8-hydroxyquinoline glycoconjugates: Modifications in the linker structure and their effect on the cytotoxicity of the obtained compounds

molecules

Article

8-Hydroxyquinoline Glycoconjugates: Modiﬁcations

in the Linker Structure and Their Eﬀect on the

Cytotoxicity of the Obtained Compounds

Monika Krawczyk ^1,2,

*

, Gabriela Pastuch-Gawołek ^1,2, Aleksandra Pluta ¹, Karol Erfurt ³,

Adrian Domin´ski ⁴and Piotr Kurcok ⁴

1

Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of

Technology, B. Krzywoustego 4, 44-100 Gliwice, Poland; gabriela.pastuch@polsl.pl (G.P.-G.);

aleksandrapluta93@o2.pl (A.P.)

Biotechnology Centre, Silesian University of Technology, B. Krzywoustego 8, 44-100 Gliwice, Poland

2

3

Department of Chemical Organic Technology and Petrochemistry, Silesian University of Technology,

B. Krzywoustego 4, 44-100 Gliwice, Poland; karol.erfurt@polsl.pl

Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34,

4

41-819 Zabrze, Poland; adrian.dominski@cmpw-pan.edu.pl (A.D.); piotr.kurcok@cmpw-pan.edu.pl (P.K.)

*

Correspondence: monika.krawczyk@polsl.pl; Tel.: +48-32-237-1759

Academic Editor: Robert Musioł

Received: 31 October 2019; Accepted: 15 November 2019; Published: 18 November 2019

ꢀꢁꢂꢀꢃꢄꢅꢆꢇ

ꢀꢁꢂꢃꢄꢅꢆ

Abstract: Small molecule nitrogen heterocycles are very important structures, widely used in the

design of potential pharmaceuticals. Particularly, derivatives of 8-hydroxyquinoline (8-HQ) are

successfully used to design promising anti-cancer agents. Conjugating 8-HQ derivatives with

sugar derivatives, molecules with better bioavailability, selectivity, and solubility are obtained.

In this study, 8-HQ derivatives were functionalized at the 8-OH position and connected with sugar

derivatives (D-glucose or D-galactose) substituted with diﬀerent groups at the anomeric position,

using copper(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC). Glycoconjugates were

tested for inhibition of the proliferation of cancer cell lines (HCT 116 and MCF-7) and inhibition

of β-1,4-galactosyltransferase activity, which overexpression is associated with cancer progression.

All glycoconjugates in protected form have a cytotoxic eﬀect on cancer cells in the tested concentration

range. The presence of additional amide groups in the linker structure improves the activity of

glycoconjugates, probably due to the ability to chelate metal ions present in many types of cancers.

The study of metal complexing properties conﬁrmed that the obtained glycoconjugates are capable of

chelating copper ions, which increases their anti-cancer potential.

Keywords: quinoline; glycoconjugates; click reaction; 1,3-dipolar cycloaddition; chelators; anticancer

properties

1. Introduction

Cancer is one of the biggest problems in modern medicine and one of the main causes of death in

the world. The high toxicity of drugs and the growing resistance of cancer cells to a significant number

of pharmaceuticals increasingly limit the possibility of obtaining successful results of anti-cancer therapy.

Therefore, it is necessary to search for new, effective chemotherapeutics characterized by low toxicity

and high selectivity profile. Analysis of the Food and Drug Administration (FDA) database revealed

that of the novel approved drugs for oncology in 2018, 7 are biologicals and 13 are small-molecules

drugs. Importantly, all of the newly reported chemotherapeutics contain an N-heterocyclic fragment in

their structure [1 ]. Small molecule nitrogen heterocycles are very important structures, widely used

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Molecules 2019, 24, 4181

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in the design of potential pharmaceuticals for several years [2 ]. Among them, the quinoline scaffold,

which is present in many classes of biologically active compounds, deserves special attention [3 –6 ].

The quinoline scaffold is often used as a privileged structure in the design of a large number of

structurally diverse molecules that exhibit promising pharmacological effects. Particularly, derivatives

of 8-hydroxyquinoline (8-HQ) are successfully applied to design chemotherapeutics used in the treatment

of bacterial [7 –9 ], fungal [10 ,11 ] and neurodegenerative diseases [12 ,13 ]. An important element of

8-HQ biological activity is the ability to chelate metal ions, which makes 8-HQ a promising anti-cancer

agent [14 –16 ].

Transition metal ions, including Fe²⁺, Cu²⁺, and Zn²⁺play a signiﬁcant role in the human organism.

They aﬀect the proper course of many key cellular processes. Therefore, it is important to maintain

homeostasis. Incorrect metabolism of the above microelements may contribute to the development of

many diseases [17,18]. There are several strategies for controlling the proper level of metals within cells

and tissues. For this purpose, a common strategy is the use of chelators or ionophores. Chelating agents

are successfully used to remove excess metal ions from the body. Whereas, ionophores are used to

transport metal ions via cell membrane in both directions [18,19]. Copper is one of the transition metals

which complex compounds have been intensively studied in recent years for anticancer applications.

As is well known, copper is an essential cofactor for cancer growth and angiogenesis. Numerous

studies have shown that an elevated level of copper is directly correlated with cancer progression.

Additionally, copper concentration correlated with the age of patients and the stage of cancer [20

Excess of copper ions was found in the serum and tissues of patients with, among others: breast [24

prostate [26

observations suggest that copper ions may be one of the selective targets for cancer treatment [20

–

24].

,

25],

,

27], colorectal [28], lung [29] and brain [30] cancers, compared to healthy people. These

,

31–33].

Among the known copper chelators include tetrathiomolybdate, trientine, and D-penicillamine

primarily used to treat Wilson⁰s disease [34]. Clinical studies have shown that these compounds are

eﬀective in inhibiting the angiogenesis of some types of cancer [35–41]. The literature also reports on

the use of 8-HQ derivatives as copper chelators. Due to the presence of free electron pairs on nitrogen

and oxygen atoms of 8-HQ, they have the ability to complex Cu²⁺ions, forming chelates, which are

then removed from the body [14–16,42,43]. However, metal ions play an important role in many

cellular processes, including those necessary for the proper functioning of the organism. Therefore,

traditional chelators can cause a deﬁciency of copper in healthy tissues. The consequence of the lack

of selectivity in directing drugs to a speciﬁc site of action may be undesirable side eﬀects resulting

from the implemented anticancer therapy. That is why the aim of many researchers is to develop more

selective and safer drugs. Therefore, an ideal anti-cancer drug should be selective for cancer cells,

thereby alleviating the undesirable toxic eﬀects of chemotherapy.

During designing new drugs, it is very important to know and use the diﬀerences between

cancer cells and healthy cells. One such diﬀerence is the speciﬁc metabolism of glucose in cancer cells.

It has been proven that cancer cells have an increased demand for glucose compared to healthy cells,

which metabolizes it to obtain the energy needed to increase proliferation. This provides the cells

with a suﬃcient amount of nutrients and energy to carry out the processes taking place during the

cell cycle. This phenomenon is known as the Warburg eﬀect and arises from mitochondrial metabolic

changes. It consists in the fact that cancer cells produce their energy through glycolysis followed

by lactic acid fermentation, characteristic of hypoxic conditions, and its level is much higher (more

than a hundred times) than in healthy cells, for which the main source of energy is mitochondrial

oxidative phosphorylation [44

overexpression of GLUT transporters. There are special proteins that mediate the transfer of sugars

across cell membranes [46 48]. Therefore, sugars are an attractive system for transporting drugs

,45]. Increased glycolysis process in cancer cells is associated with the

–

directly to cancer cells. The strategy of conjugating sugar derivatives with biological active aglycons

is widely used in research on the synthesis of new drugs, supporting the treatment against various

diseases [49]. The chelating functions of glycoconjugates are masked by the presence of a sugar unit

until the release of active aglycon in the target cells, occurring as a result of hydrolysis catalyzed by

Molecules 2019, 24, 4181

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speciﬁc β-glycosidases [50]. Consequently, drug interference in the glycolytic pathway should be

eﬀective and more selective for cancer cells.

As a result of conjugating 8-HQ derivatives with sugar derivatives, a molecule with better

bioavailability, selectivity and solubility can be obtained [50–53]. Considering the potential therapeutic

application of planned connections, this synthesis must be simple, fast, selective and eﬃcient.

An example of a reaction that meets these criteria is the reaction of 1,3-dipolar azide-alkyne cycloaddition,

which leads to receiving the 1,2,3-triazole ring between joined compounds.

We have recently shown that the 1,2,3-triazole ring is an important element for glycoconjugate

activity [54] (Figure 1 ). Except for the role of a connection between two active groups, it also has other

interesting properties. The H-C(5) atom in the triazole ring is a donor for a hydrogen bond, while

the free electron pair at the N(3) atom in the triazole can be used as an acceptor in the formation of a

hydrogen bond. Their tendency to form hydrogen bonds increases the solubility of such molecules,

which favor binding to biomolecular targets [55]. The aim of present work is to extend the library

of such combinations. The general structure of the planned glycoconjugates is shown in Figure 2.

It was decided to reverse the direction of linking reactive moieties compared to the previously reported

glycoconjugates [54], consisting of sugar azides and propargyl derivatives of 8-HQ (Figure 1) and

see how this will aﬀect the activity of glycoconjugates. In addition, it was decided to check how the

structure modiﬁcation of the linker of the quinoline glycoconjugates aﬀects their biological properties.

It was assumed that an extension of the alkyl chain between the triazole ring and quinoline or sugar part

should increase the “ﬂexibility” of the obtained compounds, which may aﬀect the cytotoxicity proﬁle of

the molecules. Moreover, insertion into a linker an additional amide or carbamate bonds, the presence

of which is observed in many biologically active compounds should improve glycoconjugates chelating

ability [56]. Therefore, it was decided to check whether the addition of this structural element to

quinoline glycoconjugates will improve their activity compared to previously obtained derivatives.

Figure 1. Structures of previously obtained glycoconjugates [54].

Figure 2. General structure of the glycoconjugates presented in this paper.

A multiplicity of structural modiﬁcations in building blocks for the synthesis of glycoconjugates

and their combination in various conﬁgurations will allow determining the relationships between

the chemical structure of this group of compounds and their biological activity. This will allow also

identifying those speciﬁc structural elements that are responsible for demonstrating biological activity.

This is important information from the point of view of the mechanisms of action of designed structures.

2. Results and Discussion

2.1. Synthesis

As mentioned above, the synthetic aim of this work was to create a large library of compounds based

on the 8-HQ scaﬀold with a sugar fragment attached via an appropriate linker. Target glycoconjugates

Molecules 2019, 24, 4181

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were obtained by modifying commercially available 8-hydroxyquinoline

1 or 8-hydroxyquinaldine 2,

and then connecting them with derivatives of D-glucose or D-galactose substituted with diﬀerent groups

at the anomeric position. A common feature of all glycoconjugates is the presence of a 1,2,3-triazole

ring in the linker structure. This improves their cytotoxic activity, probably by increasing the ability to

metal ions chelation found in many types of cancers [54,55]. In addition, the used substrates have a

relatively small size and are easy to modify, which makes them particularly interesting from the point

of view of using them to design potential drugs.

The ﬁrst part of the synthesis concerned the preparation of the corresponding quinoline derivatives

functionalized in the 8-OH position with propargyl or azide groups, that are involved in the click

chemistry reaction. The path of the syntheses is presented in Scheme 1.

Cl^-

ii

N⁺

5a-10a

R

O

n = 1-3

i

N

R

N

R

O

OH

5: R=H, n=2 (82%)

6: R=H, n=3 (75%)

7: R=H, n=4 (76%)

8: R=CH₃, n=2 (83%)

9: R=CH₃, n=3 (71%)

10: R=CH₃, n=4 (69%)

1: R=H

2: R=CH₃

N

R

3: R=H (88%)

4: R=CH₃(73%)

O

iii

n = 2-4

N₃

Scheme 1. Synthesis of 8-hydroxyquinoline derivatives 3–10. Reagents and Conditions: (i) propargyl

bromide, K₂CO₃, acetone, r.t., 24 h; (ii) 1. 2-bromoethanol or 3-bromo-1-propanol or 4-bromo-1-butanol,

K₂CO₃, acetone, r.t., 24 h; 2. methanesulfonyl chloride or p-toluenesulfonyl chloride, Et₃N, CH₂Cl₂;

r.t., 3h; 3. NaN₃, DMF, r.t., 24 h; (iii) 1-azido-2-bromoethane or 1-azido-3-bromopropane or 1-azido-

4-bromobutane, K₂CO₃, acetone, 50 ^◦C-r.t., 24 h.

Propargyl quinoline derivatives

according to the previously published procedure [54

reacted with propargyl bromide in a reaction carried out under basic conditions. The ﬁrst approach

to the synthesis of 8-(2-azidoethoxy)quinolone was the reaction of 8-HQ with 2-bromoethanol

3

or

4

were obtained in good yields (88% and 73% respectively),

,

57]. The corresponding compound or was

1

2

5

1

to obtain 8-(2-hydroxyethoxy)quinoline. The obtained alcohol was treated with methanesulfonyl

or p-toluenesulfonyl chloride in the presence of a non-nucleophilic base (TEA) followed by sodium

azide in DMF. However, the formation of the expected product

5 was no observed. Also in case of

lengthening the alkyl chain of the donor, the desired products 6–10 could not be obtained. Treatment of

8-(2-hydroxyethoxy)quinoline by azidotrimethylsilane (TMSN₃) in the presence of Lewis acid also did

not give the expected products. The application of the Appel reaction conditions, in which the alcohol

reacts with carbon tetrachloride in the presence of triphenylphosphine also not allowed to obtain the

desired products. Instead, spectroscopic data (HRMS) conﬁrmed the formation of a resonance-stabilized

structure of the tricyclic oxazaquinolinium salts 5a–10a

[58]. Finally, to obtain compounds 5–10,

a reaction of quinoline derivatives or with 1-azido-2-bromoethane, 1-azido-3-bromopropane or

1

2

1-azido-4-bromobutane as donors of desired groups was carried out. These donors were previously

obtained by monoazidation of the corresponding dibromoalkane with NaN₃in DMF [59]. The optimal

yield of the desired products was obtained by carrying out the reaction at 50 ^◦C, using an equimolar

ratio of substrates. Except for the monosubstituted derivatives (50% yields), diazidesubstituted

derivatives (25% yield) were also obtained (the yield was estimated by ¹H NMR).

Sugar derivatives substituted at the anomeric position were a second necessary structural element

for the synthesis of glycoconjugates. The synthesis route to the corresponding protected and deprotected

derivatives of D-glucose and D-galactose are shown in Schemes 2–4. The choice of sugar units is

dictated by the frequency of their occurrence and their importance for cell metabolism. The procedure

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for obtaining 2,3,4,6-tetra-O-acetyl-

β-d-glycopyranosyl amines 19 and 20 has been described in detail

in earlier works [51,54,60] (Scheme 2).

R²

R¹

HO

R²

OAc

OH

OAc

O

R¹

i

ii

iii

iv

R¹

O

R¹

OAc

AcO

N₃

NH₂

AcO

OH

OAc

OH

OAc

Br

1

2

1

2

1

2

1

2

1

2

11

12

13

14

15

16

17

18

19

20

: R =OH, R =H

: R =OAc, R =H (96%)

: R =OAc, R =H (91%)

: R =OAc, R =H (90%)

: R =OAc, R =H (100%)

1

2

1

2

1

2

1

2

1

2

: R =H, R =OH

: R =H, R =OAc (81%)

: R =H, R =OAc (90%)

: R =H, R =OAc (85%)

: R =H, R =OAc (100%)

Scheme 2. Synthesis of sugar derivatives 13

–

20. Reagents and Conditions: (i) CH₃COONa, Ac₂O, b.p.,

1 h; (ii) CH₃COOH, 33% HBr/AcOH, r.t. 1 h; (iii) NaN₃, TBASH, CHCl₃/NaHCO₃, r.t. 2 h; (iv) 20%

Pd(OH)₂/C, THF:EtOH (2:1, v/v), H₂, 1.5 bar, 2 h.

Scheme 3. Synthesis of sugar derivatives 21

–

30. Reagents and Conditions: (

i

) propargyl alcohol, BF₃Et₂O,

·

DCM, r.t., 1 h; (ii) 2-bromoethanol, BF₃·Et₂O, DCM, r.t., 2 h; (iii) NaN₃, DMF, r.t. 24 h; (iv) 1. MeONa,

MeOH, r.t. 20 min; 2. Amberlyst-15.

Scheme 4. Synthesis of sugar derivatives 31–44. Reagents and Conditions: (i) chloroacetyl chloride,

TEA, DCM, r.t., 1 h; (ii) NaN₃, DMF, r.t. 24 h; (iii) Propiolic acid, DCC, DCM, r.t. 2 h; (iv) propargyl

chloroformate, Hünig⁰s base, DCM, r.t. 2 h; (v) 1. MeONa, MeOH, r.t. 20 min; 2. Amberlyst-15.

Sugar derivatives in which the alkynyl or azide moiety was introduced by the formation of an

O-glycosidic linkage were prepared by reacting per-O-acetylated D-glucose 13 or D-galactose 14 with

Molecules 2019, 24, 4181

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propargyl alcohol or 2-bromoethanol in the presence of a Lewis acid as a catalyst (Scheme 3) [61,62].

The reactions were carried out in an anhydrous DCM in the presence of boron triﬂuoride etherate

until the complete conversion of the substrate, which was monitored by TLC. The reaction mixture

was diluted with dichloromethane and extracted with NaHCO₃and brine to wash oﬀ the acid.

The acetyl neighboring-group participation at the C-2 position of the sugar ensured the formation of

an intermediate acyloxonium ion, which for steric reasons could be “attacked” by a nucleophile only

from the opposite side, resulting in only products of the

large coupling constant from the H-1 proton equal J = 8.0 Hz observed in the ¹H NMR spectra for

compounds 21 22 and 25 26. As a result, propargyl 2,3,4,6-tetra-O-acetyl- -D-glycopyranosides

21 and 22 were obtained in good yields (89% and 83% respectively), whereas 2-bromoethyl

2,3,4,6-tetra-O-acetyl- -D-glycopyranosides 25 and 26 were obtained in slightly lower yields (76% and

71% respectively). 2-Azidoethyl 2,3,4,6-tetra-O-acetyl- -D-glycopyranosides 27 and 28 were obtained

β-conﬁguration. This is conﬁrmed by the

–

β

by substituting bromine by sodium azide in the reaction carried out in DMF in almost quantitative

yield. Conﬁrmation of bromine exchange to the azide moiety was the appearance in the ¹³C NMR

spectra of the signal of CH₂N₃carbon with a shift of about

δ = 50.55 ppm for 27 and 50.60 ppm for 28,

while the signal of CH₂Br carbon was observed at about δ = 29.83 ppm for 25 and 29.91 ppm for 26.

In the next step, sugar derivatives containing an amide or a carbamate moiety at the sugar

anomeric position were obtained by several-step synthesis presented in Scheme 4.

Derivatives of 2,3,4,6-tetra-O-acetyl-N-(β-D-glycopyranosyl)azidoacetamide 33, 34 were obtained

in two-steps procedure. 1-Aminosugars 19 or 20 were reacted with chloroacetyl chloride in the presence

of TEA, which neutralized the formed of hydrogen chloride. This approach eliminates the use of

toxic SnCl₄and tin metal to reduce glycopyranosyl azides, which has been described as a method for

the synthesis of N-glycopyranosyl chloroacetamides [63]. In the second step, the terminal chlorine

atom in compounds 31 and 32 was exchanged with an azide group by a nucleophilic substitution

reaction with sodium azide in dry DMF. The structures of the obtained products were conﬁrmed on

the basis of NMR spectra analysis. In this case, the characteristic carbon signal of CH₂N₃located at

δ = 52.59 ppm for 33 and 52.61 ppm for 34 in ¹³C NMR spectra was shifted from

42.26 ppm corresponding to chloroacetamide derivatives 31 and 32.

δ = 42.25 ppm and

In turns, structures 37 and 38 were obtained in the reaction of 1-amino sugars 19 or 20 with

propargylic acid. In these reactions activating the non-reactive carboxyl group seems to be necessary.

Of the many ways to form an amide bond, initially, it was decided to use the method developed

by Kaminski and co-workers [64 ]. This method involves creating so-called superactive ester 4-(4,6-

dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) in situ in reaction between

2-chloro-4,6-disubstituted-1,3,5-triazines (CDMT) and N-methylmorpholine (NMM). It turned out that

as a result of this reaction, only traces of expected products were formed. In the next approach,

the carbodiimide method was used to the condensation reaction using DCC as a coupling agent [65 ].

The reaction was carried out in DCM in which the isolated DCU is insoluble and could be separated from

the reaction mixture by filtration. As a result, 2,3,4,6-tetra-O-acetyl-N-(β-d-glycopyranosyl)propiolamides

37 and 38 were obtained in high yields (90% and 77% respectively).

