A Dinuclear Dysprosium Complex as an Air-Stable and Recyclable Catalyst: Applications in the Deacetylation of Carbohydrate, Aliphatic, and Aromatic Molecules

Article abstract of DOI:10.1002/asia.201801652

Two dinuclear Dy^III complexes, [Dy₂(hmb)₂(OTf)₂(H₂O)₄]?HOTf?2 THF (A?HOTf?2 THF) and [Dy₂(hmi)₃(H₂O)₂]?2 HOTf (B?2 HOTf), have been synthesized by the reaction of Dy(OTf)₃ and the Schiff-base ligands H₂hmb (N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) or H₂hmi ((2-hydroxy-3-methoxyphenyl)methylene isonicotinohydrazine). Disarmed glycosyl trichloroacetimidates can be activated by complex A in the synthesis of 1,2-trans-glycosides with primary and secondary acceptors. This method offers an efficient route to selectively deacetylated monosaccharides and disaccharides in high yields and a green catalyst that can be easily recycled and reused.

Full text of DOI:10.1002/asia.201801652

CHEMISTRY
AN ASIAN JOURNAL
www.chemasianj.org
Accepted Article
Title: Dinuclear Dysprosium Complex as Air-Stable and Recyclable
Catalyst: Application in Deacetylation of Carbohydrate, Aliphatic
and Aromatic Molecules
Authors: Ting-Yu Chiu, Wei Chin, Jiun-Rung Guo, Chien-Fu Liang, and
Po-Heng Lin
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10.1002/asia.201801652
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Dinuclear Dysprosium Complex as Air-Stable and Recyclable Catalyst:
Application in Deacetylation of Carbohydrate, Aliphatic and Aromatic
Molecules
Ting-Yu Chiu, Wei Chin, Jiun-Rung Guo, Chien-Fu Liang, and Po-Heng Lin*
Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
Keywords: Dinuclear dysprosium complex • deacetylation • carbohydrate • recycling catalyst
*To whom correspondence should be addressed. E-mail: poheng@dragon.nchu.edu.tw (P.-H. Lin) Tel:
886-4-22840411-724; Fax: 886-4-22862547.
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Abstract
Two dinuclear DyIII complexes, [Dy2(hmb)2(OTf)2(H2O)4]·HOTf·2THF (A·HOTf·2THF) and
[Dy2(hmi)3(H2O)2]·2HOTf (B·2HOTf), have been synthesized by the reaction of Dy(OTf)3 and the
Schiff-base ligands, H2hmb (N’-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) or H2hmi ((2-
hydroxy-3-methoxyphenyl)methylene
isonicotinohydrazine).
Disarmed
glycosyl
trichloroacetimidates can be activated by complex A in the synthesis of 1,2-trans glycosides
involving primary and secondary acceptors. This method offers an efficient solution for selectively
deacetylated monosaccharides and disaccharides with high yields as well as a green catalyst which
could be easily recycled and reused.
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1. Introduction
Metal salts, such as AlCl3, BF3, TiCl4, SnCl4, AlMe3, VO(OTf)2 have been used as Lewis acid
catalysts and electron pair acceptors of organic reactions due to their reactivity and selectivity.[1] In
the last three decades, trivalent lanthanide salts, especially lanthanide triflate (Ln(OTf)3),[2] have been
the subject of numerous research articles in organic synthesis due to their stability and Lewis acidity
in water,[2e] such as in C-X (X: C, N, O, P and S) bond formation.[3] Moreover, lanthanide salts were
also involved in organic synthesis as catalysts, in reactions such as direct acetylation of alcohols with
acetic acid.[2f] In addition, selective deprotection of multiple identical functional groups which has
been observed using lanthanide salts as catalysts is very important in organic synthesis. Recently,
Ln(OTf)3 were further selected as highly efficient catalysts for glycosylations and anomeric
deacetylations.[4] Interestingly, regioselective anomeric deacetylation is an important step in
oligosaccharide assembly used for the preparation of glycosyl trichloroacetimidate or glycosyl
phosphates.[5] So far, numerous selectively deprotecting reagents are reported to perform this
transformation. However, disadvantages associated with some of these reagents are toxicity and low
regioselectivity.[6] Therefore, a highly chemoselective and environmentally friendly catalyst for
anomeric deacetylation would extend the scope of this transformation.
