Chemical Synthesis of Modified Hyaluronic Acid Disaccharides

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Accepted Article

Title: Chemical Synthesis of Modified Hyaluronic Acid Disaccharides

Authors: Marco Mende, Martin Nieger, and Stefan Bräse

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To be cited as: Chem. Eur. J. 10.1002/chem.201701238

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Chemical Synthesis of Modified Hyaluronic Acid Disaccharides

Marco Mende,^[a]Martin Nieger,^[b]and Stefan Bräse*^{[a, c]}

Abstract: Herein a chemical synthesis towards new modified

hyaluronic acid oligomers for structure-related biological activity tests

using only commercially available D-glucose and D-glucosamine

hydrochloride is reported. The syntheses of various protected

hyaluronic acid disaccharides bearing new functional groups at the

C-6-position of the former β-D-glucuronic acid moiety are described.

The orthogonal protecting group pattern creates a readily access to

polyelectrolyte nature of hyaluronic acid polymers induce the

unique viscoelastic properties^[5]and the ability to absorb huge

amounts of water.^[6]The biosynthesis takes place at the inner

side of the cell membrane operated by three membranous

hyaluronic acid synthase enzymes (HAS1, HAS2 or HAS3). The

polysaccharide is released into the extracellular matrix, where it

represents one of its major components. The biosynthesis

requires uridine diphosphate glucuronic acid (UDP-GlcA) and

uridine diphosphate N-acetylglucosamine (UDP-GlcNAc).^[7]

Besides its moisturizing effects^[5a]and lubrication of tissue in

joints,^[8]hyaluronic acid is also involved in essential biological

processes like cell migration, proliferation, adhesion and

recognition^[9]as well as in tumor progression.^[10]

1

the appropriate higher oligomers. Also H NMR studies of the new

derivatives are displayed, showing the effect of the group

replacement on the intramolecular electronic environment.

Introduction

There are two common cell surface receptors which interact

with hyaluronic acid molecules. These are called CD44 and

RHAMM (Receptor for Hyaluronic Acid Mediated-Motility).^[11]The

chain length of the polysaccharide plays a crucial role for the

resulting effect, especially small hyaluronic acid oligomers,

emerging due to hyaluronidase (HYAL) activity, possess an

extraordinary high biological activity. For example high

molecular weight hyaluronic acid molecules suppress

angiogenesis, while small fragments stimulate the same process.

There are many more examples for such opposing impacts

depending on the chain length.^[12]Moreover, it is well known that

small hyaluronic acid fragments are participating in inflammation

procedures and tumor metastasis by interaction with the

mentioned receptors.^[13]This issue generates an attractive

starting point for structural chemical modifications of hyaluronic

acid molecules to investigate changes of the biological activities

or the generation of new properties due to a change of the

secondary-/tertiary structure and the polyelectrolyte behavior.

Many chemical syntheses towards native hyaluronic acid

oligomers are known in literature. There are plenty of chemical

preparations starting from unprotected monosaccharide building

blocks,^[14]semi-chemical methods using isolated precursors^[15]

and some solid-phase approaches.^[16]Concerning modifications

of sugar molecules, there are many reactions for various

monosaccharides and also some other oligomers but referring to

hyaluronic acid disaccharides and its higher oligomers there is a

huge lack of procedures.

Hyaluronic acid, first isolated from the vitreous humor of a cow,^[1]

is a linear polysaccharide and member of the glycosamino-

glycans, which occurs ubiquitously in all vertebrates. Its

molecular weight can reach values up to 10⁷Da. The

polysaccharide itself consists of a disaccharide repeating unit

composed of β-D-glucuronic acid (GlcA) and N-acetyl-β-D-

glucosamine (GlcNAc) with the following structure motif:

[(β1→4)-GlcA-(β1→3)-GlcNAc-]_n(Figure 1).^[2]

Figure 1. General chemical structure of a single native hyaluronic acid

polymer chain in solution with its twisted backbone.^[3]

Due to different types of hydrogen bonds, the polysaccharide

is able to form very complex secondary and tertiary structures in

solution.^[4]This structural order in combination with the

Based on the preliminary work by Virlouvet et al.^[14e]we now

report the syntheses of several protected hyaluronic acid

disaccharides bearing new functional groups at the C-6-position

of the former β-D-glucuronic acid moiety (Table 1). Applying our

established orthogonal protecting group pattern, we also created

a readily access towards higher hyaluronic acid oligomers with

chemical modifications. Additionally the impact of the functional

group variation on the intramolecular electronic environment is

depicted through ¹H NMR studies.

[a]

M. Mende, Prof. Dr. S. Bräse

Karlsruhe Institute of Technology, Institute of Organic Chemistry

Fritz-Haber-Weg 6, 76131 Karlsruhe (Germany)

phone: +49 721 608-42902, fax: +49 721 608-48581

e-mail: braese@kit.edu

[b]

[c]

Dr. M. Nieger

Department of Chemistry

University of Helsinki, P. O. Box 55, 00014 University of Helsinki (Finland)

Prof. Dr. S. Bräse

Karlsruhe Institute of Technology, Institute of Toxicology and Genetics

Hermann-von-Helmholtz-Platz 1

76344 Eggenstein-Leopoldshafen (Germany)

Supporting information for this article is available on the WWW under

http://dx.doi.org/10.1002/chem.2017xxxxx.

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With these three building blocks in hand, studies were

performed to figure out the most effective compound for the

installation of new groups to the anomeric center with high

stereoselectivity under various conditions. The results are

depicted in Table 2.

Table 1. Leitmotif of the hyaluronic acid disaccharide derivatives and

naming.

For the preparation of the β-allyl protected glucose 5 three

methods were tested, all of them using allyl alcohol as the

nucleophile. The highest yield (64%) was achieved starting from

α-bromide 4 using indium(III) chloride as activator,^[14e]while

under the same conditions the α-iodide 2 gave a yield of 22%.

A direct glycosylation reaction of the peracetylated D-glucose (3)

under BF₃∙ OEt₂activation led to a yield of 4.8%, revealing that

glucose derivatives compared to the appropriate mannosides

are not suitable for such transformations.^[18]

Thioethers are very convenient compounds for glycosylation

strategies, because a thioether group connected to the anomeric

center can serve both as a temporary protecting group and as

an activatable group for glycosylations. Thus we synthesized the

two β-thioethers 6 and 7 utilizing different conditions.

Suffix

X

Suffix

X

Suffix

X

a

b

c

d

e

f

CH₂H

g

h

i

CH₂SAc

CH₂F

CH₂Cl

CH₂Br

CH₂I

m

n

o

p

q

CHNOH

COOH

COOMe

CN

CH₂N₃

CH₂OH

CH₂OAc

CH₂OTs

CH₂OPMB

j

k

l

Tetrazole

CHO

PMB = p-methoxybenzyl

Table 2. Preparation of various β-donor building block precursors for the

syntheses of hyaluronic acid derivatives.

Entry

Sub-

strate

Conditions

Product

Yield^[a]

[%]

Results and Discussion

Donor building block syntheses

AllylOH,

InCl₃, 4 Å MS,

CH₂Cl₂, r.t.,

5 d

1

2

4^[b]

2^[b]

64^[c]

22^[d]

For the syntheses of the new orthogonally protected, modified

hyaluronic acid disaccharides 37a–37q (Table 4) we prepared

three new donor building blocks (21f, 22f, 24, Scheme 2), each

of which showed its advantages and disadvantages during the

reaction sequence and the subsequent glycosylation procedure.

Commercially available D-glucose (1) was used as the starting

compound for each reaction sequence. First of all, the

peracetylated α-D-glucopyranosyl iodide (2) was prepared using

a one-pot method reported by Valerio et al.^[17]Also the

peracetylated α-D-glucopyranosyl bromide (4) was provided

AllylOH,

BF₃∙ OEt₂,

4 Å MS,

CH₂Cl₂,

0 °C → r.t.,

24 h

3

3^[b]

5

4.8

PhSH,

TBAHS,

1.5 M Na₂CO₃,

EtOAc, r.t.,

2 d

4

5

4^[b]

86^[c]

applying

a

two-step procedure. In this approach the

peracetylated D-glucose (3) was prepared in 95% yield as a 5:1

mixture of the anomers.^[17]In the next step, the α-bromide 4 was

obtained by general α-bromination of sugar molecules shown by

Virlouvet et al. (Scheme 1).^[14e]

PhSH,

BF₃∙ OEt₂,

CH₂Cl₂,

3^[b]

6

15

0 °C → r.t.,

18 h

Thiourea, EtI,

NEt₃, MeCN,

r.t., 17 h

6

7

2^[b]

4^[b]

87^[d]

57^[c]

EtSH,

TBAHS,

1.5 M Na₂CO₃,

EtOAc, r.t.,

1 h

8

4^[b]

7

traces

[a] Isolated yield. [b] Crude starting material was used. [c] Yield over

three steps. [d] Yield over two steps. MS = molecular sieves,

TBAHS = tetrabutylammonium hydrogen sulfate.

Scheme 1. Syntheses of α-glycosyl halides starting from commercially

available D-glucose (1). a i. I₂, Ac₂O, r.t., 1 h; ii. I₂, Et₃SiH, CH₂Cl₂, 40 °C, 1 h;

b I₂, Ac₂O, r.t., 1 h, 92%, α/β 5:1; c 33% HBr in AcOH, CH₂Cl₂, 0 °C → r.t.,

16 h.

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Scheme 2. Syntheses of the three different orthogonal protected β-D-glucoside building blocks 21f, 22f and 24 for the preparation of modified hyaluronic acid

derivatives. a 25% NH₃aq., MeOH, r.t., 18 h, 99% 8, 96% 9, 94% 10; b p-methoxybenzaldehyde dimethyl acetal, p-TsOH, MeCN, 40 °C, 3 h, 62% 11, 95% 12,

71% 13; c Ac₂O, DMAP, CH₂Cl₂, r.t., 1 h, 93% 14, 99% 15, 83% 16; d NaBH₃CN, TFA, 4 Å MS, DMF, 0 °C → r.t., 3 d, 88% 17, 57% 18, 94% 19; e levulinic acid,

DIC, DMAP, CH₂Cl₂0 °C → r.t., 15 h, 99% 20f, 98% 21f, 79% 22f; f Pd(OAc)₂, NaOAc, AcOH, H₂O, r.t., 20 h, 70% (for R = OAllyl); g NBS, CH₂Cl₂, H₂O, r.t., 1.5 h

(for R = SEt) or 15 h (for R = SPh); h Cl₃CCN, DBU, CH₂Cl₂, 0 °C, 2 h, 57% (starting from R = OAllyl), 11% (over two steps, starting from R = SPh), 35%

(over two steps, starting from R = SEt). PMB = p-methoxybenzyl, Lev = levulinoyl, p-TsOH = p-toluenesulfonic acid, DMAP = 4-dimethylaminopyridine,

TFA = trifluoroacetic acid, MS = molecular sieves, DMF = N,N-dimethylformamide, DIC = N,N’-diisopropylcarbodiimide, NBS = N-bromosuccinimide,

DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene.

A very useful method for the preparation of phenyl thioether 6 in

high stereoselectivity starting from α-bromide 4 was published

by Desai et al. using basic conditions and phase-transfer

catalysis.^[19]An adoption of this reaction to the synthesis of ethyl

thioether 7 led to traces of the desired product. The acidity of

ethanethiol (pK_a= 10.54) compared to thiophenol (pK_a= 6.52)

might not be high enough and additionally the solubility of both

reagents in the depicted solvent system is too different.^[20]With a

moderate yield of 15% a direct glycosylation reaction of the

peracetylated D-glucose (3) succeeded under BF₃∙ OEt₂

activation using thiophenol as the nucleophile. The highest yield

(87%) for the preparation of ethyl thioether 7 with good

stereoselectivity and purity was achieved using the two-step

procedure by Valerio et al. utilizing α-iodide 2 as the starting

material. Transferring this procedure to the α-bromide 4 the yield

slightly decreased (57%) while the product still showed high

stereoselectivity and extremely high purity.

acetic anhydride and DMAP (4-dimethylaminopyridine) as a

catalyst. Regioselective reductive opening of the formed acetals

14, 15 and 16 to the corresponding alcohols 17, 18 and 19 was

realized with sodium cyanoborohydride and TFA (trifluoroacetic

acid) in dry DMF (N,N-dimethylformamide) to expose only the

free hydroxy group in C-4-position and to create simultaneously

the p-methoxybenzyl ether (PMB) in C-6-position. The last

hydroxy group was then furnished with a levulinoyl protecting

group via esterification reaction of levulinic acid applying

Steglich conditions. Thus the preparations of the β-thioether

donor building blocks 21f and 22f were finished. For the

synthesis of the trichloroacetimidate building block 24 two more

steps were required. The first step was the palladium(II)-induced

cleavage of the allyl group on molecule 20f followed by the

base-catalyzed reaction of the hemiacetal 23 with trichloro-

acetonitrile to yield the final trichloroacetimidate building block

24. Both steps were performed in moderate yields. It was also

possible to generate the trichloroacetimidate building block 24

from the β-thioethers 21f and 22f in two-step procedures, but

with lower yields.

To synthesize the desired orthogonal protected donor building

blocks 21f, 22f and 24

a sequence of protection and

deprotection steps based on our preliminary work^[14e]was

performed, starting from the β-allyl protected glucose 5 or

alternatively from the β-thioether 6 or 7 (Scheme 2). The first five

steps of the sequence were the same for each starting

compound and were accomplished in good to excellent overall

yields (36–50%). First of all the esters were cleaved using

aqueous ammonia to yield the alcohols 8, 9 and 10. Then the

hydroxy groups in C-4- and C-6-position were selectively

protected as an acetal forming an energetic favorable 1,3-di-

oxane heterocycle through treatment with p-methoxybenz-

aldehyde dimethyl acetal under acid catalysis to provide the

diols 11,12 and 13. The two remaining hydroxy groups were

protected with acetyl groups via an esterification reaction using

With an overall yield of 42% phenyl thioether 21f showed the

most efficient reaction sequence, while ethyl thioether 22f

reached 36%, followed by the trichloroacetimidate 24 with 13%

however including also two more reaction steps. Besides the two

additional steps and the lowest overall yield, the large-scale

synthesis of the trichloroacetimidate 24 also needed expensive

palladium(II) acetate for the deprotection of the allyl protection

group. One advantage of this approach is that strongly odorous

sulfur compounds were not needed. Furthermore the donor

building blocks 21f and 24 have the advantage of being solid

compounds which makes them easier to handle for the

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Selective oxidative removal of the p-methoxybenzyl ether (PMB)

group succeeded in a good yield (72%) using ceric ammonium

nitrate (CAN), providing disaccharide 37c for subsequent

modification reactions.^[14e]

subsequent reactions, compared to ethyl thioether 22f which is a

viscous oil.

All three donor building blocks 21f, 22f and 24 bear an

orthogonal protecting group pattern, necessary for the synthesis

of our new hyaluronic acid derivatives. A selective access to the

hydroxy groups in C-4- and C-6-position is required since the

one in C-4-position is needed to build up the β(1→4)-glycosidic

bond for the oligomer elongation steps and the one in

C-6-position is required for the modification reactions. The

remaining hydroxy groups were protected with acetyl groups.