In order to obtain sugar derivatives containing a carbamate group at the sugar anomeric position,

reactions of 1-amino sugars 19 and 20 with propargyl chloroformate, which is a reactive acylating agent,

were also carried out. This reaction requires the presence of a tertiary amine in the reaction medium

to entrap the formed HCl and avoid conversion of the amine into its non-reactive hydrochloride

salt [66]. However, the use of TEA gave only moderate yield, while the replacement of TEA with

N,N-diisopropylethylamine allowed obtaining the desired products 41 and 42 in high yields (81% and

88% respectively).

The ester type protecting groups in the sugar part increase the lipophilicity of glycoconjugates

and improved its passive transport inside the cell, where are enzymes capable of hydrolyzing them.

However, for some biological studies, it is also necessary to use compounds with unprotected hydroxyl

groups. The removal of the acetyl protecting groups from sugars was carried out according to the classic

Molecules 2019, 24, 4181

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Zemplén protocol under alkaline conditions using a solution of sodium methoxide in methanol (0.2

molar equiv.) [67]. The ﬁnal step was to neutralize the reaction mixture with the use of Amberlyst-15

ion exchange resin, after which the mixture was ﬁltered to give compounds 23, 24, 29, 30, 35, 36, 39, 40,

43, 44 suﬃciently pure for further reactions.

For the preparation of glycoconjugates, the obtained protected or deprotected derivatives of

D-glucose or D-galactose were combined with derivatives of 8-HQ using copper(I)-catalyzed 1,3-dipolar

azide-alkyne cycloaddition (CuAAC) [68

shown in Scheme 5 . The reactants were combined in an equimolar ratio in a THF/i-PrOH/H₂O solvent

system at room temperature. As the source of copper ions, CuSO₄5H₂O was used. Whereas, sodium

,69]. A general scheme for the synthesis of glycoconjugates is

·

ascorbate (NaAsc) was a reducing agent for Cu ions from II for the I oxidation stage. Due to the

using Cu(I) as a catalyst, the reaction was carried out at room temperature and only 1,4-disubstituted

1,2,3-triazoles were obtained. It is worth noting that both protected and deprotected sugar derivatives

can be used for this reaction. This eliminates the need for a ﬁnal deprotection of glycoconjugates, which

could adversely aﬀect the yields of the unprotected products. The crude products of these reactions were

puriﬁed by column chromatography. As a result of the CuAAC reaction, glycoconjugates 45–108 were

obtained with the yields shown in the Tables 1–5 . The structure of substrates for CuAAC reactions and

all obtained glycoconjugates were conﬁrmed by ¹H and ¹³C NMR spectroscopy. For glycoconjugates,

HRMS analyses were also performed. All these data are included in the Supplementary Materials.

The physicochemical properties, such as melting point and optical rotation, were also determined.

Scheme 5. General scheme for the synthesis of glycoconjugates 45

(i) CuSO₄·5H₂O, NaAsc, i-PrOH, THF, H₂O, r.t., 24 h.

–108. Reagents and Conditions:

2.2. Biological Studies

2.2.1. Cytotoxicity Evaluation of Glycoconjugates

Glycoconjugates have been tested for their potential anticancer activity in vitro. For this purpose,

the whole range of obtained glycoconjugates and substrates used for their synthesis were subjected to

a cytotoxicity screening using MTT assay on cell lines: HCT 116 (colorectal carcinoma cell line) and

MCF-7 (human breast adenocarcinoma cell line). In these lines, overexpression of the glucose and

galactose transporters was observed [49,70–73]. For compounds presenting the highest antiproliferative

activity within the cancer cell line, cytotoxicity tests on Normal Human Dermal Fibroblast-Neonatal

cells (NHDF-Neo) were also be performed, to determine their selectivity index. Tests were conducted

for glycoconjugates solutions at concentrations ranging from 0.01 mM to 0.8 mM. The determined

IC₅₀values, deﬁned as 50% cell growth inhibition compared to the untreated control, are shown in

Tables 6 and 7). The eﬀect of the length and structure of the linker connecting quinoline with the sugar

fragment for the activity of glycoconjugates was investigated.

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Table 1. Yields of glycoconjugates 45–68.

General

Structure

Product

R¹

R²

R³

R⁴

n

8-HQ Derivative Sugar Derivative

Yield [%]

45

46

47

48

49

50

51

52

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

5

8

5

8

21

22

21

22

23

24

23

24

73

74

100

71

95

67

88

78

2

53

54

55

56

57

58

59

60

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

6

9

6

9

21

22

21

22

23

24

23

24

100

65

77

100

76

3

4

87

65

61

62

63

64

65

66

67

68

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

7

10

7

10

21

22

21

22

23

24

23

24

96

93

92

100

72

90

76

66

Table 2. Yields of glycoconjugates 69–76.

General

Structure

Product

R¹

R²

R³

R⁴

8-HQ Derivative

Sugar Derivative

Yield [%]

69

70

71

72

73

74

75

76

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

3

4

3

4

27

28

27

28

29

30

29

30

78

62

97

77

62

55

58

59

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Table 3. Yields of glycoconjugates 77–84.

General

Structure

Product

R¹

R²

R³

R⁴

8-HQ Derivative

Sugar Derivative

Yield [%]

77

78

79

80

81

82

83

84

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

3

4

3

4

33

34

33

34

35

36

35

36

67

74

81

78

60

58

61

78

Table 4. Yields of glycoconjugates 85–100.

General

Structure

Product

R¹

R²

R³

R⁴

n

8-HQ Derivative

Sugar Derivative

Yield [%]

85

86

87

88

89

90

91

92

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

5

8

5

8

37

38

37

38

39

40

39

40

85

86

87

88

89

90

91

92

2

93

94

95

96

97

98

99

100

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

6

9

6

9

37

38

37

38

39

40

39

40

93

94

95

96

97

98

99

100

3

Table 5. Yields of glycoconjugates 101–108.

General

Structure

Product

R¹

R²

R³

R⁴

8-HQ Derivative

Sugar Derivative

Yield [%]

101

102

103

104

105

106

107

108

Ac

H

OAc

H

OAc

H

OH

H

OH

H

OAc

H

OAc

H

OH

H

OH

H

CH₃

H

CH₃

6

9

6

9

41

42

41

42

43

44

43

44

94

90

68

64

83

82

80

78

Molecules 2019, 24, 4181

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Table 6. Screening of cytotoxicity of substrates 1–10 used for glycoconjugation.

Activity IC₅₀[µM] ^a

Compound

MCF-7 ^c

HCT 116 ^b

NHDF-Neo ^b

1

2

3

4

5

6

7

8

>800

0.24 ± 0.01

43.18 ± 1.78

95.95 ± 4.29

223.63 ± 8.06

27.27 ± 0.06

244.44 ± 1.34

67.18 ± 3.49

633.02 ± 6.39

166.70 ± 7.15

114.72 ± 1.23

0.70 ± 0.01

>800

346.77 ± 2.23

>800

83.02 ± 1.83

461.39 ± 1.34

237.48 ± 2.11

>800

295.51 ± 7.37

196.47 ± 7.38

5.60 ± 0.10

26.60 ± 0.60

-

37.71 ± 0.94

-

188.14 ± 2.47

168.14 ± 1.13

>20

9

10

Doxorubicin

Cytotoxic was evaluated using the MTT assay; ^bIncubation time 24 h; ^cIncubation time 72 h.

a

Table 7. Screening of cytotoxicity of glycoconjugates derivatives of 8-hydroxyquinoline 45–108.

Activity IC₅₀[µM] ^a

Compound

MCF-7 ^c

HCT 116 ^b

NHDF-Neo ^b

HCT 116 ^b

NHDF-Neo ^b

45

46

47

48

53

54

55

56

61

62

63

64

69

70

71

72

77

78

79

80

85

86

87

88

93

94

95

96

101

102

103

104

217.0 ± 4.7

248.8 ± 7.1

229.6 ± 2.6

257.1 ± 7.2

143.0 ± 2.3

168.9 ± 1.0

135.1 ± 7.0

244.8 ± 4.7

328.8 ± 9.0

389.5 ± 4.9

294.7 ± 1.8

499.8 ± 2.7

240.0 ± 2.3

280.9 ± 8.9

290.6 ± 7.0

763.3 ± 5.4

246.2 ± 6.2

119.1 ± 5.6

142.9 ± 2.9

519.2 ± 7.2

239.1 ± 3.0

270.6 ± 7.5

379.8 ± 1.4

272.3 ± 1.2

137.3 ± 2.1

229.8 ± 4.7

217.1 ± 1.5

249.2 ± 5.5

246.2 ± 1.3

369.0 ± 4.7

295.2 ± 8.2

515.7 ± 4.3

196.5 ± 1.9

196.5 ± 3.1

375.6 ± 8.3

231.8 ± 9.6

200.6 ± 1.1

190.4 ± 3.0

221.1 ± 2.4

240.2 ± 3.8

254.8 ± 3.6

233.1 ± 5.8

214.8 ± 1.7

241.9 ± 2.8

105.9 ± 4.1

217.9 ± 5.2

136.0 ± 1.5

317.8 ± 8.5

192.7 ± 3.7

39.1 ± 0.9

405.9 ± 5.7

49

50

51

52

57

58

59

60

65

66

67

68

73

74

75

76

81

82

83

84

89

90

91

92

97

98

99

100

105

106

107

108

>800

605.2 ± 1.3

320.2 ± 4.9

788.8 ± 7.5

>800

-

262.4 ± 1.7

-

214.8 ± 6.4

213.1 ± 3.0

426.8 ± 3.8

-

382.4 ± 2.1

>800

-

>800

216.1 ± 9.7

220.0 ± 2.5

715.2 ± 9.6

-

219.1 ± 2.4

103.6 ± 2.5

480.8 ± 4.4

-

426.1 ± 1.3

>800

112.8 ± 1.6

194.4 ± 0.6

>800

87.9 ± 4.1

384.7 ± 8.3

>800

94.7 ± 0.5

166.3 ± 5.8

226.6 ± 4.0

301.0 ± 4.4

203.8 ± 3.6

129.7 ± 1.8

211.9 ± 1.1

178.9 ± 6.8

95.7 ± 0.02

256.0 ± 9.6

781.2 ± 3.5

297.9 ± 2.1

176.4 ± 1.8

203.6 ± 4.9

177.6 ± 2.6

223.4 ± 8.6

-

382.6 ± 2.4

>800

690.3 ± 4.0

629.0 ± 1.2

>800

113.4 ± 0.9

677.9 ± 2.8

702.6 ± 1.9

-

>800

163.1 ± 1.1

-

>800

595.9 ± 9.0

>800

696,7 ± 1.6

436.3 ± 3.1

-

>800

586.0 ± 5.6

-

630.2 ± 2.7

>800

Cytotoxic was evaluated using the MTT assay; ^bIncubation time 24 h; ^cIncubation time 72 h.

a

As part of the experiments, it was checked whether the building blocks necessary to obtain ﬁnal

glycoconjugates are able to limit the proliferation of cancer cells (Table 6). Sugar derivatives appeared

to be inactive on the tested cell lines. However, the high toxicity of parent compounds

1 and 2 towards

the MCF-7 cancer cell line was observed. A lower IC₅₀value was determined for 8-HQ than for

doxorubicin commonly used in cancer treatment. This observation indicates the huge sensitivity of

this particular cancer cell line to 8-HQ and gives hope for even more eﬀective therapeutics based

on the 8-HQ scaﬀold. In addition, some of the derivatives of 8-HQ 5–10 were toxic to the tested

Molecules 2019, 24, 4181

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cell lines. However, further experiments have shown that they also cause the death of healthy cells.

Therefore, the next studies checked whether the addition of the sugar moiety to aglycon would aﬀect

the selectivity of the obtained glycoconjugates.

The results of the cytotoxicity assay indicate that the glycoconjugates with a deprotected sugar

unit (right part of Table 7 ) are mostly unable to inhibit cell proliferation in the tested concentration

range. This is probably related to their hindered penetration into the cell through the lipid biological

barriers, due to the high hydrophilicity of the compounds, compared to glycoconjugates having acetyl

protecting groups. The exception is compound 81, whose IC₅₀= 112.8

±

1.6 µM for HCT 116 and 87.9

±

4.1 M for MCF-7. For its protected analog 77, the IC₅₀value twice as high was determined for both

µ

tumor cell lines. Most likely, in this case, GLUT transporters had a more important role in transporting

into the cell, and passive transport is less important. Unfortunately, this compound is also toxic to

healthy cells, so it cannot be considered a selective drug.

All glycoconjugates containing ester protection of hydroxyl groups in the sugar part proved

to be active on the tested cancer cell lines in the tested concentration range (left part of Table 7).

Their non-polar nature should facilitate the process of crossing through phospholipid bilayer and

penetrating into the cell, where then intracellular hydrolytic enzymes are able to remove the acetyl

groups. In addition, as opposed to substrates, some of the obtained glycoconjugates showed low

cytotoxicity to NHDF-Neo cells, especially glycoconjugates 45

Moreover, for the HCT 116 cell line, all protected glycoconjugates exhibit higher antiproliferative

activity relative to aglycons and . This fact conﬁrms the accuracy of the assumption that in this

, 46, 85, and 86 derived from quinoline 5.

1

2

case, the presence of the sugar fragment improves the distribution and absorption of the compound,

and thus its activity.

In the beginning, it was decided to check the eﬀect of the length of the linker between the

1,2,3-triazole fragment and the derivative of 8-HQ for glycoconjugate activity (compounds 45

The lowest IC₅₀values were obtained for glycoconjugates 53 56, whose alkyl chain between triazole

and 8-HQ consisted of 3 carbon atoms. However, further elongation of the alkyl chain in the compounds

61 64 resulted in a decrease in the cytotoxic activity of glyconjugates. Therefore, no further chain

extension seems necessary. On the other hand, the alkyl chain extension between the 1,2,3-triazole

ring and the sugar moiety in compounds 69 72 did not signiﬁcantly aﬀect the antiproliferative activity

of glycoconjugates. Noteworthy is compound 71, which turned out to be more active than the

unconjugated quinoline derivative and for which the selectivity index, calculated as the ratio of the

–68).

–

4

IC₅₀value determined for healthy cells to the IC₅₀value determined for tumor cells, equal 5.3 for

MCF-7 lines and 2.5 for HCT 116 lines. This observation makes it interesting in the aspect of further,

more detailed studies involving diﬀerent cell lines.

Glycoconjugates 77

be more active relative to the tested cancer cell lines. Among them, the most promising results were

obtained for compounds 78 and 93. For the MCF-7 cell line, the IC₅₀value equals 39.1 0.9 M and

95.7 0.02

M, respectively. However, for HCT 116 not much higher IC₅₀were noted: 119.1 ± 5.6 µM

and 137.3 2.1 M, respectively. Unfortunately, these compounds were also toxic to healthy cells,

–100 containing an additional amide bond in the linker structure proved to

±

µ

±

µ

±

µ

so they cannot be considered selective drugs. It was noted that compound with 8-HQ fragment usually

showed higher cytotoxicity compared to derivatives with 2Me8HQ unit, while the type of sugar moiety

did not signiﬁcantly aﬀect to the glycoconjugate activity. Importantly, compounds 86–88 did not

show any ability to inhibit the proliferation of healthy cells while having a moderate ability to inhibit

cancer cells.

Recently, an important role in drug design has been played by compounds containing a carbamate

moiety in the structure. Carbamates are usually more stable under enzymatic hydrolysis than the

corresponding esters and are generally more susceptible to hydrolysis than amides. Carbamate

prodrugs have been designed for selective hydrolysis by human carboxylesterases to release active

drugs [56,74]. It appeared that glycoconjugates 101 and 103, based on the D-glucose moiety, showed

Molecules 2019, 24, 4181

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low cytotoxicity to healthy cells while showing signiﬁcant antiproliferative activity against cancer cells.

For these compounds, a selectivity index for the MCF-7 cell line was 3.9 and 3.3 respectively.

2.2.2. Inhibitory Activity Against β-1,4-GalT

Tested cancer cell lines are characterized by overexpression of the

β-1,4-galactosyltransferase

(β-1,4-GalT) [75]. This enzyme belongs to the group of glycosyltransferases (GTs). Due to a number of

important functions that GTs perform, among others: post-translational protein modiﬁcations and

synthesis of oligosaccharide chains, they are an important object of research on potential anticancer

drugs. A high rate of glycosylation is a common disorder of cancer cell metabolism, and the expression

of GTs can be associated with cancer progression. GTs are a group of metal-dependent enzymes,

therefore the presence of a species capable of binding divalent metal ions in the molecule of potential

inhibitor appears to be necessary to inhibit the activity of these enzymes [75,76]. It seems appropriate

to use glycoconjugates derivatives of 8-HQ to coordinate the metal ions present in the active centers of

many enzymes, and thus to inhibit their activity.

It was decided to evaluate the obtained glycoconjugates for their inhibitory activity against enzyme

from the glycosyltransferases group. Therefore, the experiments will be carried out using commercially

available metal-dependent β-1,4-GalT I from bovine milk. To evaluate the activity of tested compounds,

concentrations of substrate and product of the enzymatic reaction in the reaction mixtures was

determined by RP-HPLC method, which is a modiﬁcation of the Vidal method [77]. This method uses

UDP-Gal, a natural β-1,4-GalT donor type substrate and (6-esculetinyl) β-D glucopyranoside (esculine)

as glycosyl ﬂuorescent acceptor. The number of products formed in the reaction with the addition of

glycoconjugates as potential enzyme inhibitors was compared with the number of products in reactions

carried out under the same conditions without the addition of inhibitors (test reactions). Analyzes

were conducted in the linear range of the peak area from the product and substrate concentration.

Experiments were conducted for glycoconjugates solutions at concentrations ranging from 0.1 mM to

0.8 mM. For the most active compounds, IC₅₀values were designated. The results are presented in

Table 8.

Table 8. Bovine milk β-1,4-Galactosyltransferase I assay results.

Compound

Percentage of Inhibition at 0.8 mM [%]

IC₅₀[mM]

49

50

51

52

57

58

59

60

65

66

67

68

73

74

75

76

81

82

83

84

65 ± 0.27

10 ± 0.17

64 ± 0.23

8 ± 0.17

0.57

-

0.60

-

0.40

-

0.40

-

72 ± 0.03

2 ± 0.37

68 ± 0.25

6 ± 0.47

70 ± 0.19

8 ± 0.51

0.46

-

0.35

73 ± 0.03

4 ± 0.45

-

45 ± 0.17

14 ± 0.22

35 ± 0.06

7 ± 0.29

33 ± 0.29

17 ± 0.07

18 ± 0.25

14 ± 0.07

In this study, the inﬂuence of the alkyl chain length between the 1,2,3-triazole fragment and the

8-HQ derivative (49 52, 57 60, 65 68), as well as between the 1,2,3-triazole fragment and the sugar

–

Molecules 2019, 24, 4181

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unit (73

amide bond in the structure of the glycoconjugate linker (81

experience [54], only glycoconjugates with an unprotected sugar part were tested.

Experiments have shown that parent compounds and substrates 10 are not able to inhibit

–76) for enzyme inhibition was tested. In addition, the eﬀect of the presence of an additional

–

84) was analyzed. Based on previous

1

,

2

3–

the enzyme, which may indicate that the sugar fragment is necessary to obtain inhibitory activity.

For glycoconjugates obtained as a result of CuAAC reactions between sugar derivatives containing a

propargyl moiety and quinoline derivatives containing an azide moiety, the results indicate that all

tested glycoconjugates derivatives of D-glucose showed higher activity compared to their analogs

containing the D-galactose unit. However, the type of 8-HQ derivative did not matter in this case.

Considering the eﬀect of linker length between the 1,2,3-triazole fragment and the 8-HQ derivative,

it can be clearly stated that the extension of the alkyl chain increases the inhibition of

β-1,4-GalTI

by glycoconjugates. In this group of compounds (49 52, 57 60, 65 68), all glycoconjugates based on

–

D-glucose moiety showed the ability to inhibit the enzyme by over 50% compared to the test reaction.

However, for compound 67, having four carbon atoms in the alkyl linker, the lowest IC₅₀value was

determined (0.35 mM). It is probable, that an extension of the alkyl chain length between the triazole

ring and quinolone, increases the “ﬂexibility” of the molecule, which may have a better ﬁt into the

active center of the enzyme. Much lower ability to inhibition of the model enzyme was observed for

glycoconjugates that were obtained in the CuAAC reaction of sugar derivatives containing an azide

group and quinoline derivatives containing the propargyl moiety. Glycoconjugates with an ethoxy

fragment between the 1,2,3-triazole and sugar units (73

–

76) were not able to inhibit

β-1,4-GalTI by

50%. However, they showed slightly increased activity compared to glycoconjugates 81

–

84, containing

an additional amide fragment in the structure. The amide fragment is in close distance to the aromatic

moiety, which creates a high rigidity of the molecule and probably makes it diﬃcult to ﬁt into the

active center of the enzyme. Therefore, the addition of an amide fragment is not a good idea for the

design of β-1,4-GalT inhibitors.

