeLa, MCF-7 and MDA-MB-23148 (Table 2), on HCT-116,
Caco-2 and NiH 3T3 cell lines they were not tested. Table 2 also in-
cludes the known IC50 values for the HCl salts of jaspine B (1.HCl)
and ent-4.HCl.11
To allow comparison, most recently, Shaw and co-workers34 re-
ported in vitro anticancer activity for 2-epi-jaspine B (4) against seven
cancer cell lines (A549: IC50 = 4.8 μM, DU-145: IC50 = 2 μM, MCF-7:
IC50 = 4.04 μM, A-172: IC50 = 4.59 μM, PLC/PFR/5: IC50 = 1.36 μM, 786-
O: IC50 = 1.08 μM, DLD-1: IC50 = 0.5 μM). As shown in Table 2, 2-epi-
jaspine B (4.HCl) displayed higher or comparable antiproliferative/
cytotoxic activities than conventional anticancer agents such as
cisplatin, etoposide and doxorubicin. Compound 4.HCl demon-
strated remarkable in vitro potency on both leukaemia and solid
tumour cell lines. Moreover, this compound was found to be more
active on MDA-MB-231 and HCT-116 cells than natural jaspine B
(1.HCl), whose IC50 values on these lines were at least 4× higher.
On the other hand, the cytotoxicity of ent-4.HCl was significantly
reduced, especially on MDA-MB-231 and HeLa cells.
3. Conclusions
2.2. Antiproliferative/cytotoxic activity
In conclusion, the convergent total synthesis of cytotoxic 2-epi-
jaspine B (4.HCl) has been performed from the commercially
available and inexpensive l-arabinose. Key steps in the developed
route are construction of the oxazolidinone 24 employing the
Overman rearrangement to establish the stereocentre bearing the
amino group and the Wittig transformation to build up the long hy-
drocarbon side chain. The final 2-epimer of the natural jaspine B
demonstrated significant antiproliferative/cytotoxic activities against
all tested cancer cell lines. This makes compound 4.HCl an appro-
priate candidate for further screening and evaluation.
The final 2-epi-jaspine B (4.HCl) was in vitro screened for its
antiproliferative/cytotoxic activities against six different human
cancer cell lines MDA-MB-231 (mammary gland adenocarci-
noma), MCF-7 (mammary gland adenocarcinoma), HCT-116 (colon
carcinoma), Caco-2 (colon carcinoma), Jurkat (acute T-lymphoblastic
leukaemia), HeLa (cervical adenocarcinoma), and a non-malignant
cell line NiH 3T3 (mouse fibroblasts) using the MTT assay. The
obtained results are summarized in Table 2 as IC50 values. Com-
mercially available anticancer substances etoposide, cisplatin and
Scheme 4. Reagents and conditions: (a) BnBr, NaH, TBAI, 0 °C→rt; (b) H2, 10% Pd/C, EtOH, rt; (c), IBX, MeCN, reflux, 33 (78% from 30, 81% from 32).

74
E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
was carried out with either ultraviolet light (254 nm), or spraying
with a solution of phosphomolybdic acid, a basic potassium per-
manganate solution, or a solution of concentrated H2SO4, with
subsequent heating. 1H NMR and 13C NMR spectra were recorded
in CDCl3, CD3OD and C6D6 on a Varian Mercury Plus 400 FT NMR
(400.13 MHz for 1H and 100.6 MHz for 13C) or on a Varian Premium
COMPACT 600 (599.87 MHz for 1H and 150.84 MHz for 13C) spec-
trometer using TMS as internal reference. For 1H, δ are given in parts
per million (ppm) relative to TMS (δ = 0.0), CD3OD (δ = 4.84) and C6D6
(δ = 7.15) and for 13C relative to CDCl3 (δ = 77.0), CD3OD (δ = 49.05)
and C6D6 (δ = 128.02). The multiplicity of the 13C NMR signals con-
cerning the 13C—1H coupling was determined by the DEPT method.
Chemical shifts (in ppm) and coupling constants (in Hz) were ob-
tained by first-order analysis; assignments were derived from COSY
and H/C correlation spectra. Infrared (IR) spectra were measured
with a Nicolet 6700 FT-IR spectrometer and expressed in v values
(cm−1). Optical rotations were measured on a P-2000 Jasco polar-
imeter and reported as follows: [α]D (c in grams per 100 mL, solvent).
Melting points were recorded on a Kofler hot block, and are uncor-
rected. Microwave reactions were carried out on the focused
microwave system (CEM Discover). The temperature content of the
vessel was monitored using a calibrated infrared sensor mounted
under the vessel. At the end of all reactions the contents of vessel
were cooled rapidly using a stream of compressed air. Small quan-
tities of reagents (μL) were measured with appropriate syringes
Fig. 4. Some selected NOE enhancements for 42.
4. Experimental
4.1. Chemistry
All commercial reagents were used in the highest available purity
from Aldrich, Merck and Acros Organics without further purifica-
tion. Solvents were dried and purified before use according to
standard procedures. For flash column chromatography on silica gel,
Kieselgel 60 (0.040–0.063 mm, 230–400 mesh, Merck) was used.
Solvents for chromatography (n-hexane, ethyl acetate, methanol,
dichloromethane) were distilled before use. Thin layer chromatog-
raphy was run on Merck silica gel 60 F254 analytical plates; detection
Scheme 5. Reagents and conditions: (a) p-TsOH, MeOH, rt; (b) TrCl, pyridine, DMAP, 60 °C; (c) BnBr, NaH, TBAI, DMF, 0 °C→rt; (d) p-TsOH, MeOH/CH2Cl2, rt; (e) (i) IBX, MeCN,
reflux; (ii) C13H27PPh3Br, LHMDS, THF, rt; (f) H2, 10% Pd/C, EtOH, rt; (g) H2, 10% Pd/C, EtOH, 35% HCl, 60 °C; (h) 6 M HCl, 120 °C; (j) Ac2O, pyridine, DMAP, rt.
Table 2
Antiproliferative activity of 2-epi-jaspine B on six human cancer cell lines (MDA-MB-231, MCF-7, HCT-116, Caco-2, Jurkat and HeLa) and non-malignant mouse fibroblasts
NiH 3T3
a
Compd no.
Cell line, IC50 SD (μmol × L−1
)
MDA-MB-231
MCF-7
HCT-116
Caco-2
Jurkat
0.4 0.14
6.45 1.06
0.50 0.27
12 1.8
HeLa
0.45 0.2
23.28 1.31
0.61 0.27
7.7 2.3
NiH 3T3
6.2 0.7
17.30 6.60
4.60 0.90
NT
NT
NT
4.HCl
0.55 0.08
21.94 1.90
2.35 1.20
14.7 2.7
21.2 4.2
0.2 0.8
0.7 0.3
12.50 5.06
0.41 0.09
11.4 2.4
10.9 2.1
0.5 0.024
0.47 0.25
8.44 1.09
2.59 1.02
NT
NT
NT
0.35 0.35
5.96 0.51
0.35 0.11
NT
NT
NT
ent-4.HClb
1.HClb
Cisplatinc
Etoposidec
Doxorubicinc
1.2 1.5
0.078 0.02
3.9 2.3
0.2 0.06
NT, not tested.
a
The potency of compounds was determined using the MTT assay after 72 h incubation of cells and given as IC50 (concentration of a tested compound that decreased
amount of viable cells to 50% relative to untreated control cells, see Section 4.2).
b
Values for the HCl salt of jaspine B (1.HCl) and ent-4.HCl were reported in Ref. 11 and were utilized from the same source.
Values for the clinically available anticancer drugs were reported in Ref. 48 and were utilized from the same source.
c

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
75
(Hamilton). All reactions were performed under an atmosphere of
nitrogen, unless otherwise noted.
ported}. IR υmax 2995, 2857, 1722, 1450, 1378, 1276, 1097 cm−1; 1H
NMR (400 MHz, CDCl3): δ 1.35 (s, 3H, CH3), 1.55 (s, 3H, CH3), 4.08
(d, 1H, J = 2.8 Hz, H-3), 4.39–4.43 (m, 2H, H-4), 4.48–4.50 (m, 2H,
2 × H-5), 4.58 (d, 1H, J = 11.9 Hz, OCH2Ph), 4.65 (d, 1H, J = 11.9 Hz,
OCH2Ph), 4.69 (d, 1H, J = 3.9 Hz, H-2), 5.95 (d, 1H, J = 3.9 Hz, H-1),
7.25–7.31 (m, 5H, Ph), 7.40–7.44 (m, 2H, Ph), 7.53–7.58 (m, 1H, Ph),
7.99–8.01 (m, 2H, Ph); 13C NMR (100 MHz, CDCl3): δ 26.3 (CH3), 27.2
(CH3), 64.4 (C-5), 71.8 (OCH2Ph), 82.3 (C-4), 82.7 (C-3), 84.8 (C-2),
105.8 (C-1), 113.1 (Cq), 127.8 (2 × CHPh), 128.0 (CHPh), 128.3 (2 × CHPh),
128.5 (2 × CHPh), 129.7 (2 × CHPh), 129.8 (Ci), 133.1 (CHPh), 137.0 (Ci),
4.1.1. 3-O-Benzyl-1,2-O-isopropylidene-5-O-trityl-β-L-
arabinofuranose (8)42
To a solution of the known furanose 711 (15.4 g, 35.6 mmol) in
dry DMF (93 mL) that had been pre-cooled to 0 °C was added NaH
(2.14 g, 53 mmol, 60% dispersion in mineral oil). After 5 min, TBAI
(0.26 g, 0.71 mmol) was added, followed by dropwise addition of
BnBr (5.1 mL, 43 mmol). The resulting mixture was stirred for 10 min
at 0 °C and then at room temperature for another 30 min. The excess
hydride was decomposed by the cautious addition of MeOH (1.1 mL).
The mixture was then poured into ice-water (130 mL) and ex-
tracted with Et2O (2 × 140 mL). The combined organic extracts were
dried over Na2SO4, the solvent was evaporated, and the residue was
purified by flash chromatography on silica gel (n-hexane/ethyl
acetate, 9:1) to furnish 17.68 g (95%) of compound 8 as a colourless
foam {[α]D26 +1.1 (c 0.51, CHCl3), lit.42 [α]D22 −55.2 (c 1.5, CHCl3)}. IR
166.1 (C
=O). Anal. calcd for C22H24O6: C, 68.74; H, 6.29. Found: C,
68.79; H, 6.24.
4.1.4. (2S,3R)-3-(Benzyloxy)-2,4-dihydroxybutyl benzoate (12)
A solution of 10 (9.05 g, 23.5 mmol) in TFA/H2O (4:1, 42 mL) was
stirred at room temperature for 1.5 h. Then, EtOAc (92 mL) and water
(83 mL) were added, and the resulting mixture was neutralized with
solid NaHCO3 (~38.7 g). The insoluble material was filtered off, and
the filtrate was washed with the further portions of EtOAc
(2 × 85 mL). The combined organic extracts were dried over Na2SO4,
the solvent was evaporated, and the residue was chromatographed
on silica gel (n-hexane/ethyl acetate, 1:1) to afford 7.62 g (94%) of
compound 11 (mixture of anomers) as a colourless oil, which was
used immediately to the next reaction without spectral
characterization.