Acceptor building block synthesis

Our selected acceptor building block 36 for the preparation of

the modified hyaluronic acid disaccharides 37a–37q was

adopted from preliminary work of Virlouvet et al.^[14e]This building

block also possesses an orthogonal protecting group pattern

necessary for the desired hyaluronic acid derivative reactions.

The allyl protection group can be removed selectively by

conversion with palladium(II) acetate also in the presence of the

protecting groups at the donor building blocks. This is important,

because the C-1’-position of the acceptor moiety in combination

with the C-4-position of the donor building block moiety is

needed to build up the β(1→4)-glycosidic bond for the

oligomerization reactions. In addition the other protecting groups

(acetyl, benzyl and trichloroacetamide) are very stable under

many conditions and therefore eminently suitable for further

transformations.

Scheme 3. Synthesis of the orthogonal protected disaccharide repeating unit

37c for modification reactions and elongation steps. a NIS, AgOTf, 4 Å MS,

CH₂Cl₂, –30 °C, 3 h, 79% (for R = β-SEt); b i. TMSOTf, 4 Å MS, CH₂Cl₂, 0 °C,

2 h; ii. NEt₃, 32% (for R = α-OTCA); c CAN, MeCN, H₂O, r.t., 1 h, 72%.

TCA = trichloroacetimidate,

PMB = p-methoxybenzyl,

Lev = levulinoyl,

Bn = benzyl, NIS = N-iodosuccinimide, TfO = triflate, MS = molecular sieves,

TMS = trimethylsilyl, CAN = ceric ammonium nitrate.

Model system synthesis

For test reaction purposes we synthesized a monosaccharide

model system, which bears all functional groups that are also

located on the protected disaccharide 37c, except for the benzyl

group. Therefore, we wanted to explore the stability of our

protecting group pattern during further modification reactions.

For an exact identification of the new compounds we further

Glycosylation reactions

Utilizing the building blocks displayed in the upper sections, the

synthesis of the fully protected disaccharide repeating unit 37f

with the essential orthogonal protecting group pattern as well as

the selective deprotection step of the p-methoxybenzyl ether

(PMB) group, revealing an access towards modification

reactions, is shown in Scheme 3. The highest yield (79%) for the

glycosylation reaction was achieved with the ethyl thioether

donor building block 22f using an assembly of N-iodo-

succinimide (NIS) and silver(I) triflate as the activation reagent

for the thioether. Connection of the phenyl thioether donor

building block 21f to the acceptor building block 36 was not

successful under the same conditions. Furthermore, other

common glycosylation procedures, especially concerning the

toleration towards the used protecting groups, did not succeed.

However, the glycosylation of the trichloroacetimidate 24 with

our acceptor building block 36 applying trimethylsilyl triflate

(TMSOTf) as an activator gave a moderate yield (32%). Both

performed glycosylations provided the requested β(1→3)-glyco-

sidic bond in a very high stereoselectivity triggered through the

neighboring group effect of the acetyl group in C-2-position. The

fully protected disaccharide repeating unit 37f can be taken as a

key intermediate towards its higher oligomers, because of the

selective access to the hydroxy groups (C-4- and C-1’-position)

required for the formation of the β(1→4)-glycosidic bonds.

1

aimed at the receipt of clear H NMR spectra with a minimum

amount of overlapping signals (like in the case of disaccharides).

The synthesis of our model system 41c, which can be easily

realized in excellent yields even on a multi-gram scale, is a

combination of the syntheses of the acceptor and donor building

block from the preliminary work of Virlouvet et al. starting from

commercially available D-glucosamine hydrochloride (25)

(Scheme 4).^[14e]The first six steps for the preparation of triol 31

were synthesized according to literature.^[14e]The next four steps

are similar to the reaction sequence for the donor building blocks

shown above, meaning selective acetal formation of the hydroxy

groups in C-4- and C-6-position forming alcohol 38 followed by

acetylation of the remaining hydroxy group in C-3-position

leading to acetal 39. Then regioselective reductive opening of

the acetal protecting group to form alcohol 40 and esterification

reaction of the last hydroxy group in C-4-position using levulinic

acid to get the fully protected glucosamine 41f. After

deprotection of the p-methoxybenzyl ether (PMB) group using

ceric ammonium nitrate (CAN), the free hydroxy group in C-6-

position was exposed, providing the primary alcohol 41c

(Scheme 4) for subsequent modification reactions.

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performed in very good yields by preparing first the acyl

chlorides in situ followed by conversion with methanol as

nucleophile (Entry 23–24). The acyl chlorides represent very

interesting intermediates, as they generate a versatile access to

a wide range of other adducts. Starting from the crude

aldehydes 41l and 37l the oximes 41m and 37m were

synthesized effectively as

a mixture of their trans- and

cis-isomers with distinct excess of the trans-formation

a

(Entry 19–20). Subsequent dehydration of these compounds

using phosphoryl chloride led to the respective nitriles 41p and

37p in good yields (Entry 21–22). These nitriles were

successfully converted to the tetrazoles 41q and 37q in good

yields by 1,3-dipolar cycloaddition using TMS-azide as

1,3-dipole (Entry 29–30).

Scheme 4. Synthesis of the model system 41c for modification reactions.

a p-methoxybenzaldehyde dimethyl acetal, p-TsOH, MeCN, 40 °C, 5 h, 82%;

b Ac₂O, DMAP, CH₂Cl₂, r.t., 1.5 h, 95%; c NaBH₃CN, TFA, 4 Å MS, DMF,

0 °C → r.t., 5 d, 96%; d levulinic acid, DIC, DMAP, CH₂Cl₂0 °C → r.t., 3 d,

The already modified thioether donor building block 22a was

synthesized for the preparation of the 6-deoxy-disaccharide 37a

in very good yields over three steps starting from the ethyl

thioether 22f. The first step was the deprotection of the

p-methoxybenzyl ether (PMB) group followed by bromination of

the corresponding alcohol 22c via Appel reaction^[21]to the

bromide 22j and subsequent radical cleavage of the bromine

atom leading to the 6-deoxy-β-D-glucose derivative 22a. The

glycosylation reaction of this donor building block 22a with our

acceptor building block 36 to 6-deoxy-disaccharide 37a gave a

yield of 33% (Scheme 5). In this case the modification reaction

was done before the glycosylation, because of the radical

cleavage of the bromine atom in the third step which could also

demerge the chlorine atoms of the trichloroacetyl group on the

D-glucosamine moiety.

98%;

e CAN, MeCN, H₂O, r.t., 1 h, 95%. PMB = p-methoxybenzyl,

Lev = levulinoyl, p-TsOH = p-toluenesulfonic acid, DMAP = 4-dimethylamino-

pyridine, TFA = trifluoroacetic acid, MS = molecular sieves, DMF = N,N-di-

methylformamide, DIC = N,N’-diisopropylcarbodiimide, CAN = ceric ammoni-

um nitrate.

Modification reactions

Model system 41c can be taken as a good surrogate for the

disaccharide 37c, because their protecting group patterns are

similar. To verify the stability of the protecting groups, we

performed all desired modification reactions primarily on our

model system and then transferred them to the respective

disaccharide. Table 3 shows the results of our studies.

We were able to synthesize the four common halides (F, Cl,

Br, I) (Entry 1–8) in good yields starting from the primary alcohol

41c respectively 37c via Appel reactions^[21]or by nucleophilic

substitutions. Due to an esterification reaction using acetic

anhydride and catalytic amounts of DMAP (4-dimethylamino-

pyridine) the acetylated compounds 41d and 37d were

synthesized in very good yields, utilizing the primary alcohols

41c and 37c (Entry 9–10). An activation of the primary alcohol

41c or 37c through the installation of a tosyl group under basic

conditions for subsequent modifications was also possible in

good yields (Entry 11–12). The tosylates 41e and 37e were then

converted successfully to the thioacetates 41g and 37g

(Entry 25–26) and to the azides 41b and 37b (Entry 27–28) in

very good yields by nucleophilic substitutions in a polar solvent

at elevated temperature. A mild direct oxidation of the primary

alcohol to the carboxylic acid 41n or 37n was also realized in

very high yields using a hypervalent iodine reagent^[22](Entry 15–

16). Furthermore, a stepwise oxidation first preparing the

aldehyde 41l or 37l with Dess-Martin periodinane^[23](Entry 13–

14) followed by a Pinnick Oxidation to the corresponding

carboxylic acid 41n or 37n (Entry 17–18) was feasible.^[24]

Moreover, esterification reactions of the carboxylic acid 41n or

37n to the appropriate methyl glucuronates 41o or 37o were

Scheme 5. Synthesis of the protected hyaluronic acid disaccharide derivative

37a bearing a methyl group at the C-5-position of the glucose moiety. a CAN,

MeCN, H₂O, r.t., 2 h, 87%; b CBr₄, PPh₃, pyridine, 0 °C → r.t., 16 h, 83%;

c Bu₃SnH, AIBN, toluene, 130 °C, 5 h, 78%; d 36, NIS, TMSOTf, 4 Å MS,

CH₂Cl₂, –30 °C, 1.5 h, 33%. Lev = levulinoyl, PMB = p-methoxybenzyl,

Bn = benzyl, CAN = ceric ammonium nitrate, AIBN = azobisisobutyronitrile,

NIS = N-iodosuccinimide, TfO = triflate, MS = molecular sieves, TMS = tri-

methylsilyl.

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Table 3. Modification reactions of the synthesized model system and the appropriate protected hyaluronic acid disaccharide derivative.

Entry

Substrate

Conditions

Product

Yield^[a][%]

1

2

41c

37c

R¹= CH₂OH

R³= CH₂OH

41h

37h

R²= CH₂F

R⁴= CH₂F

23

59

DAST, CH₂Cl₂, r.t., 2 h

3

4

41c

37c

R¹= CH₂OH

R³= CH₂OH

41i

37i

R²= CH₂Cl

R⁴= CH₂Cl

83

65

CCl₄, PPh₃, pyridine, r.t., 2 d

CBr₄, PPh₃, pyridine, 0 °C → r.t., 16 h

I₂, imidazole, PPh₃, toluene, r.t., 7 d

Ac₂O, DMAP, CH₂Cl₂, r.t., 2 h

5

6

41c

37c

R¹= CH₂OH

R³= CH₂OH

41j

37j

R²= CH₂Br

R⁴= CH₂Br

67

68

7

8

41c

37c

R¹= CH₂OH

R³= CH₂OH

41k

37k

R²= CH₂I

R⁴= CH₂I

77

60

9

10

41c

37c

R¹= CH₂OH

R³= CH₂OH

41d

37d

R²= CH₂OAc

R⁴= CH₂OAc

92

87

11

12

41c

37c

R¹= CH₂OH

R³= CH₂OH

41e

37e

R²= CH₂OTs

R⁴= CH₂OTs

91

56

TsCl, pyridine, r.t., 16 h

13

14

41c

37c

R¹= CH₂OH

R³= CH₂OH

41l

37l

R²= CHO

R⁴= CHO

not isolated^[b]

DMP, CH₂Cl₂, r.t., 1 h

15

16

41c

37c

R¹= CH₂OH

R³= CH₂OH

41n

37n

R²= COOH

R⁴= COOH

87

83

BAIB, TEMPO, CH₂Cl₂, H₂O, r.t., 2.5 h

NaClO₂, isoamylene, NaH₂PO₄, MeCN, H₂O, 10 °C → r.t., 17 h

H₂NOH ∙ HCl, Na₂CO₃, THF, H₂O, 0 °C → r.t., 2 h

POCl₃, MeCN, r.t. → 65 °C, 1.5 h

17

18

41l

37l

R¹= CHO

R³= CHO

41n

37n

R²= COOH

R⁴= COOH

73^[c]

61^[c]

19

20

41l

37l

R¹= CHO

R³= CHO

41m

37m

R²= CHNOH

R⁴= CHNOH

43^[c]

45^[c]

21

22

41m

37m

R¹= CHNOH

R³= CHNOH

41p

37p

R²= CN

R⁴= CN

63

40

23

24

41n

37n

R¹= COOH

R³= COOH

41o

37o

R²= COOMe

R⁴= COOMe

71

80

i. oxalyl chloride, DMF, CH₂Cl₂, 0 °C → r.t., 1 h; ii. MeOH, r.t., 2 h

KSAc, DMF, 80 °C, 2 h

25

26

41e

37e

R¹= CH₂OTs

R³= CH₂OTs

41g

37g

R²= CH₂SAc

R⁴= CH₂SAc

94

84

27

28

41e

37e

R¹= CH₂OTs

R³= CH₂OTs

41b

37b

R²= CH₂N₃

R⁴= CH₂N₃

84

78

NaN₃, DMF, 80 °C, 5 h

29

30

41p

37p

R¹= CN

R³= CN

41q

37q

R²= Tetrazole

R⁴= Tetrazole

55

47

TMSN₃, Bu₂SnO, toluene, 120 °C, 5 h

[a] Isolated yield. [b] Further use without purification. [c] Yield over two steps. Lev = levulinoyl, Bn = benzyl, DMAP = 4-dimethylaminopyridine,

TsO = tosylate, DAST = diethylaminosulfur trifluoride, BAIB = (diacetoxyiodo)benzene, TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl,

DMP = Dess-Martin periodinane.

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Table 4. Chemical shifts (in ppm) of the sugar scaffold protons and the amide proton related to the functional group at the C-6-position of the

D-glucose moiety of the protected hyaluronic acid disaccharide derivative. The highlighted values in each column always represent the lowest

and the highest chemical shift of the appropriate proton, representing the impact of the different functional groups on all the protons. 6-H

protons are not shown.^[a–b]

Entry

Disaccharide

NH

1-H

2-H

3-H

4-H

5-H

1’-H

2’-H

3’-H

4’-H

5’-H

6a’-H

6b’-

H

1

37a

37b

37c

37d

37e

37f

R¹= CH₃

6.88

6.92

7.00

7.04

7.01

7.04

6.93

6.86

6.90

6.92

6.94

6.95

7.34

6.98

6.86

8.02

4.55

4.68

4.64

4.63

4.61

4.60

4.62

4.60

4.66

4.68

4.67

4.64

4.75

4.66

4.57

5.13

4.90

4.88

4.91

4.84

4.87

4.92

4.91

4.88

4.94

4.92

4.93

4.95

5.05

5.02

5.09

5.14

5.09

5.03

5.04

5.05

5.09

5.08

5.12

5.15

5.12

5.03

5.36

4.78

4.96

4.91

5.03

4.92

5.04

4.95

5.03

4.99

4.95

4.88

5.05

5.15

5.12

5.28

5.27

3.51

3.58

3.48

3.63

3.67

3.58

3.60

3.66

3.64

3.46

4.02

4.01

3.95

4.29

5.27

4.90

4.83

4.77

4.97

4.76

4.87

4.92

4.87

4.90

4.88

4.84

4.82

4.93

4.86

4.70

3.51

3.68

3.73

3.50

3.67

3.57

3.58

3.60

3.59

3.64

3.70

3.58

3.77

3.54

3.49

4.11

4.38

4.35

4.37

4.46

4.33

4.36

4.38

4.41

4.40

4.39

4.36

4.39

4.43

4.49

4.24

4.90

4.96

4.92

4.97

4.92

4.93

4.97

4.92

4.99

5.02

4.94

4.97

4.99

4.97

4.91

3.73

3.68

3.80

3.68

3.67

3.71

3.70

3.68

3.69

3.66

3.60

3.58

3.65

3.58

3.57

3.58

3.60

3.59

3.58

3.59

3.58

3.59

3.58

3.66

3.57

3.58

3.54

3.57

3.58

3.60

3.59

3.58

3.59

3.58

3.53

3.54

3.55

3.61

2

R¹= CH₂N₃

R¹= CH₂OH

R¹= CH₂OAc

R¹= CH₂OTs

R¹= CH₂OPMB

R¹= CH₂SAc

R¹= CH₂F

3

4

5

6

7

37g

37h

37i

8

9

R¹= CH₂Cl

R¹= CH₂Br

R¹= CH₂I

10

11

12

13

14

15

16

37j

37k

37m

37n

37o

37p

37q

R¹= HCNOH

R¹= COOH

R¹= COOMe

R¹= CN

R¹= Tetrazole

[a] All data were measured at 600 MHz in CDCl₃as solvent using 7.26 ppm as the reference peak. [b] If the peaks of the depicted protons

were located in multiplets, the center of this multiplet was chosen as the appropriate peak for the table. For the exact position of the multiplets

see the experimental section.