On the other hand, coordination complexes or metal clusters serve as homogeneous catalysts in
several important industrial reactions due to the improvement of catalyst specificity and directed
change of its activity.[7] Indeed, lanthanide-based metal clusters have been of increasing interest due
to their fascinating structural diversity as well as their electronic, optical,[8] magnetic,[9] and catalytic
properties.[10] However, to the best of our knowledge, there is no study focused on using metal
clusters as catalysts in anomeric deacetylation reactions to date, especially for carbohydrate
chemistry.
High activity, specificity and industrial applications could be achieved by exploring novel
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lanthanide clusters with different ligand systems.[11] Schiff-base ligands have been selected due to
their obvious advantages in the literatures, such as ease of synthesis, low cost, a hard donor atom
framework, and tunable steric and electronic effects.[12] However, selecting Ln(OTf)3 as a lanthanide
[13]
precursor with Schiff-base ligands
for synthesizing pure 4f-complexes were relatively rare but
coordinated triflate ions may be the key to activate the organic reactions. Herein, three novel di-
nuclear dysprosium complexes have been synthesized which complex A·HOTf·2THF,
[Dy2(hmb)2(OTf)2(H2O)4]·HOTf·2THF, was highlighting for the first time that lanthanide cluster
complexes can be effective in deacetylation reactions and selective for the anomeric position of
carbohydrates.[4,14] Moreover, the process can reduce reagent waste due to the recyclability of the
catalyst without decreasing catalytic ability which perfectly fits the sustainable green model.
2. Results and Discussion
Syntheses and Crystal Structure Determination
The synthetic pathways of dinuclear dysprosium complexes A and B are shown in Scheme 1.
Reaction of H2hmb with one equivalent of Dy(OTf)3 in a THF/MeCN mixture gave the dinuclear
complex [Dy2(hmb)2(OTf)2(H2O)4]·HOTf·2THF (A·HOTf·2THF). Pale yellow crystals of A were
grown by vapor diffusion of diethyl ether into the mother liquor over three days at ambient
temperature. No additional base in the synthetic conditions would allow a slower growth of suitable
crystals for single-crystal XRD. The presence of THF in the reaction seems to be crucial since it
could be the lattice solvent for recrystallization. The similar dinuclear molecule structure can also be
obtained in acetone. The detail of structure description will be discussed later. Indeed, H2hmb ligand
has been applied for synthesizing dinuclear complexes for Single-molecule magnet [10e,15] and catalyst
of copolymerization.[10d] However, complex A is still very important for the application since the
literature complexes with acetate and nitrate counter ions only partially dissolved in MeOH which
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complex A is the only dinuclear complex in this series can be acted as a homogenous catalyst.
Due to the keto-enol forms of the ligands, H2hmb and H2hmi have been applying for the syntheses of
multinuclear metal clusters with different ratio of DyIII to counter ions.[10d] We also selected H2hmi as
a ligand for the further complex preparation and [Dy2(hmi)3(H2O)2]·2HOTf (B·2HOTf) could be
obtained under the synthetic conditions of [DyIII]/[H2hmi] = 1/1 with 8 eq. pyridine as base in
EtOH/MeCN mixing solution. All complexes are isolated as air-stable crystalline solids and fully
characterized by IR spectroscopy and elemental analysis. Single-crystal structures of complexes A
A·HOTf·2THF, A·( CH3)2CO and B were further confirmed with X-ray diffraction.
Scheme 1. Synthetic Routes for Complexes A and B
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Structures of Dinuclear complexes
The X-ray structures of A and B are described in the following discussion. The selected bond
distances between metal and ligand are present in Table 1.