(neat) υmax 3058, 3031, 2935, 1448, 1209, 1066 cm−1 1H NMR
;
(400 MHz, CDCl3): δ 1.18 (s, 3H, CH3), 1.25 (s, 3H, CH3), 3.23 (dd, 1H,
J = 9.3 Hz, J = 7.9 Hz, H-5), 3.38 (dd, 1H, J = 9.3 Hz, J = 5.4 Hz, H-5),
4.11 (m, 1H, H-3), 4.31 (ddd, 1H, J = 7.7 Hz, J = 5.4 Hz, J = 2.3 Hz, H-4),
4.58–4.64 (m, 3H, H-2, OCH2Ph), 5.87 (d, 1H, J = 4.0 Hz, H-1), 7.19–
7.43 (m, 20H, Ph); 13C NMR (100 MHz, CDCl3): δ 26.1 (CH3), 26.7 (CH3),
63.6 (C-5), 71.5 (OCH2Ph), 83.0 (C-3), 84.1 (C-4), 84.9 (C-2), 86.7 (CqTr),
105.7 (C-1), 112.4 (Cq), 127.0 (3 × CHPh), 127.7 (2 × CHPh), 127.8
(7 × CHPh), 128.5 (2 × CHPh), 128.7 (6 × CHPh), 137.4 (Ci), 143.8 (3 × Ci).
Anal. calcd for C34H34O5: C, 78.14; H, 6.56. Found: C, 78.09; H, 6.61.
To a solution of 11 (7.62 g, 22.1 mmol) in MeOH/H2O (1:1, 52 mL)
was added NaIO4 (5.58 g, 26 mmol), and the resulting suspension
was stirred at room temperature. After 1.5 h, the solid parts were
removed by filtration and the filtrate was concentrated in vacuo.
The residue obtained was diluted with a saturated NaHCO3 solu-
tion (55 mL) and extracted with CH2Cl2 (2 × 100 mL). The combined
organic layers were dried over Na2SO4, stripped of solvent, and the
crude product was immediately used to the next reaction.
A solution of the prepared crude aldehyde (7.57 g, 22.1 mmol)
in MeOH/CH2Cl2 (4:1, 90 mL) was cooled to 0 °C and treated with
NaBH4 (0.835 g, 22.1 mmol). The resulting mixture was stirred for
10 min at 0 °C and then at room temperature for the further 50 min.
After neutralization with Amberlite IR-120 (H+ form), the insolu-
ble material was filtered off, the filtrate was concentrated in vacuo,
and the residue was flash-chromatographed through a short column
of silica gel (n-hexane/ethyl acetate, 1:1). This procedure yielded
6.58 g (94%) of crystalline compound 12; mp 59–60 °C (recrystal-
4.1.2. 3-O-Benzyl-1,2-O-isopropylidene-β-L-
arabinofuranose (9)43,44,46
To a solution of 8 (17.45 g, 33 mmol) in CH2Cl2/MeOH (339 mL,
2:1) was added CSA (0.39 g, 1.7 mmol), and the resulting mixture
was stirred at room temperature. After 5 h, the reaction was
quenched by neutralization with Et3N, solvents were removed in
vacuo, and the crude product was flash-chromatographed through
a short column of silica gel (n-hexane/ethyl acetate, 3:1) to afford
7.58 g (81%) of derivative 9 as white crystals; mp 73–74 °C (recrys-
26
tallized from n-hexane/ethyl acetate); [α]D −31.6 (c 0.23, CHCl3)
{lit.43 mp 73–77 °C, [α]D20 −22.4 (concentration and solvent not re-
20
ported), lit.44 mp 80–82 °C, [α]D not reported, lit.46 mp 77–78 °C, [α]D
−19.2 (c 1.7, CHCl3)}. IR (neat) υmax 3489, 2977, 2940, 2908, 2889,
1379, 1211, 1079 cm−1; 1H NMR (400 MHz, CDCl3): δ 1.34 (s, 3H, CH3),
1.53 (s, 3H, CH3), 3.73–3.74 (m, 2H, 2 × H-5), 3.98 (d, 1H, J = 3.2 Hz,
H-3), 4.20 (dt, 1H, J = 5.4 Hz, J = 5.4 Hz, J = 3.5 Hz, H-4), 4.56 (d, 1H,
J = 11.7 Hz, OCH2Ph), 4.65 (d, 1H, J = 11.7 Hz, OCH2Ph), 4.68 (d, 1H,
J = 4.1 Hz, H-2), 5.92 (d, 1H, J = 4.1 Hz, H-1), 7.26–7.38 (m, 5H, Ph).
13C NMR (100 MHz, CDCl3): δ 26.3 (CH3), 27.1 (CH3), 62.6 (C-5), 71.9
(OCH2Ph), 82.7 (C-3), 85.2 (C-2), 85.5 (C-4), 105.6 (C-1), 112.9 (Cq),
127.7 (2 × CHPh), 128.0 (CHPh), 128.5 (2 × CHPh), 137.1 (Ci). Anal. calcd
for C15H20O5: C, 64.27; H, 7.19. Found: C, 64.22; H, 7.23.
23
lized from n-hexane/ethyl acetate); [α]D −40.2 (c 0.50, CHCl3). IR
υmax 3498, 3392, 3062, 3032, 2918, 2892, 1705, 1601, 1583, 1431,
1
1371, 1276 cm−1; H NMR (400 MHz, CD3OD): δ 3.55–3.59 (m, 1H,
H-3), 3.77 (dd, 1H, J = 11.9 Hz, J = 4.4 Hz, H-4), 3.92 (dd, 1H, J = 11.9 Hz,
J = 3.6 Hz, H-4), 4.05 (ddd, 1H, J = 7.4 Hz, J = 5.7 Hz, J = 3.0 Hz, H-2),
4.38 (dd, 1H, J = 11.5 Hz, J = 5.7 Hz, H-1), 4.48 (dd, 1H, J = 11.5 Hz,
J = 3.1 Hz, H-1), 4.56 (d, 1H, J = 11.5 Hz, OCH2Ph), 4.73 (d, 1H,
J = 11.5 Hz, OCH2Ph), 7.15–7.33 (m, 5H, Ph), 7.42–7.46 (m, 2H, Ph),
7.55–7.60 (m, 1H, Ph), 7.99–8.01 (m, 2H, Ph); 13C NMR (100 MHz,
CD3OD): δ 61.5 (C-4), 67.6 (C-1), 70.0 (C-2), 73.3 (OCH2Ph), 80.9
(C-3), 128.7 (CHPh), 129.2 (2 × CHPh), 129.4 (2 × CHPh), 129.5 (2 × CHPh),
130.7 (2 × CHPh), 131.5 (Ci), 134.3 (CHPh), 139.7 (Ci), 168.2
4.1.3. 5-O-Benzoyl-3-O-benzyl-1,2-O-isopropylidene-β-L-
arabinofuranose (10)43,45
To a solution of 9 (7.41 g, 26.4 mmol) in dry pyridine (119 mL)
that was cooled to 0 °C were successively added BzCl (3.7 mL,
32 mmol) and DMAP (0.32 g, 2.6 mmol). The resulting mixture was
stirred for 10 min at 0 °C and then at room temperature for another
1.5 h. The mixture was concentrated and co-evaporated three times
with toluene (3 × 20 mL). The residue was dissolved in EtOAc
(132 mL) and washed with water (66 mL). The organic layer was
dried over Na2SO4, the solvent was removed in vacuo, and the crude
product was chromatographed on silica gel (n-hexane/ethyl acetate,
9:1) to give 9.25 g (91%) of compound 10 in the form of white crys-
(C=O). Anal. calcd for C18H20O5: C, 68.34; H, 6.37. Found: C, 68.29;
H, 6.41.
4.1.5. [(4′S,5′R)-5-(Benzyloxy)-2′,2′-dimethyl-1′,3′-dioxan-
4′-yl]methyl benzoate (13)
To a solution of 12 (6.49 g, 20.5 mmol) in dry CH2Cl2 (113 mL)
were successively added 2,2-DMP (7.6 mL, 61.5 mmol) and cata-
lytic amounts of p-TsOH (160 mg, 0.82 mmol). The resulting solution
was stirred at room temperature. After 2 h, no starting material was
identified in the mixture (judged by TLC), which was then washed
with a saturated NaHCO3 solution (2 × 110 mL). The organic layer
was dried over Na2SO4, the solvent was evaporated in vacuo, and
23
tals; mp 79–80 °C (recrystallized from n-hexane/ethyl acetate); [α]D
−19.9 (c 0.45, CHCl3) {lits.43,45 [α]D and melting point not re-

76
E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
the residue was subjected to flash chromatography on silica gel
4.1.8. (2E)-3-[(4′S,5′R)-5′-(Benzyloxy)-2′,2′-dimethyl-1′,
(n-hexane/ethyl acetate, 5:1) to give 6.58 g (90%) of derivative 13
as a colourless oil; [α]D −56.5 (c 0.63, CHCl3). IR υmax 2992, 2942,
3′-dioxan-4′-yl]prop-2-en-1-ol (15)
24
To a solution of 14 (4.92 g, 15.4 mmol) in dry CH2Cl2 (116 mL)
that had been pre-cooled to −50 °C was added DIBAl-H (38.4 mL,
46 mmol, ~1.2 M solution in toluene) dropwise, and the resulting
solution was stirred at −50 °C for 30 min. The excess hydride was
decomposed by the cautious addition of MeOH (15.1 mL). After
warming to room temperature, the mixture was poured into a 30%
aqueous solution of K/Na tartrate (323 mL) and stirred at room tem-
perature for 1.5 h. The aqueous phase was then extracted with CH2Cl2
(2 × 180 mL). The combined organic extracts were dried over Na2SO4,
the solvent was evaporated, and the residue was chromatographed
on silica gel (n-hexane/ethyl acetate, 3:1) to give 4.15 g (97%) of com-
pound 15 as a colourless oil; [α]D27 −44.0 (c 0.48, CHCl3). IR υmax 3412,
2992, 2869, 1497, 1370, 1262, 1198 cm−1; 1H NMR (400 MHz, CDCl3):
δ 1.40 (s, 3H, CH3), 1.49 (s, 3H, CH3), 3.32 (dt, 1H, J = 9.3 Hz, J = 9.3 Hz,
J = 5.4 Hz, H-5′), 3.70 (dd, 1H, J = 11.4 Hz, J = 9.3 Hz, H-6′), 3.92 (dd,
1H, J = 11.4 Hz, J = 5.4 Hz, H-6′), 4.14–4.15 (m, 2H, 2 × H-1), 4.20 (dd,
1H, J = 9.0 Hz, J = 6.6 Hz, H-4′), 4.51 (d, 1H, J = 11.7 Hz, OCH2Ph), 4.55
(d, 1H, J = 11.7 Hz, OCH2Ph), 5.75 (tdd, 1H, J = 15.6 Hz, J = 6.3 Hz,
J = 1.5 Hz, J = 1.5 Hz, H-3), 5.99 (td, 1H, J = 15.6 Hz, J = 5.2 Hz, J = 5.2 Hz,
H-2), 7.26–7.36 (m, 5H, Ph); 13C NMR (100 MHz, CDCl3): δ 19.4 (CH3),
28.5 (CH3), 62.6 (C-6′), 62.9 (C-1), 72.5 (OCH2Ph), 73.0 (C-4′), 74.3
(C-5′), 98.7 (Cq), 127.9 (3 × CHPh), 128.4 (2 × CHPh), 128.7 (C-3), 132.7
(C-2), 137.8 (Ci). Anal. calcd for C16H22O4: C, 69.04; H, 7.97. Found:
C, 69.08; H, 7.92.