2.3. Study of Metal Complexing Properties

Previously it was mentioned that cancer cells exhibit an increased concentration of copper

ions [20–24]. Moreover, it is broadly known that some quinoline derivatives possess metal ions

complexing properties [18] what is essential for their anti-proliferative properties [51]. Bivalent metal

ions are coordinated by phenol oxygen atom as well as nitrogen atom of 8-HQ ring with the formation

of an 8HQ-metal ion complex with stoichiometry 2:1 [78]. In addition, 1,2,3-triazole ring also has a

metal-complexation ability [79]. Therefore, it is interesting if the addition of linker containing such

fragment having metal ions chelation ability into 8-HQ might signiﬁcantly increase the metal ion

complexation capability. The capability of complexes formation by investigated glycoconjugates

and stoichiometry of such complexes was evaluated for compounds 101 and 93 with copper ions by

spectroscopic titration experiments using UV-VIS. The UV-VIS spectrum of 101 is shown in Figure 3a.

The addition of subsequent copper ion portions to glycoconjugate solution results in a gradual lowering

of absorption bands at 242 nm and 310 nm. In addition, increase of the absorption band at 265 nm

was observed. Importantly, during titration two well-deﬁned isosbestic points around 250 nm and

286 nm were noted indicating the glycoconjugate-copper ion complex formation. The stoichiometry of

obtained complexes was determined with Job⁰s plot using the changes in absorption band at 265 nm.

The plotted graph presenting the diﬀerence in absorbance,

∆

A = A_x

−

A₀as a function of molar fraction

[101]/[101 + Cu²⁺] was shown in Figure 3 b. Maximum observed at molar fraction 0.5 in obtained curve

indicates a formation of 1:1 complex of glycoconjugate:copper ion, regardless of the type of linker (see

Supplementary Materials).

ESI-MS spectra showed that copper ions are complexed by investigated glycoconjugates. The ESI-MS

spectrum in positive ions mode of the investigated compound 101 (Figure 4a) revealed the presence

of the ion at m/z = 658.35 (adduct [101 + H]⁺) corresponding to protonated glycoconjugate molecule

and less intensive one corresponding to its sodium adduct, m/z = 680.36 [101 + Na]⁺. Additionally,

Molecules 2019, 24, 4181

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ions of 101₂aggregate (dimer) adducts can be noticed, respectively at m/z = 1314.23 [101₂+ H]⁺,

1337.26 [101₂+ Na]⁺and 1353.19 [101₂+ K]⁺. In the ESI-MS of glycoconjugate partially titrated with

copper ions (Figure 4b) the most abundant peak at m/z = 720.15 correspondings to [101 + Cu(I)]⁺

is visible. The second intensive signal m/z = 658.2 is derived from glycoconjugate still present in

the solution. Moreover the signals at m/z = 1377.17 and at m/z = 360.28 corresponding to dimer

101₂complex with Cu [101₂+ Cu(I)]⁺and complex [101 + Cu(II)]²⁺were observed. The ESI-MS/MS

fragmentation spectrum of the ion with m/z = 1377.17 (see Supplementary Data) reveals only one peak

at m/z = 720 corresponding to complex [101 + Cu(I)]⁺. It conﬁrms that ion at m/z = 1377.17 corresponds

to Cu⁺-dimer complex (101₂is present in the initial solution, see Figure 4 a). Thus, complex with

apparent 2:1 stoichiometry is observed, but in fact, the complex is formed probably only with one of

the 101 molecules of the dimer. Moreover, in the signals ascribed to formed complexes characteristic

two peaks with the diﬀerence of 2 Da are observed. Such spectrum is typical of copper complexes due

to existence of copper in two basic isotopic forms (⁶³Cu (69,17%) and ⁶⁵Cu (30,83%)) [80]. It may seem

surprising that copper(I) complexes are observed in the ESI-MS spectrum since copper(II) was used for

titration. This phenomenon can be explained by a reduction reaction proceeding under the conditions

of the analysis as a result of charge transfer between the metal complexes and the solvent molecules in

the gas-phase [81–83].

Figure 3.

(a)—UV spectrum of compound 101 with the addition of copper sulfate pentahydrate in

methanol; (b)—Job⁰s plot of 101 with Cu²⁺. The absorbance was monitored at 265 nm.

Figure 4. Cont.

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Figure 4. ESI-MS (positive-ion mode) spectrum of (a) 101 compound and (b) 101 compound after

addition of Cu²⁺ions into 101 solution.

3. Materials and Methods

3.1. General Information

NMR spectra were recorded with an Agilent spectrometer at a frequency of 400 MHz using TMS

or DSS as the internal standards and CDCl₃, CD₃OD, DMSO-d6 or D₂O as the solvents. NMR solvents

were purchased from ACROS Organics (Geel, Belgium). Chemical shifts (δ) are expressed in ppm

and coupling constants (J) in Hz. The following abbreviations were used to explain the observed

multiplicities: s: singlet, d: doublet, dd: doublet of doublets, ddd: doublet of doublet of doublets,

t: triplet, dd-t: doublet of doublets resembling a triplet (with similar values of coupling constants), m:

multiplet, p: pentet (quintet), b: broad. High-resolution mass spectra (HRMS) were recorded with a

WATERS LCT Premier XE system using the electrospray-ionization (ESI) technique. Optical rotations

were measured with a JASCO P-2000 polarimeter using a sodium lamp (589.3 nm) at room temperature.

Melting point measurements were performed on OptiMelt (MPA 100) Stanford Research Systems.

Reactions were monitored by thin-layer chromatography (TLC) on precoated plates of silica gel 60 F254

(Merck Millipore, Burlington, MA, USA). The TLC plates were visualized under UV light (λ = 254 nm)

or by charring the plates after spraying with 10% solution of sulfuric acid in ethanol. Crude products

were puriﬁed using column chromatography performed on Silica Gel 60 (70–230 mesh, Fluka, St. Louis,

MI, USA), developed using toluene:EtOAc or CHCl₃:MeOH as solvent systems. All evaporations were

performed on a rotary evaporator under diminished pressure at 40 ^◦C. Reversed-phase HPLC analyses

were performed using JASCO LC 2000 apparatus equipped with a reverse-phase column (Nucleosil

100 C18.5

µ

m, 25

×

0.4 cm; mobile phase: H₂O/MeCN 90:10, ﬂow rate 0.8 mL/min) with a ﬂuorescence

detector (FP). Fluorescence for substrate and product was read at 385 nm excitation/540 nm emission.

The absorbance on MTT assay was measured spectrophotometrically at the 570 nm wavelength using

a plate reader (Epoch, BioTek, USA).

All of the chemicals used in the experiments were purchased from Sigma- Aldrich, ACROS Organics,

Fluka and Avantor and were used without purification. 8- Hydroxyquinoline

1, 8-hydroxyquinaldine

2

, D-glucose 11 and D-galactose 12 are commercially available (Sigma-Aldrich). 8-(2-Propyn-1-

yloxy)quinoline

glucopyranose 13

-D-glucopyranosyl bromide 1

2,3,4,6-tetra-O-acetyl- -D-glucopyranosyl azide 1

3

[

57], 2-methyl-8-(2-propyn-1-yloxy)quinoline

54], 1,2,3,4,6-penta-O-acetyl- -D-galactopyranose 14

54], 2,3,4,6-tetra-O-acetyl-

4

[

57], 1,2,3,4,6-penta-O-acetyl-

β

-D-

β

[

54], 2,3,4,6-tetra-O-acetyl-

α

5

[

α

-D-galactopyranosyl bromide 16 [

54],

β

7

[54], 2,3,4,6-tetra-O-acetyl-

β-D-galactopyranosyl

Molecules 2019, 24, 4181

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azide 1

galactopyranosyl amine 20

propargyl 2,3,4,6-tetra-O-acetyl-

-D-glucopyranoside 25 62], 2-bromoethyl 2,3,4,6-tetra-O-acetyl-

azidoethyl 2,3,4,6-tetra-O-acetyl- -D-glucopyranoside 27 62], 2-azidoethyl 2,3,4,6-tetra-O-acetyl-

62], 2,3,4,6-tetra-O-acetyl-N-( -D-glucopyranosyl)propiolamide 37 65],

-D-galactopyranosyl)propiolamide 38 65], 2,3,4,6-tetra-O-acetyl-N-( -D-

66] and 2,3,4,6-tetra-O-acetyl-N-( -D-galactopyranosyl)-O-

66] were prepared according to the respective published procedures. Propargyl

-D-glucopyranoside 23, propargyl -D-galactopyranoside 24, 2-azidoethyl -D-glucopyranoside

-D-galactopyranoside 30, N-( -D-glucopyranosyl)azidoacetamide 35, N-(

N-( -D-glucopyranosyl)propiolamide 39 N-(

-D- glucopyranosyl)-O-propargyl carbamate 43, N-(

8

[

54], 2,3,4,6-tetra-O-acetyl-

60], propargyl 2,3,4,6-tetra-O-acetyl-

-D-galactopyranoside 22 61], 2-bromoethyl 2,3,4,6-tetra-O-acetyl-

-D-galactopyranoside 26 62], 2-

β

-D-glucopyranosyl amine 19

[

β

60], 2,3,4,6-tetra-O-acetyl-

-D-glucopyranoside 21

β

-D-

[

61],

β

[

β

[

β

[

β

[

β-

D-galactopyranoside 28

2,3,4,6-tetra-O-acetyl-N-(

[

β

[

β

[

glucopyranosyl)-O-propargyl carbamate 41

propargyl carbamate 42

[

β

[

β

29, 2-azidoethyl

galactopyranosyl)azidoacetamide 36

galactopyranosyl)propiolamide 40 N- (

β

β-D-

,

β

,

β

galactopyranosyl)-O-propargyl carbamate 44 were obtained by Zemplén protocol [67] by deacetylation

of the corresponding sugar derivatives.

3.2. Chemistry

3.2.1. General Procedure for the Synthesis of Quinoline Derivatives 5–10

To a solution of 1,2-dibromoethane or 1,3-dibromopropane or 1,4-dibromobutane (23.1 mmol)

in dry DMF (10 mL), sodium azide (23.1 mmol, 1.5 g) was added. The reaction mixture was stirred

overnight at 50 ^◦C. Afterwards, the reaction mixture was diluted with ether and the organic layer was

washed (three times) with H₂O (3

sulfate (MgSO₄), concentrated under vacuum to aﬀord the corresponding azide as a clear oil, which

was used in the next reaction without further puriﬁcation.

×

10 mL). The organic layer was dried over anhydrous magnesium

Obtained 1-azido-2-bromoethane or 1-azido-3-bromopropane or 1-azido-4-bromobutane (4.0 mmol),

was added to a solution of 8-hydroxyquinoline

1 or 8-hydroxyquinaldine 2 (4.0 mmol) in acetone

(20 mL), followed by addition of potassium carbonate (10.0 mmol, 1.38 g). The reaction mixture was

heated under reﬂux for 4 h and then at room temperature overnight. After completion, the reaction

mixture was ﬁltered oﬀ and the ﬁltrate was concentrated under vacuum and puriﬁed by column

chromatography (toluene:AcOEt; gradient 20:1 to 2:1) to give products 5–10.

8-(2-Azidoethoxy)quinolone

5

: Starting from 1-azido-2-bromoethane and 8-hydroxyquinoline

1

,

24

product was obtained as a brown oil (702.7 mg, 82%); [

CDCl₃):

α

]

=

0.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz,

−

D

δ

3.87 (t, 2H, J = 5.6 Hz, CH₂N), 4.43 (t, 2H, J = 5.6 Hz, CH₂O), 7.12 (dd, 1H, J = 2.5 Hz, J =

6.5 Hz, H-7_chin), 7.41–7.50 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.14 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin),

8.96 (dd, 1H, J = 1.7 Hz, J = 4.2 Hz, H-2_chin); ¹³C NMR (100 MHz, CDCl₃):

δ 50.06, 67.64, 109.77, 120.66,

121.70, 126.52, 129.61, 135.95, 140.39, 149.51, 154.19.

8-(3-Azidopropoxy)quinolone

6

: Starting from 1-azido-3-bromopropane and 8-hydroxyquinoline

1

,

24

product was obtained as a brown oil (684.7 mg, 75%); [

CDCl₃):

α

]

=

0.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz,

−

D

δ

2.28 (p, 2H, J = 6.4 Hz, CH₂), 3.65 (t, 2H, J = 6.6 Hz, CH₂N), 4.33 (t, 2H, J = 6.2 Hz, CH₂O),

7.09 (dd, 1H, J = 1.4 Hz, J = 7.5 Hz, H-7_chin), 7.38–7.49 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.13 (dd,

1H, J = 1.8 Hz, J = 8.3 Hz, H-4_chin), 8.95 (dd, 1H, J = 1.8 Hz, J = 4.2 Hz, H-2_chin); ¹³C NMR (100 MHz,

CDCl₃): δ 28.67, 48.44, 65.70, 109.08, 119.97, 121.62, 126.69, 129.55, 136.04, 140.28, 149.31, 154,50.

8-(4-Azidobutoxy)quinoline

7

: Starting from 1-azido-4-bromobutane and 8-hydroxyquinoline

1

,

23

product was obtained as a brown oil (736.5 mg, 76%); [

CDCl₃):

4.29 (t, 2H, J = 6.5 Hz, CH₂O), 7.07 (dd, 1H, J = 1.2 Hz, J = 7.6 Hz, H-7_chin), 7.37–7.49 (m, 3H, H-3_chin

H-5_chin, H-6_chin), 8.14 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.95 (dd, 1H, J = 1.7 Hz, J = 4.2 Hz,

α

]

=

−

0.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz,

D

δ

1.90 (p, 2H, J = 7.0 Hz, CH₂), 2.11 (p, 2H, J = 6.5 Hz, CH₂), 3.42 (t, 2H, J = 6.9 Hz, CH₂N),

,

Molecules 2019, 24, 4181

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H-2_chin); ¹³C NMR (100 MHz, CDCl₃):

136.06, 140.26, 149.28, 154,59.

δ

25.86, 26.31, 51.29, 68.26, 108.90, 119.72, 121.58, 126.71, 129.56,

2-Methyl-8-(2-azidoethoxy)quinolone

8

: Starting from 1-azido-2-bromoethane and 2-methylo-8-

23

hydroxyquinoline

2

, product was obtained as a brown oil (757.8 mg, 83%); [

α

]

= 0.4 (c = 1.0,

−

D

CHCl₃); ¹H NMR (400 MHz, CDCl₃):

δ

2.79 (s, 3H, CH₃), 3.83 (t, 2H, J = 5.5 Hz, CH₂N), 4.43 (t, 2H, J =

5.5 Hz, CH₂O), 7.10 (dd, 1H, J = 2.6 Hz, J = 6.4 Hz, H-7_chin), 7.31 (d, 1H, J = 8.4 Hz, H-3_chin), 7.35–7.44

(m, 2H, H-5_chin, H-6_chin), 8.03 (d, 1H, J = 8.4 Hz, H-4_chin); ¹³C NMR (100 MHz, CDCl₃):

δ 25.66, 50.19,

68.05, 110.41, 120.62, 122.57, 125.49, 127.82, 136.00, 140.06, 153.78, 158,36.

2-Methyl-8-(3-azidopropoxy)quinolone

hydroxyquinoline , product was obtained as a brown oil (688.1 mg, 71%); [

CHCl₃); ¹H NMR (400 MHz, CDCl₃):

2.28 (p, 2H, J = 6.5 Hz, CH₂), 2.78 (s, 3H, CH₃), 3.65 (t, 2H, J =

9: Starting from 1-azido-3-bromopropane and 2-methylo-8-

24

2

α

]

= −0.6 (c = 1.0,

D

δ

6.6 Hz, CH₂N), 4.33 (t, 2H, J = 6.3 Hz, CH₂O), 7.07 (dd, 1H, J = 2.4 Hz, J = 6.5 Hz, H-7_chin), 7.30 (d,

1H, J = 8.4 Hz, H-3_chin), 7.33–7.42 (m, 2H, H-5_chin, H-6_chin), 8.01 (d, 1H, J = 8.4 Hz, H-4_chin); ¹³C NMR

(100 MHz, CDCl₃):

154.01, 158,18.

δ 25.71, 28.64, 48.48, 66.03, 109.73, 119.95, 122.52, 125.65, 127.76, 136.11, 140.00,

2-Methyl-8-(4-azidobutoxy)quinoline 10: Starting from 1-azido-4-bromobutane and 2-methylo-8-

22

hydroxyquinoline

2

, product was obtained as a brown oil (707.4 mg, 69%); [

α

]

= 0.6 (c = 1.0,

−

D

CHCl₃); ¹H NMR (400 MHz, CDCl₃):

δ

1.89 (p, 2H, J = 7.0 Hz, CH₂), 2.10 (p, 2H, J = 6.7 Hz, CH₂), 2.78

(s, 3H, CH₃), 3.45 (t, 2H, J = 6.9 Hz, CH₂N), 4.27 (t, 2H, J = 6.5 Hz, CH₂O), 7.03 (dd, 1H, J = 1.8 Hz, J =

7.1 Hz, H-7_chin), 7.29 (d, 1H, J = 8.4 Hz, H-3_chin), 7.32–7.41 (m, 2H, H-5_chin, H-6_chin), 8.00 (d, 1H, J =

8.4 Hz, H-4_chin); ¹³C NMR (100 MHz, CDCl₃): δ 25.71, 25.89, 26.24, 51.36, 68.46, 109.35, 119.66, 122.49,

125.64, 127.74, 136.08, 139.91, 154.13, 158,13.

3.2.2. General Procedure for the Synthesis of Sugar Derivatives 31 and 32

To a solution of 2,3,4,6-tetra-O-acetyl-

-D-galactopyranosyl amine 20 (1.7 g, 4.9 mmol) in dry CH₂CL₂(20 mL), triethylamine (2 mL) was

added. The reaction mixture was cooled to 0 ^◦C and chloroacetyl chloride was added dropwise (613

L,

7.7 mmol) then stirring was continued at room temperature. After 1 h, the resulting mixture was diluted

with dichloromethane (90 mL) and washed with brine (2 60 mL). The combined organic layer was

β-D-glucopyranosyl amine 19 or 2,3,4,6-tetra-O-acetyl-

β

µ

×

dried over anhydrous MgSO₄, concentrated under vacuum and puriﬁed by column chromatography

(toluene:AcOEt; gradient 8:1 to 2:1) to give products 31–32.

2,3,4,6-Tetra-O-acetyl-N-(

β

β-D-glucopyranosyl)chloroacetamide 31: Starting from 2,3,4,6-tetra-O-acetyl-

-D-glucopyranosyl amine 19, product was obtained as a white solid (1.41 g, 68%); m.p.: 160–163 ^◦C;

24

[

α

]

= 8.3 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

δ 2.03, 2.04, 2.06, 2.09 (4s, 12H, CH₃CO),

D

3.84 (ddd, 1H, J = 2.1 Hz, J = 4.4 Hz, J = 10.1 Hz, H-5_glu), 4.00 and 4.07 (qAB, 2H, J = 15.4 Hz, CH₂Cl),

4.10 (dd, 1H, J = 2.1 Hz, J = 12.5 Hz, H-6a_glu), 4.31 (dd, 1H, J = 4.4 Hz, J = 12.5 Hz, H-6b_glu), 5.01 (dd-t,

1H, J = 9.4 Hz, J = 10.0 Hz, H-1_glu), 5.09 (dd-t, 1H, J = 9.4 Hz, J = 10.1 Hz, H-4_glu), 5.21 (dd-t, 1H, J =

9.0 Hz, J = 9.4 Hz, H-3_glu), 5.33 (dd-t, 1H, J = 9.0 Hz, J = 9.4 Hz, H-2_glu), 7.29 (d, 1H, J = 9.0 Hz, CONH);

¹³C NMR (100 MHz, CDCl₃):

δ 20.57, 20.61, 20.72, 20.76, 42.25, 61.56, 68.09, 70.26, 72.55, 73.83, 78.54,

166.81, 169.49, 169.87, 170.58, 170.79; HRMS (ESI-TOF): calcd for C₁₆H₂₂ClNO₁₀Na ([M + Na]⁺): m/z

446.0830; found: m/z 446.0834.

2,3,4,6-Tetra-O-acetyl-N-(β-D-galactopyranosyl)chloroacetamide 32: Starting from 2,3,4,6-tetra-O-

acetyl-β-_◦D-galactopyranosyl amine 20, product was obtained as a white solid (1.66 g, 80%); m.p.:

= 21.3 (c = 1.0, CHCl₃); H NMR (400 MHz, CDCl₃): δ 2.01, 2.04, 2.07, 2.16 (4s,

D

25

1

143-144 C; [

α

]

12H, CH₃CO), 4.01 and 4.08 (qAB, 2H, J = 15.5 Hz, CH₂Cl), 4.04-4.18 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal),

5.11-5.24 (m, 3H, H-1_gal, H-2_gal, H-3_gal), 5.45 (dd, 1H, J = 0. 7 Hz, J = 3.0 Hz, H-4_gal), 7.32 (d, 1H, J =

6.9 Hz, CONH); ¹³C NMR (100 MHz, CDCl₃):

δ 20.54, 20.61, 20.67, 20.71, 42.26, 61.12, 67.10, 67.97,

Molecules 2019, 24, 4181

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70.72, 72.58, 78.84, 166.71, 169.76, 170.01, 170.34, 171.06; HRMS (ESI-TOF): calcd for C₁₆H₂₂ClNO₁₀Na

([M + Na]⁺): m/z 446.0830; found: m/z 446.0832.