Table 1. Selected bond lengths (Å ) and angles (°) for complex A
A·HOTf·2THF
A∙(CH3)2CO
Complex
Dy1 – Dy1a
Dy1 – O1
3.7752(8)
2.309(5)
2.337(5)
2.335(6)
2.525(5)
2.487(6)
2.487(6)
2.399(5)
2.399(6)
2.533(5)
107.33(19)
72.67(19)
75.57(20)
3.7750(6)
2.318(4)
2.366(4)
2.335(5)
2.508(4)
2.465(5)
2.486(5)
2.389(5)
2.404(5)
2.533(5)
107.41(16)
72.59(16)
75.18(19)
Dy1 –O1a
Dy1 – O2
Dy1 – O3
Dy1 – O4
Dy1 – O5
Dy1 – O7
Dy1 – O8
Dy1 – N1
Dy1 – O1 – Dy1a
O1 – Dy1 – O1a
O7 – Dy1 – O8
Structural description of A
Single crystal X-Ray diffraction reveals that [Dy2(hmb)2(OTf)2(H2O)4]∙HOTf∙2THF
(A∙HOTf∙2THF) crystallizes in the triclinic P-1 space group. The structure of complex A is shown in
Figure 1. The tetradentate hmb2– ligand coordinates to the Dy centers in the di-nuclear unit via three
O atoms (O(1), O(2) and O(3)) and one N atom (N(1)). The metal centers are bridged by the
phenolate groups of two ligands with a Dy-O-Dy(A) angle of 107.33(19)°, and the distances between
Dy1 and Dy1a is 3.7752(8) Å. The remaining four coordination sites of each lanthanide ion are filled
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by four terminal H2O molecules and two bridging triflate anions. Crystallographic data and charge
balance considerations indicated that both O1 and O2 atoms of the ligand are deprotonated and the
oxidation state of the ligand is 2- which is similar to the mononuclear complexes in the literature.
[15,16]
The coordination geometry of DyIII centers were distorted D3h tricapped trigonal prism as
determine by SHAPE 2.1.[17]
Figure 1. Molecular structure of centrosymmetric complex [Dy2(hmb)2(OTf)2(H2O)4], A. Symmetry
equivalent positions are denoted by an additional “a” in the label. Color code: Orange (Dy), Red (O),
Blue (N), Grey (C), Yellow (S) and Green (F). H atoms were omitted for clarity
Single crystal X-Ray diffraction displays that [Dy2(hmb)2(OTf)2(H2O)4]∙(CH3)2CO (A∙
(CH3)2CO) crystallizes in the triclinic P-1 space group.(Table S1) Using acetone instead of
THF/MeCN in the syntheses resulted in different co-solvents in the molecular structure which only
slightly effected the unit cell, bond distances and angles. (Table 1) Since the dinuclear complex acted
as a homogenous catalyst in deacetylation reactions, the minor solid state differences between
complexes A∙HOTf∙2THF and A∙(CH3)2CO may not affect the activity or selectivity of deacetylation.
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We focused on complex A·HOTf·2THF for the following metal-catalyzed organic reactions.
Structural description of B
[Dy2(hmi)3(H2O)2]∙2HOTf (B∙2HOTf) was obtained through the reaction of H2hmi(1 eq.),
pyridine(8 eq.), Dy(OTf)3(1 eq.) in EtOH and MeCN. Single crystal X-Ray diffraction reveals that
complex B∙2HOTf crystallizes in the orthorhombic Pbca space group. The structure of complex B is
shown in Figure 2 with selected bond lengths in Table S2. Two DyIII ions are nine-coordinate and
asymmetric in each molecule. There are three ligands coordinated to the Dy centers in the dinuclear
unit via two O atoms and one N atom. The DyIII centers are bridged by the phenoxide groups of three
ligands with Dy1-O2-Dy2, Dy1-O5-Dy2 and Dy1-O8-Dy2 angles of 98.71(14)°, 96.67(14)° and
99.76(14)°, respectively and a Dy1…Dy2 intramolecular distance of 3.5444(4) Å . The remaining six
coordination sites of Dy2 are filled by two nitrogens (N4 and N7) and three oxygen (O1, O6 and O9)
atoms from three ligands and one water molecule (O11). Two methoxy (O4 and O7) and one nitrogen
(N1) and one oxygen (O3) atom from the other ligand coordinate to Dy2. The remaining two
coordination sites of Dy1 are filled by one water molecule (O10) and the pyridyl N atom (N6a) from
neighboring complexes resulting in a one-dimensional chain of the dinuclear units. (Figure 3) Charge
balance considerations indicated the enol form of hmi2- was observed that bridged phenoxides (O2,
O5 and O8) as well as O3, O6 and O9 were deprotonated. The coordination geometry of Dy1 and
Dy2 were distorted D3h tricapped trigonal prism and C4v capped square antiprism, respectively, as
determine by SHAPE 2.1.[17]
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Figure 2. Molecular structure of [Dy2(hmi)3(H2O)2], B. N6a is pyridyl N atom from neighboring
complexes. Color code: Orange (Dy), Red (O), Blue (N), Grey (C), Yellow (S) and Green (F). H
atoms were omitted for clarity
Figure 3. 1-D chain of complex [Dy2(hmi)3(H2O)2]∞ as viewed along b axis.