2871, 1717, 1602, 1452, 1371, 1269, 1094 cm−1; 1H NMR (400 MHz,
CDCl3): δ 1.40 (s, 3H, CH3), 1.50 (s, 3H, CH3), 3.61 (ddd, 1H, J = 9.2 Hz,
J = 8.8 Hz, J = 5.2 Hz, H-5′), 3.75 (dd, 1H, J = 11.4 Hz, J = 8.8 Hz, H-6′),
3.99 (dd, 1H, J = 11.4 Hz, J = 5.2 Hz, H-6′), 4.05 (ddd, 1H, J = 9.1 Hz,
J = 4.6 Hz, J = 2.7 Hz, H-4′), 4.43–4.52 (m, 3H, 2 × H-1, OCH2Ph), 4.57
(d, 1H, J = 11.5 Hz, OCH2Ph), 7.21–7.28 (m, 5H, Ph), 7.41–7.45 (m, 2H,
Ph), 7.54–7.56 (m, 1H, Ph), 8.00–8.02 (m, 2H, Ph); 13C NMR (100 MHz,
CDCl3): δ 19.5 (CH3), 28.2 (CH3), 62.5 (C-6′), 64.2 (C-1), 70.3 (C-5′),
71.1 (C-4′), 72.1 (OCH2Ph), 99.0 (Cq), 127.9 (2 × CHPh), 128.0 (CHPh),
128.3 (2 × CHPh), 128.5 (2 × CHPh), 129.7 (2 × CHPh), 130.1 (Ci), 132.9
(CHPh), 137.5 (Ci), 166.4 (C
=O). Anal. calcd for C21H24O5: C, 70.77;
H, 6.79. Found: C, 70.83; H, 6.75.
4.1.6. [(4′S,5′R)-5′-(Benzyloxy)-2′,2′-dimethyl-1′,3′-dioxan-
4′-yl]methanol (6)
A solution of 13 (6.5 g, 18.2 mmol) in dry MeOH (190 mL) was
cooled to 0 °C and then treated with solid K2CO3 (0.76 g, 5.5 mmol).
The resulting mixture was stirred for 15 min at 0 °C, and then at
room temperature for another 4.5 h before dilution with Et2O
(255 mL). The solid Na2SO4 wad added, the insoluble material was
removed by filtration, the filtrate was concentrated, and the residue
was chromatographed on silica gel (n-hexane/ethyl acetate, 3:1) to
furnish 4.23 g (92%) of compound 6 as a colourless oil; [α]D24 −55.9
(c 0.57, CHCl3). IR υmax 3464, 3031, 2992, 2872, 1455, 1372, 1199,
1074 cm−1
;
1H NMR (400 MHz, CDCl3): δ 1.38 (s, 3H, CH3), 1.47 (s,
4.1.9. N-{(1′S)-1-[(4″S,5″R)-5″-(Benzyloxy)-2″,2″-dimethyl-1″,
3″-dioxan-4″-yl] allyl}-2,2,2-trichloroacetamide (17) and N-{(1′R)-
1-[(4″S,5″R)-5″-(benzyloxy)-2″,2″-dimethyl-1″,3″-dioxan-4″-yl]
allyl}-2,2,2-trichloroacetamide (18)
To a suspension of NaH (0.38 g, 15.8 mmol, 60% dispersion in
mineral oil) in dry THF (11.5 mL) that had been pre-cooled to 0 °C
was added a solution of 15 (1.98 g, 7.11 mmol) in dry THF (11.5 mL).
The resulting mixture was stirred at 0 °C for 30 min and then was
treated with CCl3CN (0.86 mL, 8.64 mmol). After stirring at the same
temperature for 30 min, the mixture was filtered through a small
pad of Celite, the filtrate was concentrated in vacuo, and the crude
imidate 16 (quant) was used in subsequent Overman rearrange-
ment without further purification.
3H, CH3), 2.01 (br s, 1H, OH), 3.56 (dt, 1H, J = 9.1 Hz, J = 9.1 Hz,
J = 5.3 Hz, H-5′), 3.66–3.72 (m, 2H, H-1, H-6′), 3.76–3.80 (m, 2H, H-1,
H-4′), 3.92 (dd, 1H, J = 11.3 Hz, J = 5.3 Hz, H-6′), 4.53 (d, 1H, J = 11.6 Hz,
OCH2Ph), 4.58 (d, 1H, J = 11.6 Hz, OCH2Ph), 7.27–7.37 (m, 5H, Ph);
13C NMR (100 MHz, CDCl3): δ 19.6 (CH3), 28.4 (CH3), 62.4 (C-6′), 62.5
(C-1), 70.2 (C-5′), 72.3 (OCH2Ph), 72.9 (C-4′), 98.8 (Cq), 127.9 (2 × CHPh),
128.0 (CHPh), 128.5 (2 × CHPh), 137.8 (Ci). Anal. calcd for C14H20O4:
C, 66.65; H, 7.99. Found: C, 66.60; H, 7.94.
4.1.7. Ethyl (2E)-3-[(4′S,5′R)-5′-(benzyloxy)-2′,2′-dimethyl-1′,3′-
dioxan-4′-yl]acrylate (14)
IBX (11.16 g, 40.0 mmol) was added to a solution of alcohol 6
(4.02 g, 15.8 mmol) in acetonitrile (143 mL), and the resulting mixture
was stirred and heated to reflux for 30 min. Then, the insoluble parts
were removed by filtration and the filtrate was concentrated in vacuo.
The obtained crude product was used immediately in subsequent
reaction without chromatographic purification.
Imidate 16 (0.10 g, 0.24 mmol) was weighed into a 10-mL glass
pressure microwave tube equipped with a magnetic stirbar. o-Xylene
(3.2 mL) and anhydrous K2CO3 (37.3 mg, 0.27 mmol) were then added.
The tube was closed with a silicon septum and the reaction mixture
was subjected to the microwave irradiation (for the temperatures
and the reaction times, see Table 1). Removal of the solvent and chro-
matography on silica gel (n-hexane/ethyl acetate, 3:1) gave the
corresponding trichloroacetamides 17 and 18 as colourless oils (for
the combined yields, see Table 1). Requiring a greater amount of
the rearranged products 17 and 18, the aforementioned procedure
was repeated several times at 130 °C using 0.25 g of the starting
imidate 16.
To a solution of the crude aldehyde (3.95 g, 15.8 mmol) in dry
CH2Cl2 (158 mL) was added stabilized ylide (Ph3P=CHCO2Et, 6.05 g,
17.4 mmol), and the resulting mixture was stirred at room tem-
perature for 30 min before evaporating of dichloromethane. The
obtained residue was purified by flash chromatography on silica gel
(n-hexane/ethyl acetate, 9:1) to afford 5.01 g (98%) of compound 14
27
as a colourless oil; [α]D −53.7 (c 0.38, CHCl3). IR υmax 2991, 2939,
Diastereoisomer 17: [α]D27 −50.2 (c 0.95, CHCl3). IR υmax 3421, 2992,
2875, 1717, 1500, 1226, 1167 cm−1; 1H NMR (400 MHz, CDCl3): δ 1.38
(s, 3H, CH3), 1.45 (s, 3H, CH3), 3.48 (dt, 1H, J = 8.8 Hz, J = 8.8 Hz,
J = 5.2 Hz, H-5″), 3.68 (dd, 1H, J = 11.5 Hz, J = 8.4 Hz, H-6″), 3.89–
3.95 (m, 2H, H-4″, H-6″), 4.47 (d, 1H, J = 11.6 Hz, OCH2Ph), 4.55 (d,
1H, J = 11.6 Hz, OCH2Ph), 4.71 (dt, 1H, J = 8.4 Hz, J = 8.4 Hz, J = 3.1 Hz,
H-1′), 5.23–5.29 (m, 2H, 2 × H-3′), 5.79 (ddd, 1H, J = 17.3 Hz,
J = 10.3 Hz, J = 8.2 Hz, H-2′), 7.13 (d, 1H, J = 8.3 Hz, NH), 7.26–7.38 (m,
5H, Ph); 13C NMR (100 MHz, CDCl3): δ 19.7 (CH3), 27.9 (CH3), 54.1
(C-1′), 62.2 (C-6″), 70.6 (C-5″), 71.6 (OCH2Ph), 73.4 (C-4″), 92.7 (CCl3),
99.3 (Cq), 120.4 (C-3′), 127.9 (2 × CHPh), 128.1 (CHPh), 128.5 (2 × CHPh),
2871, 1717, 1660, 1367, 1301, 1259, 1159, 1095 cm−1 1H NMR
;
(400 MHz, CDCl3): δ 1.30 (t, 3H, J = 7.1 Hz, CH3), 1.41 (s, 3H, CH3), 1.48
(s, 3H, CH3), 3.32 (dt, 1H, J = 9.2 Hz, J = 9.2 Hz, J = 5.3 Hz, H-5′), 3.71
(dd, 1H, J = 11.5 Hz, J = 9.0 Hz, H-6′), 3.91 (dd, 1H, J = 11.5 Hz, J = 5.3 Hz,
H-6′), 4.21 (q, 2H, J = 7.1 Hz, CH2), 4.34 (ddd, 1H, J = 9.5 Hz,
J = 4.4 Hz, J = 1.7 Hz, H-4′), 4.53 (m, 2H, OCH2Ph), 6.13 (dd, 1H,
J = 15.7 Hz, J = 1.7 Hz, H-2), 7.07 (dd, 1H, J = 15.7 Hz, J = 4.4 Hz, H-3),
7.27–7.37 (m, 5H, Ph); 13C NMR (100 MHz, CDCl3): δ 14.2 (CH3), 19.4
(CH3), 28.3 (CH3), 60.4 (CH2), 62.7 (C-6′), 71.5 (C-4′), 72.5 (OCH2Ph),
74.1 (C-5′), 98.9 (Cq), 121.7 (C-2), 127.9 (2 × CHPh), 128.0 (CHPh), 128.5
(2 × CHPh), 137.5 (Ci), 144.5 (C-3), 166.5 (C
=
O). Anal. calcd for
131.4 (C-2′), 137.5 (Ci), 160.7 (C
=O). Anal. calcd for C18H22Cl3NO4:
C18H24O5: C, 67.48; H, 7.55. Found: C, 67.42; H, 7.59.
C, 51.14; H, 5.25; N, 3.31. Found: C, 51.19; H, 5.20; N, 3.36.