3.2.3. General Procedure for the Synthesis of Sugar Derivatives 33 and 34

To a solution of 2,3,4,6-tetra-O-acetyl-N-(

β-D-glucopyranosyl)chloroacetamide 31 or 2,3,4,6-tetra-O-

acetyl-N-( -D-galactopyranosyl)chloroacetamide 32 (1.0 g, 2.36 mmol) in dry DMF (15 mL), sodium

β

azide (753 mg, 11.59 mmol) was added. The reaction mixture was stirred at room temperature for

24 h. After completion reaction, the solvent was evaporated under reduced pressure, and the residue

was diluted with ethyl acetate (50 mL) and extracted with water (30 mL), 0.25 M HCl (20 mL) and

brine (20 mL). The combined organic layer was dried over anhydrous MgSO₄, concentrated under

vacuum, to aﬀord the corresponding azide 33 and 34, which were used for the next reaction without

further puriﬁcation.

2,3,4,6-tetra-O-acetyl-N-(

N-( -D-glucopyranosyl)chloroacetamide 31, product was obtained as a white solid (975.0 mg, 96%);

m.p.: 150-153 ^◦C; [ = 12.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

δ 2.03, 2.04, 2.06, 2.09 (4s,

D

β-D-glucopyranosyl)azidoacetamide 33: Starting from 2,3,4,6-tetra-O-acetyl-

β

24

α

]

12H, CH₃CO), 3.83 (ddd, 1H, J = 2.1 Hz, J = 4.4 Hz, J = 10.1 Hz, H-5_glu), 3.95 and 4.00 (qAB, 2H, J =

16.9 Hz, CH₂N), 4.09 (dd, 1H, J = 2.1 Hz, J = 12.5 Hz, H-6a_glu), 4.30 (dd, 1H, J = 4.4 Hz, J = 12.5 Hz,

H-6b_glu), 4.98 (dd-t, 1H, J = 9.4 Hz, J = 9.8 Hz, H-1_glu), 5.08 (dd-t, 1H, J = 9.4 Hz, J = 10.1 Hz, H-4_glu),

5.22 (dd-t, 1H, J = 9.0 Hz, J = 9.4 Hz, H-3_glu), 5.32 (dd-t, 1H, J = 9.0 Hz, J = 9.8 Hz, H-2_glu), 7.10 (d, 1H, J

= 9.1 Hz, CONH); ¹³C NMR (100 MHz, CDCl₃):

δ 20.57, 20.61, 20.72, 20.75, 52.59, 61.56, 68.08, 70.45,

72.57, 73.78, 78.15, 167.41, 169.50, 169.86, 170.57, 170.88; HRMS (ESI-TOF): calcd for C₁₆H₂₂N₄O₁₀Na

([M + Na]⁺): m/z 453.1234; found: m/z 453.1236.

2,3,4,6-tetra-O-acetyl-N-(

N-( -D-galactopyranosyl)chloroacetamide 32, product was obtained as a white solid (873.5 mg, 86%);

m.p.: 60–63 ^◦C; [ _D= 25.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

] δ 2.01, 2.04, 2.07, 2.16 (4s,

β-D-galactopyranosyl)azidoacetamide 34: Starting from 2,3,4,6-tetra-O-acetyl-

β

24

α

12H, CH₃CO), 3.96 and 4.01 (qAB, 2H, J = 16.8 Hz, CH₂N), 4.02–4.17 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal),

5.11–5.25 (m, 3H, H-1_gal, H-2_gal, H-3_gal), 5.45 (dd, 1H, J = 1.1 Hz, J = 2.9 Hz, H-4_gal), 7.13 (d, 1H, J =

8.5 Hz, CONH); ¹³C NMR (100 MHz, CDCl₃):

δ 20.54, 20.60, 20.67, 20.70, 52.61, 61.14, 67.11, 68.17,

70.73, 72.52, 78.43, 167.31, 169.76, 170.00, 170.35, 171.15; HRMS (ESI-TOF): calcd for C₁₆H₂₂N₄O₁₀Na

([M + Na]⁺): m/z 453.1234; found: m/z 453.1227.

3.2.4. Synthesis of Glycoconjugates 45–108

The appropriate derivatives of 8-hydoxyquinoline 3–10 (0.5 mmol) and sugar derivatives 21

30 33 44 (0.5 mmol) were dissolved in dry THF (5 mL) and i-PrOH (5 mL). To the obtained

solution, CuSO₄5H₂O (0.1 mmol, 25.0 mg) dissolved in H₂O (2.5 mL) and sodium ascorbate (0.2 mmol,

–24,

27

–

,

–

·

39.6 mg) dissolved in H₂O (2.5 mL) were added. The reaction mixture was stirred for 24 h at room

temperature. The progress of the reaction was monitored on TLC in an CHCl₃:CH₃OH eluents system

(20:1 for protected or 2:1 for unprotected compounds). After completion, the reaction mixture was

concentrated in vacuo and puriﬁed using column chromatography (dry loading; toluene:AcOEt, 2:1

and CHCl₃:MeOH, 100:1 for fully protected glycoconjugates or CHCl₃:MeOH, gradient: 50:1 to 2:1 for

glycoconjugates with unprotected sugar part) to give products 45–108.

Glycoconjugate 45: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-glucopyranoside 21 and

, product was obtained as a yellow solid (219.2 mg, 73%); m.p.: 130–133 ^◦C;

36.0 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.84, 1.97, 2.01, 2.07 (4s, 12H, CH₃CO),

8-(2-azidoethoxy)quinoline

5

24

[

α

]

−

D

3.66 (ddd, 1H, J = 2.3 Hz, J = 4.6 Hz, J = 9.8 Hz, H-5_glu), 4.10 (dd, 1H, J = 2.3 Hz, J = 12.3 Hz, H-6a_glu),

4.21 (dd, 1H, J = 4.6 Hz, J = 12.3 Hz, H-6b_glu), 4.63 (d, 1H, J = 8.0 Hz, H-1_glu), 4.59–4.70 (m, 2H, CH₂N),

4.80 and 4.88 (qAB, 2H, J = 12.7 Hz, CH₂C), 4.95 (dd, 1H, J = 8.0 Hz, J = 9.4 Hz H-2_glu), 5.01 (t, 2H, J

= 5.2 Hz, CH₂O), 5.04 (dd-t, 1H, J = 9.4 Hz, J = 9.8 Hz, H-4_glu), 5.13 (dd-t, 1H, J = 9.4 Hz, J = 9.4 Hz,

H-3_glu), 7.05 (dd, 1H, J = 2.1 Hz, J = 6.4 Hz, H-7_chin), 7.42–7.55 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.21

Molecules 2019, 24, 4181

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(d, 1H, J = 8.1 Hz, H-4_chin), 8.27 (s, 1H, H-5_triaz), 8.99 (d, 1H, J = 2.9 Hz, H-2_chin); ¹³C NMR (100 MHz,

CDCl₃): 20.47, 20.48, 20.59, 20.75, 49.75, 61.84, 62.40, 67.89, 68.34, 71.17, 71.82, 72.86, 99.32, 110.31,

δ

121.07, 121.95, 125.10, 126.87, 129.65, 136.68, 139.55, 143.93, 149.26, 153.45, 169.36, 169.40, 170.18, 170.66;

HRMS (ESI-TOF): calcd for C₂₈H₃₃N₄O₁₁([M + H]⁺): m/z 601.2146; found: m/z 601.2148.

Glycoconjugate 46: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-galactopyranoside 22 and

, product was obtained as a yellow solid (222.2 mg, 74%); m.p.: 69–72 ^◦C;

30.0 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.85, 1.95, 2.05, 2.13 (4s, 12H, CH₃CO),

8-(2-azidoethoxy)quinoline

5

24

[

α

]

−

D

3.83-3.92 (m, 1H, H-5_gal), 4.10-4.16 (m, 2H, H-6a_gal, H-6b_gal), 4.60 (d, 1H, J = 8.0 Hz, H-1_gal), 4.62–4.69

(m, 2H, CH₂N), 4.79 and 4.90 (qAB, 2H, J = 12.6 Hz, CH₂C), 4.94 (dd, 1H, J = 3.4 Hz, J = 10.4 Hz

H-3_gal), 4.97-5.05 (m, 2H, CH₂O), 5.17 (dd, 1H, J = 8.0 Hz, J = 10.4 Hz, H-2_gal), 5.35 (dd, 1H, J = 0.7 Hz,

J = 3.4 Hz, H-4_gal), 6.99–7.12 (m, 1H, H-7_chin), 7.38–7.58 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.12–8.34

(m, 2H, H-4_chin, H-5_triaz), 8.99 (bs, 1H, H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.26, 20.28, 20.35,

20.47, 49.18, 61.17, 61.76, 67.25, 67.43, 68.53, 69.91, 70.19, 98.99, 110.74, 120.57, 121.98, 124.93, 126.84,

129.15, 136.26, 139.30, 143.07, 149.00, 153.50, 169.03, 169.41, 169.85, 169.88; HRMS (ESI-TOF): calcd for

C₂₈H₃₃N₄O₁₁([M + H]⁺): m/z 601.2146; found: m/z 601.2145.

Glycoconjugate 47: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-glucopyranoside 21 and

, product was obtained as a yellow solid (307.3 mg, 100%); m.p.:

32.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.83, 1.91, 1.98, 2.02

2-methyl-8-(2-azidoethoxy)quinoline

8

24

119-123 ^◦C; [

α

]

−

D

(4s, 12H, CH₃CO), 2.69 (s, 3H, CH₃), 3.93 (ddd, 1H, J = 2.4 Hz, J = 4.9 Hz, J = 10.0 Hz, H-5_glu), 4.01

(dd, 1H, J = 2.4 Hz, J = 12.3 Hz, H-6a_glu), 4.15 (dd, 1H, J = 4.9 Hz, J = 12.3 Hz, H-6b_glu), 4.59 (t, 2H, J =

4.9 Hz, CH₂N), 4.65 and 4.81 (qAB, 2H, J = 12.3 Hz, CH₂C), 4.74 (dd, 1H, J = 8.0 Hz, J = 9.6 Hz H-2_glu),

4.87 (d, 1H, J = 8.0 Hz, H-1_glu), 4.86–4.95 (m, 3H, CH₂O, H-4_glu), 5.20 (dd-t, 1H, J = 9.6 Hz, J = 9.6 Hz,

H-3_glu), 7.20 (dd, 1H, J = 1.2 Hz, J = 7.7 Hz, H-7_chin), 7.39-7.46 (m, 2H, H-3_chin, H-6_chin), 7.50 (dd, 1H, J

= 1.2 Hz, J = 8.2 Hz, H-5_chin), 8.20 (d, 1H, J = 8.4 Hz, H-4_chin), 8.59 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz,

DMSO-d6):

δ 20.15, 20.22, 20.34, 20.46, 25.01, 49.18, 61.60, 61.90, 67.58, 68.04, 70.58, 70.80, 72.05, 98.51,

111.21, 120.48, 122.52, 125.45, 125.65, 127.35, 136.04, 139.29, 142.89, 153.20, 157.55, 168.88, 169.20, 169.45,

169.99; HRMS (ESI-TOF): calcd for C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z 615.2302; found: m/z 615.2304.

Glycoconjugate 48: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-galactopyranoside 22 and

, product was obtained as a yellow solid (218.2 mg, 71%); m.p.:

20.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.83, 1.89, 2.01, 2.11 (4s,

2-methyl-8-(2-azidoethoxy)quinoline

8

23

52–56 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.69 (s, 3H, CH₃), 3.99–4.10 (m, 2H, H-5_gal, H-6a_gal), 4.13–4.21 (m, 1H, H-6b_gal), 4.59 (t,

2H, J = 5.0 Hz, CH₂N), 4.64 and 4.81 (qAB, 2H, J = 12.3 Hz, CH₂C), 4.79 (d, 1H, J = 8.0 Hz, H-1_gal),

4.86–4.97 (m, 3H, CH₂O, H-2_gal), 5.11 (dd, 1H, J = 0.9 Hz, J = 10.3 Hz, H-4_gal), 5.24 (dd, 1H, J = 3.6 Hz, J

= 10.3 Hz, H-3_gal), 7.20 (dd, 1H, J = 1.2 Hz, J = 7.7 Hz, H-7_chin), 7.38-7.47 (m, 2H, H-3_chin, H-6_chin), 7.50

(dd, 1H, J = 1.2 Hz, J = 8.2 Hz, H-5_chin), 8.21 (d, 1H, J = 8.4 Hz, H-4_chin), 8.60 (s, 1H, H-5_triaz); ¹³C NMR

(100 MHz, DMSO-d6):

δ 20.25, 20.28, 20.35, 20.47, 25.01, 49.19, 61.19, 61.76, 67.26, 67.59, 68.53, 69.89,

70.20, 98.94, 111.22, 120.48, 122.52, 125.40, 125.66, 127.35, 136.04, 139.31, 142.97, 153.21, 157.56, 168.98,

169.40, 169.85, 169.89; HRMS (ESI-TOF): calcd for C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z 615.2302; found: m/z

615.2303.

Glycoconjugate 49: Starting from propargyl

β

-D-glucopyranoside 23 and 8-(2-azidoethoxy)quinoline

25

5

, product was obtained as a yellow solid (205.4 mg, 95%); m.p.: 42-45 ^◦C; [

α

]

= −17.2 (c = 1.0,

D

MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 2.92-3.09 (m, 2H, H-2_glu, H-5_glu), 3.10-3.17 (m, 2H, H-3_glu,

H-4_glu), 3.40–3.50 (m, 1H, H-6a_glu), 3.66–3.75 (m, 1H, H-6b_glu), 4.08 (bs, 1H, OH), 4.27 (d, 1H, J = 7.8 Hz,

H-1_glu), 4.57 (bs, 1H, OH), 4.60–4.66 (m, 3H, CH₂N, CH₂C), 4.83–4.95 (m, 4H, CH₂O, CH₂C, OH), 5.02

(bs, 1H, OH), 7.25 (dd, 1H, J = 1.5 Hz, J = 7.5 Hz, H-7_chin), 7.47–7.58 (m, 3H, H-3_chin, H-5_chin, H-6_chin),

8.32 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.40 (s, 1H, H-5_triaz), 8.89 (dd, 1H, J = 1.7 Hz, J = 4.2 Hz,

H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ 49.12, 61.15, 61.47, 67.36, 70.10, 73.37, 76.70, 76.94, 102.14,

Molecules 2019, 24, 4181

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110.57, 120.51, 121.91, 124.96, 126.71, 129.08, 135.85, 139.69, 143.78, 149.27, 153.68; HRMS (ESI-TOF):

calcd for C₂₀H₂₅N₄O₇([M + H]⁺): m/z 433.1723; found: m/z 433.1723.

Glycoconjugate 50: Starting from propargyl

5

β

-D-galactopyranoside 24 and 8-(2-azidoethoxy)quinoline

, product was obtained as a yellow solid (144.9 mg, 67%); m.p.: 44–45 ^◦C; [

α

]

= −12.9 (c = 1.0,

23

D

MeOH); ¹H NMR (400 MHz, DMSO-d6): δ 3.21–3.39 (m, 3H, H-2_gal, H-3_gal, H-4_gal), 3.40–3.48 (m, 1H,

H-5_gal), 3.50–3.57 (m, 1H, H-6a_gal), 3.59–3.66 (m, 1H, H-6b_gal), 4.21 (d, 1H, J = 7.4 Hz, H-1_gal), 4.61 and

4.83 (qAB, 2H, J = 12.2 Hz, CH₂C), 4.63 (t, 2H, J = 5.2 Hz, CH₂N), 4.90 (t, 2H, J = 5.2 Hz, CH₂O), 7.25

(dd, 1H, J = 1.5 Hz, J = 7.5 Hz, H-7_chin), 7.47–7.58 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.32 (dd, 1H, J =

1.7 Hz, J = 8.3 Hz, H-4_chin), 8.40 (s, 1H, H-5_triaz), 8.89 (dd, 1H, J = 1.7 Hz, J = 4.2 Hz, H-2_chin); ¹³C NMR

(100 MHz, DMSO-d6):

δ 49.11, 60.52, 61.31, 67.37, 68.18, 70.44, 73.40, 75.32, 102.69, 110.58, 120.51, 121.92,

124.91, 126.70, 129.07, 135.83, 139.70, 143.85, 149.30, 153.69; HRMS (ESI-TOF): calcd for C₂₀H₂₅N₄O₇

([M + H]⁺): m/z 433.1723; found: m/z 433.1725.

Glycoconjugate 51: Starting from propargyl

quinoline

(c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-glucopyranoside 23 and 2-methyl-8-(2-azidoethoxy)

24

8

, product was obtained as a yellow solid (196.4 mg, 88%); m.p.: 120–121 ^◦C; [

α

]

= 20.0

−

D

δ

2.69 (s, 3H, CH₃), 2.92–3.08 (m, 2H, H-2_glu, H-5_glu),

3.09-3.19 (m, 2H, H-3_glu, H-4_glu), 3.40–3.49 (m, 1H, H-6a_glu), 3.66–3.73 (m, 1H, H-6b_glu), 4.09 (bs, 1H,

OH), 4.27 (d, 1H, J = 7.8 Hz, H-1_glu), 4.33 (bs, 1H, OH), 4.53 (t, 1H, J = 5.6 Hz, OH), 4.60 (t, 2H, J =

5.2 Hz, CH₂N), 4.63 and 4.87 (qAB, 2H, J = 12.1 Hz, CH₂C), 4.89 (t, 2H, J = 5.2 Hz, CH₂O), 4.99 (d,

1H, J = 4.9 Hz, OH), 7.21 (dd, 1H, J = 1.3 Hz, J = 7.7 Hz, H-7_chin), 7.39–7.45 (m, 2H, H-3_chin, H-6_chin),

7.50 (dd, 1H, J = 1.2 Hz, J = 8.2 Hz, H-5_chin), 8.20 (d, 1H, J = 8.4 Hz, H-4_chin), 8.54 (s, 1H, H-5_triaz); ¹³

NMR (100 MHz, DMSO-d6): 25.11, 49.11, 61.14, 61.48, 67.56, 70.08, 73.35, 76.70, 76.93, 102.19, 111.16,

C

δ

120.45, 122.54, 125.21, 125.66, 127.35, 136.01, 139.28 143.77, 153.21, 157.61; HRMS (ESI-TOF): calcd for

C₂₁H₂₇N₄O₇([M + H]⁺): m/z 447.1880; found: m/z 447.1882.

Glycoconjugate 52: Starting from propargyl

quinoline

c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranoside 24 and 2-methyl-8-(2-azidoethoxy)

24

8

, product was obtained as a yellow solid (174.1 mg, 78%); m.p.: 52–54 ^◦C; [

α

]

= −15.0

D

(

δ 2.69 (s, 3H, CH₃), 3.21–3.38 (m, 4H, H-2_gal, H-3_gal,

H-4_gal, H-5_gal), 3.49–3.57 (m, 1H, H-6a_gal), 3.60–3.66 (m, 1H, H-6b_gal), 4.22 (d, 1H, J = 7.3 Hz, H-1_gal),

4.32 (d, 1H, J = 4.5 Hz, OH), 4.58 (t, 1H, J = 5.6 Hz, OH), 4.60 (t, 2H, J = 5.2 Hz, CH₂N), 4.60 and 4.87

(qAB, 2H, J = 12.0 Hz, CH₂C), 4.66 (d, 1H, J = 5.2 Hz, OH), 4.83 (t, 1H, J = 2.2 Hz, OH), 4.89 (t, 2H,

J = 5.2 Hz, CH₂O), 7.21 (dd, 1H, J = 1.3 Hz, J = 7.7 Hz, H-7_chin), 7.38–7.46 (m, 2H, H-3_chin, H-6_chin),

7.50 (dd, 1H, J = 1.2 Hz, J = 8.2 Hz, H-5_chin), 8.20 (d, 1H, J = 8.4 Hz, H-4_chin), 8.54 (s, 1H, H-5_triaz); ¹³

NMR (100 MHz, DMSO-d6): 25.10, 49.11, 60.45, 61.28, 67.57, 68.13, 70.41, 73.42, 75.28, 102.72, 111.18,

C

δ

120.45, 122.53, 125.19, 125.66, 127.35, 136.01, 139.28, 143.79, 153.21, 157.62; HRMS (ESI-TOF): calcd for

C₂₁H₂₇N₄O₇([M + H]⁺): m/z 447.1880; found: m/z 447.1879.