NMR studies

anyway due to the different groups connected to this position.

The highlighted values always display the lowest and highest

data.

To explore the impact of the new functional groups on the

structure of our new disaccharide derivatives 37a–37q we took a

closer look on the chemical shifts of all the sugar scaffold

protons and the amide proton to detect changes in the electronic

environment of our molecules. Table 4 shows all the chemical

shifts of these protons, except the protons at C-6-position of the

β-D-glucose moiety, because their chemical shift should vary

Since the free carboxylic acid functionality is also located on

the native hyaluronic acid disaccharide and an important part of

the complex secondary-/tertiary structure, we took disaccharide

37n as our reference for the comparison of the chemical shifts.

The amide proton of the tetrazole functionalized disaccharide

37q showed an extraordinary high chemical shift (8.02 ppm)

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compared to the others, especially to the nitrile 37p (6.85 ppm).

This illustrates that there is an interaction between the amide

proton and the functional group at the C-6-position of the β-D-

glucose moiety even on a “disaccharide scale”. But not only the

amide proton was affected by the modifications, also other

protons showed significant changes in their chemical shifts. For

example the chemical shift of the proton at the anomeric center

of the reducing end (1’H) reached values from 4.70 to 4.97 ppm.

These changes shown in Table 4 reveal that the exchange

reactions have a huge impact on the electronic environment. For

the appropriate higher oligomers this modification could have

interesting influences on the complex structure of hyaluronic

acid oligomers and could lead to attractive compounds.

chromatography using a mixture of cyclohexane/ethyl acetate (1:1) as

eluent. The product 37f was obtained as a yellowish foam in 79% yield

(15.0 g).

Method b: Acceptor 36 (79.2 mg, 160 µmol, 1.00 Equiv.) and donor 24

(120 mg, 191 µmol, 1.20 Equiv.) were dissolved in 10.0 mL of absolute

dichloromethane under argon atmosphere and 4 Å molecular sieve

powder (20 mg) was added. The mixture was stirred for 1 h at room

temperature and then cooled down to 0 °C. Trimethylsilyl trifluoro-

methanesulfonate (7.44 µL, 9.19 mg, 41.1 µmol, 0.257 Equiv.) was

added and the mixture was stirred for 2 h at 0 °C. Triethylamine (52.3 µL,

38.2 mg, 378 µmol, 2.36 Equiv.) was added and the solvent was

removed under reduced pressure. The crude product was purified by

flash chromatography using a mixture of cyclohexane/ethyl acetate (1:1)

as eluent. The product 37f was obtained as a white foam in 32% yield

(48.3 mg).

Conclusions

R_f= 0.33 (cyclohexane/EtOAc 1:1); m.p. 50–63 °C; ¹H NMR (600 MHz,

CDCl₃, 25 °C, TMS): δ = 7.38–7.25 (m, 5H, Ph), 7.25–7.20 (m, 2H, PMP),

7.04 (d, ³J = 7.8 Hz, 1H, NH), 6.88–6.82 (m, 2H, PMP), 5.83 (dddd, ³J_trans

We successfully developed the syntheses of various new

hyaluronic acid disaccharide derivatives bearing a distinct

protecting group pattern for subsequent oligomerizations using

only commercially available D-glucose (Glc) and N-acetyl-D-

glucosamine (GlcNAc). Thereto, we designed a model system

with similar protecting groups to verify their stability for our

modification reactions. The approaches were performed on a

multi-gram scale with good to excellent yields. Based on the

reported ¹H NMR studies we found the electronic environment

within the disaccharides to be affected in a strong way by the

modifications, especially the amide proton, which is an important

part of the complex structure of hyaluronic acid oligomers due to

hydrogen bonding. With the used protecting group pattern

subsequent elongation steps and also deprotection sequences

should succeed in an easy way. On top of this, late stage

modifications are conceivable.

= 16.9 Hz, J_cis= 10.6 Hz, ³J = 6.3 Hz, ³J = 5.4 Hz, 1H, CH₂CH=CH₂),

3

5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.4 Hz, 1H, CH₂CH=CH_cisH_trans),

3

5.17 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.0 Hz, 1H, CH₂CH=CH_cisH_trans),

5.08–5.00 (m, 2H, 3-H, 4-H), 4.93 (t, ³J = 9.2 Hz, 1H, 4‘-H), 4.89–4.84 (m,

3

2

2H, 2-H, 1‘-H), 4.60 (d, J = 7.9 Hz, 1H, 1-H), 4.54 (d, J = 12.1 Hz, 1H,

2

CH_aH_bPh), 4.52 (d, J = 12.1 Hz, 1H, CH_aH_bPh), 4.39 (s, 2H, CH₂PMP),

4.36 (t, ³J = 9.4 Hz, 1H, 3‘-H), 4.32 (ddt, ²J = 12.9 Hz, ³J = 5.2 Hz, ⁴J =

1.3 Hz, 1H, CH_aH_bCH=CH₂), 4.07 (ddt, ²J = 12.9 Hz, ³J = 6.3 Hz, ⁴J = 1.2

Hz, 1H, CH_aH_bCH=CH₂), 3.78 (s, 3H, OCH₃), 3.68–3.65 (m, 1H, 5‘-H),

3.63–3.51 (m, 5H, 5-H, 6a-H, 2‘-H, 6‘-H), 3.47 (dd, ²J = 10.7 Hz, ³J = 5.9

Hz, 1H, 6b-H), 2.66–2.61 (m, 2H, CH₃COCH₂CH₂COO), 2.38–2.34 (m,

2H, CH₃COCH₂CH₂COO), 2.12 (s, 3H, CH₃COCH₂CH₂COO), 2.01 (s, 3H,

CH₃COO), 1.97 (s, 3H, CH₃COO), 1.91 (s, 3H, CH₃COO) ppm; ¹³C NMR

(150 MHz, CDCl₃, 25 °C, TMS): δ = 206.0 (C_q, CH₃COCH₂CH₂COO),

171.2 (C_q, CH₃COCH₂CH₂COO), 170.3 (C_q, CH₃COO), 169.5 (C_q,

CH₃COO), 169.3 (C_q, CH₃COO), 161.7 (C_q, CCl₃CONH), 159.2 (C_q,

C_ArOCH₃), 137.7 (C_q, C_Ar(Ph)), 133.3 (+, CH₂CH=CH₂), 129.6 (C_q, C_Ar

(PMP)), 129.6 (+, 2 × C_ArH (PMP)), 128.3 (+, 2 × C_ArH (Ph)), 127.8 (+, 2

× C_ArH (Ph)), 127.7 (+, C_ArH (Ph)), 118.1 (–, CH₂CH=CH₂), 113.7 (+, 2 ×

C_ArH (PMP)), 99.3 (+, C-1), 98.0 (+, C-1‘), 92.4 (C_q, CCl₃CONH), 76.1 (+,

C-3‘), 73.5 (–, CH₂Ph), 73.4 (+, C-5‘), 73.1 (–, CH₂PMP), 73.0 (+, C-5),

72.8 (+, C-3), 71.3 (+, C-2), 70.2 (–, CH₂CH=CH₂), 69.2 (–, C-6’), 69.0 (+,

C-4), 68.9 (+, C-4‘), 68.4 (–, C-6), 58.0 (+, C-2‘), 55.2 (+, OCH₃), 37.7 (–,

CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.7 (–,

CH₃COCH₂CH₂COO), 20.6 (+, CH₃COO), 20.6 (+, CH₃COO), 20.5 (+,

CH₃COO) ppm; IR (ATR): ̃ = 2870, 1750, 1716, 1612, 1514, 1366, 1218,

1150, 1049, 820, 756, 699, 673, 602, 488 cm^–1; MS (FAB, 3-NBA): m/z

(%): 958/960/962/964 (30/40/18/5) [M–H]⁺, 923/925/927/929 (21/21/6/1),

865/867/869/871 (34/24/9/3), 440 (29), 435 (38), 405 (100); HRMS (FAB,

3-NBA): calcd for C₄₃H₅₃O₁₇N³⁵Cl₃[M+H]⁺: 960.2374; found: 960.2376.

Experimental Section

For information concerning the measurements and working

techniques as well as the analytical data of all the other

compounds please use our supporting information.

Allyl O-(2,3-di-O-acetyl-4-O-levulinoyl-6-O-p-methoxybenzyl-β-D-glucopy-

ranosyl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-

glucopyranoside (37f): Method a: Acceptor 36 (8.54 g, 17.2 mmol,

1.00 Equiv.) and donor 22f (11.4 g, 21.6 mmol, 1.26 Equiv.) were

dissolved in 340 mL of absolute dichloromethane under argon

atmosphere and 4 Å molecular sieve powder (17.4 g) was added. The

mixture was stirred for 1 h at room temperature and then cooled down to

–30 °C. N-Iodosuccinimide (5.80 g, 25.8 mmol, 1.50 Equiv.) and silver

trifluoromethanesulfonate (1.33 g, 5.16 mmol, 0.300 Equiv.) were added

consecutively and the mixture was stirred for 3 h. The mixture was

filtered through a pad of celite and the filtrate was washed with

Allyl

O-(2,3-di-O-acetyl-4-O-levulinoyl-β-D-glucopyranosyl)-(1→3)-4-O-

5% aqueous

Na₂S₂O₃-solution

(200 mL),

saturated

aqueous

acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopyranoside

(37c): PMB protected disaccharide 37f (1.57 g, 1.63 mmol, 1.00 Equiv.)

was dissolved in a mixture of 17.3 mL of acetonitrile and 2.47 mL of

water. Ceric ammonium nitrate (1.79 g, 3.26 mmol, 2.00 Equiv.) was

NaHCO₃-solution (200 mL) and water (200 mL). The organic layer was

separated and dried over Na₂SO₄. The solvent was removed under

reduced pressure and the crude product was purified by flash

10.1002/chem.201701238

Chemistry - A European Journal

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added and the solution was stirred for 1 h at room temperature. The

solution was diluted with dichloromethane (200 mL) and washed with

water (100 mL). The aqueous layer was extracted with dichloromethane

(3 × 100 mL). The organic layers were combined and dried over Na₂SO₄.

The solvent was removed under reduced pressure and the crude product

R_f= 0.63 (cyclohexane/EtOAc 1:2); m.p. 73–81 °C; ¹H NMR (600 MHz,

CDCl₃, 25 °C, TMS): δ = 7.35–7.26 (m, 5H, Ph), 6.86 (d, ³J = 7.7 Hz, 1H,

NH), 5.85 (dddd, ³J_trans= 16.8 Hz, ³J_cis= 10.6 Hz, ³J = 6.2 Hz, ³J = 5.4 Hz,

1H, CH₂CH=CH₂), 5.26 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.3 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.19 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.0 Hz, 1H,

was purified by flash chromatography using

a

mixture of

CH₂CH=CH_cisH_trans), 5.09 (t, ³J = 9.4 Hz, 1H, 3-H), 5.03 (t, ³J = 9.7 Hz, 1H,

4-H), 4.95–4.88 (m, 2H, 2-H, 4‘-H), 4.87 (d, ³J = 8.0 Hz, 1H, 1‘-H), 4.60 (d,

³J = 8.0 Hz, 1H, 1-H), 4.57–4.37 (m, 5H, 6-H, 3‘-H, CH₂Ph), 4.34 (ddt,

²J = 12.8 Hz, ³J = 5.1 Hz, ⁴J = 1.3 Hz, 1H, CH_aH_bCH=CH₂), 4.08 (ddt,

²J = 12.7 Hz, ³J = 6.4 Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 3.73–3.69 (m,

1H, 5‘-H), 3.67–3.53 (m, 4H, 5-H, 2‘-H, 6‘-H), 2.77–2.67 (m, 2H,

CH₃COCH₂CH₂COO), 2.52–2.41 (m, 2H, CH₃COCH₂CH₂COO), 2.15 (s,

3H, CH₃COCH₂CH₂COO), 2.03 (s, 3H, CH₃COO), 2.00 (s, 3H, CH₃COO),

1.97 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃, 25 °C, TMS): δ

= 206.2 (C_q, CH₃COCH₂CH₂COO), 171.3 (C_q, CH₃COCH₂CH₂COO),

170.3 (C_q, CH₃COO), 169.6 (C_q, CH₃COO), 169.1 (C_q, CH₃COO), 161.9

(C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 ×

C_ArH), 127.8 (+, 2 × C_ArH), 127.7 (+, C_ArH), 118.4 (–, CH₂CH=CH₂), 100.2

(+, C-1), 97.7 (+, C-1‘), 92.3 (C_q, CCl₃CONH), 80.7 (–, d, ¹J_C-F= 175.8 Hz,

cyclohexane/ethyl acetate (1:2) as eluent. The product 37c was obtained

as a white solid in 72% yield (991 mg).