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
77
Diastereoisomer 18: [α]D28 −3.1 (c 0.83, CHCl3). IR υmax 3422, 2992,
2874, 1716, 1455, 1284, 1225, 1153 cm−1; 1H NMR (400 MHz, CDCl3):
δ 1.38 (s, 3H, CH3), 1.46 (s, 3H, CH3), 3.43 (dt, 1H, J = 9.5 Hz, J = 9.5 Hz,
J = 5.4 Hz, H-5″), 3.68 (dd, 1H, J = 11.2 Hz, J = 9.7 Hz, H-6″), 3.87 (dd,
1H, J = 9.5 Hz, J = 1.5 Hz, H-4″), 3.91 (dd, 1H, J = 11.3 Hz, J = 5.4 Hz,
H-6″), 4.51 (m, 2H, OCH2Ph), 4.81–4.85 (m, 1H, H-1′), 5.24–5.31 (m,
2H, 2 × H-3′), 5.86 (ddd, 1H, J = 17.2 Hz, J = 10.5 Hz, J = 5.1 Hz, H-2′),
7.26–7.37 (m, 6H, Ph, NH); 13C NMR (100 MHz, CDCl3): δ 19.1 (CH3),
28.5 (CH3), 52.5 (C-1′), 62.3 (C-6″), 70.4 (C-5″), 72.7 (OCH2Ph), 73.6
(C-4″), 92.7 (CCl3), 99.1 (Cq), 117.0 (C-3′), 128.3 (CHPh), 128.5 (2 × CHPh),
as a colourless oil; [α]D26 −2.5 (c 1.12, CHCl3). IR υmax 3399, 2886, 1693,
1511, 1454, 1208, 1058 cm−1; 1H NMR (400 MHz, CDCl3): δ 1.38 (s,
3H, CH3), 1.44 (s, 3H, CH3), 2.50 (br s, 1H, OH), 3.53–3.59 (m, 2H,
H-2′, H-5″), 3.70 (dd, 1H, J = 11.5 Hz, J = 8.3 Hz, H-6″), 3.79 (1H, dd,
J = 12.1 Hz, J = 2.5 Hz, H-2′), 3.98 (dd, 1H, J = 11.5 Hz, J = 5.0 Hz, H-6″),
4.06 (dd, 1H, J = 9.5 Hz, J = 3.3 Hz, H-4″), 4.15–4.20 (m, 1H, H-1′), 4.47
(d, 1H, J = 11.9 Hz, OCH2Ph), 4.62 (d, 1H, J = 11.9 Hz, OCH2Ph), 7.29–
7.38 (m, 5H, Ph), 7.45 (d, 1H, J = 7.9 Hz, NH); 13C NMR (100 MHz,
CDCl3): δ 19.4 (CH3), 28.0 (CH3), 51.7 (C-1′), 60.5 (C-2′), 62.2 (C-
6″), 70.5 (C-5″), 71.4 (OCH2Ph), 74.1 (C-4″), 92.5 (CCl3), 99.6 (Cq), 128.0
128.6 (2 × CHPh), 133.9 (C-2′), 137.1 (Ci), 161.5 (C=O). Anal. calcd for
(2 × CHPh), 128.2 (CHPh), 128.6 (2 × CHPh), 137.2 (Ci), 161.6 (C=O). Anal.
C18H22Cl3NO4: C, 51.14; H, 5.25; N, 3.31. Found: C, 51.10; H, 5.30; N,
3.26.
calcd for C17H22Cl3NO5: C, 47.85; H, 5.20; N, 3.28. Found: C, 47.80;
H, 5.24; N, 3.33.
4.1.10. (4S,5R)-5-(Benzyloxy)-2,2-dimethyl-4-[(1′E)-
3′-thiocyanatoprop-1′-en-1′-yl]-1,3-dioxane (19)
4.1.12. N-{(1′R)-1-[(4″S,5″R)-5′-(Benzyloxy)-2″,2″-dimethyl-1″,
3″-dioxan-4″-yl]-2′-hydroxyethyl}-2,2,2-trichloroacetamide (23)
According to the same procedure described for the preparation
of 22, compound 18 (1.39 g, 3.29 mmol) afforded after ozonolysis
and the reductive workup (NaHB4, 0.56 g, 14.8 mmol) the residue,
which was purified by flash chromatography on silica gel (n-hexane/
ethyl acetate, 3:1). This procedure yielded 1.23 g (88%) of derivative
23 as a colourless oil; [α]D26 −27.0 (c 0.43, CHCl3). IR υmax 3416, 2992,
2877, 1713, 1505, 1455, 1227, 1164 cm−1; 1H NMR (400 MHz, CD3OD):
δ 1.35 (s, 3H, CH3), 1.46 (s, 3H, CH3), 3.37 (dt, 1H, J = 9.2 Hz, J = 9.2 Hz,
J = 5.3 Hz, H-5″), 3.58–3.67 (m, 2H, 2 × H-2′), 3.68 (dd, 1H, J = 11.3 Hz,
J = 9.1 Hz, H-6″), 3.90 (dd, 1H, J = 11.4 Hz, J = 5.3 Hz, H-6″), 4.02 (dd,
1H, J = 9.5 Hz, J = 1.2 Hz, H-4″), 4.34–4.37 (m, 1H, H-1′), 4.50 (d, 1H,
J = 11.1 Hz, OCH2Ph), 4.54 (d, 1H, J = 11.1 Hz, OCH2Ph), 7.25–7.36 (m,
5H, Ph); 13C NMR (100 MHz, CD3OD): δ 19.8 (CH3), 28.7 (CH3), 53.5
(C-1′), 61.2 (C-2′), 63.5 (C-6″), 71.6 (C-4″, C-5″), 73.4 (OCH2Ph), 94.0
(CCl3), 100.4 (Cq), 129.0 (CHPh), 129.5 (4 × CHPh), 139.3 (Ci), 163.9
A solution of compound 15 (0.195 g, 0.70 mmol) in dry CH2Cl2
(6 mL) was cooled to 0 °C and then successively treated with Et3N
(0.148 mL, 1.05 mmol) and MsCl (0.08 mL, 1.05 mmol). The result-
ing mixture was stirred for 15 min at 0 °C and then at room
temperature for another 20 min. After evaporation of the solvent,
the residue was diluted with Et2O, the insoluble material was fil-
tered off, washed with Et2O, and the solvent was evaporated. The
obtained crude product was used in the next reaction without further
purification.
To a solution of the crude mesylate (0.25 g, 0.70 mmol) in dry
acetonitrile (6 mL) that had been pre-cooled to 5 °C was added KSCN
(0.116 g, 1.19 mmol), and the resulting mixture was then stirred at
room temperature for 6.5 h before evaporating of the solvent. To
the obtained residue, Et2O was added to give salts, which were
removed by filtration. The filtrate was concentrated to provide a pale
yellow oil, which was subjected to the flash chromatography on silica
gel (n-hexane/ethyl acetate, 7:1) to yield 0.208 g (93%) of com-
pound 19 as white crystals; mp 48.5–50 °C (recrystallized from
(C=O). Anal. calcd for C17H22Cl3NO5: C, 47.85; H, 5.20; N, 3.28. Found:
C, 47.89; H, 5.18; N, 3.24.
27
n-hexane/ethyl acetate); [α]D −24.6 (c 0.41, CHCl3). IR υmax 2992,
4.1.13. (4S)-4-[(4′S,5′R)-5′-(Benzyloxy)-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (24)
2939, 2871, 2154, 1455, 1379, 1261, 1199, 1083 cm−1
;
1H NMR
(400 MHz, CDCl3): δ 1.40 (s, 3H, CH3), 1.48 (s, 3H, CH3), 3.34 (dt, 1H,
J = 9.3 Hz, J = 9.3 Hz, J = 5.4 Hz, H-5), 3.56–3.57 (m, 2H, 2 × H-3′), 3.69
(dd, 1H, J = 11.4 Hz, J = 9.3 Hz, H-6), 3.90 (dd, 1H, J = 11.4 Hz, J = 5.4 Hz,
H-6), 4.23 (dd, 1H, J = 9.3 Hz, J = 3.8 Hz, H-4), 4.54 (d, 1H, J = 11.6 Hz,
OCH2Ph), 4.58 (d, 1H, J = 11.6 Hz, OCH2Ph), 5.88–5.99 (m, 2H, H-1′,
H-2′), 7.27–7.36 (m, 5H, Ph); 13C NMR (100 MHz, CDCl3): δ 19.4 (CH3),
28.5 (CH3), 35.9 (C-3′), 62.7 (C-6), 72.0 (C-4), 72.6 (OCH2Ph), 74.6
(C-5), 98.9 (Cq), 111.8 (SCN), 124.2 (C-2′), 127.9 (CHPh), 128.0
(2 × CHPh), 128.4 (2 × CHPh), 135.1 (C-1′), 137.8 (Ci). Anal. calcd for
C17H21NO3S: C, 63.92; H, 6.63; N, 4.39. Found: C, 63.97; H, 6.59; N,
4.35.
A solution of 22 (0.92 g, 2.16 mmol) in dry CH2Cl2 (25.7 mL) was
cooled to 0 °C and then treated with DBU (32 μL, 0.22 mmol). The
resulting solution was stirred for 10 min at 0 °C and then for room
temperature for another 6 h. After evaporating of the solvent, the
residue was chromatographed on silica gel (n-hexane/ethyl acetate,
1:2) to afford 0.59 g (89%) of oxazolidinone 24 as a colourless oil;
26
[α]D −40.7 (c 0.34, CHCl3). IR υmax 3288, 2991, 2874, 1747, 1455,
1265, 1168, 1089 cm−1; 1H NMR (400 MHz, CDCl3): δ 1.35 (s, 3H, CH3),
1.45 (s, 3H, CH3), 3.47 (dt, 1H, J = 9.0 Hz, J = 9.0 Hz, J = 5.0 Hz, H-5′),
3.69 (m, 2H, H-4′, H-6′), 3.87 (td, 1H, J = 8.6 Hz, J = 5.7 Hz, J = 5.7 Hz,
H-4), 3.99 (dd, 1H, J = 11.5 Hz, J = 5.0 Hz, H-6′), 4.27 (t, 1H, J = 8.8 Hz,
H-5), 4.34 (dd, 1H, J = 8.9 Hz, J = 5.6 Hz, H-5), 4.44 (d, 1H, J = 11.5 Hz,
OCH2Ph), 4.60 (d, 1H, J = 11.5 Hz, OCH2Ph), 5.38 (br s, 1H, NH), 7.27–
7.41 (m, 5H, Ph); 13C NMR (100 MHz, CDCl3): δ 19.4 (CH3), 28.1 (CH3),
54.7 (C-4), 61.9 (C-6′), 66.3 (C-5), 71.5 (OCH2Ph), 72.6 (C-5′), 72.7
(C-4′), 99.3 (Cq), 128.1 (2 × CHPh), 128.4 (CHPh), 128.8 (2 × CHPh), 136.9
The corresponding rearrangements of 19 were realized accord-
ing to our procedures reported in the literature.11,41
4.1.11. N-{(1′S)-1-[(4″S,5″R)-5′-(Benzyloxy)-2″,2″-dimethyl-1″,
3″-dioxan-4″-yl]-2′-hydroxyethyl}-2,2,2-trichloroacetamide (22)
Ozone was introduced to a solution of 17 (1.33 g, 3.15 mmol) in
CH2Cl2/MeOH (120 mL, 1:5) at −78 °C for 15 min. After the com-
plete consumption of the starting material (judged by TLC), nitrogen
was passed through the cold solution for 5 min in order to remove
the excess ozone. Then NaHB4 (0.535 g, 14.2 mmol) was added in
portions, and the resulting mixture was stirred for 30 min at −78 °C
and then at 0 °C for another 30 min. The reaction was quenched by
the neutralization with a 1 M aqueous HCl solution, the solvent was
removed, and the residue was partitioned between EtOAc (92 mL)