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Deacetylation of aliphatic and aromatic molecules
In order to study the catalytic activity of complex A in deacetylation reactions, we have examined
aromatic derivatives as our initial substrate model, including phenyl and benzyl acetates (1a-1e).
Deacetylation is readily accomplished upon stirring the substrates for 24-48 hours with heating in the
presence of a catalytic amount of complex A (5 mol%) in methanol (0.04 M), as shown in Scheme 2.
Remarkably, the acetyl group with different functionalized aromatic derivatives, including electron
withdrawing/donating groups, can all be deprotected with high yields in 24 hours. These deprotection
processes were previously commonly carried out either in strong acidic/basic conditions or under
mild and/or neutral conditions requiring at least one equivalence or excess (>1 mol eq.) reagent per
deprotecting acetate group.[15] Selecting complex A as a catalyst in deacetylation can reduce the
reagent usage since the acetyl group can be converted to the free hydroxyl group sufficiently in
catalytic amounts (5 mol%).
Scheme 2. Selective deacetylation of different functionalized aromatic derivatives.
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In addition to the outstanding reactivity of complex A, another advantage of this dinuclear
complex, in metal-catalyzed organic reactions, is the possibility of recycling the catalytic system with
separation of the organic product formed through a simple extraction with organic solvents.
Previously, in the literature, lanthanide salts used as catalysts in acetylation and/or deacetylation
reactions could be recycled from the aqueous phase without loss of activity.[4a,18] However, the drying
process is complicated in order to recover the lanthanide salt from the aqueous layer. The solubility
of complex A and products (2a-2e) were different in ether which offers easy recovery by way of
filtration. The crude products were concentrated in vacuum and then extracted with ether. Upon
addition of ether, the catalyst precipitated out of solution immediately, was recovered through
filtration and reused in the next experiment for the next deacetylation reaction. Any residual catalyst
A can be easily detected by naked eyes or UV-Vis spectrum due to the light yellow color (Figure S2,
29627 M-1cm-1 at 388 nm). Moreover, the lifetime of a catalytic system is another important factor to
be considered. All the entries in Scheme 2 can be completed by the same batch of catalyst through
recycling without losing yield. (Figure 4) To compare the deacetylation efficiency of complex A with
the other complexes, we also examined the same aromatic derivatives in the same reaction conditions
with complex B. Only the acetyl group of 4-nitrophenol acetate (2b) can all be deprotected within 24
hours and complex B was almost inactive to all the rest of aromatic derivatives (2a, 2c-2e) were
almost inactive. The deacetylation of 2b can be explained by electronic effect of strong electron
withdrawing group from nitro group that result to acetyl group could be removed very easily by trace
DyIII ions from complex B in the solution. (Scheme S1) Furthermore, complex B may not be a good
catalyst for the rest of examples due to the saturated coordination environment filled by three
tetradentate ligands, hmi2-. No coordinated ions (triflate) on dysprosium centers for complex B might
result to the lack of leaving group which forbidden aromatic derivatives interacted with Dy centers
directly.
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Figure 4. Percent yield of 2a-2e using the recycling technique of the catalyst from the same batch
of complex A. All reaction conditions were the same as those used for the individual reaction (2a-2e)
as reported in the SI.
For further application of this protocol, we looked to address the chemoselective
monodeacetylation of diacetate molecules which is an important and challenging issue in synthetic
organic transformations. According to the literature, the monoacetates of symmetrical diols were
prepared by selective monodeacetylation of diacetates by lipase and zeolite.[19] We have utilized our
developed reaction conditions used for the aromatic derivatives for the deprotection of the
monoacetate group of 1,5-diacetoxypentane (Scheme 3). The reaction mixture was stirred for 18
hours and the filtrate was evaporated under vacuum. The residue dissolved in ether and the yellow
powder, complex A, was filtered. Compound 4a, 5-acetoxypentane-1-ol, was obtained after
purification by column chromatography over silica gel (yield: 71%). Although both acetate groups
are primary acetates, the lipase and zeolite were not able to further deprotect the second acetate.[19]
Interestingly, as we extended the reaction time to 84 hours, the second acetate was also deprotected
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and pentanediol (4b) was obtained with 74% yield.