R_f= 0.25 (cyclohexane/EtOAc 1:2); m.p. 75–91 °C; ¹H NMR (600 MHz,

CDCl₃, 25 °C, TMS): δ = 7.37–7.23 (m, 5H, Ph), 7.00 (d, ³J = 8.2 Hz, 1H,

NH), 5.83 (dddd, ³J_trans= 16.8 Hz, ³J_cis= 10.5 Hz, ³J = 6.2 Hz, ³J = 5.1 Hz,

3

1H, CH₂CH=CH₂), 5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.6 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.18 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.4 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.14 (t, ³J = 9.5 Hz, 1H, 3-H), 4.96–4.86 (m, 3H, 2-H,

3

4-H, 4‘-H), 4.77 (d, J = 7.6 Hz, 1H, 1‘-H), 4.64 (d, J = 7.9 Hz, 1H, 1-H),

4.56 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.52 (d, ²J = 12.0 Hz, 1H,

CH_aH_bPh), 4.37 (t, ³J = 9.1 Hz, 1H, 3‘-H), 4.32 (ddt, ²J = 13.0 Hz, ³J = 5.1

Hz, ⁴J = 1.4 Hz, 1H, CH_aH_bCH=CH₂), 4.05 (ddt, ²J = 13.0 Hz, ³J = 6.2 Hz,

⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 3.82–3.77 (m, 1H, 5‘-H), 3.77–3.68 (m,

2H, 6a-H, 2’-H), 3.65 (dd, ²J = 10.7 Hz, ³J = 3.6 Hz, 1H, 6a‘-H), 3.61–

3.55 (m, 2H, 6b-H, 6b‘-H), 3.51–3.45 (m, 1H, 5-H), 3.07 (s, 1H, 6-OH),

2.78–2.67 (m, 2H, CH₃COCH₂CH₂COO), 2.53–2.40 (m, 2H,

CH₃COCH₂CH₂COO), 2.16 (s, 3H, CH₃COCH₂CH₂COO), 2.03 (s, 3H,

CH₃COO), 2.02 (s, 3H, CH₃COO), 2.01 (s, 3H, CH₃COO) ppm; ¹³C NMR

(100 MHz, CDCl₃, 25 °C, TMS): δ = 206.4 (C_q, CH₃COCH₂CH₂COO),

172.1 (C_q, CH₃COCH₂CH₂COO), 170.4 (C_q, CH₃COO), 170.2 (C_q,

CH₃COO), 169.5 (C_q, CH₃COO), 161.9 (C_q, CCl₃CONH), 137.7 (C_q, C_Ar),

133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 × C_ArH), 127.8 (+, 2 × C_ArH), 127.7 (+,

C_ArH), 118.0 (–, CH₂CH=CH₂), 99.7 (+, C-1), 98.4 (+, C-1‘), 92.4 (C_q,

CCl₃CONH), 75.6 (+, C-3‘), 74.5 (+, C-5), 73.5 (–, CH₂Ph), 72.8 (+, C-5‘),

72.4 (+, C-3), 71.3 (+, C-2), 70.3 (+, C-4‘), 70.0 (–, CH₂CH=CH₂), 69.1 (–,

C-6’), 69.0 (+, C-4), 61.4 (–, C-6), 57.2 (+, C-2‘), 37.7 (–,

CH₃COCH₂CH₂COO), 29.5 (+, CH₃COCH₂CH₂COO), 27.7 (–,

CH₃COCH₂CH₂COO), 21.0 (+, CH₃COO), 20.6 (+, CH₃COO), 20.6 (+,

CH₃COO) ppm; IR (ATR): ̃ = 2872, 1751, 1714, 1529, 1366, 1216, 1151,

1036, 902, 821, 756, 698, 670, 603, 488 cm^–1; MS (FAB, 3-NBA): m/z

2

C-6), 76.6 (+, C-3‘), 73.5 (–, CH₂Ph), 73.3 (+, C-5), 72.6 (+, d, J_C-F

= 18.9 Hz, C-5‘), 72.5 (+, C-3), 71.1 (+, C-2), 70.2 (–, CH₂CH=CH₂), 69.3

3

(+, C-4‘), 69.1 (–, C-6’), 67.6 (+, d, J_C-F= 6.7 Hz, C-4), 58.5 (+, C-2‘),

37.7 (–, CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.6 (–,

CH₃COCH₂CH₂COO), 20.7 (+, CH₃COO), 20.6 (+, CH₃COO), 20.6 (+,

CH₃COO) ppm; ¹⁹F NMR: (376 MHz, CDCl₃, 25 °C): δ = –123.6 ppm; IR

(ATR): ̃ = 3342, 2869, 1752, 1717, 1527, 1367, 1215, 1148, 1053, 1032,

912, 837, 821, 756, 698, 672, 603, 491, 390 cm^–1; MS (FAB, 3-NBA): m/z

(%):

840/842/844/846

(16/17/10/6)

[M–H]⁺,

784/786/788/790

(100/98/38/11) [M–OAllyl]⁺, 663 (80), 634/636/638/640 (65/72/25/7) [M–

OAllyl–OAc–Bn]⁺, 506 (47); HRMS (FAB, 3-NBA): calcd for

C₃₅H₄₂O₁₅N³⁵Cl₃F [M–H]⁺: 840.1599; found: 840.1602.

Allyl O-(2,3-di-O-acetyl-6-chloro-6-deoxy-4-O-levulinoyl-β-D-glucopyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glu-

copyranoside (37i): Alcohol 37c (110 mg, 131 µmol, 1.00 Equiv.) was

dissolved in 5.00 mL of dry pyridine under argon atmosphere. Triphenyl-

phosphane (77.2 mg, 294 µmol, 2.25 Equiv.) and tetrachloromethane

(127 µL, 201 mg, 1.31 mmol, 10.0 Equiv.) were added consecutively. The

solution was stirred for 2 d at room temperature. After that, 1.00 mL of

methanol was added and the stirring was continued for further 30 min.

The solvent was removed under reduced pressure and the crude product

(%):

862/864/866/868

(53/54/22/2)

[M+Na]⁺,

838/840/842/844

(38/52/27/6) [M–H]⁺, 782/784/786/788 (96/100/35/2) [M–OAllyl]⁺; HRMS

(FAB, 3-NBA): calcd for C₃₅H₄₅O₁₆N³⁵Cl₃[M+H]⁺: 840.1798; found:

840.1795.

was purified by flash chromatography using

a

mixture of

cyclohexane/ethyl acetate (1:2) as eluent. The product 37i was obtained

Allyl O-(2,3-di-O-acetyl-6-deoxy-6-fluoro-4-O-levulinoyl-β-D-glucopyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloro-acetamido-β-D-glu-

copyranoside (37h): Alcohol 37c (164 mg, 195 µmol,1.00 Equiv.) was

dissolved in 10.0 mL of absolute dichloromethane under argon

atmosphere and (diethylamino)sulfur trifluoride (49.5 µL, 60.3 mg,

374 µmol, 1.92 Equiv.) was added. The solution was stirred for 2 h at

room temperature and washed with saturated aqueous NaHCO₃-solution

(100 mL). The organic layer was separated and dried over Na₂SO₄. The

solvent was removed under reduced pressure and the crude product was

purified by flash chromatography using a mixture of cyclohexane/ethyl

acetate (1:2) as eluent. The product 37h was obtained as a white solid in

59% yield (98.8 mg).

as a white solid in 65% yield (73.0 mg).

R_f= 0.67 (cyclohexane/EtOAc 1:2); m.p. 65–85 °C (decomposition); ¹H

NMR (500 MHz, CDCl₃, 25 °C, TMS): δ = 7.36–7.26 (m, 5H, Ph), 6.91 (d,

3

³J = 7.7 Hz, 1H, NH), 5.84 (dddd, J_trans= 16.9 Hz, J_cis= 10.4 Hz,

³J = 6.3 Hz, J = 5.3 Hz, 1H, CH₂CH=CH₂), 5.26 (dq, J_trans= 17.2 Hz, J

and ⁴J = 1.5 Hz, 1H, CH₂CH=CH_cisH_trans), 5.19 (dq, ³J_cis= 10.4 Hz, ²J and

⁴J = 1.3 Hz, 1H, CH₂CH=CH_cisH_trans), 5.09 (t, ³J = 9.4 Hz, 1H, 3-H), 5.03–

4.96 (m, 2H, 4-H, 4‘-H), 4.91 (dd, ³J = 9.5 Hz, ³J = 8.0 Hz, 1H, 2-H), 4.89

(d, ³J = 7.9 Hz, 1H, 1‘-H), 4.65 (d, ³J = 8.0 Hz, 1H, 1-H), 4.55 (d, ²J =

12.0 Hz, 1H, CH_aH_bPh), 4.52 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.40 (t, ³J =

9.3 Hz, 1H, 3‘-H), 4.34 (ddt, ²J = 12.8 Hz, ³J = 5.2 Hz, ⁴J = 1.3 Hz, 1H,

CH_aH_bCH=CH₂), 4.07 (ddt, ²J = 12.8 Hz, ³J = 6.4 Hz, ⁴J = 1.1 Hz, 1H,

3

2

10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

CH_aH_bCH=CH₂), 3.74–3.63 (m, 3H, 5-H, 6a-H, 5‘-H), 3.62–3.54 (m, 3H,

C_ArH), 127.9 (+, 2 × C_ArH), 127.7 (+, C_ArH), 118.2 (–, CH₂CH=CH₂), 99.5

(+, C-1), 97.8 (+, C-1‘), 92.3 (C_q, CCl₃CONH), 76.4 (+, C-3‘), 73.5 (–,

CH₂Ph), 73.4 (+, CH), 73.4 (+, CH), 72.3 (+, C-3), 71.1 (+, C-2), 70.7 (+,

C-4), 70.2 (–, CH₂CH=CH₂), 69.1 (–, C-6’), 68.8 (+, C-4‘), 58.1 (+, C-2‘),

2

3

2’-H, 6‘-H), 3.50 (dd, J = 12.1 Hz, J = 6.6 Hz, 1H, 6b-H), 2.76–2.69 (m,

2H, CH₃COCH₂CH₂COO), 2.53–2.40 (m, 2H, CH₃COCH₂CH₂COO), 2.16

(s, 3H, CH₃COCH₂CH₂COO), 2.03 (s, 3H, CH₃COO), 2.00 (s, 3H,

CH₃COO), 1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃,

37.7

(–,

CH₃COCH₂CH₂COO),

30.6

(–,

C-6),

29.6

(+,

25 °C, TMS):

δ

=

206.1 (C_q, CH₃COCH₂CH₂COO), 171.4 (C_q,

CH₃COCH₂CH₂COO), 27.7 (–, CH₃COCH₂CH₂COO), 20.9 (+, CH₃COO),

20.6 (+, CH₃COO), 20.5 (+, CH₃COO) ppm; IR (ATR): ̃ = 3341, 2869,

1751, 1716, 1526, 1422, 1367, 1215, 1147, 1049, 902, 821, 756, 698,

672, 602, 540, 484 cm^–1; MS (MALDI, matrix: DHB/CHCA 1:1): m/z:

924/926/928/930 [M+Na]⁺; HRMS (FAB, 3-NBA): calcd for

C₃₅H₄₄O₁₅N⁷⁹Br³⁵Cl₃[M+H]⁺: 902.0954; found: 902.0954.

CH₃COCH₂CH₂COO), 170.3 (C_q, CH₃COO), 169.5 (C_q, CH₃COO), 169.1

(C_q, CH₃COO), 161.8 (C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+,

CH₂CH=CH₂), 128.4 (+, 2 × C_ArH), 127.9 (+, 2 × C_ArH), 127.7 (+, C_ArH),

118.3 (–, CH₂CH=CH₂), 99.7 (+, C-1), 97.7 (+, C-1‘), 92.3 (C_q,

CCl₃CONH), 76.5 (+, C-3‘), 73.6 (–, CH₂Ph), 73.6 (+, CH), 73.4 (+, CH),

72.5 (+, C-3), 71.2 (+, C-2), 70.3 (–, CH₂CH=CH₂), 69.7 (+, C-4), 69.2 (–,

C-6’), 68.9 (+, C-4‘), 58.4 (+, C-2‘), 43.0 (–, C-6), 37.7 (–,

CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.7 (–,

CH₃COCH₂CH₂COO), 20.8 (+, CH₃COO), 20.7 (+, CH₃COO), 20.6 (+,

CH₃COO) ppm; IR (ATR): ̃ = 2922, 2854, 1752, 1716, 1526, 1367, 1216,

1148, 1049, 821, 756, 671, 603, 488 cm^–1; MS (FAB, 3-NBA): m/z (%):

880/882/884/886 (11/17/9/2) [M+Na]⁺, 856/858/860/862 (11/16/9/3) [M–

H]⁺, 800/802/804/806 (73/100/54/14) [M–OAllyl]⁺, 650/652/654/656

(38/47/23/6) [M–OAllyl–OAc–Bn]⁺; HRMS (FAB, 3-NBA): calcd for

C₃₅H₄₄O₁₅N³⁵Cl₄[M+H]⁺: 858.1460; found: 858.1457.

Allyl O-(2,3-di-O-acetyl-6-deoxy-6-iodo-4-O-levulinoyl-β-D-glucopyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glu-

copyranoside (37k): Alcohol 37c (209 mg, 248 µmol, 1.00 Equiv.) was

dissolved in 24.0 mL of absolute toluene under argon atmosphere and

triphenylphosphane (104 mg, 397 µmol, 1.60 Equiv.), imidazole (53.5 g,

786 µmol, 3.17 Equiv.) and iodine (126 mg, 497 µmol, 2.00 Equiv.) were

added consecutively. The mixture was stirred for 7 d at room temperature.

After that, the mixture was diluted with ethyl acetate (50 mL) and all the

solids were filtered off. The filtrate was washed with saturated aqueous

Na₂S₂O₃-solution (50 mL) and saturated aqueous NaHCO₃-solution

(50 mL). The organic layer was separated and dried over Na₂SO₄. The

solvent was removed under reduced pressure and the crude product was

purified by flash chromatography using a mixture of cyclohexane/ethyl

acetate (1:1) as eluent. The product 37k was obtained as a white solid in

60% yield (142 mg).

Allyl O-(2,3-di-O-acetyl-6-bromo-6-deoxy-4-O-levulinoyl-β-D-glucopyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glu-

copyranoside (37j): Alcohol 37c (508 mg, 604 µmol, 1.00 Equiv.) was

dissolved in 20.0 mL of dry pyridine under argon atmosphere and cooled

down to 0 °C. Triphenylphosphane (317 mg, 1.21 mmol, 2.00 Equiv.) and

tetrabromomethane (204 mg, 616 µmol, 1.02 Equiv.) were added

consecutively. The solution was slowly warmed up to room temperature

and stirred overnight (ca. 16 h). After that, 1.00 mL of methanol was

added and the stirring was continued for further 1 h. The solvent was

removed under reduced pressure and the crude product was purified by

flash chromatography using a mixture of cyclohexane/ethyl acetate (1:2)

as eluent. The product 37j was obtained as a white foam in 68% yield

(370 mg).