and a saturated NH4Cl solution (46 mL). The aqueous layer was then
washed with the further portion of EtOAc (92 mL). The combined
organic extracts were dried over Na2SO4, stripped solvent, and the
residue was chromatographed through a short column of silica gel
(n-hexane/ethyl acetate, 4:1) to give 1.275 g (95%) of compound 22
(Ci), 159.2 (C=O). Anal. calcd for C16H21NO5: C, 62.53; H, 6.89; N,
4.56. Found: C, 62.49; H, 6.92; N, 4.52.
4.1.14. (4R)-4-[(4′S,5′R)-5′-(Benzyloxy)-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (25)
Similar to the preceding procedure, compound 23 (1.15 g,
2.7 mmol) was treated with DBU (40 μL, 0.27 mmol) at 0 °C. After
stirring (6 h) at room temperature, the flash chromatography (silica
gel, n-hexane/ethyl acetate, 2:1) of the residue gave 0.705 g (85%)
of crystalline compound 25; mp 99–101 °C (recrystallized from
26
n-hexane/ethyl acetate); [α]D −87.6 (c 0.36, CHCl3). IR υmax 3221,
2922, 1753, 1418, 1304, 1265, 1162, 1087 cm−1; 1H NMR (400 MHz,
CDCl3): δ 1.37 (s, 3H, CH3), 1.45 (s, 3H, CH3), 3.41 (dt, 1H, J = 8.9 Hz,
J = 8.9 Hz, J = 5.1 Hz, H-5′), 3.62–3.72 (m, 2H, H-4′, H-6′), 3.89 (m,

78
E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
1H, H-4), 3.98 (dd, 1H, J = 11.4 Hz, J = 5.1 Hz, H-6′), 4.31–4.38 (m, 2H,
2 × H-5), 4.41 (d, 1H, J = 11.5 Hz, OCH2Ph), 4.57 (d, 1H, J = 11.5 Hz,
OCH2Ph), 5.59–5.61 (m, 1H, NH), 7.26–7.40 (m, 5H, Ph); 13C NMR
(100 MHz, CDCl3): δ 19.5 (CH3), 28.1 (CH3), 54.7 (C-4), 61.9 (C-6′),
68.8 (C-5), 71.6 (OCH2Ph), 72.1 (C-5′), 73.2 (C-4′), 99.3 (Cq), 128.1
(2 × CHPh), 128.4 (CHPh), 128.7 (2 × CHPh), 137.0 (Ci), 159.2 (C=O). Anal.
calcd for C16H21NO5: C, 62.53; H, 6.89; N, 4.56. Found: C, 62.57; H,
6.84; N, 4.61.
J = 2.5 Hz, H-5′), 3.65 (ddd, 1H, J = 8.9 Hz, J = 6.7 Hz, J = 2.0 Hz, H-4),
3.82 (dd, 1H, J = 13.1 Hz, J = 2.5 Hz, H-6′), 3.98 (dd, 1H, J = 13.1 Hz,
J = 2.4 Hz, H-6′), 4.03 (t, 1H, J = 2.3 Hz, H-4′), 4.20–4.27 (m, 3H, H-5,
NCH2Ph, OCH2Ph), 4.61 (d, 1H, J = 15.5 Hz, NCH2Ph), 4.64 (d, 1H,
J = 12.3 Hz, OCH2Ph), 4.68 (dd, 1H, J = 9.4 Hz, J = 6.9 Hz, H-5), 7.22–
7.35 (m, 10H, Ph); 13C NMR (100 MHz, CDCl3): δ 18.8 (CH3), 28.4 (CH3),
46.5 (NCH2Ph) 57.5 (C-4), 60.2 (C-6′), 63.9 (C-5), 67.4 (C-4′), 70.6
(OCH2Ph), 71.0 (C-5′), 99.0 (Cq), 127.7 (4 × CHPh), 127.8 (CHPh), 128.0
(CHPh), 128.5 (2 × CHPh), 128.8 (2 × CHPh), 136.2 (Ci), 137.2 (Ci), 158.9
4.1.15. (4S)-3-Benzyl-4-[(4′S,5′R)-5′-(benzyloxy)-2′,
(C=O). Anal. calcd for C23H27NO5: C, 69.50; H, 6.85; N, 3.52. Found:
2′-dimethyl-1′,3′-dioxan-4′-yl]oxazolidin-2-one (27)
C, 69.45; H, 6.88; N, 3.58.
A solution of 24 (95 mg, 0.31 mmol) in dry DMF (0.5 mL) was
cooled to 0 °C and then treated with NaH (18.5 mg, 0.77 mmol, 60%
dispersion in mineral oil). Next, benzyl bromide (44.5 μL, 0.37 mmol)
and TBAI (1.1 mg, 3.1 μmol) were successively added. The result-
ing mixture was stirred for 10 min at 0 °C and then at room
temperature for 30 min. The excess hydride was removed by the cau-
tious addition of MeOH (0.1 mL), the mixture was poured into ice-
water (2 mL) and extracted with Et2O (2 × 5 mL). The combined
organic extracts were dried over Na2SO4, the solvent was evapo-
rated, and the residue was subjected to flash chromatography on
silica gel (n-hexane/ethyl acetate, 5:1) to furnish 113 mg (92%) of
compound 27 as white crystals; mp 81–82 °C (recrystallized from
4.1.18. (4S)-3-Benzyl-4-[(4′S,5′R)-5′-hydroxy-2′,
2′-dimethyl-1′,3′-dioxan-4′-yl]oxazolidin-2-one (30)
A solution of 27 (70 mg, 0.18 mmol) in dry EtOH (6.8 mL) was
treated with 10% Pd/C (6.1 mg) under an atmosphere of hydrogen,
and the resulting suspension was stirred for 7 h at room temper-
ature. After filtration of the mixture through a small pad of Celite,
the filtrate was concentrated, and the residue was chromatographed
on silica gel (n-hexane/ethyl acetate, 1:1) to afford 52.5 mg (97%)
of compound 30 as white crystals; mp 127–128 °C (recrystallized
from n-hexane/ethyl acetate); [α]D27 −5.7 (c 0.30, CHCl3). IR υmax 3434,
1728, 1713, 1474, 1374, 1265, 1164 cm−1; 1H NMR (600 MHz, CDCl3):
δ 1.28 (s, 3H, CH3), 1.37 (s, 3H, CH3), 3.05 (d, 1H, J = 5.8 Hz, OH), 3.52
(m, 1H, H-5′), 3.59 (dd, 1H, J = 11.2 Hz, J = 9.2 Hz, H-6′), 3.79 (dd, 1H,
J = 9.5 Hz, J = 1.6 Hz, H-4′), 3.84 (dd, 1H, J = 11.2 Hz, J = 5.4 Hz, H-6′),
4.04 (ddd, 1H, J = 9.5 Hz, J = 5.6 Hz, J = 1.6 Hz, H-4), 4.23 (dd, 1H,
J = 9.5 Hz, J = 8.6 Hz, H-5), 4.27 (d, 1H, J = 15.3 Hz, NCH2Ph), 4.47 (dd,
1H, J = 8.4 Hz, J = 5.7 Hz, H-5), 4.66 (d, 1H, J = 15.3 Hz, NCH2Ph), 7.27–
7.34 (m, 5H, Ph); 13C NMR (150 MHz, CDCl3): δ 18.7 (CH3), 28.3 (CH3),
46.6 (NCH2Ph), 55.3 (C-4), 62.8 (C-5′), 62.9 (C-5), 64.5 (C-6′), 71.2
(C-4′), 99.0 (Cq), 127.9 (CHPh), 128.1 (2 × CHPh), 128.7 (2 × CHPh), 135.1
27
n-hexane/ethyl acetate); [α]D −29.1 (c 0.32, CHCl3). IR υmax 2995,
2920, 1736, 1482, 1426, 1369, 1291, 1268, 1169 cm−1 1H NMR
;
(600 MHz, CDCl3): δ 1.28 (s, 3H, CH3), 1.35 (s, 3H, CH3), 3.24 (dt, 1H,
J = 8.9 Hz, J = 8.9 Hz, J = 5.3 Hz, H-5′), 3.65 (dd, 1H, J = 11.5 Hz, J = 8.6 Hz,
H-6′), 3.77–3.85 (m, 3H, H-4, H-4′, H-5), 3.93 (dd, 1H, J = 11.5 Hz,
J = 5.2 Hz, H-6′), 4.22 (d, 1H, J = 15.2 Hz, NCH2Ph), 4.28 (dd, 1H,
J = 7.1 Hz, J = 4.4 Hz, H-5), 4.30 (d, 1H, J = 11.7 Hz, OCH2Ph), 4.51 (d,
1H, J = 11.7 Hz, OCH2Ph), 4.72 (d, 1H, J = 15.2 Hz, NCH2Ph), 7.15–
7.16 (m, 2H, Ph), 7.31–7.36 (m, 8H, Ph); 13C NMR (150 MHz, CDCl3):
δ 19.0 (CH3), 28.0 (CH3), 46.5 (NCH2Ph), 54.9 (C-4), 62.0 (C-6′), 62.3
(C-5), 69.2 (C-4′), 69.3 (C-5′), 71.7 (OCH2Ph), 99.2 (Cq), 127.8 (CHPh),
128.1 (2 × CHPh), 128.3 (3 × CHPh), 128.6 (2 × CHPh), 128.7 (2 × CHPh),
(Ci), 159.3 (C=O). Anal. calcd for C16H21NO5: C, 62.53; H, 6.89; N,
4.56. Found: C, 62.59; H, 6.84; N, 4.61.
136.1 (Ci), 136.9 (Ci), 158.8 (C
H, 6.85; N, 3.52. Found: C, 69.45; H, 6.89; N, 3.56.