Glycoconjugate 53: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

azidopropoxy)quinoline

= 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

β

-D-glucopyranoside 21 and 8-(3-

25

6

, product was obtained as a yellow oil (307.3 mg, 100%); [

α

]

= −21.4 (c

D

δ

1.88, 1.92, 1.98, 2.03 (4s, 12H, CH₃CO), 2.43 (p, 2H,

J = 6.5 Hz, CH₂), 3.99 (ddd, 1H, J = 2.4 Hz, J = 4.9 Hz, J = 10.0 Hz, H-5_glu), 4.10 (dd, 1H, J = 2.4 Hz,

J = 12.3 Hz, H-6a_glu), 4.15–4.24 (m, 3H, CH₂N, H-6b_glu), 4.66 (t, 2H, J = 6.9 Hz, CH₂O), 4.65 and 4.80

(qAB, 2H, J = 12.1 Hz, CH₂C), 4.76 (dd, 1H, J = 8.0 Hz, J = 9.6 Hz H-2_glu), 4.88 (d, 1H, J = 8.0 Hz,

H-1_glu), 4.91 (dd-t, 1H, J = 9.6 Hz, J = 9.7 Hz, H-4_glu), 5.25 (dd-t, 1H, J = 9.6 Hz, J = 9.6 Hz, H-3_glu), 7.19

(dd, 1H, J = 1.9 Hz, J = 7.1 Hz, H-7_chin), 7.47–7.53 (m, 2H, H-3_chin, H-6_chin), 7.56 (dd, 1H, J = 4.0 Hz,

J = 8.2 Hz, H-5_chin), 8.24 (s, 1H, H-5_triaz), 8.33 (dd, 1H, J = 1.6 Hz, J = 8.2 Hz, H-4_chin), 8.89 (bs, 1H,

H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.23, 20.25, 20.35, 20.47, 29.57, 46.66, 61.64, 61.85, 65.39,

68.11, 70.61, 70.83, 72.03, 98.47, 109.82, 119.93, 121.85, 124.50, 126.77, 129.03, 135.78, 139.79, 142.94,

149.01, 154.20, 168.92, 169.22, 169.48, 170.01; HRMS (ESI-TOF): calcd for C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z

615.2302; found: m/z 615.2303.

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Glycoconjugate 54: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-galactopyranoside 22 and

25

8-(3-azidopropoxy)quinoline

6

, product was obtained as a yellow oil (307.3 mg, 100%); [

α

]

= −16.2

D

(c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ

1.89, 1.90, 2.01, 2.11 (4s, 12H, CH₃CO), 2.43 (p, 2H,

J = 6.4 Hz, CH₂), 4.01–4.11 (m, 2H, H-5_gal, H-6a_gal), 4.15–4.24 (m, 3H, H-6b_gal, CH₂N), 4.64 and 4.79

(qAB, 2H, J = 12.4 Hz, CH₂C), 4.66 (t, 2H, J = 6.8 Hz, CH₂O), 4.79 (d, 1H, J = 8.0 Hz, H-1_gal), 4.92 (dd,

1H, J = 8.0 Hz, J = 10.3 Hz, H-2_gal), 5.15 (dd, 1H, J = 3.6 Hz, J = 10.3 Hz, H-3_gal), 5.25 (dd, 1H, J = 0.9 Hz,

J = 3.6 Hz, H-4_gal), 7.20 (dd, 1H, J = 1.5 Hz, J = 7.4 Hz, H-7_chin), 7.46–7.61 (m, 3H, H-3_chin, H-5_chin

H-6_chin), 8.24 (s, 1H, H-5_triaz), 8.31–8.35 (m, 1H, H-4_chin), 8.90 (bs, 1H, H-2_chin); ¹³C NMR (100 MHz,

DMSO-d6): 20.28, 20.29, 20.35, 20.47, 29.58, 46.66, 61.22, 61.72, 65.39, 67.28, 68.57, 69.91, 70.19, 98.89,

,

δ

109.81, 119.94, 124.47, 125.27, 126.76, 128.16, 128.86, 135.77, 143.00, 148.99, 154.22, 169.03, 169.42, 169.86,

169.89; HRMS (ESI-TOF): calcd for C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z 615.2302; found: m/z 615.2302.

Glycoconjugate 55: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

2-methyl-8-(3-azidopropoxy)quinoline , product was obtained as a yellow oil (204.3 mg, 65%);

20.2 (c = 1.0, CHCl₃); H NMR (400 MHz, DMSO-d6): 1.88, 1.92, 1.98, 2.03 (4s, 12H,

β-D-glucopyranoside 21 and

9

23

1

[

α

]

=

−

δ

D

CH₃CO), 2.42 (p, 2H, J = 6.5 Hz, CH₂), 2.67 (s, 3H, CH₃), 3.98 (ddd, 1H, J = 2.4 Hz, J = 4.9 Hz, J =

10.0 Hz, H-5_glu), 4.04 (dd, 1H, J = 2.4 Hz, J = 12.4 Hz, H-6a_glu), 4.15–4.24 (m, 3H, CH₂N, H-6b_glu),

4.64 and 4.80 (qAB, 2H, J = 12.3 Hz, CH₂C), 4.65 (t, 2H, J = 6.9 Hz, CH₂O), 4.75 (dd, 1H, J = 8.0 Hz, J

= 9.6 Hz H-2_glu), 4.87 (d, 1H, J = 8.0 Hz, H-1_glu), 4.91 (dd-t, 1H, J = 9.6 Hz, J = 9.8 Hz, H-4_glu), 5.24

(dd-t, 1H, J = 9.6 Hz, J = 9.6 Hz, H-3_glu), 7.16 (dd, 1H, J = 1.2 Hz, J = 7.6 Hz, H-7_chin), 7.38–7.50 (m, 3H,

H-3_chin, H-5_chin, H-6_chin), 8.19 (d, 1H, J = 8.4 Hz, H-4_chin), 8.25 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz,

DMSO-d6):

δ 20.23, 20.24, 20.35, 20.48, 25.05, 29.52, 46.64, 61.64, 61.83, 65.57, 68.11, 70.60, 70.83, 72.03,

98.46, 110.37, 119.86, 122.44, 124.47, 125.70, 127.32, 135.98, 139.32, 142.93, 153.67, 157.30, 168.92, 169.23,

169.48, 170.01; HRMS (ESI-TOF): calcd for C₃₀H₃₇N₄O₁₁([M + H]⁺): m/z 629.2459; found: m/z 629.2458.

Glycoconjugate 56: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

2-methyl-8-(3-azidopropoxy)quinoline

8.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

(p, 2H, J = 6.3 Hz, CH₂), 2.67 (s, 3H, CH₃), 4.01–4.11 (m, 2H, H-5_gal, H-6a_gal), 4.15–4.24 (m, 3H, H-6a_gal

β

-D-galactopyranoside 22 and

24

9

, product was obtained as a yellow oil (242.0 mg, 77%); [

α

]

D

=

−

δ 1.89, 1.90, 2.01, 2.11 (4s, 12H, CH₃CO), 2.42

,

CH₂N), 4.64 and 4.79 (qAB, 2H, J = 12.6 Hz, CH₂C), 4.66 (t, 2H, J = 6.9 Hz, CH₂O), 4.78 (d, 1H, J =

8.0 Hz, H-1_gal), 4.92 (dd, 1H, J = 8.0 Hz, J = 10.4 Hz, H-2_gal), 5.14 (dd, 1H, J = 3.6 Hz, J = 10.4 Hz, H-3_gal),

5.25 (dd, 1H, J = 0.9 Hz, J = 3.6 Hz, H-4_gal), 7.16 (dd, 1H, J = 0.8 Hz, J = 7.5 Hz, H-7_chin), 7.37–7.51 (m,

3H, H-3_chin, H-5_chin, H-6_chin), 8.19 (d, 1H, J = 8.4 Hz, H-4_chin), 8.25 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz,

DMSO-d6): δ18.53, 20.28, 20.29, 20.35, 20.48, 29.53, 46.64, 61.23, 61.70, 65.55, 68.57, 69.91, 70.19, 72.20,

98.88, 110.33, 119.87, 122.45, 124.46, 125.71, 127.31, 135.96, 139.32, 143.02, 153.26, 158.61, 169.03, 169.43,

169.87, 169.90; HRMS (ESI-TOF): calcd for C₃₀H₃₇N₄O₁₁([M + H]⁺): m/z 629.2459; found: m/z 629.2455.

Glycoconjugate 57: Starting from propargyl

β

-D-glucopyranoside 23 and 8-(3-azidopropoxy)quinoline

24

6

, product was obtained as a white solid (223.2 mg, 100%); m.p.: 77–79 ^◦C; [

α

]

= −19.2 (c = 1.0,

D

MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 2.42 (p, 2H, J = 6.4 Hz, CH₂), 2.94-3.09 (m, 2H, H-2_glu, H-5_glu),

3.10-3.17 (m, 2H, H-3_glu, H-4_glu), 3.40–3.50 (m, 1H, H-6a_glu), 3.67–3.75 (m, 1H, H-6b_glu), 4.05–4.11 (m,

1H, OH), 4.21 (t, 2H, J = 6.1 Hz, CH₂N), 4.27 (d, 1H, J = 7.8 Hz, H-1_glu), 4.34 (t, 1H, J = 5.1 Hz, OH), 4.57

(t, 1H, J = 5.9 Hz, OH), 4.64 (t, 1H, J = 7.1 Hz, CH₂O), 4.64 and 4.85 (qAB, 2H, J = 12.2 Hz, CH₂C), 5.01

(d, 1H, J = 4.9 Hz, OH), 7.20 (dd, 1H, J = 2.2 Hz, J = 6.8 Hz, H-7_chin), 7.47–7.58 (m, 3H, H-3_chin, H-5_chin

H-6_chin), 8.29 (s, 1H, H-5_triaz), 8.32 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.90 (dd, 1H, J = 1.6 Hz, J =

4.1 Hz, H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

29.61, 46.61, 61.16, 61.57, 65.43, 70.11, 73.39, 76.69,

,

δ

76.94, 102.14, 109.84, 119.92, 121.86, 124.42, 126.79, 129.04, 135.81, 139.76, 143.89, 149.07, 154.19; HRMS

(ESI-TOF): calcd for C₂₁H₂₇N₄O₇([M + H]⁺): m/z 447.1880; found: m/z 447.1880.

Glycoconjugate 58: Starting from propargyl

quinoline , product was obtained as a yellow solid (169.7 mg, 76%); m.p.: 50–54 C; [

11.2 (c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

2.42 (p, 2H, J = 6.5 Hz, CH₂), 3.22-3.40 (m,

β-D-galactopyranoside 24 and 8-(3-azidopropoxy)

◦

24

6

α

]

=

D

−

δ

Molecules 2019, 24, 4181

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4H, H-2_gal, H-3_gal, H-4_gal, H-5_gal), 3.50-3.58 (m, 1H, H-6a_gal), 3.60–3.66 (m, 1H, H-6b_gal), 4.20 (t, 2H, J =

6.0 Hz, CH₂N), 4.21 (d, 1H, J = 6.3 Hz, H-1_gal), 4.34 (d, 1H, J = 4.4 Hz, OH), 4.57–4.71 (m, 2H, OH), 4.62

and 4.83 (qAB, 2H, J = 12.4 Hz, CH₂C), 4.64 (t, 2H, J = 7.0 Hz, CH₂O), 4.86 (d, 1H, J = 5.7 Hz, OH),

7.20 (dd, 1H, J = 2.1 Hz, J = 6.8 Hz, H-7_chin), 7.46–7.59 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.28 (s, 1H,

H-5_triaz), 8.32 (dd, 1H, J = 1.6 Hz, J = 8.4 Hz, H-4_chin), 8.90 (dd, 1H, J = 1.7 Hz, J = 4.1 Hz, H-2_chin); ¹³

NMR (100 MHz, DMSO-d6): 29.62, 46.61, 60.53, 61.42, 65.44, 68.18, 70.47, 73.39, 75.32, 102.70, 109.85,

C

δ

119.91, 121.85, 124.36, 126.79, 129.04, 135.79, 139.76, 143.96, 149.08, 154.19; HRMS (ESI-TOF): calcd for

C₂₁H₂₇N₄O₇([M + H]⁺): m/z 447.1880; found: m/z 447.1879.

Glycoconjugate 59: Starting from propargyl

quinoline

1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-glucopyranoside 23 and 2-methyl-8-(3-azidopropoxy)

23

9

, product was obtained as a yellow solid (200.3 mg, 87%); m.p.: 47-50 ^◦C; [

α

]

= −16.6 (c =

D

δ

2.42 (p, 2H, J = 6.5 Hz, CH₂), 2.68 (s, 3H, CH₃), 2.93–3.09

(m, 2H, H-2_glu, H-5_glu), 3.10–3.20 (m, 2H, H-3_glu, H-4_glu), 3.40–3.50 (m, 1H, H-6a_glu), 3.66–3.75 (m, 1H,

H-6b_glu), 4.20 (t, 2H, J = 6.2 Hz, CH₂N), 4.26 (d, 1H, J = 7.8 Hz, H-1_glu), 4.34 (t, 2H, J = 5.0 Hz, OH),

4.56 (t, 1H, J = 5.8 Hz, OH), 4.63 and 4.84 (qAB, 2H, J = 12.2 Hz, CH₂C), 4.64 (t, 2H, J = 6.9 Hz, CH₂O),

5.00 (d, 1H, J = 4.9 Hz, OH), 7.16 (dd, 1H, J = 1.3 Hz, J = 7.6 Hz, H-7_chin), 7.38–7.49 (m, 3H, H-3_chin

H-5_chin, H-6_chin), 8.19 (d, 1H, J = 8.4 Hz, H-4_chin), 8.26 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

25.09, 29.57, 46.60, 61.16, 61.56, 65.57, 70.12, 73.40, 76.70, 76.95, 102.15, 110.35, 119.86, 122.48, 124.40,

,

δ

125.75, 131.21, 136.01, 139.31, 143.15, 150.40, 153.68; HRMS (ESI-TOF): calcd for C₂₂H₂₉N₄O₇([M +

H]⁺): m/z 461.2036; found: m/z 461.2039.

Glycoconjugate 60: Starting from propargyl

quinoline

(c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranoside 24 and 2-methyl-8-(3-azidopropoxy)

24

9

, product was obtained as a brown solid (149.7 mg, 65%); m.p.: 50–54 ^◦C; [

α

]

= 4.6

−

D

δ

2.42 (p, 2H, J = 6.5 Hz, CH₂), 2.67 (s, 3H, CH₃),

3.22–3.42 (m, 4H, H-2_gal, H-3_gal, H-4_gal, H-5_gal), 3.49–3.57 (m, 1H, H-6a_gal), 3.60–3.66 (m, 1H, H-6b_gal),

4.20 (t, 2H, J = 5.9 Hz, CH₂N), 4.21 (d, 1H, J = 7.0 Hz, H-1_gal), 4.34 (bs, 1H, OH), 4.54-4.72 (m, 4H,

CH₂O, CH₂C, OH), 4.77-4.89 (m, 2H, CH₂C, OH), 7.16 (dd, 1H, J = 1.2 Hz, J = 7.6 Hz, H-7_chin), 7.37-7.50

(m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.19 (d, 1H, J = 8.4 Hz, H-4_chin), 8.26 (s, 1H, H-5_triaz); ¹³C NMR

(100 MHz, DMSO-d6):

δ 25.00, 29.56, 46.58, 60.52, 61.40, 65.59, 68.18, 70.48, 73.40, 75.31, 102.71, 110.44,

119.85, 122.51, 124.32, 125.81, 127.34, 136.18, 139.12, 143.96, 153.58, 157.34; HRMS (ESI-TOF): calcd for

C₂₂H₂₉N₄O₇([M + H]⁺): m/z 461.2036; found: m/z 461.2038.

Glycoconjugate 61: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

β

-D-glucopyranoside 21 and 8-(4-

23

azidobutoxy)quinoline

7

, product was obtained as a yellow oil (301.7 mg, 96%); [

α

]

= −17.8 (c =

D

1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃): δ 1.61 (bs, 2H, CH₂), 1.92, 1.98, 2.01, 2.08 (4s, 12H, CH₃CO),

2.26 (p, 2H, J = 7.1 Hz, CH₂), 3.69 (ddd, 1H, J = 2.4 Hz, J = 4.7 Hz, J = 9.9 Hz, H-5_glu), 4.12 (dd, 1H, J

= 2.4 Hz, J = 12.3 Hz, H-6a_glu), 4.24 (dd, 1H, J = 4.7 Hz, J = 12.3 Hz, H-6a_glu), 4.28 (t, 2H, J = 6.1 Hz,

CH₂N), 4.58 (t, 2H, J = 6.9 Hz, CH₂O), 4.68 (d, 1H, J = 8.0 Hz, H-1_glu), 4.81 and 4.93 (qAB, 2H, J =

12.6 Hz, CH₂C), 5.00 (dd, 1H, J = 8.0 Hz, J = 9.5 Hz H-2_glu), 5.08 (dd-t, 1H, J = 9.4 Hz, J = 9.8 Hz, H-4_glu),

5.17 (dd-t, 1H, J = 9.4 Hz, J = 9.4 Hz, H-3_glu), 7.05 (dd, 1H, J = 1.4 Hz, J = 7.5 Hz, H-7_chin), 7.38–7.49 (m,

3H, H-3_chin, H-5_chin, H-6_chin), 7.95 (s, 1H, H-5_triaz), 8.14 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.93

(dd, 1H, J = 1.7 Hz, J = 4.2 Hz, H-2_chin); ¹³C NMR (100 MHz, CDCl₃):

δ 20.60, 20.67, 20.75, 20.79, 25.61,

27.83, 49.93, 61.85, 62.86, 68.36, 71.24, 71.89, 72.86, 77.22, 99.66, 108.81, 119.91, 121.71, 123.74, 126.69,

129.54, 135.96, 140.35, 143.77, 149.32, 154.59, 169.35, 169.42, 170.19, 170.65; HRMS (ESI-TOF): calcd for

C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z 629.2459; found: m/z 629.2458.

Glycoconjugate 62: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

8-(4-azidobutoxy)quinoline

= 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranoside 22 and

25

7

, product was obtained as a yellow oil (292.3 mg, 93%); [

α

]

= −12.8 (c

D

δ

1.78–1.87 (m, 2H, CH₂), 1.90, 1.90, 2.01, 2.10 (4s, 12H,

CH₃CO), 2.05–2.10 (m, 2H, CH₂), 4.01-4.11 (m, 2H, H-5_gal, H-6a_gal), 4.16-4.25 (m, 3H, H-6b_gal, CH₂N),

4.54 (t, 2H, J = 7.0 Hz, CH₂O), 4.64 and 4.80 (qAB, 2H, J = 12.4 Hz, CH₂C), 4.81 (d, 1H, J = 8.0 Hz, H-1_gal),

4.92 (dd, 1H, J = 8.0 Hz, J = 10.3 Hz, H-2_gal), 5.15 (dd, 1H, J = 3.6 Hz, J = 10.3 Hz, H-3_gal), 5.25 (dd, 1H, J

Molecules 2019, 24, 4181

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= 0.9 Hz, J = 3.6 Hz, H-4_gal), 7.17–7.21 (m, 1H, H-7_chin), 7.47–7.57 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.25

(s, 1H, H-5_triaz), 8.31 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.85 (bs, 1H, H-2_chin); ¹³C NMR (100 MHz,

DMSO-d6):

δ 20.29, 20.32, 20.35, 20.48, 25.53, 27.04, 49.08, 61.21, 61.81, 67.28, 67.85, 68.58, 69.90, 70.19,

98.97, 109.37, 119.55, 121.79, 124.44, 126.80, 129.00, 135.76, 139.72, 142.87, 148.92, 154.38, 169.05, 169.42,

169.86, 169.89; HRMS (ESI-TOF): calcd for C₃₀H₃₇N₄O₁₁([M + H]⁺): m/z 629.2459; found: m/z 629.2459.

Glycoconjugate 63: Starting from propargyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside 21 and

2-methyl-8-(4-azidobutoxy)quinoline 10, product was obtained as a yellow oil (295.6 mg, 92%);

23

[

α

]

= δ 1.80 (p, 2H, J = 6.6 Hz, CH₂), 1.88,

18.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

−

D

1.91, 1.97, 2.02 (4s, 12H, CH₃CO), 2.08 (p, 2H, J = 7.4 Hz, CH₂), 2.63 (s, 3H, CH₃), 3.97 (ddd, 1H, J =

2.4 Hz, J = 4.9 Hz, J = 10.0 Hz, H-5_glu), 4.03 (dd, 1H, J = 2.4 Hz, J = 12.4 Hz, H-6a_glu), 4.14–4.24 (m, 3H,

CH₂N, H-6b_glu), 4.59 (t, 2H, J = 6.9 Hz, CH₂O), 4.64 and 4.80 (qAB, 2H, J = 12.4 Hz, CH₂C), 4.75 (dd,

1H, J = 8.0 Hz, J = 9.7 Hz H-2_glu), 4.90 (d, 1H, J = 8.0 Hz, H-1_glu), 4.91 (dd-t, 1H, J = 9.7 Hz, J = 9.7 Hz,

H-4_glu), 5.24 (dd-t, 1H, J = 9.6 Hz, J = 9.6 Hz, H-3_glu), 7.15 (dd, 1H, J = 1.8 Hz, J = 7.2 Hz, H-7_chin),

7.38–7.47 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.18 (d, 1H, J = 8.4 Hz, H-4_chin), 8.34 (s, 1H, H-5_triaz); ¹³

NMR (100 MHz, DMSO-d6): 20.23, 20.30, 20.34, 20.47, 24.93, 25.25, 27.23, 49.08, 61.64, 61.92, 68.09,

C

δ

68.14, 70.60, 70.82, 72.03, 98.53, 109.64, 119.42, 122.41, 124.62, 125.74, 127.26, 135.96, 139.19, 142.70,

153.89, 157.21, 168.92, 169.21, 169.46, 170.00; HRMS (ESI-TOF): calcd for C₃₁H₃₉N₄O₁₁([M + H]⁺): m/z

643.2615; found: m/z 643.2618.