R_f= 0.44 (cyclohexane/EtOAc 1:1); m.p. 60–75 °C (decomposition); ¹H

NMR (600 MHz, CDCl₃, 25 °C, TMS): δ = 7.37–7.26 (m, 5H, Ph), 6.94 (d,

3

³J = 7.9 Hz, 1H, NH), 5.84 (dddd, J_trans= 16.9 Hz, J_cis= 10.5 Hz,

³J = 6.3 Hz, J = 5.3 Hz, 1H, CH₂CH=CH₂), 5.26 (dq, J_trans= 17.2 Hz, J

and ⁴J = 1.4 Hz, 1H, CH₂CH=CH_cisH_trans), 5.18 (dq, ³J_cis= 10.4 Hz, ²J and

⁴J = 1.2 Hz, 1H, CH₂CH=CH_cisH_trans), 5.08 (t, ³J = 9.5 Hz, 1H, 3-H), 5.02 (t,

³J = 9.0 Hz, 1H, 4‘-H), 4.92–4.83 (m, 3H, 2-H, 4-H, 1‘-H), 4.67 (d, ³J = 8.0

Hz, 1H, 1-H), 4.56 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.52 (d, ²J = 12.0 Hz,

1H, CH_aH_bPh), 4.39 (t, ³J = 9.2 Hz, 1H, 3‘-H), 4.34 (ddt, ²J = 12.9 Hz, ³J =

5.1 Hz, ⁴J = 1.3 Hz, 1H, CH_aH_bCH=CH₂), 4.07 (ddt, ²J = 12.9 Hz, ³J = 6.3

Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 3.73–3.66 (m, 2H, 2‘-H, 5‘-H),

3

2

R_f= 0.69 (cyclohexane/EtOAc 1:2); m.p. 77–86 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS): δ = 7.36–7.25 (m, 5H, Ph), 6.97 (d, ³J = 7.8 Hz, 1H,

NH), 5.83 (dddd, ³J_trans= 15.7 Hz, ³J_cis= 10.5 Hz, ³J = 6.2 Hz, ³J = 5.3 Hz,

1H, CH₂CH=CH₂), 5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.5 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.18 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.1 Hz, 1H,

3

2

3.62–3.56 (m, 2H, 6‘-H), 3.49–3.43 (m, 1H, 5-H), 3.39 (dd, J = 11.1 Hz,

3

³J = 2.4 Hz, 1H, 6a-H), 3.05 (dd, ²J = 11.1 Hz, ³J = 8.6 Hz, 1H, 6b-H),

2.78–2.68 (m, 2H, CH₃COCH₂CH₂COO), 2.49 (ddd, ²J = 17.2 Hz, ³J =

7.3 Hz, ³J = 5.2 Hz, 1H, CH₃COCH₂CH_aH_bCOO), 2.44 (ddd, ²J = 17.3 Hz,

³J = 6.6 Hz, ³J = 5.4 Hz, 1H, CH₃COCH₂CH_aH_bCOO), 2.16 (s, 3H,

CH₃COCH₂CH₂COO), 2.03 (s, 3H, CH₃COO), 2.02 (s, 3H, CH₃COO),

1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR (150 MHz, CDCl₃, 25 °C, TMS): δ

= 206.1 (C_q, CH₃COCH₂CH₂COO), 171.5 (C_q, CH₃COCH₂CH₂COO),

170.2 (C_q, CH₃COO), 169.5 (C_q, CH₃COO), 169.2 (C_q, CH₃COO), 161.7

(C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂), 128.4 (+, 2 ×

C_ArH), 127.9 (+, 2 × C_ArH), 127.7 (+, C_ArH), 118.2 (–, CH₂CH=CH₂), 99.4

(+, C-1), 97.8 (+, C-1‘), 92.4 (C_q, CCl₃CONH), 76.2 (+, C-3‘), 73.8 (+, C-

5), 73.6 (–, CH₂Ph), 73.8 (+, C-5‘), 72.1 (+, C-3), 72.0 (+, C-2), 71.4 (+,

C-4), 70.2 (–, CH₂CH=CH₂), 69.2 (–, C-6’), 68.7 (+, C-4‘), 58.0 (+, C-2‘),

37.7 (–, CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.7 (–,

CH₃COCH₂CH₂COO), 21.6 (+, CH₃COO), 20.6 (+, CH₃COO), 20.6 (+,

CH₃COO), 2.89 (–, C-6) ppm; IR (ATR): ̃ = 3345, 2920, 1751, 1717,

CH₂CH=CH_cisH_trans), 5.08 (t, ³J = 9.5 Hz, 1H, 3-H), 4.99 (t, ³J = 9.1 Hz, 1H,

4‘-H), 4.94 (t, ³J = 9.6 Hz, 1H, 4-H), 4.91 (dd, ³J = 9.6 Hz, ³J = 8.1 Hz, 1H,

3

2-H), 4.88 (d, J = 7.9 Hz, 1H, 1‘-H), 4.66 (d, J = 8.0 Hz, 1H, 1-H), 4.55

(d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.51 (d, ²J = 11.9 Hz, 1H, CH_aH_bPh),

4.38 (t, ³J = 9.4 Hz, 1H, 3‘-H), 4.33 (ddt, ²J = 12.9 Hz, ³J = 5.1 Hz, ⁴J =

1.4 Hz, 1H, CH_aH_bCH=CH₂), 4.07 (ddt, ²J = 12.9 Hz, ³J = 6.3 Hz, ⁴J = 1.2

Hz, 1H, CH_aH_bCH=CH₂), 3.68 (ddd, ³J = 9.8 Hz, ³J = 6.5 Hz, ³J = 3.8 Hz,

1H, 5‘-H), 3.66–3.61 (m, 2H, 5-H, 2‘-H), 3.60–3.53 (m, 3H, 6a-H, 6‘-H),

3.30 (dd, ²J = 11.5 Hz, ³J = 7.4 Hz, 1H, 6b-H), 2.78–2.67 (m, 2H,

CH₃COCH₂CH₂COO), 2.52–2.40 (m, 2H, CH₃COCH₂CH₂COO), 2.15 (s,

3H, CH₃COCH₂CH₂COO), 2.02 (s, 3H, CH₃COO), 2.01 (s, 3H, CH₃COO),

1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR (150 MHz, CDCl₃, 25 °C, TMS): δ

= 206.2 (C_q, CH₃COCH₂CH₂COO), 171.4 (C_q, CH₃COCH₂CH₂COO),

170.2 (C_q, CH₃COO), 169.5 (C_q, CH₃COO), 169.2 (C_q, CH₃COO), 161.8

(C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 ×

10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

1526, 1420, 1367, 1217, 1146, 1048, 903, 820, 756, 698, 670, 601, 481,

dissolved in 10.0 mL of dry pyridine under argon atmosphere and cooled

down to 0 °C. p-Toluenesulfonyl chloride (74.1 mg, 389 µmol,

1.50 Equiv.) was added. The solution was stirred overnight (ca. 16 h) at

room temperature. The solvent was removed under reduced pressure

and the crude product was dissolved in 70 mL of dichloromethane and

washed with saturated aqueous NaHCO₃-solution (50 mL). The organic

layer was separated and dried over Na₂SO₄. The solvent was removed

under reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (1:2) as

eluent. The product 37e was obtained as a white solid in 56% yield

(144 mg).

436, 397 cm^–1

;

MS (MALDI, matrix: DHB/CHCA 1:1): m/z:

972/974/976/978 [M+Na]⁺.

Allyl O-(2,3,6-tri-O-acetyl-4-O-levulinoyl-β-D-glucopyranosyl)-(1→3)-4-O-

acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopyranoside

(37d): Alcohol 37c (136 mg, 162 µmol, 1.00 Equiv.) was dissolved in 10.0

mL of absolute dichloromethane under argon atmosphere and acetic

anhydride (21.6 µL, 23.1 mg, 226 µmol, 1.40 Equiv.) and DMAP (3.96 mg,

32.4 µmol, 0.200 Equiv.) were added consecutively. The solution was

stirred for 1.5 h at room temperature. The solution was washed with

saturated aqueous NaHCO3-solution (30 mL). The organic layer was

separated and dried over Na2SO4. The solvent was removed under

reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (1:2) as

eluent. The product 37d was obtained as a white solid in 87% yield

(124 mg).

R_f= 0.66 (cyclohexane/EtOAc 1:2); m.p. 71–78 °C; ¹H NMR (600 MHz,

CDCl₃, 25 °C, TMS): δ = 7.80–7.72 (m, 2H, Ts), 7.38–7.26 (m, 7H, Ph,

3

Ts), 7.01 (d, ³J = 8.2 Hz, 1H, NH), 5.83 (dddd, J_trans= 16.8 Hz, J_cis

=

10.7 Hz, ³J = 6.1 Hz, ³J

=

5.5 Hz, 1H, CH₂CH=CH₂), 5.26 (dq,

³J_trans= 17.2 Hz, ²J and ⁴J = 1.3 Hz, 1H, CH₂CH=CH_cisH_trans), 5.17 (dq,

4

³J_cis= 10.4 Hz, ²J and J = 1.0 Hz, 1H, CH₂CH=CH_cisH_trans), 5.03 (t, ³J =

9.5 Hz, 1H, 3-H), 4.95–4.88 (m, 2H, 4-H, 4‘-H), 4.84 (dd, ³J = 9.4 Hz, ³J =

8.1 Hz, 1H, 2-H), 4.76 (d, ³J = 8.0 Hz, 1H, 1‘-H), 4.61 (d, ³J = 7.9 Hz, 1H,

1-H), 4.54 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.51 (d, ²J = 12.0 Hz, 1H,

CH_aH_bPh), 4.36–4.30 (m, 2H, 3‘-H, CH_aH_bCH=CH₂), 4.17 (dd, ²J = 11.2

Hz, ³J = 2.0 Hz, 1H, 6a-H), 4.11 (dd, ²J = 11.2 Hz, ³J = 5.7 Hz, 1H, 6b-H),

4.06 (ddt, ²J = 12.9 Hz, ³J = 6.3 Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂),

3.72–3.62 (m, 3H, 5-H, 2‘-H, 5‘-H), 3.57 (dd, ²J = 10.9 Hz, ³J = 3.1 Hz,

1H, 6a‘-H), 3.54 (dd, ²J = 10.9 Hz, ³J = 5.7 Hz, 1H, 6b‘-H), 2.73 (ddd,

R_f= 0.44 (cyclohexane/EtOAc 2:3); m.p. 56–63 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS): δ = 7.36–7.26 (m, 5H, Ph), 7.04 (d, ³J = 7.4 Hz, 1H,

NH), 5.83 (dddd, ³J_trans= 16.9 Hz, ³J_cis= 10.5 Hz, ³J = 6.2 Hz, ³J = 5.7 Hz,

1H, CH₂CH=CH₂), 5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.4 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.18 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.0 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.09 (t, ³J = 9.4 Hz, 1H, 3-H), 5.03 (t, ³J = 9.6 Hz, 1H,

4-H), 5.00–4.94 (m, 2H, 1’-H, 4‘-H), 4.91 (dd, ³J = 9.3 Hz, ³J = 8.1 Hz, 1H,

2-H), 4.63 (d, ³J = 8.0 Hz, 1H, 1-H), 4.55 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh),

4.51 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.46 (t, ³J = 9.6 Hz, 1H, 3’-H), 4.33

(ddt, ²J = 12.7 Hz, ³J = 5.3 Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 4.22 (dd,

²J = 12.4 Hz, ³J = 5.3 Hz, 1H, 6a-H), 4.12 (dd, ²J = 12.4 Hz, ³J = 2.0 Hz,

1H, 6b-H), 4.07 (ddt, ²J = 12.7 Hz, ³J = 6.4 Hz, ⁴J = 1.2 Hz, 1H,

²J = 18.5 Hz, J = 7.1 Hz, J = 5.6 Hz, 1H, CH₃COCH_aH_bCH₂COO), 2.66

(ddd, ²J = 18.5 Hz, ³J = 7.1 Hz, ³J = 6.9 Hz, 1H, CH₃COCH_aH_bCH₂COO),

2.44 (s, 3H, ArCH₃), 2.45–2.34 (m, 2H, CH₃COCH₂CH₂COO), 2.14 (s, 3H,

CH₃COCH₂CH₂COO), 2.01 (s, 3H, CH₃COO), 1.97 (s, 3H, CH₃COO),

1.87 (s, 3H, CH₃COO) ppm; ¹³C NMR (150 MHz, CDCl₃, 25 °C, TMS): δ

= 206.0 (C_q, CH₃COCH₂CH₂COO), 171.2 (C_q, CH₃COCH₂CH₂COO),

170.2 (C_q, CH₃COO), 169.5 (C_q, CH₃COO), 169.2 (C_q, CH₃COO), 161.8

(C_q, CCl₃CONH), 145.3 (C_q, C_ArSO₃), 137.7 (C_q, C_Ar(Ph)), 133.2 (+,

CH₂CH=CH₂), 132.5 (C_q, C_ArCH₃), 129.9 (+, 2 × C_ArH (Ts)), 128.3 (+, 2 ×

C_ArH (Ph)), 128.0 (+, 2 × C_ArH (Ts)), 127.8 (+, 2 × C_ArH (Ph)), 127.7 (+,

C_ArH (Ph)), 118.1 (–, CH₂CH=CH₂), 99.8 (+, C-1), 98.1 (+, C-1‘), 92.4 (C_q,

CCl₃CONH), 76.2 (+, C-3‘), 73.5 (–, CH₂Ph), 73.4 (+, C-5‘), 72.3 (+, C-3),

71.7 (+, C-5), 71.0 (+, C-2), 70.1 (–, CH₂CH=CH₂), 69.2 (–, C-6’), 69.0 (+,

C-4‘), 68.2 (+, C-4), 67.0 (–, C-6), 57.9 (+, C-2‘), 37.6 (–,

CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.6 (–,

CH₃COCH₂CH₂COO), 21.7 (+, ArCH₃), 20.7 (+, CH₃COO), 20.6 (+,

CH₃COO), 20.5 (+, CH₃COO) ppm; IR (ATR): ̃ = 3347, 2871, 1753,

1717, 1597, 1526, 1365, 1216, 1190, 1175, 1146, 1053, 993, 940, 819,

757, 698, 669, 602, 552, 491, 395 cm^–1; MS (FAB, 3-NBA): m/z (%):

992/994/996/998 (10/11/5/1) [M–H]⁺, 936/938/940/942 (100/95/56/9) [M–

OAllyl]⁺; HRMS (FAB, 3-NBA): calcd for C₄₂H₄₉O₁₈N³⁵Cl₃³²S [M–H]⁺:

992.1730; found: 992.1731.

3

2

3

CH_aH_bCH=CH₂), 3.70–3.61 (m, 2H, 5-H, 5‘-H), 3.58 (dd, J = 10.8 Hz, J

= 3.1 Hz, 1H, 6a’-H), 3.54 (dd, ²J = 10.8 Hz, ³J = 5.5 Hz, 1H, 6b’-H), 3.50

(dt, ³J = 10.1 Hz, ³J = 7.8 Hz, 1H, 2’-H), 2.73 (ddd, ²J = 18.5 Hz, ³J = 7.1

3

2

3

Hz, J = 5.7 Hz, 1H, CH₃COCH_aH_bCH₂COO), 2.66 (ddd, J = 18.6 Hz, J

= 6.7 Hz, ³J = 5.3 Hz, 1H, CH₃COCH_aH_bCH₂COO), 2.51–2.40 (m, 2H,

CH₃COCH₂CH₂COO), 2.14 (s, 3H, CH₃COCH₂CH₂COO), 2.06 (s, 3H,

CH₃COO), 2.02 (s, 3H, CH₃COO), 2.00 (s, 3H, CH₃COO), 1.93 (s, 3H,

CH₃COO) ppm; ¹³C NMR (150 MHz, CDCl₃, 25 °C, TMS): δ = 205.9 (C_q,

CH₃COCH₂CH₂COO), 171.3 (C_q, CH₃COCH₂CH₂COO), 170.5 (C_q,

CH₃COO), 170.3 (C_q, CH₃COO), 169.4 (C_q, CH₃COO), 169.1 (C_q,

CH₃COO), 161.9 (C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+,

CH₂CH=CH₂), 128.4 (+, 2 × C_ArH), 127.9 (+, 2 × C_ArH), 127.7 (+, C_ArH),

118.4 (–, CH₂CH=CH₂), 99.3 (+, C-1), 97.6 (+, C-1‘), 92.3 (C_q,

CCl₃CONH), 76.1 (+, C-3‘), 73.6 (–, CH₂Ph), 73.3 (+, C-5‘), 72.5 (+, C-3),

71.9 (+, C-5), 71.2 (+, C-2), 70.4 (–, CH₂CH=CH₂), 69.1 (–, C-6’), 68.8 (+,

C-4‘), 68.1 (+, C-4), 61.9 (–, C-6), 58.5 (+, C-2‘), 37.6 (–,

CH₃COCH₂CH₂COO), 29.6 (+, CH₃COCH₂CH₂COO), 27.7 (–,

CH₃COCH₂CH₂COO), 20.7 (+, CH₃COO), 20.6 (+, CH₃COO), 20.6 (+,

CH₃COO), 20.6 (+, CH₃COO) ppm; IR (ATR): ̃ = 3334, 2924, 1746,

1716, 1526, 1365, 1216, 1146, 1034, 901, 837, 821, 756, 699, 675, 601,

Allyl O-(2,3-di-O-acetyl-4-O-levulinoyl-β-D-gluco-hexodialdo-1,5-pyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glu-

copyranoside (37l): Alcohol 37c (484 mg, 575 µmol, 1.00 Equiv.) was

dissolved in 25 mL of dichloromethane and Dess-Martin-periodinane

(488 mg, 1.15 mmol, 2.00 Equiv.) was added. The mixture was stirred for

3 h at room temperature, diluted with dichloromethane (20 mL) and then

filtered through a pad of celite. The filtrate was washed with 5% aqueous

489, 429, 381 cm^–1

904/906/908/910 [M+Na]⁺.