=
O). Anal. calcd for C23H27NO5: C, 69.50;
4.1.19. (4R)-3-Benzyl-4-[(4′S,5′R)-5′-hydroxy-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (31)
By the similar procedure as described for the preparation of 30,
compound 28 (97 mg, 0.244 mmol) and 10% Pd/C (8.4 mg) af-
forded after stirring for 28 h under an atmosphere of hydrogen and
chromatography on silica gel (n-hexane/ethyl acetate, 1:1) 70.7 mg
(94%) of alcohol 31 in the form of white crystals; mp 115–116 °C
4.1.16. (4R)-3-Benzyl-4-[(4′S,5′R)-5′-(benzyloxy)-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (28)
Using the same procedure as described for the preparation of
27, compound 25 (0.10 g, 0.325 mmol) was converted into crystal-
line derivative 28 (124 mg, 96%, n-hexane/ethyl acetate, 5:1); mp
77–78 °C (recrystallized from n-hexane/ethyl acetate); [α]D27 −34.2
(c 0.26, CHCl3). IR υmax 2906, 2878, 1732, 1454, 1395, 1271, 1169 cm−1;
1H NMR (400 MHz, CDCl3): δ 1.33 (s, 3H, CH3), 1.34 (s, 3H, CH3), 3.45–
3.50 (m, 1H, H-5′), 3.66 (dd, 1H, J = 11.5 Hz, J = 7.5 Hz, H-6′), 3.71–
3.76 (m, 1H, H-4), 3.87–3.90 (m, 2H, H-4′, H-6′), 4.18 (t, 1H, J = 9.0 Hz,
H-5), 4.31–4.35 (m, 3H, H-5, NCH2Ph, OCH2Ph), 4.44 (d, 1H, J = 11.1 Hz,
OCH2Ph), 4.79 (d, 1H, J = 15.2 Hz, NCH2Ph), 7.28–7.34 (m, 5H, Ph);
13C NMR (100 MHz, CDCl3): δ 19.8 (CH3), 27.4 (CH3), 47.8 (NCH2Ph),
56.3 (C-4), 61.9 (C-6′), 64.4 (C-5), 71.7 (OCH2Ph), 72.7 (C-4′), 72.8
(C-5′), 99.3 (Cq), 127.6 (CHPh), 127.9 (2 × CHPh), 128.2 (3 × CHPh), 128.6
26
(recrystallized from n-hexane/ethyl acetate); [α]D −8.5 (c 0.26,
CHCl3). IR υmax 3369, 2917, 2851, 1731, 1498, 1430, 1336, 1256 cm−1;
1H NMR (600 MHz, CDCl3): δ 1.33 (s, 3H, CH3), 1.34 (s, 3H, CH3), 3.20
(d, 1H, J = 6.0 Hz, OH), 3.60 (dd, 1H, J = 11.4 Hz, J = 8.4 Hz, H-6′), 3.65–
3.70 (m, 1H, H-5′), 3.76 (td, 1H, J = 8.8 Hz, J = 6.0 Hz, J = 6.0 Hz, H-4),
3.84 (dd, 1H, J = 11.2 Hz, J = 5.0 Hz, H-6′), 3.86 (dd, 1H, J = 8.8 Hz,
J = 6.2 Hz, H-4′), 4.28 (t, 1H, J = 9.2 Hz, H-5), 4.38 (d, 1H, J = 15.2 Hz,
NCH2Ph), 4.46 (dd, 1H, J = 9.5 Hz, J = 5.8 Hz, H-5), 4.78 (d, 1H,
J = 15.2 Hz, NCH2Ph), 7.26–7.35 (m, 5H, Ph); 13C NMR (150 MHz,
CDCl3): δ 19.4 (CH3), 27.9 (CH3), 47.8 (NCH2Ph), 56.8 (C-4), 64.6 (C-
5), 64.7 (C-5′, C-6′), 74.0 (C-4′), 98.9 (Cq), 127.7 (CHPh), 127.9 (2 × CHPh),
(4 × CHPh), 136.5 (Ci), 137.0 (Ci), 158.9 (C
=
O). Anal. calcd for
128.7 (2 × CHPh), 136.4 (Ci), 159.4 (C=O). Anal. calcd for C16H21NO5:
C23H27NO5: C, 69.50; H, 6.85; N, 3.52. Found: C, 69.54; H, 6.81; N,
3.57.
C, 62.53; H, 6.89; N, 4.56. Found: C, 62.48; H, 6.85; N, 4.60.
4.1.20. (4S)-3-Benzyl-4-[(4′S,5′S)-5′-hydroxy-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (32)
4.1.17. (4S)-3-Benzyl-4-[(4′S,5′S)-5′-(benzyloxy)-2′,2′-dimethyl-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (29)
Using the same procedure as described for the preparation of
30 and 31, compound 29 (101 mg, 0.256 mmol) was converted into
derivative 32 (3 h, 75 mg, 96% (n-hexane/ethyl acetate, 1:1, white
amorphous compound); [α]D26 −5.0 (c 0.48, CHCl3). IR υmax 3573, 2991,
1736, 1478, 1428, 1334, 1266, 1173 cm−1; 1H NMR (400 MHz, CDCl3):
δ 1.27 (s, 3H, CH3), 1.39 (s, 3H, CH3), 2.77–2.79 (m, 1H, OH), 3.36–
3.38 (m, 1H, H-5′), 3.74–3.80 (m, 2H, H-4, H-6′), 3.93–3.94 (m, 1H,
H-4′), 4.00–4.04 (m, 1H, H-6′), 4.25–4.30 (m, 2H, H-5′, NCH2Ph), 4.47
According to the same experiment described for the prepara-
tion of 27 and 28, the known compound 2611 (90 mg, 0.29 mmol)
was transformed to the crystalline derivative 29 (106 mg, 91%,
n-hexane/ethyl acetate, 1:2); mp 78–79 °C (recrystallized from
26
n-hexane/ethyl acetate); [α]D +36.2 (c 0.50, CHCl3). IR υmax 2871,
1743, 1728, 1496, 1423, 1322, 1264, 1198, 1144 cm−1 1H NMR
;
(400 MHz, CDCl3): δ 1.20 (s, 3H, CH3), 1.40 (s, 3H, CH3), 3.15 (q, 1H,

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
79
(dd, 1H, J = 9.0 Hz, J = 6.0 Hz, H-5), 4.70 (d, 1H, J = 15.4 Hz, NCH2Ph),
7.28–7.36 (m, 5H, Ph); 13C NMR (100 MHz, CDCl3): δ 18.0 (CH3), 29.1
(CH3), 47.0 (NCH2Ph) 56.6 (C-4), 64.1 (C-5′), 64.4 (C-5), 65.4 (C-6′),
69.6 (C-4′), 99.3 (Cq), 127.8 (3 × CHPh), 128.7 (2 × CHPh), 136.2 (Ci),
(100 MHz, CD3OD): δ 55.3 (C-4), 61.2 (C-3′), 67.0 (C-5), 71.5 (C-1′),
73.1 (OCH2Ph), 81.1 (C-2′), 129.0 (CHPh), 129.5 (4 × CHPh), 139.5 (Ci),
162.6 (C=O). Anal. calcd for C13H17NO5: C, 58.42; H, 6.41; N, 5.24.
Found: C, 58.36; H, 6.45; N, 5.30.
159.0 (C
=O). Anal. calcd for C16H21NO5: C, 62.53; H, 6.89; N, 4.56.
Found: C, 62.58; H, 6.85; N, 4.52.
4.1.24. (4S)-4-[(1′S,2′R)-2′-(Benzyloxy)-1′-hydroxy-
3′-(trityloxy)propyl]oxazolidin-2-one (36)
4.1.21. (4S)-3-Benzyl-4-[(4′S)-2′,2′-dimethyl-5′-oxo-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (33)
To a solution of 35 (0.20 g, 0.75 mmol) in dry pyridine (7.3 mL)
were successively added trityl chloride (0.625 g, 2.24 mmol) and
DMAP (91.5 mg, 0.75 mmol), and the resulting solution was stirred
and heated at 60 °C. After 8 h, another portion of TrCl (0.2 g,
0.75 mmol) and DMAP (91.5 mg, 0.75 mmol) was added, and the
mixture was stirred at 60 °C for further 15 h. After cooling to room
temperature, the mixture was poured into ice-water (4.5 mL) and
extracted with Et2O (3 × 9 mL). The combined organic extracts were
dried over Na2SO4, the solvent was evaporated, and the residue was
chromatographed through a short column of silica gel (n-hexane/
ethyl acetate, 1:1) to furnish 0.36 g (95%) of compound 36 as a white
4.1.21.1. Modification of 30 into ketone 33. To a solution of 30 (30 mg,
0.1 mmol) in acetonitrile (0.9 mL) wad added IBX (55 mg, 0.2 mmol),
and the resulting suspension was stirred and heated to reflux for
2 h. After cooling of the mixture to room temperature, the insolu-
ble parts were filtered off, the filtrate was concentrated in vacuo,
and the residue was chromatographed through a small pad of silica
gel (n-hexane/ethyl acetate, 2:1) to furnish 23.2 mg (78%) of crys-
talline compound 33.
23
4.1.21.2. Modification of 32 into 33. Similar to the preceding exper-
iment, compound 32 (69 mg, 0.22 mmol) was converted into
derivative 33 (55.5 mg, 81%, n-hexane/ethyl acetate, 2:1).
foam; [α]D −21.8 (c 0.23, CHCl3). IR υmax 3306, 3058, 3030, 2921,
1
2873, 1732, 1448, 1219, 1062 cm−1; H NMR (400 MHz, CD3OD): δ
3.27–3.30 (m, 1H, H-3′), 3.41 (dd, 1H, J = 10.3 Hz, J = 3.5 Hz, H-3′),
3.50–3.54 (m, 1H, H-2′), 3.85 (dd, 1H, J = 6.6 Hz, J = 3.0 Hz, H-1′), 4.00–
4.04 (m, 1H, H-4), 4.07–4.11 (m, 1H, H-5), 4.31 (dd, 1H, J = 8.3 Hz,
J = 5.4 Hz, H-5), 4.44 (d, 1H, J = 11.5 Hz, OCH2Ph), 4.63 (d, 1H,
J = 11.5 Hz, OCH2Ph), 7.20–7.47 (m, 20H, Ph); 13C NMR (100 MHz,
CDCl3): δ 55.4 (C-4), 64.1 (C-3′), 66.9 (C-5), 71.9 (C-1′), 73.5 (OCH2Ph),
80.5 (C-2′), 88.3 (CqTr), 128.2 (3 × CHPh), 128.9 (7 × CHPh), 129.3
(2 × CHPh), 129.5 (2 × CHPh), 130.0 (6 × CHPh), 139.5 (Ci), 145.4 (3 × Ci),
Diastereoisomer 33: mp 130–131 °C (recrystallized from
n-hexane/ethyl acetate); [α]D26 −213.8 (c 0.26, CHCl3). IR υmax 1748,
1731, 1483, 1426, 1361, 1253, 1167 cm−1; 1H NMR (400 MHz, CDCl3):
δ 1.37 (s, 3H, CH3), 1.44 (s, 3H, CH3), 4.01 (d, 1H, J = 17.6 Hz, H-6′),
4.12–4.23 (m, 4H, H-4, H-5, H-6′, NCH2Ph), 4.27–4.31 (m, 1H, H-5),
4.45 (m, 1H, H-4′), 4.80 (d, 1H, J = 15.4 Hz, NCH2Ph), 7.27–7.38 (m,
5H, Ph); 13C NMR (100 MHz, CDCl3): δ 23.4 (CH3), 23.6 (CH3), 46.5
(NCH2Ph), 53.8 (C-4), 62.9 (C-5), 66.8 (C-6′), 71.2 (C-4′), 101.5 (Cq),
128.0 (2 × CHPh), 128.1 (CHPh), 129.0 (2 × CHPh), 135.4 (Ci), 158.4
162.6 (C=O). Anal. calcd for C32H31NO5: C, 75.42; H, 6.13; N, 2.75.
Found: C, 75.35; H, 6.18; N, 2.70.
(C=O), 207.5 (C=O). Anal. calcd for C16H19NO5: C, 62.94; H, 6.27;
N, 4.59. Found: C, 62.89; H, 6.32; N, 4.63.
4.1.25. (4S)-3-Benzyl-4-[(1′S,2′R)-1′,2′-bis(benzyloxy)-
3′-(trityloxy)propyl]oxazolidin-2-one (37)
4.1.22. (4R)-3-Benzyl-4-[(4′S)-2′,2′-dimethyl-5′-oxo-1′,
3′-dioxan-4′-yl]oxazolidin-2-one (34)
To a solution of 36 (0.34 g, 0.67 mmol) in dry DMF (1.6 mL) that
had been pre-cooled to 0 C were successively added NaH (80.1 mg,
3.34 mmol, 60% dispersion in mineral oil), BnBr (0.19 mL, 1.6 mmol)
and TBAI (4.9 mg, 0.013 mmol). The resulting mixture was stirred
for 15 min at 0 °C, and then at room temperature for another 45 min.