Glycoconjugate 64: Starting from propargyl 2,3,4,6-tetra-O-acetyl-

2-methyl-8-(4-azidobutoxy)quinoline 10, product was obtained as a yellow oil (321.3 mg, 100%); [

β

-D-galactopyranoside 22 and

24

α

]

D

=

−

13.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ

1.81 (p, 2H, J = 6.6 Hz, CH₂), 1.89, 1.89, 2.00,

2.10 (4s, 12H, CH₃CO), 2.03–2.10 (m, 2H, CH₂), 2.63 (s, 3H, CH₃), 4.01–4.11 (m, 2H, H-5_gal, H-6a_gal),

4.15–4.25 (m, 3H, H-6a_gal, CH₂N), 4.59 (t, 2H, J = 7.0 Hz, CH₂O), 4.64 and 4.80 (qAB, 2H, J = 12.9 Hz,

CH₂C), 4.81 (d, 1H, J = 8.0 Hz, H-1_gal), 4.92 (dd, 1H, J = 8.0 Hz, J = 10.3 Hz, H-2_gal), 5.14 (dd, 1H, J =

3.6 Hz, J = 10.3 Hz, H-3_gal), 5.24 (dd, 1H, J = 0.9 Hz, J = 3.6 Hz, H-4_gal), 7.15 (dd, 1H, J = 1.8 Hz, J =

7.2 Hz, H-7_chin), 7.38–7.47 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.18 (d, 1H, J = 8.4 Hz, H-4_chin), 8.33 (s, 1H,

H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.22, 20.28, 20.34, 20.47, 24.93, 25.26, 27.25, 49.08, 61.20,

61.78, 67.28, 68.14, 68.57, 69.89, 70.19, 98.95, 109.64, 119.41, 122.40, 124.57, 125.74, 127.26, 135.96, 139.19,

142.78, 153.89, 157.21, 168.02, 169.41, 169.84, 169.88; HRMS (ESI-TOF): calcd for C₃₁H₃₉N₄O₁₁([M +

H]⁺): m/z 643.2615; found: m/z 643.2612.

Glycoconjugate 65: Starting from propargyl

β

-D-glucopyranoside 23 and 8-(4-azidobutoxy)quinoline

7

,

product was obtained as a yellow solid (165.8 mg, 72%); m.p.: 49–51 ^◦C; [

α

]

= −20.2 (c = 1.0, MeOH);

24

D

¹H NMR (400 MHz, DMSO-d6):

δ 1.77-1.89 (m, 2H, CH₂), 2.03-2.15 (m, 2H, CH₂), 2.94–3.09 (m, 2H,

H-2_glu, H-5_glu), 3.10–3.17 (m, 2H, H-3_glu, H-4_glu), 3.40–3.50 (m, 1H, H-6a_glu), 3.67–3.75 (m, 1H, H-6b_glu),

4.05–4.11 (m, 1H, OH), 4.21 (m, 2H, CH₂N), 4.27 (d, 1H, J = 7.8 Hz, H-1_glu), 4.34 (t, 1H, J = 5.1 Hz, OH),

4.52 (t, 1H, J = 6.8 Hz, CH₂O), 4.57 (t, 1H, J = 5.9 Hz, OH), 4.64 and 4.85 (qAB, 2H, J = 12.2 Hz, CH₂C),

5.01 (d, 1H, J = 4.9 Hz, OH), 7.17–7.22 (m, 1H, H-7_chin), 7.45–7.61 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.28

(s, 1H, H-5_triaz), 8.31–8.35 (m, 1H, H-4_chin), 8.87 (bs, 1H, H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ

25.61, 26.96, 49.06, 61.16, 61.59, 67.84, 70.11, 73.38, 76.70, 76.95, 102.15, 109.35, 119.64, 121.85, 124.42,

126.84, 128.86, 135.68, 139.79, 143.73, 148.98, 154.35; HRMS (ESI-TOF): calcd for C₂₂H₂₉N₄O₇([M +

H]⁺): m/z 461.2036; found: m/z 461.2036.

Glycoconjugate 66: Starting from propargyl

β

-D-galactopyranoside 24 and 8-(4-azidobutoxy)quinoline

24

7

, product was obtained as a yellow solid (207.2 mg, 90%); m.p.: 62–64 ^◦C; [

α

]

= −13.0 (c = 1.0,

D

MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 1.83 (p, 2H, J = 6.3 Hz, CH₂), 2.08 (p, 2H, J = 7.1 Hz, CH₂),

3.24–3.30 (m, 1H, H-2_gal), 3.33–3.48 (m, 3H, H-3_gal, H-4_gal, H-5_gal), 3.50–3.57 (m, 1H, H-6a_gal), 3.61–3.66

(m, 1H, H-6b_gal), 4.21 (t, 2H, J = 6.3 Hz, CH₂N), 4.22 (d, 1H, J = 7.5 Hz, H-1_gal), 4.31–4.36 (m, 2H, OH),

4.52 (t, 2H, J = 7.0 Hz, CH₂O), 4.62 and 4.83 (qAB, 2H, J = 12.1 Hz, CH₂C), 4.67 (d, 1H, J = 5.1 Hz, OH),

4.87 (d, 1H, J = 4.6 Hz, OH), 7.17–7.21 (m, 1H, H-7_chin), 7.46–7.57 (m, 3H, H-3_chin, H-5_chin, H-6_chin),

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8.27 (s, 1H, H-5_triaz), 8.31 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.87 (dd, 1H, J = 1.7 Hz, J = 4.1 Hz,

H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

25.59, 26.98, 49.03, 60.52, 61.45, 67.82, 68.18, 70.47, 73.40,

δ

75.32, 102.73, 109.39, 119.55, 121.80, 124.33, 126.80, 129.00, 135.75, 139.71, 143.77, 148.99, 154.38; HRMS

(ESI-TOF): calcd for C₂₂H₂₉N₄O₇([M + H]⁺): m/z 461.2036; found: m/z 461.2035.

Glycoconjugate 67: Starting from propargyl

β

-D-glucopyranoside 23 and 2-methyl-8-(4-azidobutoxy)

quinoline 10, product was obtained as an orange solid (180.3 mg, 76%); m.p.: 75–78 ^◦C; [

α

]

= −17.6

24

D

(c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 1.82 (p, 2H, J = 6.5 Hz, CH₂), 2.08 (p, 2H, J = 7.0 Hz,

CH₂), 2.64 (s, 3H, CH₃), 2.94–3.09 (m, 2H, H-2_glu, H-5_glu), 3.10–3.19 (m, 2H, H-3_glu, H-4_glu), 3.41–3.49

(m, 1H, H-6a_glu), 3.66–3.74 (m, 1H, H-6b_glu), 4.20 (t, 2H, J = 6.3 Hz, CH₂N), 4.27 (d, 1H, J = 7.8 Hz,

H-1_glu), 4.55 (d, 1H, J = 5.9 Hz, OH), 4.56 (t, 2H, J = 6.9 Hz, CH₂O), 4.64 and 4.86 (qAB, 2H, J = 12.2 Hz,

CH₂C), 4.89 (t, 2H, J = 5.2 Hz, OH), 4.91 (t, 1H, J = 4.7 Hz, OH), 5.01 (d, 1H, J = 4.9 Hz, OH), 7.15

(dd, 1H, J = 1.8 Hz, J = 7.1 Hz, H-7_chin), 7.38–7.47 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.18 (d, 1H, J =

8.4 Hz, H-4_chin), 8.31 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 25.40, 25.44, 27.09, 49.07,

61.13, 61.55, 68.07, 70.09, 73.37, 76.69, 76.93, 102.13, 109.62, 119.44, 122.43, 124.51, 125.78, 127.28, 135.98,

139.16, 145.72, 148.08, 153.85; HRMS (ESI-TOF): calcd for C₂₃H₃₁N₄O₇([M + H]⁺): m/z 475.2193; found:

m/z 475.2194.

Glycoconjugate 68: Starting from propargyl

β

-D-galactopyranoside 24 and 2-methyl-8-(4-azidobutoxy)

quinoline 10, product was obtained as an orange solid (156.6 mg, 66%); m.p.: 38–41 ^◦C; [

α

]

= −6.0 (c

23

D

= 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 1.82 (m, 2H, CH₂), 2.08 (m, 2H, CH₂), 2.64 (s, 3H,

CH₃), 3.23–3.43 (m, 4H, H-2_gal, H-3_gal, H-4_gal, H-5_gal), 3.49–3.58 (m, 1H, H-6a_gal), 3.61–3.66 (m, 1H,

H-6b_gal), 4.15–4.25 (m 3H, H-1_gal, CH₂N), 4.56 (t, 2H, J = 6.8 Hz, CH₂O), 4.62 and 4.83 (qAB, 2H, J

= 12.1 Hz, CH₂C), 7.16 (m, 1H, H-7_chin), 7.36–7.52 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.19 (d, 1H, J =

8.2 Hz, H-4_chin), 8.29 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 24.94, 25.40, 27.10, 49.06, 60.50,

61.43, 68.08, 68.17, 70.47, 73.41, 75.31, 102.73, 109.74, 119.43, 122.45, 124.40, 125.81, 127.28, 136.09, 139.06,

143.74, 153.83, 157.26; HRMS (ESI-TOF): calcd for C₂₃H₃₁N₄O₇([M + H]⁺): m/z 475.2193; found: m/z

475.2199.

Glycoconjugate 69: Starting from 2-azidoethyl 2,3,4,6-tetra-O-acetyl-

β

-D-glucopyranoside 27 and

, product was obtained as a yellow solid (234.2 mg, 78%); m.p.:

13.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.92, 1.98, 2.02, 2.06 (4s, 12H,

8-(2-propyn-1-yloxy)quinoline

3

22

52–55 ^◦C; [

α

]

−

D

CH₃CO), 3.67 (ddd, 1H, J = 2.4 Hz, J = 4.7 Hz, J = 10.0 Hz, H-5_glu), 3.93–3.99 (m, 1H, CH₂O), 4.11

(dd, 1H, J = 2.4 Hz, J = 12.4 Hz, H-6a_glu), 4.19–4.24 (m, 2H, H-6b_glu, CH₂O_.), 4.48 (d, 1H, J = 7.9 Hz,

H-1_glu), 4.49–4.62 (m, 2H, CH₂N), 4.95 (dd, 1H, J = 7.9 Hz, J = 9.5 Hz H-2_glu), 5.04 (dd, 1H, J = 9.4 Hz,

J = 10.0 Hz, H-4_glu), 5.16 (dd-t, 1H, J = 9.4 Hz, J = 9.5 Hz, H-3_glu), 5.54 (s, 2H, CH₂O_chin), 7.32–7.50

(m, 4H, H-3_chin, H-5_chin, H-6_chin,H-7_chin), 7.84 (s, 1H, H-5_triaz), 8.14 (d, 1H, J = 8.0 Hz, H-4_chin), 8.94

(bs, 1H, H-2_chin); ¹³C NMR (100 MHz, CDCl₃):

δ 20.53, 20.55, 20.64, 20.70, 50.06, 61.74, 62.79, 67.58,

68.25, 70.90, 71.99, 72.52, 100.54, 110.09, 120.29, 121.63, 124.62, 126.77, 129.50, 136.05, 140.21, 143.85,

149.26, 153.90, 169.29, 169.35, 170.08, 170.54; HRMS (ESI-TOF): calcd for C₂₈H₃₃N₄O₁₁([M + H]⁺): m/z

601.2146; found: m/z 601.2149.

Glycoconjugate 70: Starting from 2-azidoethyl 2,3,4,6-tetra-O-acetyl-

β

-D-galactopyranoside 28 and

, product was obtained as a yellow solid (186.2 mg, 62%); m.p.:

18.4 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.90, 2.00, 2.09, 2.10 (4s,

8-(2-propyn-1-yloxy)quinoline

3

23

55–58 ^◦C; [

α

]

−

D

12H, CH₃CO), 3.91–3.99 (m, 1H, CH₂O), 4.00-4.22 (m, 4H, H-6a_gal, H-6b_gal, H-5_gal, CH₂O), 4.53–4.66

(m, 2H, CH₂N), 4.74 (d, 1H, J = 8.0 Hz, H-1_gal), 4.91 (dd, 1H, J = 8.0 Hz, J = 10.4, H-2_gal), 5.12 (dd, 1H, J

= 3.6 Hz, J = 10.4 Hz, H-3_gal), 5.25 (dd, 1H, J = 0.8 Hz, J = 3.6 Hz, H-4_gal), 5.35 (s, 2H, CH₂O_chin), 7.41

(dd, 1H, J = 3.4 Hz, J = 5.6 Hz, H-7_chin), 7.50–7.57 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.15 (s, 1H, H-5_triaz),

8.31 (dd, 1H, J = 1.6 Hz, J = 8.3 Hz, H-4_chin), 8.83 (bs, 1H, H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ

20.28, 20.32, 20.34, 20.47, 49.34, 61.21, 61.88, 67.26, 68.31, 69.98, 70.08, 79.14, 99.61, 110.10, 120.05,

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121.82, 124.97, 126.72, 129.03, 135.75, 139.75, 142.46, 148.92, 153.85, 169.13, 169.43, 169.86, 169.88; HRMS

(ESI-TOF): calcd for C₂₈H₃₃N₄O₁₁([M + H]⁺): m/z 601.2146; found: m/z 601.2140.

Glycoconjugate 71: Starting from 2-azidoethyl 2,3,4,6-tetra-O-acetyl-

β

-D-glucopyranoside 27 and

, product was obtained as a pink solid (298.1 mg, 97%); m.p.:

13.0 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.89, 1.92, 1.98, 2.01 (4s,

2-methyl-8-(2-propyn-1-yloxy)quinoline

4

24

50–53 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.63 (s, 3H, CH₃), 3.91–4.00 (m, 2H, H-5_glu, CH₂O), 4.04 (dd, 1H, J = 2.5 Hz, J = 12.4 Hz,

H-6a_glu), 4.09–4.13 (m, 1H, CH₂O), 4.17 (dd, 1H, J = 5.0 Hz, J = 12.4 Hz, H-6b_glu), 4.52–4.66 (m, 2H,

CH₂N), 4.75 (dd, 1H, J = 8.1 Hz, J = 9.7 Hz, H-2_glu), 4.85 (d, 1H, J = 8.1 Hz, H-1_glu), 4.90 (dd-t, 1H, J =

9.4 Hz, J = 9.8 Hz, H-4_glu), 5.23 (dd-t, 1H, J = 9.4 Hz, J = 9.7 Hz, H-3_glu), 5.34 (s, 2H, CH₂O_chin), 7.37

(dd, 1H, J = 1.7 Hz, J = 7.4 Hz, H-7_chin), 7.41 (d, 1H, J = 8.4 Hz, H-3_chin), 7.43 (dd, 1H, J = 7.4 Hz, J

= 8.1 Hz, H-6_chin), 7.47 (dd, 1H, J = 1.7 Hz, J = 8.1 Hz, H-5_chin), 8.16 (s, 1H, H-5_triaz), 8.18 (d, 1H, J =

8.4 Hz, H-4_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.19, 20.20, 20.31, 20.43, 24.85, 49.27, 61.60, 61.71,

67.39, 68.07, 70.51, 71.87, 79.12, 99.12, 110.26, 119.83, 122.40, 125.05, 125.60, 127.29, 135.90, 139.17, 142.50,

153.34, 157.19, 168.98, 169.19, 169.44, 169.97; HRMS (ESI-TOF): calcd for C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z

615.2302; found: m/z 615.2303.

Glycoconjugate 72: Starting from 2-azidoethyl 2,3,4,6-tetra-O-acetyl-

β

-D-galactopyranoside 28 and

, product was obtained as a pink solid (236.6 mg, 77%); m.p.:

13.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.89, 1.90, 2.00, 2.10 (4s,

2-methyl-8-(2-propyn-1-yloxy)quinoline

4

24

60–63 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.62 (s, 3H, CH₃), 3.95 (m, 1H, CH₂O), 4.00–4.08 (m, 2H, H-6a_gal, H-6b_gal), 4.08–4.21 (m,

2H, CH₂O, H-5_gal), 4.52–4.66 (m, 2H, CH₂N), 4.74 (d, 1H, J = 8.0 Hz, H-1_gal), 4.92 (dd, 1H, J = 8.0 Hz, J

= 10.4, H-2_gal), 5.12 (dd, 1H, J = 3.6 Hz, J = 10.4 Hz H-3_gal), 5.25 (dd, 1H, J = 0.8 Hz, J = 3.6 Hz, H-4_gal),

5.34 (s, 2H, CH₂O_chin), 7.37 (dd, 1H, J = 1.6 Hz, J = 7.4 Hz, H-7_chin), 7.41 (d, 1H, J = 8.4 Hz, H-3_chin),

7.43 (dd, 1H, J = 7.4 Hz, J = 8.2 Hz, H-6_chin), 7.47 (dd, 1H, J = 1.6 Hz, J = 8.2 Hz, H-5_chin), 8.15 (s, 1H,

H-5_triaz), 8.18 (d, 1H, J = 8.4 Hz, H-4_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.30, 20.37, 20.50, 21.05,

24.89, 49.36, 61.23, 61.79, 67.29, 68.31, 70.01, 70.11, 79.17, 99.65, 110.33, 119.90, 122.46, 125.05, 125.67,

127.35, 135.96, 139.23, 142.58, 153.40, 157.25, 169.18, 169.46, 169.89, 169.9k2; HRMS (ESI-TOF): calcd for

C₂₉H₃₅N₄O₁₁([M + H]⁺): m/z 615.2302; found: m/z 615.2305.

Glycoconjugate 73: Starting from 2-azidoethyl

quinoline , product was obtained as a beige solid (134.1 mg, 62%); m.p.: 60–63 C; [

(c = 1.0, MeOH); H NMR (400 MHz, DMSO-d6):

β-D-glucopyranoside 29 and 8-(2-propyn-1-yloxy)

◦

23

3

α

]

=

−

9.6

D

1

δ

2.95-3.08 (m, 1H, H-5_glu), 3.10–3.19 (m, 3H,

H-2_glu, H-3_glu, H-4_glu), 3.40-3.48 (m, 1H, H-6a_glu), 3.65–3.72 (m, 1H, H-6b_glu), 3.91–3.98 (m, 1H, CH₂O),

4.07-4.14 (m, 1H, CH₂O), 4.26 (d, 1H, J = 7.8 Hz, H-1_glu), 4.52–4.56 (m, 1H, OH), 4.60–4.66 (m, 2H,

CH₂N), 4.88–4.96 (m, 2H, OH), 5.10–5.14 (d, 1H, J = 4.7 Hz, OH), 5.34 (s, 2H, CH₂O_chin), 7.39–7.45 (m,

1H, H-7_chin), 7.50–7.57 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.32 (dd, 1H, J = 1.8 Hz, J = 8.1 Hz, H-4_chin),

8.38 (s, 1H, H-5_triaz), 8.83 (dd, 1H, J = 1.8 Hz, J = 4.1 Hz, H-2_chin); ¹³C NMR (100 MHz, DMSO-d6):

δ

49.74, 61.06, 61.82 67.36, 70.01, 73.27, 76.59, 76.96, 102.95, 109.96, 119.95, 121.81, 125.69, 126.73, 129.03,

135.78, 139.67, 142.32, 148.96, 153.84; HRMS (ESI-TOF): calcd for C₂₀H₂₅N₄O₇([M + H]⁺): m/z 433.1723;

found: m/z 433.1719.

Glycoconjugate 74: Starting from 2-azidoethyl

quinoline

NMR (400 MHz, D₂O):

β

-D-galactopyranoside 30 and 8-(2-propyn-1-yloxy)

25

3

, product was obtained as a brown oil (118.9 mg, 55%); [

α

]

_D= 10.8 (c = 1.0, MeOH); ¹H

δ

3.44-3.54 (m, 1H, H-2_gal), 3.57–3.74 (m, 4H, H-3_gal, H-5_gal, H-6a_gal, H-6b_gal),

3.91 (d, 1H, J = 3.2 Hz, H-4_gal), 4.11-4.21 (m, 1H, CH₂O), 4.30–4.40 (m, 2H, CH₂O, H-1_gal), 4.72-4.78 (m,

2H, CH₂N_triaz), 5.66 (s, 2H, CH₂O_chin), 7.78 (dd, 1H, J = 2.3 Hz, J = 6.4 Hz, H-7_chin), 7.85-7.97 (m, 2H,

H-3_chin, H-5_chin), 8.06–8.16 (m, 1H, H-6_chin), 8.35 (s, 1H, H-5_triaz), 9.05 (d, 1H, J = 4.7 Hz, H-2_chin), 9.14

(d, 1H, J = 8.1 Hz, H-4_chin); ¹³C NMR (100 MHz, D₂O):

δ 50.49, 60.83, 62.27, 67.96, 68.45, 70.52, 72.54,

75.05, 102.97, 114.63, 120.83, 122.17, 126.24, 129.37, 129.92, 130.37, 142.07, 143.05, 147.30, 147.5; HRMS

(ESI-TOF): calcd for C₂₀H₂₅N₄O₇([M + H]⁺): m/z 433.1723; found: m/z 433.1720.