; MS (MALDI, matrix: DHB/CHCA 1:1): m/z:

Allyl

O-(2,3-di-O-acetyl-4-O-levulinoyl-6-O-tosyl-β-D-glucopyranosyl)-

(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopy-

ranoside (37e): Alcohol 37c (218 mg, 259 µmol, 1.00 Equiv.) was

10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

Na₂S₂O₃-solution (100 mL), saturated aqueous NaHCO₃-solution

(100 mL) and water (100 mL). The organic layer was separated and dried

over Na₂SO₄. The solvent was removed under reduced pressure and the

crude product of 37l was used for the subsequent reactions without

further purifications.

1), 98.5 (+, C-1‘), 92.5 (C_q, CCl₃CONH), 76.8 (+, C-3‘), 73.5 (–, CH₂Ph),

73.1 (+, C-5‘), 72.1 (+, CH), 72.0 (+, CH), 70.8 (+, C-2), 70.1 (–,

CH₂CH=CH₂), 69.3 (+, C-4), 69.1 (+, C-4‘), 69.0 (–, C-6’), 57.7 (+, C-2‘),

37.7 (–, CH₃COCH₂CH₂COO), 29.7 (+, CH₃COCH₂CH₂COO), 27.8 (–,

CH₃COCH₂CH₂COO), 20.8 (+, CH₃COO), 20.6 (+, CH₃COO), 20.6 (+,

CH₃COO) ppm; IR (ATR): ̃ = 2941, 1750, 1717, 1523, 1367, 1216, 1147,

1042, 821, 756, 698, 671, 602, 490 cm^–1; MS (FAB, 3-NBA): m/z (%):

876/878/880 (95/100/44) [M+Na]⁺, 852/854/856/858 (20/28/17/2) [M–H]⁺,

796/798/800/802 (67/71/28/4) [M–OAllyl]⁺; HRMS (FAB, 3-NBA): calcd

for C₃₅H₄₃O₁₇N³⁵Cl₃[M+H]⁺: 854.1591; found: 854.1593.

Allyl O-(2,3-di-O-acetyl-4-O-levulinoyl-β-D-glucopyranuronosyl)-(1→3)-4-

O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopyranoside

(37n): Method a: Alcohol 37c (130 mg, 155 µmol, 1.00 Equiv.) was

dissolved in 15.0 mL of a mixture of dichloromethane/water (2:1).

(2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (5.09 mg, 32.6 µmol, 0.210 Equiv.)

and (diacetoxyiodo)benzene (124 mg, 386 µmol, 2.50 Equiv.) were

added and the solution was stirred for 5 h at room temperature. The

reaction was quenched with saturated aqueous Na₂S₂O₃-solution

(10 mL) and washed with saturated aqueous NaCl-solution (50 mL). The

organic layer was separated and dried over Na₂SO₄. The solvent was

removed under reduced pressure and the crude product was purified by

flash chromatography using a mixture of ethyl acetate combined with

6% glacial acetic acid as eluent. The product 37n was obtained as a

white solid in 83% yield (109 mg).

Allyl O-(2,3-di-O-acetyl-4-O-levulinoyl-β-D-gluco-hexodialdo-1,5-pyrano-

syl oxime)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-

D-glucopyranoside (37m): Aldehyde 37l (crude product) (1.21 g,

1.44 mmol, 1.00 Equiv.) was dissolved in 100 mL of tetrahydrofuran and

a

solution of hydroxylamine hydrochloride (100 mg, 1.44 mmol,

1.00 Equiv.) dissolved in 2.90 mL of water was added dropwise. The

mixture was cooled down to 0 °C and a solution of sodium carbonate

(183 mg, 1.73 mmol, 1.20 Equiv.) dissolved in 1.73 mL of water was

added dropwise. The solution was slowly warmed up to room

temperature and stirred for 3 h. The mixture was diluted with water

(100 mL) and then extracted with ethyl acetate (3 × 150 mL). The organic

layers were combined and dried over Na₂SO₄. The solvent was removed

under reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (2:3) as

eluent. The product 37m was obtained as a white solid in 45% yield

(550 mg) as a 33:1 mixture of the trans/cis-isomers.

Method b: Aldehyde 37l (crude product) (1.44 g, 1.72 mmol, 1.00 Equiv.)

was dissolved in 80.0 mL of a mixture of acetonitrile/water (5:2) and

NaH₂PO₄(55.1 mg, 459 µmol, 0.267 Equiv.) and 2-methyl-2-butene

(250 µL, 169 mg, 2.41 mmol, 1.40 Equiv.) were added consecutively. The

mixture was cooled down to 0 °C and a solution of NaClO₂(217 mg,

2.41 mmol, 1.40 Equiv.) dissolved in 1.92 mL of water was added

dropwise. The solution was slowly warmed up to room temperature and

stirred overnight (ca. 18 h). Afterwards, it was extracted with dichloro-

methane (2 × 70 mL). The organic layers were combined and dried over

Na₂SO₄. The solvent was removed under reduced pressure and the

crude product was purified by flash chromatography using a mixture of

ethyl acetate combined with 6% glacial acetic acid as eluent. The product

37n was obtained as white solid in 61% yield (893 mg) over two steps.

R_f= 0.31 (cyclohexane/EtOAc 2:3); m.p. 85–92 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS) data for the trans-isomer: δ = 8.32 (s, 1H, OH),

7.36–7.23 (m, 6H, Ph, HC=N), 7.05 (d, ³J = 8.0 Hz, 1H, NH), 5.83 (dddd,

3

³J_trans= 16.7 Hz, J_cis= 10.5 Hz, ³J = 6.1 Hz, ³J = 5.4 Hz, 1H,

3

CH₂CH=CH₂), 5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.4 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.18 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.2 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.12 (t, ³J = 9.5 Hz, 1H, 3-H), 5.05 (t, ³J = 9.6 Hz, 1H,

4-H), 4.93 (dd, ³J = 9.2 Hz, ³J = 8.2 Hz, 1H, 2-H), 4.92 (t, ³J = 9.1 Hz, 1H,

4‘-H), 4.79 (d, ³J = 8.0 Hz, 1H, 1‘-H), 4.66 (d, J = 7.9 Hz, 1H, 1-H), 4.55

R_f= 0.28 (EtOAc + 6% glacial acetic acid); m.p. 84–103 °C; ¹H NMR (500

3

MHz, CDCl₃, 25 °C, TMS): δ = 7.46 (d, J = 8.2 Hz, 1H, NH), 7.35–7.22

(d, ²J = 12.1 Hz, 1H, CH_aH_bPh), 4.51 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh),

4.37–4.29 (m, 2H, 3‘-H, CH_aH_bCH=CH₂), 4.06 (ddt, ²J = 12.8 Hz, ³J = 6.3

Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 4.02 (dd, ³J = 9.7 Hz, ³J = 6.7 Hz,

3

(m, 5H, Ph), 6.05 (s, 1H, COOH), 5.83 (dddd, J_trans= 16.7 Hz, J_cis

=

10.5 Hz, ³J = 6.1 Hz, ³J

=

5.4 Hz, 1H, CH₂CH=CH₂), 5.25 (dq,

³J_trans= 17.2 Hz, ²J and ⁴J = 1.4 Hz, 1H, CH₂CH=CH_cisH_trans), 5.21–5.09

(m, 3H, 3-H, 4-H, CH₂CH=CH_cisH_trans), 4.97 (t, ³J = 9.2 Hz, 1H, 4‘-H), 4.92

2

3

1H, 5-H), 3.71–3.63 (m, 2H, 2‘-H, 5‘-H), 3.58 (dd, J = 10.9 Hz, J = 3.1

Hz, 1H, 6a‘-H), 3.54 (dd, ²J = 10.9 Hz, ³J = 5.7 Hz, 1H, 6b‘-H), 2.74–2.62

(m, 2H, CH₃COCH₂CH₂COO), 2.52–2.39 (m, 2H, CH₃COCH₂CH₂COO),

2.15 (s, 3H, CH₃COCH₂CH₂COO), 2.04 (s, 3H, CH₃COO), 2.01 (s, 3H,

CH₃COO), 1.92 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃,

3

(t, ³J = 8.5 Hz, 1H, 2-H), 4.79 (d, J = 8.0 Hz, 1H, 1‘-H), 4.75 (d, J = 7.9

Hz, 1H, 1-H), 4.55 (d, ²J = 12.1 Hz, 1H, CH_aH_bPh), 4.50 (d, ²J = 12.0 Hz,

1H, CH_aH_bPh), 4.39 (t, ³J = 9.5 Hz, 1H, 3‘-H), 4.32 (ddt, ²J = 13.0 Hz, ³J =

5.1 Hz, ⁴J = 1.4 Hz, 1H, CH_aH_bCH=CH₂), 4.05 (ddt, ²J = 13.0 Hz, ³J = 6.2

Hz, ⁴J = 1.2 Hz, 1H, CH_aH_bCH=CH₂), 4.01 (d, ³J = 9.5 Hz, 1H, 5-H),

3.81–3.73 (m, 1H, 2‘-H), 3.71–3.64 (m, 1H, 5‘-H), 3.59 (dd, ²J = 10.8 Hz,

25 °C, TMS) data for the trans-isomer:

δ

=

206.8 (C_q,

CH₃COCH₂CH₂COO), 171.4 (C_q, CH₃COCH₂CH₂COO), 170.3 (C_q,

CH₃COO), 169.4 (C_q, CH₃COO), 169.3 (C_q, CH₃COO), 161.9 (C_q,

CCl₃CONH), 146.2 (+, HC=N), 137.7 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂),

128.4 (+, 2 × C_ArH), 127.9 (+, 2 × C_ArH), 127.8 (+, C_ArH), 118.3 (–,

CH₂CH=CH₂), 100.3 (+, C-1), 98.0 (+, C-1‘), 92.4 (C_q, CCl₃CONH), 77.1

(+, C-3‘), 73.6 (–, CH₂Ph), 73.3 (+, C-5‘), 72.0 (+, C-3), 71.8 (+, C-5),

71.1 (+, C-2), 70.2 (–, CH₂CH=CH₂), 69.6 (+, C-4), 69.5 (+, C-4‘), 69.2 (–,

C-6’), 58.1 (+, C-2‘), 37.6 (–, CH₃COCH₂CH₂COO), 29.8 (+,

CH₃COCH₂CH₂COO), 27.7 (–, CH₃COCH₂CH₂COO), 21.0 (+, CH₃COO),

20.7 (+, CH₃COO), 20.6 (+, CH₃COO) ppm; IR (ATR): ̃ = 3336, 2866,

2

3

³J = 2.8 Hz, 1H, 6a‘-H), 3.54 (dd, J = 10.8 Hz, J = 5.4 Hz, 1H, 6b‘-H),

2.73–2.67 (m, 2H, CH₃COCH₂CH₂COO), 2.52–2.44 (m, 2H,

CH₃COCH₂CH₂COO), 2.14 (s, 3H, CH₃COCH₂CH₂COO), 2.05 (s, 3H,

CH₃COO), 2.01 (s, 3H, CH₃COO), 1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR

(125 MHz, CDCl₃, 25 °C, TMS): δ = 207.4 (C_q, CH₃COCH₂CH₂COO),

171.4 (C_q, CH₃COCH₂CH₂COO), 170.3 (C_q, CH₃COO), 170.3 (C_q,

CH₃COO), 169.6 (C_q, CH₃COO), 168.8 (C_q, COOH), 161.9 (C_q,

CCl₃CONH), 137.6 (C_q, C_Ar), 133.3 (+, CH₂CH=CH₂), 128.4 (+, 2 × C_ArH),

127.9 (+, 2 × C_ArH), 127.8 (+, C_ArH), 118.0 (–, CH₂CH=CH₂), 99.6 (+, C-

10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

1750, 1716, 1526, 1367, 1215, 1145, 1032, 955, 820, 739, 698, 601, 490,

403 cm^–1; MS (FAB, 3-NBA): m/z (%): 853/855/857/859 (25/28/11/3)

[M+H]⁺, 795/797/799/801 (50/55/20/5) [M–OAllyl]⁺; 663 (100), 647 (51),

578 (32); HRMS (FAB, 3-NBA): calcd for C₃₅H₄₄O₁₆N₂³⁵Cl₃[M+H]⁺:

853.1751; found: 853.1752.

consecutively. The mixture was heated up to 120 °C and stirred for 5 h.

After that, the mixture was cooled down to room temperature, diluted with

ethyl acetate (50 mL) and washed with an aqueous 0.1 M HCl-solution

(30 mL). The organic layer was dried over Na₂SO₄. The solvent was

removed under reduced pressure and the crude product was purified by

preparative HPLC (5–95% acetonitrile + 0.1% TFA in 30 min, 25 °C, t_Ret

= 27.5 min). After lyophilization the product 37q was obtained as a white

solid in 47% yield (48.2 mg).