The excess hydride was decomposed by the cautious addition of
MeOH. The mixture was poured into ice-water (8 mL) and ex-
tracted with E2O (2 × 16 mL). The combined organic layers were dried
over Na2SO4, the solvent was evaporated in vacuo, and the residue
was subjected to flash chromatography on silica gel (n-hexane/
ethyl acetate, 3:1) to afford 0.434 g (94%) of compound 37 as white
crystals; mp 145–147 °C (recrystallized from n-hexane/ethyl acetate);
According to the same procedure described for the preparation
of 33, compound 31 (35 mg, 0.11 mmol) and IBX (64 mg, 0.23 mmol)
gave 31 mg (89%) of ketone 34 as a colourless oil (n-hexane/ethyl
acetate, 2:1); [α]D26 −54.3 (c 0.42, CHCl3). IR υmax 2987, 1736, 1496,
1376, 1222, 1094 cm−1; 1H NMR (400 MHz, CDCl3): δ 1.41 (br s, 6H,
2 × CH3), 3.88–3.93 (m, 2H, 2 × H-6′), 3.98–4.03 (m, 1H, H-4), 4.14
(dd, 1H, J = 9.4 Hz, J = 6.0 Hz, H-5), 4.30–4.31 (m, 1H, H-4′), 4.41 (d,
1H, J = 15.2 Hz, NCH2Ph), 4.49 (t, 1H, J = 9.3 Hz, H-5), 4.63 (d, 1H,
J = 15.1 Hz, NCH2Ph), 7.25–7.35 (m, 5H, Ph); 13C NMR (100 MHz,
CDCl3): δ 23.4 (CH3), 23.5 (CH3), 48.2 (NCH2Ph), 53.6 (C-4), 64.7 (C-
5), 66.4 (C-6′), 76.5 (C-4′), 101.5 (Cq), 127.8 (CHPh), 128.3 (2 × CHPh),
23
[α]D −33.9 (c 0.39, CHCl3). IR υmax 3027, 2927, 2871, 1743, 1494,
128.6 (2 × CHPh), 136.1 (Ci), 159.0 (C
for C16H19NO5: C, 62.94; H, 6.27; N, 4.59. Found: C, 62.99; H, 6.21;
N, 4.55.
=
O), 206.8 (C
=
O). Anal. calcd
1478, 1447, 1430, 1360, 1321, 1246, 1201 cm−1; 1H NMR (400 MHz,
CDCl3): δ 3.06 (dd, 1H, J = 10.4 Hz, J = 5.9 Hz, H-3′), 3.19 (dd, 1H,
J = 10.4 Hz, J = 4.8 Hz, H-3′), 3.54–3.58 (m, 1H, H-2′), 3.63 (d, 1H,
J = 15.4 Hz, NCH2Ph), 3.74 (dd, 1H, J = 9.4 Hz, J = 6.2 Hz, H-4), 3.90–
3.96 (m, 2H, H-1′, H-5), 4.21 (d, 1H, J = 11.6 Hz, OCH2Ph), 4.34 (d,
1H, J = 11.8 Hz, OCH2Ph), 4.42 (d, 1H, J = 11.6 Hz, OCH2Ph), 4.48 (dd,
1H, J = 8.7 Hz, J = 6.1 Hz, H-5), 4.52 (d, 1H, J = 15.4 Hz, NCH2Ph), 4.53
(d, 1H, J = 11.7 Hz, OCH2Ph), 7.08–7.37 (m, 30H, Ph); 13C NMR
(100 MHz, CDCl3): δ 45.8 (NCH2Ph), 54.9 (C-4), 62.5 (C-3′), 63.1 (C-
5), 72.1 (OCH2Ph), 72.7 (OCH2Ph), 73.4 (C-1′), 76.8 (C-2′), 87.2 (CqTr),
127.2 (2 × CHPh), 127.7 (CHPh), 127.8 (2 × CHPh), 127.9 (7 × CHPh), 128.0
(CHPh), 128.1 (2 × CHPh), 128.3 (2 × CHPh), 128.4 (2 × CHPh), 128.5
(9 × CHPh), 128.7 (2 × CHPh), 136.0 (Ci), 137.5 (2 × Ci), 143.6 (3 × Ci),
4.1.23. (4S)-4-[(1′S,2′R)-2′-(Benzyloxy)-1′,
3′-dihydroxypropyl]oxazolidin-2-one (35)
A solution of 24 (0.28 g, 0.91 mmol) in MeOH (17.5 mL) was
treated with p-TsOH (17.3 mg, 0.09 mmol) and the resulting mixture
was stirred at room temperature for 4 h. Following complete con-
sumption of the starting material (TLC monitoring), the reaction was
stopped, the solvent was evaporated in vacuo, and the residue was
then chromatographed on silica gel (ethyl acetate) to give 0.225 g
(92%) of compound 35 as white crystals; mp 101–103 °C (recrys-
tallized from ethyl acetate); [α]D24 −43.8 (c 0.60, MeOH). IR υmax 3437,
3316, 2921, 2883, 1721, 1426, 1244, 1051 cm−1; 1H NMR (400 MHz,
CD3OD): δ 3.38 (td, 1H, J = 7.6 Hz, J = 4.0 Hz, J = 4.0 Hz, H-2′), 3.71 (dd,
1H, J = 12.0 Hz, J = 4.0 Hz, H-3′), 3.74–3.77 (m, 1H, H-1′), 3.88 (dd,
1H, J = 12.0 Hz, J = 3.9 Hz, H-3′), 4.03–4.12 (m, 2H, H-4, H-5), 4.32
(1H, dd, J = 7.6 Hz, J = 4.6 Hz, H-5), 4.51 (d, 1H, J = 11.6 Hz, OCH2Ph),
4.72 (d, 1H, J = 11.6 Hz, OCH2Ph), 7.28–7.38 (m, 5H, Ph); 13C NMR
158.8 (C=O). Anal. calcd for C46H43NO5: C, 80.09; H, 6.28; N, 2.03.
Found: C, 80.15; H, 6.23; N, 1.97.
4.1.26. (4S)-3-Benzyl-4-[(1′S,2′R)-1′,2′-bis(benzyloxy)-
3′-hydroxypropyl]oxazolidin-2-one (38)
A solution of 37 (0.42 g, 0.61 mmol) in CH2Cl2/MeOH (7.8 mL, 2:1)
was treated with p-TsOH (116 mg, 0.61 mmol), and the resulting

80
E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
24
mixture was stirred at room temperature for 4 h before neutral-
ization with Et3N. Removal of the solvent and chromatography of
the residue on silica gel (n-hexane/ethyl acetate, 2:1) gave 0.25 g
(92%) of compound 38 as a colourless oil; [α]D24 −22.5 (c 0.91, CHCl3).
IR υmax 3421, 3030, 2921, 1717, 1604, 1454, 1243, 1058 cm−1; 1H NMR
(400 MHz, CDCl3): δ 3.40 (m, 1H, H-2′), 3.59–3.64 (m, 2H, 2 × H-
3′), 3.65 (d, 1H, J = 15.1 Hz, NCH2Ph), 3.75–3.79 (m, 2H, H-1′, H-4),
3.86 (dd, 1H, J = 9.4 Hz, J = 8.3 Hz, H-5), 4.39 (dd, 1H, J = 8.3 Hz,
J = 5.5 Hz, H-5), 4.40 (d, 1H, J = 11.9 Hz, OCH2Ph), 4.46 (d,
1H, J = 11.3 Hz, OCH2Ph), 4.56 (d, 1H, J = 11.7 Hz, OCH2Ph), 4.60 (d,
1H, J = 11.3 Hz, OCH2Ph), 4.67 (d, 1H, J = 15.1 Hz, NCH2Ph), 7.11–
7.39 (m, 15H, Ph); 13C NMR (100 MHz, CDCl3): δ 45.9 (NCH2Ph), 54.9
(C-4), 60.2 (C-3′), 62.7 (C-5), 72.4 (OCH2Ph), 73.2 (OCH2Ph), 73.6 (C-
1′), 77.6 (C-2′), 128.0 (CHPh), 128.1 (2 × CHPh), 128.2 (2 × CHPh), 128.4
(4 × CHPh), 128.6 (4 × CHPh), 128.8 (2 × CHPh), 135.7 (Ci), 137.0 (Ci),
132 °C (recrystallized from n-hexane/ethyl acetate); [α]D +3.7 (c
0.35, CHCl3). IR υmax 3333, 2916, 2848, 1745, 1708, 1470, 1427, 1243,
1085, 1026 cm−1; 1H NMR (400 MHz, CDCl3): δ 0.88 (t, 3H, J = 6.8 Hz,
CH3), 1.14–1.35 (m, 26H, 13 × CH2), 2.35 (br s, 1H, OH), 3.42 (br s,
1H, OH), 3.63–3.65 (m, 1H, H-2′), 3.75–3.76 (m, 1H, H-1′), 3.86–
3.90 (m, 1H, H-4), 4.21(d, 1H, J = 15.3 Hz, NCH2Ph), 4.27 (t, 1H,
J = 9.1 Hz, H-5), 4.54 (dd, 1H, J = 8.8 Hz, J = 7.4 Hz, H-5), 4.76 (d, 1H,
J = 15.3 Hz, NCH2Ph), 7.29–7.38 (m, 5H, Ph); 13C NMR (100 MHz,
CDCl3): δ 14.1 (CH3), 22.7 (CH2), 25.6 (CH2), 29.3 (CH2), 29.5 (2 × CH2),
29.6 (2 × CH2), 29.7 (2 × CH2), 29.8 (2 × CH2), 31.9 (CH2), 33.5 (CH2),
46.2 (NCH2Ph), 55.8 (C-4), 62.9 (C-5), 69.3 (C-1′), 72.7 (C-2′), 128.1
(3 × CHPh), 129.0 (2 × CHPh), 135.7 (Ci), 159.6 (C
=O). Anal. calcd for
C26H43NO4: C, 72.02; H, 10.00; N, 3.23. Found: C, 72.10; H, 9.94; N,
3.28.
137.3 (Ci), 158.7 (C=O). Anal. calcd for Pre C27H29NO5: C, 72.46; H,
6.53; 3.13. Found: C, 72.50; H, 6.48; N, 3.07.
4.1.29. (4S)-4-[(1′S,2′R)-1′,2′-Dihydroxyhexadecyl]oxazolidin-
2-one (41)
To a solution of 40 (59 mg, 0.14 mmol) in dry EtOH (11 mL) were
successively added 10% Pd/C (39 mg) and 35% HCl (0.14 mL), and
the resulting mixture was stirred and heated at 60 °C for 5.5 h. After
cooling to room temperature, the catalyst was removed by filtra-
tion through a small pad of Celite, the solvent was evaporated, and
the residue was chromatographed on silica gel (n-hexane/ethyl
acetate, 1:2) to afford 32 mg (69%) of compound 41 as a white solid;
mp 122–123 °C (recrystallized from n-hexane/ethyl acetate), lit.39
4.1.27. (4S)-3-Benzyl-4-[(1′S,2′R,3′Z)-1′,2′-bis(benzyloxy)hexadec-
3′-en-1′-yl]oxazolidin-2-one (39)
IBX (0.11 g, 0.40 mmol) was added to a solution of 38 (88 mg,
0.30 mmol) in acetonitrile (1.0 mL), and the resulting mixture was
stirred at reflux. After 30 min, the insoluble parts were removed by
filtration, the solvent was evaporated in vacuo, and the residue was
immediately used in the next reaction without further purification.