Molecules 2019, 24, 4181

26 of 40

Glycoconjugate 75: Starting from 2-azidoethyl

β

-D-glucopyranoside 29 and 2-methyl-8-(2-propyn-1-

24

yloxy)quinoline

4

, product was obtained as a brown oil (129.5 mg, 58%); [

α

]

= 1.6 (c = 1.0, MeOH);

D

¹H NMR (400 MHz, D₂O):

δ

3.01 (s, 3H, CH₃), 3.18 (dd-t, 1H, J = 8.2 Hz, J = 8.3 Hz, H-4_glu), 3.29 (dd-t,

1H, J = 8.6 Hz, J = 9.0 Hz, H-2_glu), 3.38–3.47 (m, 2H, H-3_glu, H-5_glu), 3.63 (dd, 1H, J = 4.7 Hz, J = 12.3 Hz,

H-6a_glu), 3.81–3.90 (m, 1H, H-6b_glu), 4.10–4.22 (m, 1H, CH₂O), 4.27–4.37 (m, 1H, CH₂O), 4.41 (d, 1H, J

= 7.8 Hz, H-1_glu), 4.68–4.77 (m, 2H, CH₂N), 5.64 (s, 2H, CH₂O_chin), 7.64–7.96 (m, 4H, H-3_chin, H-5_chin

,

H-6_chin, H-7_chin), 8.30 (s, 1H, H-5_triaz), 8.91 (d, 1H, J = 8.3 Hz, H-4_chin); ¹³C NMR (100 MHz, D₂O):

δ

19.99, 50.45, 60.60, 62.10, 67.96, 69.49, 72.88, 75.53, 75.82, 102.32, 114.65, 120.85, 124.20, 126.25, 128.08,

129.08, 129.44, 146.30, 146.98, 155.63, 157.49; HRMS (ESI-TOF): calcd for C₂₁H₂₇N₄O₇([M + H]⁺): m/z

447.1880; found: m/z 447.1880.

Glycoconjugate 76: Starting from 2-azidoethyl

yloxy)quinoline

(c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranoside 30 and 2-methyl-8-(2-propyn-1-

23

4

, product was obtained as a pink solid (131.7 mg, 59%); m.p.: 102-105 ^◦C; [

α

]

= 4.8

D

δ

2.63 (s, 3H, CH₃), 3.33–3.39 (m, 2H, H-2_gal, H-3_gal),

3.40–3.48 (m, 1H, H-5_gal), 3.49–3.55 (m, 2H, H-6a_gal, H-6b_gal), 3.63 (dd-t, 1H, J = 0.8 Hz, J = 3.6 Hz,

H-4_gal), 3.88–3.96 (m, 1H, CH₂O), 4.06–4.14 (m, 1H, CH₂O), 4.19 (d, 1H, J = 7.3 Hz, H-1_gal), 4.35 (d, 1H,

J = 4.6 Hz, OH), 4.53–4.64 (m, 3H, CH₂N, OH), 4.69 (d, 1H, J = 5.0 Hz, OH), 4.95 (d, 1H, J = 4.4 Hz, OH),

5.33 (s, 2H, CH₂O_chin), 7.38 (dd, 1H, J = 2.0 Hz, J = 7.2 Hz, H-7_chin), 7.41 (d, 1H, J = 8.4 Hz, H-3_chin),

7.44 (dd, 1H, J = 7.2 Hz, J = 7.8 Hz, H-6_chin), 7.47 (dd, 1H, J = 1.8 Hz, J = 7.8 Hz, H-5_chin), 8.18 (d, 1H, J =

8.4 Hz, H-4_chin), 8.37 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 24.89, 49.75, 60.46, 61.66, 67.16,

68.14, 70.35, 73.29, 75.39, 103.53, 110.20, 119.77, 122.42, 125.65, 125.69, 127.30, 135.93, 139.16, 142.39,

153.37, 157.23; HRMS (ESI-TOF): calcd for C₂₁H₂₇N₄O₇([M + H]⁺): m/z 447.1880; found: m/z 447.1881.

Glycoconjugate 77: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-glucopyranosyl)azidoacetamide 33 and

, product was obtained as a light yellow solid (205.5 mg, 67%); m.p.:

1.94, 1.97, 1.99, 2.00 (4s, 12H,

8-(2-propyn-1-yloxy)quinoline

3

25

97–100 ^◦C; [

α

]

_D= 4.4 (c = 0.6, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ

CH₃CO), 3.99 (m, 1H, H-6a_glu), 4.10–4.18 (m, 2H, H-5_glu, H-6b_glu), 4.87 (dd-t, 1H, J = 9.4 Hz, J = 9.4 Hz,

H-4_glu), 4.93 (dd-t, 1H, J = 9.7 Hz, J = 9.7 Hz, H-2_glu), 5.16 and 5.22 (qAB, 2H, J = 16.5 Hz, CH₂CO),

5.34–5.41 (m, 3H, H-1_glu, CH₂O_chin), 5.45 (dd-t, 1H, J = 9.4 Hz, J = 9.4 Hz, H-3_glu), 7.41 (dd, 1H, J =

3.6 Hz, J = 5.4 Hz, H-7_chin), 7.49–7.57 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.24 (s, 1H, H-5_triaz), 8.32 (dd,

1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.83 (d, 1H, J = 2.7 Hz, H-2_chin), 9.25 (d, 1H, J = 9.3 Hz, CONH); ¹³

NMR (100 MHz, DMSO-d6): 20.27, 20.30, 20.33, 20.48, 51.40, 61.73, 67.72, 70.58, 72.13, 72.64, 76.85,

C

δ

79.12, 109.94, 119.95, 121.81, 126.38, 126.69, 129.02, 135.73, 139.70, 142.37, 148.94, 153.82, 166.17, 169.13,

169.25, 169.44, 169.94; HRMS (ESI-TOF): calcd for C₂₈H₃₂N₅O₁₁([M + H]⁺): m/z 614.2098; found: m/z

614.2095.

Glycoconjugate 78: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-galactopyranosyl)azidoacetamide 34

, product was obtained as a yellow solid (227.0 mg, 74%); m.p.:

1.92, 1.98, 1.99, 2.12 (4s,

and 8-(2-propyn-1-yloxy)quinoline

3

22

100–103 ^◦C; [

α

]

_D= 14.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ

12H, CH₃CO), 3.98 (dd, 1H, J = 6.7 Hz, J = 11.3 Hz, H-6a_gal), 4.05 (dd, 1H, J = 5.9 Hz, J = 11.3 Hz,

H-6b_gal), 4.35 (m, 1H, H-5_gal), 5.08 (dd, 1H, J = 9.0 Hz, J = 9.4 Hz, H-2_gal), 5.13 and 5.21 (qAB, 2H, J

= 16.5 Hz, CH₂CO), 5.27-5.44 (m, 5H, H-1_gal, H-3_gal, H-4_gal, CH₂O_chin), 7.42 (dd, 1H, J = 3.2 Hz, J =

5.8 Hz, H-7_chin), 7.50–7.58 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.24 (s, 1H, H-5_triaz), 8.28–8.35 (m, 2H,

H-4_chin, H-2_chin), 9.34 (d, 1H, J = 9.5 Hz, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.33, 20.38, 20.48,

20.72, 51.37, 61.42, 61.75, 67.54, 68.24, 70.66, 71.43, 77.22, 109.95, 119.98, 121.88, 124.11, 126.39, 126.70,

135.73, 139.72, 142.38, 148.91, 153.85, 166.09, 169.31, 169.37, 169.78, 169.85; HRMS (ESI-TOF): calcd for

C₂₈H₃₂N₅O₁₁([M + H]⁺): m/z 614.2098; found: m/z 614.2091.

Glycoconjugate 79: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-glucopyranosyl)azidoacetamide 33 and

, product was obtained as a pink solid (254.2 mg, 81%); m.p.:

= 5.2 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ 1.94, 1.97, 1.99, 2.00 (4s, 12H,

D

2-methyl-8-(2-propyn-1-yloxy)quinoline

4

27

93–96 ^◦C; [

α

]

CH₃CO), 2.63 (s, 3H, CH₃), 3.94–4.03 (m, 1H, H-6a_glu), 4.06–4.18 (m, 2H, H-5_glu, H-6b_glu), 4.87 (dd-t,

Molecules 2019, 24, 4181

27 of 40

J = 9.4 Hz, J = 10.4 Hz, H-4_glu), 4.92 (dd-t, J = 9.7 Hz, J = 9.8 Hz, H-2_glu), 5.15 and 5.21 (qAB, 2H, J

= 16.5 Hz, CH₂CO), 5.33–5.48 (m, 4H, H-1_glu, H-3_glu, CH₂O_chin), 7.38 (dd, 1H, J = 1.6 Hz, J = 7.5 Hz,

H-7_chin), 7.41 (d, 1H, J = 8.4 Hz, H-3_chin), 7.43 (dd, 1H, J = 7.5 Hz, J = 8.0 Hz, H-6_chin), 7.47 (dd, 1H, J =

1.6 Hz, J = 8.0 Hz, H-5_chin), 8.18 (d, 1H, J = 8.4 Hz, H-4_chin), 8.24 (s, 1H, H-5_triaz), 9.25 (d, 1H, J = 9.3 Hz,

CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.21, 20.24, 20.27, 20.41, 24.85, 51.34, 61.53, 67.65, 70.51,

72.06, 72.57, 76.78, 79.06, 110.09, 119.72, 122.38, 125.54, 126.38, 127.27, 135.85, 139.11, 142.37, 153.27,

157.15, 166.10, 169.06, 169.19, 169.37, 169.87; HRMS (ESI-TOF): calcd for C₂₉H₃₄N₅O₁₁([M + H]⁺): m/z

628.2255; found: m/z 628.2256.

Glycoconjugate 80: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-galactopyranosyl)azidoacetamide 34

, product was obtained as a pink solid (244.8 mg, 78%);

= 11.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

δ 1.92, 1.98, 1.99, 2.12

D

and 2-methyl-8-(2-propyn-1-yloxy)quinoline

4

27

m.p.: 98–101 ^◦C; [

α

]

(4s, 12H, CH₃CO), 2.63 (s, 3H, CH₃), 3.98 (dd, 1H, J = 6.6 Hz, J = 11.3 Hz, H-6a_gal), 4.06 (dd, 1H, J =

5.9 Hz, J = 11.3 Hz, H-6b_gal), 4.35 (m, 1H, H-5_gal,), 5.07 (dd-t, 1H, J = 9.4 Hz, J = 9.4 Hz, H-2_gal), 5.12

and 5.20 (qAB, 2H, J = 16.5 Hz, CH₂CO), 5.26–5.44 (m, 5H, H-1_gal, H-3_gal, H-4_gal, CH₂O_chin), 7.32–7.54

(m, 4H, H-3_chin, H-5_chin, H-6_chin, H-7_chin)8.21 (d, 1H, J = 7.9 Hz, H-4_chin), 8.24 (s, 1H, H-5_triaz), 9.33 (d,

1H, J = 9.5 Hz, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.23, 20.26, 20.31, 20.40, 24.84, 51.30, 61.54,

67.47, 68.16, 70.59, 71.35, 77.14, 79.06, 110.10, 119.72, 122.36, 125.54, 126.38, 127.24, 135.85, 139.11, 142.36,

153.27, 157.15, 166.02, 169.23, 169.29, 169.71, 169.77; HRMS (ESI-TOF): calcd for C₂₉H₃₄N₅O₁₁([M +

H]⁺): m/z 628.2255; found: m/z 628.2253.

Glycoconjugate 81: Starting from N-(

yloxy)quinoline

16.7 (c = 2.0, DMSO); ¹H NMR (400 MHz, DMSO-d6):

β

-D-glucopyranosyl)azidoacetamide 35 and 8-(2-propyn-1-

25

3

, product was obtained as a brown solid (133.6 mg, 60%); m.p.: 160-163 ^◦C; [

α

]

=

D

δ

3.04–3.15 (m, 3H, H-2_glu, H-4_glu, H-5_glu), 3.21

(dd-t, 1H, J = 8.4 Hz, J = 8.6 Hz, H-3_glu), 3.42 (m, 1H, H-6a_glu), 3.63 (m, 1H, H-6b_glu), 4.00–4.50 (m, 4H,

OH), 4.71 (dd-t, 1H, J = 8.9 Hz, J = 9.0 Hz, H-1_glu), 5.17 and 5.22 (qAB, 2H, J = 16.5 Hz, CH₂CO), 5.57 (s,

2H, CH₂O_chin), 7.60–8.10 (m, 5H, H-3_chin, H-4_chin, H-5_chin, H-6_chin, H-7_chin), 8.39 (s, 1H, H-5_triaz), 8.96

(d, 1H, J = 7.4 Hz, H-2_chin), 9.04 (d, 1H, J = 8.8 Hz, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 51.55,

60.72, 62.36, 69.74, 72.44, 77.18, 78.65, 79.63, 112.94, 120.36, 122.56, 126.79, 128.94, 132.86, 136.25, 136.88,

141.50, 146.25, 151.30, 165.67; HRMS (ESI-TOF): calcd for C₂₀H₂₄N₅O₇([M + H]⁺): m/z 446.1676; found:

m/z 446.1679.

Glycoconjugate 82: Starting from N-(

yloxy)quinoline

14.5 (c = 2.0, DMSO); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranosyl)azidoacetamide 36 and 8-(2-propyn-1-

25

3

, product was obtained as a brown solid (129.2 mg, 58%); m.p.: 170-173 ^◦C; [

α

]

=

D

δ

3.34 (dd, 1H, J = 3.2 Hz, J = 9.4 Hz, H-3_gal),

3.36–3.46 (m, 3H, H-2_gal, H-5_gal, H-6a_gal), 3.50 (dd, 1H, J = 5.8 Hz, J = 10.5 Hz, H-6b_gal), 3.69 (d,

1H, J = 3.0 Hz, H-4_gal), 4.09–4.42 (m, 4H, OH), 4.69 (dd-t, 1H J = 8.9 Hz, J = 9.0 Hz, H-1_gal), 5.18

(s, 2H, CH₂CO), 5.60 (s, 2H, CH₂O_chin), 7.56–8.16 (m, 4H, H-3_chin, H-5_chin, H-6_chin, H-7_chin), 8.41 (s,

1H, H-5_triaz), 8.85–9.20 (m, 3H, H-2_chin, H-4_chin, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 51.62,

60.31, 68.02, 69.66, 73.85, 76.75, 79.08, 80.07, 112.53, 120.38, 126.83, 126.96, 129.01, 130.10, 141.66, 142.90,

146.07, 150.24, 152.06, 165.58; HRMS (ESI-TOF): calcd for C₂₀H₂₄N₅O₇([M + H]⁺): m/z 446.1676; found:

m/z 446.1670.

Glycoconjugate 83: Starting from N-(

β

-D-glucopyranosyl)azidoacetamide 35 and 2-methyl-8-(2-

, product was obtained as a brown solid (140.1 mg, 61%); m.p.: 135–138

2.8 (c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

= δ 2.92 (s, 3H, CH₃), 3.04–3.24 (m,

propyn-1-yloxy)quinoline

4

26

^◦C; [

α

]

−

D

3H, H-2_glu, H-4_glu, H-5_glu), 3.39–3.47 (m, 2H, H-3_glu, H-6a_glu,), 3.62 (dd, 1H, J = 1.6 Hz, J = 12.1 Hz,

H-6b_glu), 4.69 (dd-t, 1H, J = 8.9 Hz, J = 9.0 Hz, H-1_glu), 5.15 and 5.20 (qAB, 2H, J = 16.5 Hz, CH₂CO),

5.60 (s, 2H, CH₂O_chin), 7.73–7.93 (m, 4H, H-3_chin, H-5_chin, H-6_chin, H-7_chin), 8.34 (s, 1H, H-5_triaz), 8.89 (d,

1H, J = 8.3 Hz, H-4_chin), 9.04 (d, 1H, J = 8.8 Hz, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ

18.45, 51.52,

60.71, 62.31, 69.74, 72.42, 77.18, 78.65, 79.62, 113.85, 120.30, 124.31, 126.87, 127.70, 128.48, 141.31, 143.79,

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148.61, 158.29, 163.67, 165.65; HRMS (ESI-TOF): calcd for C₂₁H₂₆N₅O₇([M + H]⁺): m/z 460.1832; found:

m/z 460.1830.

Glycoconjugate 84: Starting from N-(

β

-D-galactopyranosyl)azidoacetamide 36 and 2-methyl-8-(2-

, product was obtained as a brown solid (179.2 mg, 78%); m.p.: 145–148 ^◦C;

= 5.0 (c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

δ 2.88 (s, 3H, CH₃), 3.34 (dd, 1H, J =

D

propyn-1-yloxy)quinoline

4

24

[

α

]

3.2 Hz, J = 9.4 Hz, H-3_gal), 3.37-3.54 (m, 4H, H-2_gal, H-5_gal, H-6a_gal, H-6b_gal), 3.69 (d, 1H, J = 3.0 Hz,

H-4_gal), 3.95–4.31 (m, 4H, OH), 4.67 (dd-t, 1H, J = 8.9 Hz, J = 9.0 Hz, H-1_gal), 5.17 (s, 2H, CH₂CO), 5.59

(s, 2H, CH₂O_chin), 7.62–7.98 (m, 4H, H-3_chin, H-5_chin, H-6_chin, H-7_chin), 8.34 (s, 1H, H-5_triaz), 8.84 (bs,

1H, H-4_chin), 9.01 (d, 1H, J = 9.0 Hz, CONH); ¹³C NMR (100 MHz, DMSO-d6):

δ 18.45, 51.55, 60.30,

62.27, 68.01, 69.65, 73.85, 76.74, 80.06, 113.46, 120.27, 124.12, 126.87, 128.23, 131.53, 141.40, 142.91, 149.12,

158.22, 162.36, 165.59; HRMS (ESI-TOF): calcd for C₂₁H₂₆N₅O₇([M + H]⁺): m/z 460.1832; found: m/z

460.1831.

Glycoconjugate 85: Starting from 2,3,4,6-tetra-O-acetyl-N-(β-D-glucopyranosyl)propiolamide 37 and

8-(2-azidoethoxy)quinoline

5

, product was obtained as a yellow solid (220.9 mg, 72%); m.p.: 89–94 ^◦C;

23

1

[

α

]

=

−

18.0 (c = 1.0, CHCl₃); H NMR (400 MHz, DMSO-d6):

δ

1.86, 1.94, 1.98, 2.00 (4s, 12H,

D

CH₃CO), 3.98 (dd, 1H, J = 3.9 Hz, J = 14.0 Hz, H-6a_glu), 4.07–4.18 (m, 2H, H-5_glu, H-6b_glu), 4.66 (t,

2H, J = 5.1 Hz, CH₂N), 4.90 (dd-t, 1H, J = 9.6 Hz, J = 9.6 Hz, H-4_glu), 4.98 (t, 2H, J = 5.1 Hz, CH₂O),

5.20 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-2_glu), 5.38 (dd-t, 1H, J = 9.5 Hz, J = 9.5 Hz, H-1_glu), 5.59 (dd-t,

1H, J = 9.3 Hz, J = 9.4 Hz, H-3_glu), 7.25 (dd, 1H, J = 1.4 Hz, J = 7.5 Hz, H-7_chin), 7.47–7.59 (m, 3H,

H-3_chin, H-5_chin, H-6_chin), 8.32 (dd, 1H, J = 1.7 Hz, J = 8.4 Hz, H-4_chin), 8.87 (dd, 1H, J = 1.5 Hz, J =

4.1 Hz, H-2_chin), 8.98 (s, 1H, H-5_triaz), 9.20 (d, 1H, J = 9.5 Hz, NHCO); ¹³C NMR (100 MHz, DMSO-d6):

δ

20.30, 20.31, 20.37, 20.50, 49.56, 61.85, 67.07, 67.85, 70.49, 72.04, 73.03, 76.79, 110.69, 120.60, 121.93,

126.69, 128.20, 129.08, 135.86, 139.71, 141.83, 149.25, 153.60, 160.03, 169.02, 169.32, 169.54, 169.97; HRMS

(ESI-TOF): calcd for C₂₈H₃₂N₅O₁₁([M + H]⁺): m/z 614.2098; found: m/z 614.2097.