Allyl

O-(2,3-di-O-acetyl-4-O-levulinoyl-β-D-glucopyranosylurononitrile)-

(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopy-

ranoside (37p): Oxime 37m (308 mg, 361 µmol, 1.00 Equiv.) was

dissolved in 20.0 mL of dry acetonitrile and phosphoryl chloride (32.9 µL,

55.3 mg, 361 µmol, 1.00 Equiv.) was added at room temperature. The

solution was stirred for 5 min, heated up to 65 °C and then stirred for

1.5 h. The reaction was quenched with saturated aqueous

NaHCO₃-solution and extracted with ethyl acetate (3 × 100 mL). The

organic layers were combined and dried over Na₂SO₄. The solvent was

removed under reduced pressure and the crude product was purified by

flash chromatography using a mixture of cyclohexane/ethyl acetate (1:1)

as eluent. The product 37p was obtained as a light brownish solid in

40% yield (122 mg).

m.p. 100–110 °C; ¹H NMR (600 MHz, CDCl₃, 25 °C, TMS): δ = 8.02 (sbr,

1H, NH), 7.34–7.26 (m, 5H, Ph), 5.86 (dddd, ³J_trans= 16.7 Hz, ³J_cis= 10.7

3

Hz, ³J = 5.9 Hz, J = 5.3 Hz, 1H, CH₂CH=CH₂), 5.36 (t, ³J = 9.3 Hz, 1H,

3-H), 5.30–5.23 (m, 3H, CH₂CH=CH_cisH_trans, 4-H, 5-H), 5.19 (dq,

³J_cis= 10.5 Hz, ²J and ⁴J = 1.2 Hz, 1H, CH₂CH=CH_cisH_trans), 5.13 (d,

³J = 7.9 Hz, 1H, 1-H), 5.05 (t, ³J = 8.6 Hz, 1H, 2-H), 4.91 (t, ³J = 6.8 Hz,

1H, 4’-H), 4.70 (d, ³J = 7.6 Hz, 1H, 1‘-H), 4.56 (d, ²J = 11.9 Hz, 1H,

2

CH_aH_bPh), 4.50 (d, J = 11.9 Hz, 1H, CH_aH_bPh), 4.34 (ddt, J = 13.0 Hz,

³J = 5.0 Hz, ⁴J = 1.4 Hz, 1H, CH_aH_bCH=CH₂), 4.24 (t, ³J = 8.8 Hz, 1H, 3‘-

H), 4.15–4.06 (m, 2H, CH_aH_bCH=CH₂, 2‘-H), 3.68–3.58 (m, 3H, 5’-H, 6’-

H), 2.76 (ddd, ²J = 18.5 Hz, ³J

= = 4.5 Hz, 1H,

8.8 Hz, ³J

CH₃COCH_aH_bCH₂COO), 2.64 (ddd, ²J = 18.5 Hz, ³J = 6.1 Hz, ³J = 4.8 Hz,

1H, CH₃COCH_aH_bCH₂COO), 2.55 (ddd, ²J = 16.9 Hz, ³J = 8.7 Hz, ³J =

4.3 Hz, 1H, CH₃COCH₂CH_aH_bCOO), 2.41 (ddd, ²J = 17.2 Hz, ³J = 6.1 Hz,

R_f= 0.42 (cyclohexane/EtOAc 1:1); m.p. 74–82 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS): δ = 7.36–7.24 (m, 5H, Ph), 7.08 (d, ³J = 7.7 Hz, 1H,

NH), 5.82 (dddd, ³J_trans= 16.9 Hz, ³J_cis= 10.5 Hz, ³J = 6.3 Hz, ³J = 5.4 Hz,

³J

=

4.8 Hz, 1H, CH₃COCH₂CH_aH_bCOO), 2.13 (s, 3H,

1H, CH₂CH=CH₂), 5.27 (t, ³J

= 9.6 Hz, 1H, 4-H), 5.25 (dq,

³J_trans= 17.2 Hz, ²J and ⁴J = 1.4 Hz, 1H, CH₂CH=CH_cisH_trans), 5.18 (dq,

CH₃COCH₂CH₂COO), 2.12 (s, 3H, CH₃COO), 2.06 (s, 3H, CH₃COO),

1.88 (s, 3H, CH₃COO) ppm; ¹³C NMR (150 MHz, CDCl₃, 25 °C, TMS): δ

= 206.5 (C_q, CH₃COCH₂CH₂COO), 171.2 (C_q, CH₃COCH₂CH₂COO),

170.3 (C_q, CH₃COO), 170.1 (C_q, CH₃COO), 170.1 (C_q, CH₃COO), 162.3

(C_q, CCl₃CONH), 162.3 (C_q, tetrazole), 137.4 (C_q, C_Ar), 133.1 (+,

CH₂CH=CH₂), 128.5 (+, 2 × C_ArH), 128.0 (+, 2 × C_ArH), 128.0 (+, C_ArH),

118.0 (–, CH₂CH=CH₂), 100.4 (+, C-1), 99.2 (+, C-1‘), 92.6 (C_q,

CCl₃CONH), 77.0 (+, C-3‘), 73.7 (–, CH₂Ph), 72.7 (+, C-5‘), 71.2 (+, C-3),

70.7 (+, C-2), 70.7 (+, C-4‘), 70.3 (+, C-4), 70.2 (–, CH₂CH=CH₂), 68.8 (–,

C-6’), 67.3 (+, C-5), 56.3 (+, C-2‘), 37.6 (–, CH₃COCH₂CH₂COO), 29.5 (+,

CH₃COCH₂CH₂COO), 27.7 (–, CH₃COCH₂CH₂COO), 20.7 (+, CH₃COO),

20.6 (+, CH₃COO), 20.5 (+, CH₃COO) ppm; IR (ATR): ̃ = 2870, 1753,

1718, 1526, 1368, 1214, 1146, 1040, 912, 822, 756, 698, 673, 603, 489,

398 cm^–1; MS (FAB, 3-NBA): m/z (%): 900/902/904/906 (91/100/40/7)

[M+Na]⁺, 878/880/882/884 (38/40/17/5) [M+H]⁺, 820/822/824/826

(20/21/9/6) [M–OAllyl]⁺; HRMS (FAB, 3-NBA): calcd for C₃₅H₄₃O₁₅N₅³⁵Cl₃

[M+H]⁺: 878.1816; found: 878.1815; Analytical HPLC (5–95% acetonitrile

+ 0.1% TFA in 20 min, detection at 218 nm): t_Ret= 15.1 min; IR (ATR): ̃

= 2870, 1753, 1718, 1526, 1368, 1214, 1146, 1040, 912, 822, 756, 698,

673, 603, 489, 398 cm^–1; MS (FAB, 3-NBA): m/z (%): 900/902/904/906

³J_cis= 10.4 Hz, ²J and J = 1.0 Hz, 1H, CH₂CH=CH_cisH_trans), 5.03 (t, ³J =

4

3

9.3 Hz, 1H, 3-H), 4.97–4.91 (m, 2H, 2-H, 4‘-H), 4.80 (d, J = 8.1 Hz, 1H,

1‘-H), 4.59 (d, ³J = 7.7 Hz, 1H, 1-H), 4.54 (d, ²J = 12.1 Hz, 1H, CH_aH_bPh),

4.50 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.45 (t, ³J = 9.4 Hz, 1H, 3‘-H), 4.35–

4.30 (m, 2H, 5-H, CH_aH_bCH=CH₂), 4.06 (ddt, ²J = 12.8 Hz, ³J = 6.4 Hz, ⁴J

= 1.2 Hz, 1H, CH_aH_bCH=CH₂), 3.70–3.65 (m, 1H, 5‘-H), 3.59–3.51 (m,

3H, 2‘-H, 6‘-H), 2.81 (ddd, ²J = 18.5 Hz, ³J = 8.3 Hz, ³J = 5.2 Hz, 1H,

CH₃COCH_aH_bCH₂COO), 2.66 (ddd, ²J = 18.5 Hz, ³J = 6.3 Hz, ³J = 5.1 Hz,

1H, CH₃COCH_aH_bCH₂COO), 2.59–2.45 (m, 2H, CH₃COCH₂CH₂COO),

2.14 (s, 3H, CH₃COCH₂CH₂COO), 2.03 (s, 3H, CH₃COO), 2.03 (s, 3H,

CH₃COO), 2.01 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃,

25 °C, TMS):

δ = 205.9 (C_q, CH₃COCH₂CH₂COO), 170.7 (C_q,

CH₃COCH₂CH₂COO), 170.1 (C_q, CH₃COO), 169.6 (C_q, CH₃COO), 168.9

(C_q, CH₃COO), 162.1 (C_q, CCl₃CONH), 137.6 (C_q, C_Ar), 133.1 (+,

CH₂CH=CH₂), 128.3 (+, 2 × C_ArH), 127.8 (+, 2 × C_ArH), 127.7 (+, C_ArH),

118.4 (–, CH₂CH=CH₂), 114.1 (C_q, C≡N), 100.9 (+, C-1), 97.6 (+, C-1‘),

92.2 (C_q, CCl₃CONH), 77.8 (+, C-3‘), 73.5 (–, CH₂Ph), 73.2 (+, C-5‘), 70.9

(+, C-3), 70.2 (–, CH₂CH=CH₂), 70.2 (+, C-4‘), 69.3 (+, C-2), 68.9 (–, C-

6’), 68.7 (+, C-4), 62.7 (+, C-5), 58.3 (+, C-2‘), 37.5 (–,

CH₃COCH₂CH₂COO), 29.5 (+, CH₃COCH₂CH₂COO), 27.5 (–,

CH₃COCH₂CH₂COO), 21.0 (+, CH₃COO), 20.5 (+, CH₃COO), 20.4 (+,

CH₃COO) ppm; IR (ATR): ̃ = 3335, 2922, 1753, 1716, 1524, 1368, 1210,

(91/100/40/7)

[M+Na]⁺,

878/880/882/884

(38/40/17/5)

[M+H]⁺,

820/822/824/826 (20/21/9/6) [M–OAllyl]⁺; HRMS (FAB, 3-NBA): calcd for

C₃₅H₄₃O₁₅N₅³⁵Cl₃[M+H]⁺: 878.1816; found: 878.1815; Analytical HPLC

1140, 1053, 894, 838, 821, 735, 698, 676, 601, 490, 431, 409, 381 cm^–1

;

(5–95% acetonitrile + 0.1% TFA in 20 min, detection at 218 nm): t_Ret

=

MS (MALDI, matrix: DHB/CHCA 1:1): m/z: 857/859/861/863 [M+Na]⁺.

15.1 min; elemental analysis calcd (%) for C₃₅H₄₂O₁₅N₅Cl₃: C 47.82, H

4.82, N 7.97; found C 46.38, H 4.68, N 7.55.

Allyl ((5R) 2,3-O-acetyl-4-O-levulinoyl-5-C-(2H-tetrazol-5-yl)-β-D-xylopy-

ranosyl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-

glucopyranosid (37q): Nitrile 37p (97.3 mg, 116 µmol, 1.00 Äquiv.) was

dissolved in 10.0 mL of absolute toluene under argon atmosphere and

trimethylsilyl azide (45.9 µL, 40.2 mg, 349 µmol, 3.00 Äquiv.) and

dibutyltin(IV) oxide (5.78 mg, 23.2 µmol, 0.200 Äquiv.) were added

Allyl O-(methyl 2,3-di-O-acetyl-4-O-levulinoyl-β-D-glucopyranosyluro-

nate)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-

glucopyranoside (37o): Carboxylic acid 37n (79.9 mg, 93.4 µmol,

1.00 Equiv.) was dissolved in 10.0 mL of absolute dichloromethane under

argon atmosphere and cooled down to 0 °C. Oxalyl chloride (12.2 µL,

10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

17.8 mg, 140 µmol, 1.50 Equiv.) and N,N-dimethylformamide (12.9 µL,

10.2 mg, 140 µmol, 1.50 Equiv.) were added consecutively. The solution

was stirred for 1 h at 0 °C and then 1 h at room temperature. Afterwards,

500 µL of dry methanol were added and the solution was stirred for

further 1 h. The mixture was diluted with dichloromethane (50 mL) and

washed with saturated aqueous NaHCO₃-solution (50 mL). The organic

layer was separated and dried over Na₂SO₄. The solvent was removed

under reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (2:3) as

eluent. The product 37o was obtained as a white solid in 80% yield

(65.3 mg).

R_f= 0.26 (cyclohexane/EtOAc 1:1); m.p. 64–73 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS): δ = 7.36–7.26 (m, 5H, Ph), 6.94 (d, ³J = 7.7 Hz, 1H,

NH), 5.84 (dddd, ³J_trans= 17.0 Hz, ³J_cis= 10.3 Hz, ³J = 6.3 Hz, ³J = 5.3 Hz,

1H, CH₂CH=CH₂), 5.27 (dq, J_trans= 17.3 Hz, ²J and ⁴J = 1.5 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.19 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.2 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.05 (t, ³J = 9.5 Hz, 1H, 3-H), 4.99–4.93 (m, 2H, 4-H,

4‘-H), 4.91 (d, ³J = 7.8 Hz, 1H, 1‘-H), 4.87 (dd, ³J = 9.6 Hz, ³J = 8.0 Hz,

1H, 2-H), 4.60 (d, ³J = 8.0 Hz, 1H, 1-H), 4.56 (d, ²J = 12.0 Hz, 1H,

2

CH_aH_bPh), 4.52 (d, J = 11.9 Hz, 1H, CH_aH_bPh), 4.37 (t, ³J = 9.3 Hz, 1H,

3‘-H), 4.33 (ddt, ²J = 12.8 Hz, ³J

= = 1.3 Hz, 1H,

5.3 Hz, ⁴J

CH_aH_bCH=CH₂), 4.07 (ddt, ²J = 12.8 Hz, ³J = 6.3 Hz, ⁴J = 1.2 Hz, 1H,

CH_aH_bCH=CH₂), 3.70 (ddd, ³J = 9.1 Hz, ³J = 5.4 Hz, ³J = 3.6 Hz, 1H,

5‘-H), 3.62–3.51 (m, 4H, 5-H, 2’-H, 6‘-H), 3.25 (dd, ²J = 14.4 Hz, ³J = 2.8

Hz, 1H, 6a-H), 2.96 (dd, ²J = 14.4 Hz, ³J = 7.4 Hz, 1H, 6b-H), 2.78 (dt,

²J = 18.5 Hz, ³J = 6.6 Hz, 1H, CH₃COCH_aH_bCH₂COO), 2.69 (dt, ²J = 18.5

Hz, ³J = 6.0 Hz, 1H, CH₃COCH_aH_bCH₂COO), 2.54 (t, ³J = 6.3 Hz, 2H,

CH₃COCH₂CH₂COO), 2.35 (s, 3H, CH₃COS), 2.16 (s, 3H,

CH₃COCH₂CH₂COO), 2.01 (s, 3H, CH₃COO), 1.99 (s, 3H, CH₃COO),

1.97 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃, 25 °C, TMS): δ

= 206.0 (C_q, CH₃COCH₂CH₂COO), 194.7 (C_q, CH₃COS), 171.5 (C_q,

CH₃COCH₂CH₂COO), 170.3 (C_q, CH₃COO), 169.3 (C_q, CH₃COO), 169.1

(C_q, CH₃COO), 161.8 (C_q, CCl₃CONH), 137.7 (C_q, C_Ar), 133.3 (+,

CH₂CH=CH₂), 128.4 (+, 2 × C_ArH), 127.9 (+, 2 × C_ArH), 127.7 (+, C_ArH),

118.0 (–, CH₂CH=CH₂), 99.4 (+, C-1), 97.7 (+, C-1‘), 92.3 (C_q,

CCl₃CONH), 75.8 (+, C-3‘), 73.6 (–, CH₂Ph), 73.4 (+, C-5‘), 73.3 (+, C-5),

72.4 (+, C-3), 71.3 (+, C-2), 70.5 (+, C-4‘), 70.3 (–, CH₂CH=CH₂), 69.3 (–,

C-6’), 68.9 (+, C-4), 58.3 (+, C-2‘), 37.7 (–, CH₃COCH₂CH₂COO), 30.5 (+,

CH₃COS), 29.9 (–, C-6), 29.6 (+, CH₃COCH₂CH₂COO), 27.8 (–,

CH₃COCH₂CH₂COO), 20.9 (+, CH₃COO), 20.7 (+, CH₃COO), 20.6 (+,

CH₃COO) ppm; IR (ATR): ̃ = 3349, 2927, 1752, 1718, 1527, 1366, 1216,

1147, 1051, 909, 838, 821, 734, 698, 674, 622, 488, 403 cm^–1; MS

(MALDI, matrix: DHB/CHCA 1:1): m/z: 920/922/924/926 [M+Na]⁺.