Scheme 3. Selective deacetylation of 1,5-Diacetoxypentane (Compound 3).
To extend this protocol for catalytic deacetylation by complex A, we selected a series of
peracetylated mono- and disaccharides as substrates for regioselective anomeric deacetylation by
complex A in methanol. Two monosaccharides (5 and 7) were treated in the reaction conditions
shown in Table 2. The yields of deacetylation for entries 1 and 2 are both 88 %, which are higher than
the yields obtained using commercial lanthanide triflates as catalyst.[4a,20] Moreover, we also
conducted the reaction in similar conditions without heating and the same yields could be obtained
after 60 hrs. Due to the high selectively and activity of complex A, two disaccharides (9 and 11) were
also tested under optimized conditions. The peracetylated hemiacetal 10 and 12 derived from 9 and
11 can be obtained in 64% and 84% yields, respectively. Indeed, complex A is a valuable catalyst for
deacetylation of carbohydrates since both mono- and disaccharides can be regioselectively
deacetylated at the anomeric carbon.
Complex A can also be recycled in carbohydrate deprotected reactions (Figure 5). Due to the
solubility of the monosaccharides, DCM had been selected instead of ether to extract the crude
products. Repeating entry 1 by using the yellow filtrate as the catalyst which did not dissolve in
DCM for another four cycles, quantitative conversion was still achieved with the same reaction
conditions and the yields were all maintained around 88%. Indeed, the remaining complex A in the
DCM fraction was measured by UV-Vis absorption spectra that only 0.2% residue was observed
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which confirmed the catalyst were fully recycled. On the basis of these results, we proposed a
plausible mechanism for this reaction (Scheme S2). Complex A can be a Lewis acid to utilize with
monosaccharides or disaccharides and release a triflate ion. This intermediate 1 might react with
MeOH as transesterification process and form the peracetylated hemiacetal product followed by the
triflate ions coordinated with intermediate 2 for recycling the catalyst.
Table 2. Regioselective deacetylation of monosaccharides and disaccharides.
Figure 5. The yield of compound 6 in the recycle experiments. All reaction conditions were the same
as entry 1
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Complex B was also treated as a catalyst for anomeric deacetylation of carbohydrates in the same
reaction condition. However, it is impossible to extract the product by DCM since light yellow color
was observed in both fractions. The light yellow DCM solution may indicate that the solubility of
complex B was changed or complex B was decomposed during the reaction. As the previous
proposed mechanism, the acetylated carbohydrate may coordinate on dinuclear cluster in the
deacetylation process, but there is no proper leaving group on complex B due to the lack of
coordinated triflate ion. For this reason, one of the ligands was necessary to remove in order to insert
acetylated carbohydrate leading to the decomposition of the complexes and the free ligands might
further dissolve in DCM solution.
In a previous study, the acetate groups in galactose-derived thioglycosides can be selectively
removed.[20] We also conducted a similar reaction in glucose-derived thioglycoside to study whether
complex A can be used to selectively deacetylate at other carbon positions. Because thioglycosides
serve as important building blocks for the preparation of oligosaccharides, we selected 1-
thioglucoside 13 as substrate for catalytic deacetylation. (Scheme 4) The mixture of products, 14a
and 14b, were obtained after 17 hours, where 14b was formed by acetyl group migration from C4 to
C6 during the reaction which were also shown in previous study.[20] A higher molar ratio of catalyst
was necessary for the reaction since the reactivity of C6-OAc was lower than C1-OAc. However,
after recovering the unreacted 13, the best recovery yield in optimal reaction conditions was 60%,
due to the multi-hydration side products formed during the long reaction time. Currently, ligand
modification is underway to design suitable catalysts for selective deacetylation on other positions.