To a solution of 1,1,1,3,3,3-hexamethyldisilazane (0.12 mL,
0.56 mmol) in dry THF (0.58 mL) was added n-BuLi (0.35 mL,
0.56 mmol, a 1.6 M solution in n-hexane) at room temperature. The
solution of hexamethyldisilazide (LHMDS) such generated was
treated with the salt C13H27PPh3Br (0.336 g, 0.64 mmol), and the re-
sulting dark mixture was stirred for 5 min at the same temperature.
Next, a solution of the obtained crude aldehyde (87.6 mg, 0.20 mmol)
in dry THF (0.6 mL) was added. After stirring for 1 h, the mixture
was diluted with EtOAc (10 mL) and poured into a saturated NH4Cl
solution (5 mL). The aqueous phase was washed with further por-
tions of EtOAc (2 × 5 mL). The combined organic layers were dried
over Na2SO4, the solvent was removed in vacuo, and the residue was
chromatographed on silica gel (n-hexane/ethyl acetate, 7:1) to give
23
mp = 118–120 °C for ent-41; {[α]D +7.9 (c 0.24, MeOH), lit.39
[α]D25 = −5.0 (c 0.22, MeOH) for ent-41}. IR υmax 3288, 2956, 2915,
2848, 1737, 1724, 1688, 1470, 1418, 1076, 1014 cm−1 1H NMR
;
(400 MHz, CD3OD): δ 0.88 (t, 3H, J = 6.7 Hz, CH3), 1.09–1.57 (m, 25H,
H-3′, 12 × CH2), 1.61–1.69 (m, 1H, H-3′), 3.39 (m, 2H, H-1′, H-2′), 4.07–
4.11 (m, 1H, H-4), 4.35–4.39 (m, 1H, H-5), 4.44 (dd, 1H, J = 8.6 Hz,
J = 6.0 Hz, H-5); 13C NMR (100 MHz, CD3OD): δ 14.5 (CH3), 23.8 (CH2),
26.7 (CH2), 30.5 (CH2), 30.8 (7 × CH2), 30.9 (CH2), 33.1 (CH2), 34.8 (C-
3′), 55.5 (C-4), 67.3 (C-5), 73.7 (C-2′), 75.7 (C-1′), 162.8 (C=O). Anal.
calcd for C19H37NO4: C, 66.43; H, 10.86; N, 4.08. Found: C, 66.51; H,
10.90; N, 4.12.
4.1.30. (2R,3S,4S)-4-Amino-2-tetradecyltetrahydrofuran-3-ol
hydrochloride (4.HCl)
23
86 mg (71%) of a waxy compound 39; [α]D −73.1 (c 0.36, CHCl3).
IR υmax 2919, 2850, 1736, 1478, 1453, 1435, 1421, 1364, 1259, 1201,
1177, 1089, 1067, 1047, 1027 cm−1; 1H NMR (400 MHz, CDCl3): δ 0.88
(t, 3H, J = 6.4 Hz, CH3), 1.26–1.32 (m, 20H, 10 × CH2), 1.84–1.96 (m,
2H, 2 × H-5′), 3.50–3.51 (m, 1H, H-1′), 3.58 (d, 1H, J = 15.2 Hz,
NCH2Ph), 3.79 (dd, 1H, J = 9.3 Hz, J = 6.2 Hz, H-4), 4.10 (t, 1H,
J = 9.1 Hz, H-5), 4.21–4.26 (m, 2H, H-2′, OCH2Ph), 4.31 (d, 1H,
J = 12.0 Hz, OCH2Ph), 4.51 (d, 1H, J = 12.1 Hz, OCH2Ph), 4.55–4.58 (m,
2H, OCH2Ph, NCH2Ph), 4.61–4.65 (m, 1H, H-5), 5.12–5.17 (m, 1H,
H-3′), 5.61 (dt, J = 10.7 Hz, J = 7.6 Hz, J = 7.6 Hz, H-4′), 7.14–7.37 (m,
15H, Ph); 13C NMR (100 MHz, CDCl3): δ 14.1 (CH3), 22.6 (CH2), 27.9
(C-5′), 29.3 (2 × CH2), 29.5 (2 × CH2), 29.6 (4 × CH2), 31.9 (CH2), 45.9
(NCH2Ph), 55.1 (C-4), 63.2 (C-5), 70.3 (OCH2Ph), 72.2 (OCH2Ph), 73.6
(C-2′), 76.4 (C-1′), 126.7 (C-3′), 127.5 (2 × CHPh), 127.6 (CHPh), 127.8
(CHPh), 127.9 (CHPh), 128.1 (2 × CHPh), 128.3 (2 × CHPh), 128.4 (4 × CHPh),
128.6 (2 × CHPh), 135.8 (Ci), 135.9 (C-4′), 137.6 (Ci), 137.9 (Ci), 158.8
Compound 41 (29 mg, 0.08 mmol) was treated with a 6 M
aqueous HCl solution (3.8 mL), and the resulting mixture was stirred
and heated at 120 °C for 2.5 h. After cooling to room temperature,
the solvent was evaporated in vacuo, and the residue was diluted
with Et2O. The solid part was filtered off and dried on a pump for
10 h. This procedure yielded 25 mg (89%) of compound 4.HCl as a
26
white amorphous solid {[α]D = +25.0 (c 0.16, MeOH), lit.36
{[α]D21 = +15.5 (c 0.9, MeOH), lit.39 [α]D22 = −29.6 (c 0.48, MeOH) for
ent-4.HCl}. IR υmax 3297, 3057, 2915, 2849, 2360, 2341, 1583, 1505,
1469, 1051, 1022 cm−1 1H NMR (600 MHz, CD3OD): δ 0.89 (t, 3H,
;
J = 6.9 Hz, CH3), 1.28–1.39 (m, 23H, 11 × CH2, H-CH), 1.44–1.54 (m,
2H, H-1′, H-CH), 1.59–1.65 (m, 1H, H-1′), 3.68–3.75 (m, 3H, H-2, H-4,
H-5), 4.02–4.04 (m, 1H, H-3), 4.12–4.16 (m, 1H, H-5); 13C NMR
(CD3OD, 150 MHz): δ 14.5 (CH3), 23.8 (CH2), 26.9 (CH2), 30.5 (CH2),
30.7 (3 × CH2), 30.8 (5 × CH2), 33.1 (CH2), 34.1 (C-1′), 53.7 (C-4), 69.4
(C-5), 74.4 (C-3), 85.2 (C-2). Anal. calcd for C18H38ClNO2: C, 64.35;
H, 11.40; N, 4.17. Found: C, 64.40; H, 11.45; N, 4.20.
(C=O). Anal. calcd for C40H53NO4: C, 78.52; H, 8.73; N, 2.29. Found:
C, 78.63; H, 8.80; N, 2.34.
4.1.28. (4S)-3-Benzyl-4-[(1′S,2′R)-1′,2′-
dihydroxyhexadecyl]oxazolidin-2-one (40)
4.1.31. (2R,3S,4S)-4-Acetamido-2-tetradecyltetrahydrofuran-3-yl
acetate (42)
A solution of 39 (102 mg, 0.17 mmol) in dry EtOH (13 mL) was
treated with 10% Pd/C (17.5 mg), and the resulting suspension was
stirred at room temperature under an atmosphere of hydrogen. After
3 h, the catalyst was filtered through a small pad of Celite, the fil-
trate was concentrated, and the residue was subjected to flash
chromatography on silica gel (n-hexane/ethyl acetate, 1:1) to give
64 mg (89%) of compound 40 in the form of white crystals; mp 130–
To a solution of 4.HCl (20 mg, 0.06 mmol) in pyridine (1.8 mL)
were successively added Ac2O (0.11 mL, 1.2 mmol) and DMAP (3.7 mg,
0.03 mmol), and the resulting mixture was stirred at room tem-
perature for 1 h before evaporating of the solvent. The residue was
subjected to flash chromatography on silica gel (n-hexane/ethyl
acetate, 1:2) to furnish 17 mg (75%) of compound 42 as white

E. Mezeiová et al./Carbohydrate Research 423 (2016) 70–81
81
crystals; mp 75–76 °C (recrystallized from n-hexane/ethyl acetate),
Appendix: Supplementary material
lit.23 mp 72–73 °C, lit.32 mp not reported, lit.36 mp 65–67 °C, lit.39 mp
27
75–76 °C for ent-42 {[α]D −13.3 (c 0.18, CHCl3, lit.23 [α]D22 = −15.4
Supplementary data to this article can be found online at
doi:10.1016/j.carres.2016.01.011.
(c 1.0, CHCl3), lit.32 [α]D26 = −15.1 (c 1.2, CHCl3), lit.36 [α]D21 = −14.6 (c
0.5, CHCl3), lit.39 [α]D24 = +17.7 (c 0.13, CHCl3) for ent-42}. IR υmax 3290,
2914, 2846, 2362, 2342, 1733, 1650, 1563, 1459, 1375, 1300, 1231,
1104, 1086 cm−1; 1H NMR (400 MHz, CDCl3): δ 0.88 (t, 3H, J = 6.7 Hz,
CH3), 1.25–1.45 (m, 24H, 12 × CH2), 1.49–1.67 (m, 2H, 2 × H-1′), 2.01
(s, 3H, CH3), 2.13 (s, 3H, CH3), 3.52 (t, 1H, J = 8.6 Hz, J = 8.6 Hz, H-5),
3.86 (ddd, 1H, J = 7.8 Hz, J = 5.4 Hz, J = 2.6 Hz, H-2), 4.16–4.19 (m, 1H,
H-5), 4.62–4.69 (m, 1H, H-4), 4.91 (dd, 1H, J = 5.9 Hz, J = 2.6 Hz, H-3),
5.65 (br d, 1H, J = 8.3 Hz, NH); 13C NMR (100 MHz, CDCl3): δ 14.1
(CH3), 21.0 (CH3), 22.7 (CH3), 23.3 (CH2), 25.5 (CH2), 29.3 (CH2), 29.4
(CH2), 29.5 (CH2), 29.6 (4 × CH2), 29.7 (2 × CH2), 31.9 (CH2), 33.5 (C-
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Acknowledgements
The present work was supported by the Grant Agency (Grant No.
1/0168/15 and No. 1/0398/14) of the Ministry of Education, Slovak
Republic. It was also supported by the Slovak Research and Devel-
opment Agency (Grant No. APVV-14-0883) and by the project
MediPark Košice: 26220220185 supported by Operational Pro-
gramme Research and Development (OP VaV-2012/2.2/08-RO,
contract No. OPVaV/12/2013). We thank Dr. Mária Vilková (P.J. Šafárik
University, Košice) for her assistance in NOE experiments.
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