R_f= 0.41 (cyclohexane/EtOAc 2:3); m.p. 140 °C; ¹H NMR (500 MHz,

CDCl₃, 25 °C, TMS): δ = 7.35–7.25 (m, 5H, Ph), 7.06 (d, ³J = 7.6 Hz, 1H,

NH), 5.83 (dddd, ³J_trans= 16.7 Hz, ³J_cis= 10.5 Hz, ³J = 6.1 Hz, ³J = 5.4 Hz,

3

1H, CH₂CH=CH₂), 5.25 (dq, J_trans= 17.2 Hz, ²J and ⁴J = 1.2 Hz, 1H,

3

CH₂CH=CH_cisH_trans), 5.17 (dq, J_cis= 10.4 Hz, ²J and ⁴J = 1.2 Hz, 1H,

CH₂CH=CH_cisH_trans), 5.14–5.09 (m, 2H, 3-H, 4-H), 4.97 (t, ³J = 9.3 Hz, 1H,

4‘-H), 4.94–4.89 (m, 1H, 2-H), 4.89 (d, ³J = 8.1 Hz, 1H, 1‘-H), 4.66 (d,

2

³J = 7.9 Hz, 1H, 1-H), 4.54 (d, J = 12.0 Hz, 1H, CH_aH_bPh), 4.50 (d, ²J =

12.0 Hz, 1H, CH_aH_bPh), 4.41 (t, ³J = 9.5 Hz, 1H, 3‘-H), 4.32 (ddt,

²J = 12.8 Hz, ³J = 5.2 Hz, ⁴J = 1.3 Hz, 1H, CH_aH_bCH=CH₂), 4.06 (ddt,

3

4

²J = 12.8 Hz, J = 6.4 Hz, J = 1.3 Hz, 1H, CH_aH_bCH=CH₂), 3.95 (m, 1H,

5-H), 3.71 (s, 3H, OCH₃), 3.69–3.64 (m, 1H, 5‘-H), 3.60–3.50 (m, 3H, 2‘-

H, 6‘-H), 2.71–2.65 (m, 2H, CH₃COCH₂CH₂COO), 2.46 (t, ³J = 6.2 Hz, 2H,

CH₃COCH₂CH₂COO), 2.14 (s, 3H, CH₃COCH₂CH₂COO), 2.02 (s, 3H,

CH₃COO), 2.01 (s, 3H, CH₃COO), 1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR

(125 MHz, CDCl₃, 25 °C, TMS): δ = 205.8 (C_q, CH₃COCH₂CH₂COO),

171.1 (C_q, CH₃COCH₂CH₂COO), 170.1 (C_q, CH₃COO), 169.7 (C_q,

CH₃COO), 169.1 (C_q, CH₃COO), 166.9 (C_q, COOCH₃), 161.9 (C_q,

CCl₃CONH), 137.7 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 × C_ArH),

127.8 (+, 2 × C_ArH), 127.7 (+, C_ArH), 118.2 (–, CH₂CH=CH₂), 99.5 (+, C-

1), 97.8 (+, C-1‘), 92.3 (C_q, CCl₃CONH), 76.4 (+, C-3‘), 73.5 (–, CH₂Ph),

73.4 (+, C-5‘), 72.2 (+, C-5), 71.9 (+, C-3), 70.9 (+, C-2), 70.3 (–,

CH₂CH=CH₂), 69.3 (+, C-4), 69.0 (–, C-6’), 68.7 (+, C-4‘), 58.5 (+, C-2‘),

52.8 (+, COOCH₃), 37.5 (–, CH₃COCH₂CH₂COO), 29.6 (+,

CH₃COCH₂CH₂COO), 27.6 (–, CH₃COCH₂CH₂COO), 20.6 (+, CH₃COO),

20.6 (+, CH₃COO), 20.5 (+, CH₃COO) ppm; IR (ATR): ̃ = 3344, 2924,

1753, 1714, 1522, 1434, 1366, 1262, 1216, 1133, 1092, 1049, 1018, 979,

942, 919, 887, 819, 757, 735, 693, 665, 639, 498, 444, 393 cm^–1; MS

(MALDI, matrix: DHB/CHCA 1:1): m/z: 890/892/894/896 [M+Na]⁺.

Allyl O-(2,3-di-O-acetyl-6-azido-6-deoxy-4-O-levulinoyl-β-D-glucopyrano-

syl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glu-

copyranoside (37b): Tosylate 37e (80.0 mg, 80.4 µmol, 1.00 Equiv.) was

dissolved in 5.00 mL of dry N,N-dimethylformamide and sodium azide

(6.53 mg, 100 µmol, 1.25 Equiv.) was added. The solution was heated up

to 80 °C and was stirred for 4 h. The solution was cooled down to room

temperature, diluted with water (100 mL) and extracted with ethyl acetate

(150 mL). The organic layer was washed with water (50 mL) and

saturated aqueous NaCl-solution (50 mL). The organic layer was

separated and dried over Na₂SO₄. The solvent was removed under

reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (1:1) as

eluent. The product 37b was obtained as a white foam in 78% yield

(54.6 mg).

Allyl O-(2,3-di-O-acetyl-6-acetyl-6-deoxy-4-O-levulinoyl-6-thio-β-D-gluco-

pyranosyl)-(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-

D-glucopyranoside (37g): Tosylate 37e (80.0 mg, 80.4 µmol, 1.00 Equiv.)

was dissolved in 5.00 mL of dry N,N-dimethylformamide and potassium

thioacetate (27.5 mg, 241 µmol, 3.00 Equiv.) was added. The solution

was heated up to 80 °C and stirred for 2 h. After that, the solution was

diluted with water (50 mL) and ethyl acetate (100 mL). The mixture was

washed with saturated aqueous NaHCO₃-solution (50 mL). The aqueous

layer was extracted with ethyl acetate (100 mL). The organic layers were

combined and dried over Na₂SO₄. The solvent was removed under

reduced pressure and the crude product was purified by flash

chromatography using a mixture of cyclohexane/ethyl acetate (1:1) as

eluent. The product 37g was obtained as a white foam in 84% yield

(60.7 mg).

R_f= 0.45 (cyclohexane/EtOAc 1:1); m.p. 72–82 °C (decomposition); ¹H

NMR (500 MHz, CDCl₃, 25 °C, TMS): δ = 7.36–7.25 (m, 5H, Ph), 6.93 (d,

3

³J = 8.0 Hz, 1H, NH), 5.84 (dddd, J_trans= 16.8 Hz, J_cis= 10.5 Hz,

³J = 6.2 Hz, J = 5.3 Hz, 1H, CH₂CH=CH₂), 5.26 (dq, J_trans= 17.2 Hz, J

and ⁴J = 1.4 Hz, 1H, CH₂CH=CH_cisH_trans), 5.18 (dq, ³J_cis= 10.4 Hz, ²J and

⁴J = 1.2 Hz, 1H, CH₂CH=CH_cisH_trans), 5.09 (t, ³J = 9.5 Hz, 1H, 3-H), 5.00–

4.91 (m, 2H, 4-H, 4‘-H), 4.88 (dd, ³J = 9.4 Hz, ³J = 8.0 Hz, 1H, 2-H), 4.82

(d, ³J = 7.5 Hz, 1H, 1‘-H), 4.67 (d, ³J = 7.9 Hz, 1H, 1-H), 4.55 (d, ²J =

3

2

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Chemistry - A European Journal

FULL PAPER

12.0 Hz, 1H, CH_aH_bPh), 4.51 (d, ²J = 12.0 Hz, 1H, CH_aH_bPh), 4.37–4.29

(m, 2H, 3‘-H, CH_aH_bCH=CH₂), 4.05 (ddt, ²J = 12.8 Hz, ³J = 6.3 Hz, ⁴J =

1.2 Hz, 1H, CH_aH_bCH=CH₂), 3.72–3.63 (m, 2H, 2‘-H, 5‘-H), 3.63–3.52 (m,

3H, 5-H, 6‘-H), 3.39 (d, ³J = 4.7 Hz, 2H, 6-H), 2.80–2.65 (m, 2H,

CH₃COCH₂CH₂COO), 2.52–2.37 (m, 2H, CH₃COCH₂CH₂COO), 2.15 (s,

3H, CH₃COCH₂CH₂COO), 2.03 (s, 3H, CH₃COO), 2.00 (s, 3H, CH₃COO),

1.99 (s, 3H, CH₃COO) ppm; ¹³C NMR (125 MHz, CDCl₃, 25 °C, TMS): δ

= 206.2 (C_q, CH₃COCH₂CH₂COO), 171.5 (C_q, CH₃COCH₂CH₂COO),

170.2 (C_q, CH₃COO), 169.3 (C_q, CH₃COO), 169.2 (C_q, CH₃COO), 161.7

(C_q, CCl₃CONH), 137.8 (C_q, C_Ar), 133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 ×

C_ArH), 127.8 (+, 2 × C_ArH), 127.7 (+, C_ArH), 118.2 (–, CH₂CH=CH₂), 99.5

(+, C-1), 97.8 (+, C-1‘), 92.4 (C_q, CCl₃CONH), 75.6 (+, C-3‘), 73.5 (–,

CH₂Ph), 73.4 (+, C-5‘), 73.2 (+, C-5), 72.4 (+, C-3), 71.2 (+, C-2), 70.1 (–,

CH₂CH=CH₂), 69.4 (+, C-4), 69.2 (–, C-6’), 69.0 (+, C-4‘), 57.6 (+, C-2‘),

1.96 (s, 3H, CH₃COO), 1.22 (d, ³J = 6.1 Hz, 3H, 6-H) ppm; ¹³C NMR

(125 MHz, CDCl₃, 25 °C, TMS): δ = 206.2 (C_q, CH₃COCH₂CH₂COO),

171.5 (C_q, CH₃COCH₂CH₂COO), 170.4 (C_q, CH₃COO), 169.4 (C_q,

CH₃COO), 169.3 (C_q, CH₃COO), 161.8 (C_q, CCl₃CONH), 137.6 (C_q, C_Ar),

133.2 (+, CH₂CH=CH₂), 128.3 (+, 2 × C_ArH), 127.8 (+, 2 × C_ArH), 127.7 (+,

C_ArH), 118.4 (–, CH₂CH=CH₂), 100.0 (+, C-1), 97.6 (+, C-1‘), 92.2 (C_q,

CCl₃CONH), 76.2 (+, C-3‘), 73.5 (–, CH₂Ph), 73.2 (+, C-5‘), 73.1 (+, C-4),

72.6 (+, C-3), 71.5 (+, C-2), 70.2 (–, CH₂CH=CH₂), 70.0 (+, C-5), 69.4 (+,

C-4‘), 69.0 (–, C-6’), 58.4 (+, C-2‘), 37.6 (–, CH₃COCH₂CH₂COO), 29.6 (+,

CH₃COCH₂CH₂COO), 27.7 (–, CH₃COCH₂CH₂COO), 21.0 (+, CH₃COO),

20.7 (+, CH₃COO), 20.6 (+, CH₃COO), 17.4 (+, C-6) ppm; IR (ATR): ̃ =

2872, 1750, 1715, 1528, 1367, 1217, 1149, 1055, 916, 821, 756, 698,

672, 603, 489 cm^–1; MS (FAB, 3-NBA): m/z (%): 822/824/826/828

(30/32/20/8 [M–H]⁺, 766/768/770/772 (100/99/42/8) [M–OAllyl]⁺; HRMS

(FAB, 3-NBA): calcd for C₃₅H₄₃O₁₅N³⁵Cl₃[M–H]⁺: 822.1693; found:

822.1694.

50.8

(–,

C-6),

37.7

(–,

CH₃COCH₂CH₂COO),

29.6

(+,

CH₃COCH₂CH₂COO), 27.7 (–, CH₃COCH₂CH₂COO), 20.9 (+, CH₃COO),

20.6 (+, CH₃COO), 20.6 (+, CH₃COO) ppm; IR (ATR): ̃ = 3345, 2923,

2103, 1751, 1716, 1526, 1366, 1215, 1147, 1050, 900, 821, 756, 698,

671, 602, 488, 389 cm^–1; MS (MALDI, matrix: DHB/CHCA 1:1): m/z:

887/889/891/893 [M+Na]⁺; HRMS (FAB, 3-NBA): calcd for

C₃₅H₄₄O₁₅N₄³⁵Cl₃[M+H]⁺: 865.1863; found: 865.1867.

CCDC 1534116 (6), 1534118 (7), 1534119 (13), 1534117 (15), 1534120

(16), 1534121 (27), 1534122 (29), 1534123 (30) contain the

supplementary crystallographic data for this paper. These data can be

obtained free of charge from The Cambridge Crystallographic Data

Centre via www.ccdc.cam.ac.uk/data_request/cif.

Allyl

O-(2,3-di-O-acetyl-6-deoxy-4-O-levulinoyl-β-D-glucopyranosyl)-

(1→3)-4-O-acetyl-6-O-benzyl-2-deoxy-2-trichloroacetamido-β-D-glucopy-

ranoside (37a): Acceptor 36 (737 mg, 1.48 mmol, 1.00 Equiv.) and donor

22a (730 mg, 1.87 mmol, 1.26 Equiv.) were dissolved in 10.0 mL of

absolute dichloromethane under argon atmosphere and 4 Å molecular

sieve powder (215 mg) was added. The mixture was stirred for 1 h at

room temperature and then cooled down to –30 °C. N-Iodosuccinimide

(501 mg, 2.23 mmol, 1.50 Equiv.) and trimethylsilyl trifluoromethane-

sulfonate (20.0 µL, 24.6 mg, 111 µmol, 0.0747 Equiv.) were added

consecutively and the mixture was stirred for 1.5 h. The mixture was

filtered through a pad of celite and the filtrate was washed with

Acknowledgements

We gratefully acknowledge the Baden-Württemberg Stiftung and

the DFG (SFB 1176) for the financial support of this work. We

also thank Benjamin E. Görling for his previous work on this field.

Keywords: Hyaluronic acid • Synthesis • Oligosaccharides •

Derivatization • Glycosides

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10.1002/chem.201701238

Chemistry - A European Journal

FULL PAPER

Various novel hyaluronic acid

M. Mende, M. Nieger, S.

disaccharide derivatives with

a

Bräse*

distinct protecting group pattern

providing an easy access to higher

oligomers were synthesized. ¹H

NMR studies showed essential

Page No. – Page No.

Chemical Synthesis

Towards Modified

Hyaluronic Acid

Disaccharides

changes

in

the

electronic

environment within the molecules,

especially in the hydrogen bonding

amide proton, which could result in

new

properties

or

biological

activities concerning the appropriate

higher oligomers.

Article Doi

Chemical Synthesis of Modified Hyaluronic Acid Disaccharides

DOI: 10.1002/chem.201701238

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Authors:

Article abstract of DOI:10.1002/chem.201701238

Full text of DOI:10.1002/chem.201701238

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