According to the reactions described above, reflux temperature and reaction time are key factors to
control the selectivity since all the acetyl groups on sugar may also be deprotected. For this reason,
we extended the reaction temperature and time in order to understand the reactivity of different acetyl
groups and the stability of complex A. The mixture of compound 5 and complex A was heated under
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reflux for 116 hours, after which the catalyst could not be recycled due to heating for a long period of
time. The crude product dissolved in MeOH/DCM mixer. Indeed, free H2hmb ligand, from the
decomposition of complex A, was obtained by chromatography. The dark yellow fraction can be
easily differentiated from other carbohydrates and can also be confirmed by NMR spectrum
identification. (Figure S22) The rest of unrecognized organic fractions were difficult to separate and
the fraction from the most obvious spot in TLC was shown in figure S22 and S23. Comparing two
spectrums of this fraction and compound 5 which indicated that no acetyl functional group was
observed in H-NMR around 1.8-2.2 ppm and C-NMR around 20-30 ppm. (Figure S23 and S24) The
major crude product was completely deacetylated which may have resulted from the ligand-free DyIII
salts reacting as Lewis acid catalysts.[21]
Scheme 4. Regioselective deacetylation of 1-thioglucoside (Compound 13)
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3. Conclusions
In conclusion, we successfully synthesized three dinuclear dysprosium complexes which complex
A was an effective and chemoselective catalyst for deacetylation of esters in methanol. Both high
efficiency and chemoselectivity were achieved for substrates bearing different aromatic and alkyl
chain derivatives. This method is especially valuable for preparation of peracetylated hemiacetal of
monosaccharides and disaccharides with 85-88% and 65-85% yields, respectively. Complex B as a
good comparison also indicated that the coordinated triflate ions were the key to activate the
regioselective anomeric deacetylation. Most importantly, this approach is a green alternative to using
only lanthanide salts or other described procedures, since complex A can be effectively recycled and
reused without reducing activity and selectivity. We are assured that the use of lanthanide clusters as
an environmentally friendly catalyst will continue to pave the way towards the regioselective
deacetylation of even more complicated sugars in the future.
4. Experimental Section
General methods
All chemicals and solvents were purchased from Sigma-Aldrich, Strem chemicals, and Echo
1
chemicals, used as received without further purification. H NMR spectra were acquired on a Varian
Mercury-400 spectrometer. Fourier transform IR spectra were obtained using a Thermo Scientific
Nicolet iS5 FT-IR with ATR accessory Spectrometer in 4000-650 cm-1 range. The Schiff-base pro-
ligands, (2-hydroxy-3-methoxyphenyl)methylene benzohydrazide (H2hmb) and (2-hydroxy-3-
methoxyphenyl)methylene isonicotinohydrazine (H2hmi) were prepared with similar methods
according to literature procedures.[10d]
Synthesis of [Dy2(hmb)2(OTf)2(H2O)4]·HOTf·2THF (A·HOTf·2THF)
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A solution of Dy(OTf)3 (0.125mmol, 0.076g) in MeCN (15mL) was added slowly to a solution of
H2hmb (0.125mmol, 0.034g) in THF (15mL). The mixture was stirred for 1 min at room temperature
and then filtered. After four days, X-ray-quality light yellow needle crystals were formed by vapor
diffusion of diethyl ether, which were collected by filtration, washed with ether, and dried in vacuum.
(Yield ~ 30%) The sample was maintained in contact with the ether bath to prevent deterioration of
the crystals, which have been identified crystallographically. Select IR data (cm-1): 1621(w), 1606(m),
1564(m), 1460(m), 1438(w), 1400(m), 1314(m), 1268(m), 1243(s), 1220(s), 1193(s), 1109(w),
1081(m), 1026(s), 963(m), 904(w), 847(w), 798(w), 787(w), 763(w), 746(m), 737(m), 706(m),
688(m), 630(s). Anal. Calcd. for C33H39Dy2F9N4O22S3 (A·HOTf·3H2O): C, 27.40; H, 2.45; N, 3.95%.
Found: C, 27.60; H, 2.74; N, 3.90%. CCDC reference number: 1555466.