Glycoconjugate 86: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-galactopyranosyl)propiolamide 38 and

, product was obtained as a white solid (285.3 mg, 93%); m.p.: 187–189 ^◦C;

6.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.96, 2.00, 2.01, 2.17 (4s, 12H, CH₃CO),

8-(2-azidoethoxy)quinoline

5

24

[

α

]

−

D

4.03–4.17 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal), 4.63 (t, 2H, J = 4.9 Hz, CH₂N), 5.02 (t, 2H, J = 4.9 Hz, CH₂O),

5.15 (dd, 1H, J = 3.3 Hz, J = 10.1 Hz, H-3_gal), 5.30 (dd-t, 1H, J = 9.3 Hz, J = 10.1 Hz, H-2_gal), 5.41 (dd-t,

1H, J = 9.3 Hz, J = 9.5 Hz, H-1_gal), 5.45 (dd, 1H, J = 0.6 Hz, J = 3.3 Hz, H-4_gal), 7.04 (dd, 1H, J = 1.7 Hz, J

= 7.2 Hz, H-7_chin), 7.40–7.50 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 7.83 (d, 1H, J = 9.5 Hz, NHCO); 8.14 (dd,

1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.95 (s, 1H, H-5_triaz), 9.00 (dd, 1H, J = 1.7 Hz, J = 4.2 Hz. H-2_chin);

¹³C NMR (100 MHz, CDCl₃):

δ 20.57, 20.63, 20.64, 20.67, 50.14, 61.27, 67.24, 67.53, 68.08, 71.17, 72.32,

78.15, 110.28, 121.34, 122.02, 126.42, 128.22, 129.64, 135.98, 140.36, 142.35, 149.81, 153.67, 160.32, 169.90,

170.15, 170.35, 170.46; HRMS (ESI-TOF): calcd for C₂₈H₃₂N₅O₁₁([M + H]⁺): m/z 614.2098; found: m/z

614.2095.

Glycoconjugate 87: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-glucopyranosyl)propiolamide 37 and

, product was obtained as a yellow solid (207.1 mg, 66%); m.p.:

14.8 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.85, 1.93, 1.98, 2.00 (4s,

2-methyl-8-(2-azidoethoxy)quinoline

8

24

167–172 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.72 (s, 3H, CH₃), 3.98 (dd, 1H, J = 4.5 Hz, J = 14.3 Hz, H-6a_glu), 4.07–4.18 (m, 2H, H-5_glu

,

H-6b_glu), 4.54–4.67 (m, 2H, CH₂N), 4.90 (dd-t, 1H, J = 9.4 Hz, J = 9.5 Hz, H-4_glu), 4.98 (t, 2H, J = 5.0 Hz,

CH₂O), 5.21 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-2_glu),5.38 (dd-t, 1H, J = 9.5 Hz, J = 9.5 Hz, H-1_glu), 5.60

(dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-3_glu), 7.21 (dd, 1H, J = 1.2 Hz, J = 7.7 Hz, H-7_chin), 7.38–7.46 (m, 2H,

H-3_chin, H-6_chin), 7.50 (dd, 1H, J = 1.1 Hz, J = 8.2 Hz, H-5_chin), 8.20 (d, 1H, J = 8.5, H-4_chin), 9.17 (d, 1H, J

= 9.5 Hz, NHCO), 9.20 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.29, 20.31, 20.37, 20.50,

25.00, 49.59, 61.86, 67.17, 67.85, 70.52, 72.01, 73.01, 76.75, 111.06, 120.46, 122.58, 125.63, 127.30, 128.62,

136.02, 139.28, 141.93, 153.06, 157.80, 160.08, 169.01, 169.32, 169.53, 169.97; HRMS (ESI-TOF): calcd for

C₂₉H₃₃N₅O₁₁([M + H]⁺): m/z 628.2255; found: m/z 628.2252.

Molecules 2019, 24, 4181

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Glycoconjugate 88: Starting from 2,3,4,6-tetra-O-acetyl-N-(β-D-galactopyranosyl)propiolamide 38 and

2-methyl-8-(2-azidoethoxy)quinoline

8

, product was obtained as a white solid (257.3 mg, 82%); m.p.:

25

107–109 ^◦C; [

α

]

= δ 1.95, 2.00, 2.02, 2.17 (4s, 12H,

−

7.2 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

D

CH₃CO), 2.88 (s, 3H, CH₃), 4.03–4.17 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal), 4.59 (t, 2H, J = 4.9 Hz, CH₂N),

5.00 (t, 2H, J = 4.8 Hz, CH₂O), 5.15 (dd, 1H, J = 3.4 Hz, J = 10.2 Hz, H-3_gal), 5.30 (dd-t, 1H, J = 9.4 Hz, J

= 10.2 Hz, H-2_gal), 5.42 (dd-t, 1H, J = 9.4 Hz, J = 9.5 Hz, H-1_gal), 5.45 (dd, 1H, J = 0.7 Hz, J = 3.4 Hz,

H-4_gal), 7.02 (dd, 1H, J = 1.3 Hz, J = 7.5 Hz, H-7_chin), 7.32–7.39 (m, 2H, H-3_chin, H-6_chin), 7.42 (dd, 1H, J

= 1.3 Hz, J = 8.2 Hz, H-5_chin), 7.84 (d, 1H, J = 9.6 Hz, NHCO), 8.02 (d, 1H, J = 8.4 Hz, H-4_chin), 9.26 (s,

1H, H-5_triaz); ¹³C NMR (100 MHz, CDCl₃):

δ 20.57, 20.61, 20.64, 20.66, 25.62, 50.18, 61.23, 67.23, 67.45,

68.08, 71.18, 72.25, 78.11, 110.54, 121.14, 122.90, 125.38, 127.79, 128.65, 136.04, 139.94, 142.40, 153.15,

159.03, 160.36, 169.90, 170.15, 170.34, 170.41; HRMS (ESI-TOF): calcd for C₂₉H₃₄N₅O₁₁([M + H]⁺): m/z

628.2255; found: m/z 628.2254.

Glycoconjugate 89: Starting from N-(

quinoline

= 1.0, DMSO); ¹H NMR (400 MHz, DMSO-d6):

β

-D-glucopyranosyl)propiolamide 39 and 8-(2-azidoethoxy)

28

5

, product was obtained as a white solid (133.6 mg, 60%); m.p.: 169–171 ^◦C; [

α

]

_D= 5.0 (c

δ

3.05-3.11 (m, 1H, H-5_glu), 3.13–3.18 (m, 2H, H-2_glu,

H-4_glu), 3.33–3.37 (m, 1H, H-3_glu), 3.38–3.44 (m, 1H, H-6a_glu), 3.60–3.67 (m, 1H, H-6b_glu), 4.48 (t, 1H,

J = 5.9 Hz, 6-OH), 4.66 (t, 2H, J = 4.6 Hz, CH₂N), 4.83–4.93 (m, 3H, H-1_glu, OH), 4.95–5.01 (m, 3H,

CH₂O, OH), 7.25 (d, 1H, J = 7.5 Hz, H-7_chin), 7.47–7.62 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.32 (d, 1H, J =

10.4 Hz, H-4_chin), 8.68 (d, 1H, J = 9.1 Hz, NHCO), 8.88 (bs, 1H, H-2_chin), 8.94 (s, 1H, H-5_triaz); ¹³C NMR

(100 MHz, DMSO-d6):

δ 49.52, 60.97, 67.11, 69.97, 71.83, 77.44, 78.70, 79.51, 110.64, 120.60, 121.96, 126.69,

127.68, 129.08, 135.84, 139.71, 142.53, 149.29, 153.63, 160.08; HRMS (ESI-TOF): calcd for C₂₀H₂₄N₅O₇

([M + H]⁺): m/z 446.1676; found: m/z 446.1678.

Glycoconjugate 90: Starting from N-(

quinoline

1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

β

-D-galactopyranosyl)propiolamide 40 and 8-(2-azidoethoxy)

25

5

, product was obtained as a white solid (189.3 mg, 85%); m.p.: 162–164 ^◦C; [

α

]

_D= 24.8 (c =

δ

3.34-3.54 (m, 4H, H-2_gal, H-3_gal, H-4_galH-5_gal), 3.57–3.65

(m, 1H, H-6a_gal), 3.66–3.72 (m, 1H, H-6b_gal), 4.29 (d, 1H, J = 4.9 Hz, OH), 4.56 (t, 1H, J = 5.4, 6-OH), 4.66

(t, 2H, J = 5.1 Hz, CH₂N), 4.74 (d, 1H, J = 5.5 Hz, OH), 4.79 (d, 1H, J = 5.5 Hz, OH), 4.87 (dd-t, 1H, J =

9.0 Hz, J = 9.1 Hz, H-1_gal), 4.98 (t, 2H, J = 5.0 Hz, CH₂O), 7.26 (dd, 1H, J = 1.4 Hz, J = 7.5 Hz, H-7_chin),

7.47–7.59 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.32 (dd, 1H, J = 1.5 Hz, J = 8.2 Hz, H-4_chin), 8.48 (d, 1H, J =

9.1 Hz, NHCO), 8.88 (dd, 1H, J = 1.7 Hz, J = 4.1 Hz, H-2_chin), 8.95 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz,

DMSO-d6):

δ 49.52, 60.42, 67.13, 68.37, 69.33, 74.03, 76.82, 79.93, 110.69, 120.60, 121.93, 126.68, 127.61,

129.07, 135.84, 139.72, 142.47, 149.29, 153.62, 159.97; HRMS (ESI-TOF): calcd for C₂₀H₂₄N₅O₇([M +

H]⁺): m/z 446.1676; found: m/z 446.1675.

Glycoconjugate 91: Starting from N-(

β

-D-glucopyranosyl)propiolamide 39 and 2-methyl-8-(2-

, product was obtained as a white solid (144.7 mg, 63%); m.p.: 159–161 ^◦C;

3.6 (c = 1.0, MeOH); ¹H NMR (400 MHz, DMSO-d6):

= δ 2.72 (s, 3H, CH₃), 3.03–3.12 (m, 1H,

azidoethoxy)quinoline

8

25

[α

]

−

D

H-5_glu), 3.13–3.27 (m, 2H, H-2_glu, H-4_glu), 3.34–3.46 (m, 2H, H-3_glu, H-6a_glu), 3.60–3.68 (m, 1H, H-6b_glu),

4.47 (t, 1H, J = 5.9 Hz, 6-OH), 4.55–4.67 (m, 2H, CH₂N), 4.86–4.93 (m, 3H, H-1_glu, OH), 4.94–5.02 (m,

3H, CH₂O, OH), 7.21 (dd, 1H, J = 1.2 Hz, J = 7.7 Hz, H-7_chin), 7.39–7.47 (m, 2H, H-3_chin, H-6_chin), 7.50

(dd, 1H, J = 1.1 Hz, J = 8.2 Hz, H-5_chin), 8.20 (d, 1H, J = 8.4 Hz, H-4_chin), 8.63 (d, 1H, J = 9.1 Hz, NHCO),

9.15 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz, DMSO-d6):

δ 25.07, 49.57, 60.99, 67.27, 69.97, 71.85, 77.42,

78.68, 79.47, 111.02, 120.47, 122.62, 125.64, 127.31, 128.11, 136.02, 139.28, 142.63, 153.11, 157.85, 160.12;

HRMS (ESI-TOF): calcd for C₂₀H₂₄N₅O₇([M + H]⁺): m/z 460.1832; found: m/z 460.1830.

Glycoconjugate 92: Starting from N-(

β

-D-galactopyranosyl)propiolamide 40 and 2-methyl-8-(2-

, product was obtained as a white solid (186.1 mg, 81%); m.p.: 148–151 ^◦C;

2.72 (s, 3H, CH₃), 3.34–3.55 (m, 4H,

azidoethoxy)quinoline

8

28

[

α

]

_D= 23.0 (c = 1.0, DMSO); ¹H NMR (400 MHz, DMSO-d6):

δ

H-2_gal, H-3_gal, H-4_galH-5_gal), 3.57–3.66 (m, 1H, H-6a_gal), 3.66–3.72 (m, 1H, H-6b_gal), 4.28 (d, 1H, J =

5.0 Hz, OH), 4.52–4.67 (m, 3H, CH₂N, 6-OH), 4.73 (d, 1H, J = 5.5 Hz, OH), 4.79 (d, 1H, J = 5.5 Hz, OH),

Molecules 2019, 24, 4181

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4.88 (dd-t, 1H, J = 9.0 Hz, J = 9.1 Hz, H-1_gal), 4.98 (t, 2H, J = 5.0 Hz, CH₂O), 7.21 (dd, 1H, J = 1.2 Hz, J =

7.7 Hz, H-7_chin), 7.39–7.46 (m, 2H, H-3_chin, H-6_chin), 7.50 (dd, 1H, J = 1.1 Hz, J = 8.2 Hz, H-5_chin), 8.20

(d, 1H, J = 8.4 Hz, H-4_chin), 8.43 (d, 1H, J = 9.1 Hz, NHCO), 9.16 (s, 1H, H-5_triaz); ¹³C NMR (100 MHz,

DMSO-d6):

δ 25.04, 49.56, 60.40, 67.28, 68.37, 69.36, 74.02, 76.78, 79.89, 111.08, 120.47, 122.59, 125.62,

127.30, 128.04, 136.00, 139.29, 142.57, 153.11, 157.83, 160.00; HRMS (ESI-TOF): calcd for C₂₁H₂₆N₅O₇

([M + H]⁺): m/z 460.1832; found: m/z 460.1836.

Glycoconjugate 93: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-glucopyranosyl)propiolamide 37 and

, product was obtained as a yellow solid (210.2 mg, 67%); m.p.:

18.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.89, 1.94, 1.99, 2.00 (4s,

8-(3-azidopropoxy)quinoline

6

24

178–180 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.40–2.50 (m, 2H, CH₂), 4.00 (dd, 1H, J = 4.4 Hz, J = 14.2 Hz, H-6a_glu), 4.06–4.18 (m, 2H,

H-5_glu, H-6b_glu), 4.21 (t, 2H, J = 6.0 Hz, CH₂N), 4.72 (t, 2H, J = 6.8 Hz, CH₂O), 4.91 (dd-t, 1H, J = 9.5 Hz,

J = 9.5 Hz, H-4_glu), 5.21 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-2_glu), 5.39 (dd-t, 1H, J = 9.5 Hz, J = 9.5 Hz,

H-1_glu), 5.61 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-3_glu), 7.20 (dd, 1H, J = 1.8 Hz, J = 7.1 Hz, H-7_chin),

7.46–7.59 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 8.32 (dd, 1H, J = 1.5 Hz, J = 8.1 Hz, H-4_chin), 8.90 (dd, 1H, J

= 1.7 Hz, J = 4.0 Hz, H-2_chin), 8.90 (s, 1H, H-5_triaz), 9.17 (d, 1H, J = 9.5 Hz, NHCO); ¹³C NMR (100 MHz,

DMSO-d6):

δ 20.32, 20.33, 20.38, 20.52, 29.36, 47.24, 61.85, 65.52, 67.84, 70.52, 72.04, 73.02, 76.80, 109.92,

119.97, 121.84, 126.77, 127.67, 129.03, 135.79, 139.77, 141.83, 149.07, 154.18, 160.10, 169.04, 169.32, 169.54,

169.98; HRMS (ESI-TOF): calcd for C₂₉H₃₄N₅O₁₁([M + H]⁺): m/z 628.2255; found: m/z 628.2252.

Glycoconjugate 94: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-galactopyranosyl)propiolamide 38 and

, product was obtained as a white solid (263.6 mg, 84%); m.p.: 98–100 ^◦C;

5.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.99, 2.00, 2.03, 2.17 (4s, 12H, CH₃CO),

8-(3-azidopropoxy)quinoline

6

25

[

α

]

−

D

2.62 (p, 2H, J = 6.2 Hz, CH₂), 4.04–4.18 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal), 4.24 (t, 2H, J = 5.8 Hz, CH₂N),

4.81 (t, 2H, J = 6.6 Hz, CH₂O), 5.17 (dd, 1H, J = 3.3 Hz, J = 10.2 Hz, H-3_gal), 5.31 (dd-t, 1H, J = 9.4 Hz, J

= 10.2 Hz, H-2_gal), 5.42 (dd-t, 1H, J = 9.4 Hz, J = 9.5 Hz, H-1_gal), 5.46 (dd, 1H, J = 0.6 Hz, J = 3.3 Hz,

H-4_gal), 7.06 (dd, 1H, J = 1.7 Hz, J = 7.2 Hz, H-7_chin), 7.41–7.50 (m, 3H, H-3_chin, H-5_chin, H-6_chin), 7.85 (d,

1H, J = 9.5 Hz, NHCO), 8.16 (dd, 1H, J = 1.7 Hz, J = 8.3 Hz, H-4_chin), 8.52 (s, 1H, H-5_triaz), 9.01 (dd, 1H,

J = 1.7 Hz, J = 4.2 Hz. H-2_chin); ¹³C NMR (100 MHz, CDCl₃):

δ 20.53, 20.57, 20.64, 20.68, 29.67, 47.73,

61.28, 65.36, 67.24, 68.11, 71.16, 72.33, 78.16, 109.94, 120.67, 121.82, 126.62, 127.18, 129.61, 136.09, 140.39,

142.04, 149.55, 154.23, 160.36, 169.90, 170.15, 170.36, 170.45; HRMS (ESI-TOF): calcd for C₂₉H₃₄N₅O₁₁

([M + H]⁺): m/z 628.2255; found: m/z 628.2253.

Glycoconjugate 95: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-glucopyranosyl)propiolamide 37 and

, product was obtained as a beige solid (195.7 mg, 61%); m.p.:

18.0 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, DMSO-d6):

= δ 1.88, 1.94, 1.99, 2.00 (4s,

2-methyl-8-(3-azidopropoxy)quinoline

9

24

197–198 ^◦C; [

α

]

−

D

12H, CH₃CO), 2.41–2.49 (m, 2H, CH₂), 2.67 (s, 3H, CH₃), 3.96–4.02 (m, 1H, H-6a_glu), 4.05–4.17 (m, 2H,

H-5_glu, H-6b_glu), 4.20 (t, 2H, J = 6.2 Hz, CH₂N), 4.71 (t, 2H, J = 6.9 Hz, CH₂O), 4.91 (dd-t, 1H, J = 9.5 Hz,

J = 9.5 Hz, H-4_glu), 5.20 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-2_glu), 5.38 (dd-t, 1H, J = 9.5 Hz, J = 9.5 Hz,

H-1_glu), 5.59 (dd-t, 1H, J = 9.3 Hz, J = 9.4 Hz, H-3_glu), 7.17 (dd, 1H, J = 1.3 Hz, J = 7.6 Hz, H-7_chin),

7.36–7.44 (m, 2H, H-3_chin, H-6_chin), 7.47 (dd, 1H, J = 1.2 Hz, J = 8.2 Hz, H-5_chin), 8.19 (d, 1H, J = 8.4 Hz,

H-4_chin), 8.83 (s, 1H, H-5_triaz), 9.17 (d, 1H, J = 9.5 Hz, NHCO); ¹³C NMR (100 MHz, DMSO-d6):

δ 20.31,

20.37, 20.51, 20.74, 25.03, 29.25, 47.14, 61.84, 65.56, 67.83, 70.51, 72.02, 73.01, 76.78, 110.54, 119.91, 122.44,

125.68, 127.32, 127.58, 135.97, 139.34, 141.77, 153.64, 157.35, 160.06, 169.02, 169.31, 169.53, 169.97; HRMS

(ESI-TOF): calcd for C₃₀H₃₆N₅O₁₁([M + H]⁺): m/z 642.2411; found: m/z 642.2408.

Glycoconjugate 96: Starting from 2,3,4,6-tetra-O-acetyl-N-(

β

-D-galactopyranosyl)propiolamide 38 and

, product was obtained as a white solid (202.1 mg, 63%); m.p.:

4.6 (c = 1.0, CHCl₃); ¹H NMR (400 MHz, CDCl₃):

= δ 1.98, 2.00, 2.03, 2.17 (4s, 12H,

2-methyl-8-(3-azidopropoxy)quinoline

9

25

121–123 ^◦C; [

α

]

−

D

CH₃CO), 2.60 (p, 2H, J = 6.4 Hz, CH₂), 2.80 (s, 3H, CH₃), 4.04–4.17 (m, 3H, H-5_gal, H-6a_gal, H-6b_gal),

4.24 (t, 2H, J = 5.9 Hz, CH₂N), 4.82 (t, 2H, J = 6.7 Hz, CH₂O), 5.16 (dd, 1H, J = 3.4 Hz, J = 10.2 Hz,

H-3_gal), 5.30 (dd-t, 1H, J = 9.4 Hz, J = 10.1 Hz, H-2_gal), 5.40 (dd-t, 1H, J = 9.4 Hz, J = 9.5 Hz, H-1_gal), 5.46

Article Doi

8-hydroxyquinoline glycoconjugates: Modifications in the linker structure and their effect on the cytotoxicity of the obtained compounds

DOI: 10.3390/molecules24224181

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Article abstract of DOI:10.3390/molecules24224181

Full text of DOI:10.3390/molecules24224181

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