[Dy2(hmb)2(OTf)2(H2O)4]·(CH3)2CO (A·(CH3)2CO)
To a solution of Dy(OTf)3 (0.125 mmol, 76 mg) in acetone (30 mL), H2hmb (0.125 mmol, 33 mg)
was added, and the mixture was stirred for 1 min until a yellow solution was achieved. After three
days, the synthesis yields a solution that renders pale yellow needle crystal of A, suitable for X-ray
diffraction studies. The program SQUEEZE [22] as implemented in Platon [23] was used to remove the
contribution of the disordered HOTf to the structure factors. Yield: 20 %. Select IR data (cm-1):
1621(w), 1606(m), 1564(m), 1496(w), 1460(m), 1438(w), 1400(m), 1314(m), 1268(m), 1243(s),
1220(s), 1193(s), 1168(s), 1110(w), 1081(m), 1026(s), 964(m), 903(w), 847(w), 798(w), 786(w),
763(w), 746(m), 737(m), 706(m), 688(m), 630(s). Anal. Calcd. for C33H33Dy2F9N4O19S3 (A·HOTf):
C, 28.50; H, 2.04; N, 3.83%. Found: C, 28.68; H, 2.41; N, 4.05%. CCDC reference number: 1828908
[Dy2(hmi)3(H2O)2]·2HOTf (B·2HOTf)
H2hmi (0.125 mmol, 34 mg) dissolved in EtOH (15 mL), and then pyridine (1.0 mmol, 80.8 μL)
was added. To the resultant yellow solution, Dy(OTf)3 (0.125 mmol, 76 mg) and MeCN (15 mL)
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were added, and the mixture was stirred for 1 min until a yellow solution was achieved. After about
five days, light yellow block crystals were collected from the solution. Yield: 30 %. Select IR data
(cm-1): 1605(s), 1550(s), 1521(s), 1498(w), 1459(s), 1414(m), 1385(m), 1363(m), 1291(s), 1252(s),
1221(s), 1170(s), 1106(w), 1078(m), 1029(s), 1006(w), 966(m), 908(m), 854(m), 783(w), 743(s),
698(s), 640(s). The program SQUEEZE as implemented in Platon was used to remove the
contribution of the disordered cosolvents to the structure factors. Anal. Calcd. for
C46H51Dy2F6N9O21S2 (B·2HOTf·EtOH·5H2O): C, 35.41; H, 3.68; N, 8.35%. Found: C, 35.21; H,
3.28; N, 8.03%.CCDC reference number: 1828910
General Procedure for Deacetylation of Aromatic derivatives and Anomeric Deacetylation of
Carbohydrates
A solution of 1a-e or 1-O-acetylated sugar (5, 7, 9 and 11) (100 mg) and catalyst A·HOTf·2THF (5
o
mol%) in MeOH (0.04 M) was stirred at heating temperature (50 C ~ reflux) under nitrogen
atmosphere and until full conversion by TLC analysis. The reaction mixture was cooled to room
temperature and dried in vacuum. The residue dissolved in DCM and sonicated for a few seconds, the
catalyst was filtered and collected from the filter paper. The catalyst could redissolve in MeOH and
reuse. The crude products were collected from DCM solutions and purified by column
chromatography on silica gel (ethyl acetate/hexane). The details of reaction yield and product
analysis are shown in SI.
5-hydroxypentyl acetate (4a)
A solution of 3 (100 mg) and catalyst A (37.9 mg, 5 mol%) in MeOH (13.2 mL, 0.04M) was
stirred at heating temperature (reflux) for 18 hours under nitrogen atmosphere. The reaction mixture
was cooled to room temperature and dried in vacuum. Dissolve the residual by DCM and sonicate for
a few seconds, the catalyst was filtered and collected from the filter paper. The catalyst could
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redissolved in MeOH for reuse. The crude products were collected from DCM solutions and purified
by column chromatography to afford the product 4a (55.3 mg, 71% yield). The products analysis is
shown in SI.
1,5-Pentanediol (4b)
A solution of 3 (100 mg) and catalyst A (37.9 mg, 5 mol%) in MeOH (13.2 mL, 0.04M) was
stirred at heating temperature (reflux) for 96 hours under nitrogen atmosphere. The reaction mixture
was cooled to room temperature and dried in vacuum. Dissolve the residual by DCM and sonicate for
a few seconds, the catalyst was filtered and collected from the filter paper. The catalyst can be
redissolved in MeOH for reused. The crude products were collected from DCM solutions and
purified by column chromatography to afford the product 4b (40.5 mg, 73% yield).
Acknowledgments
We gratefully acknowledge the financial support from National Chung Hsing University and the
Ministry of Science and Technology, Taiwan (MOST 105-2113-M-005-011 and 107-2113-M-005-003
to P.-H. Lin and MOST 105-2113-M-005-006 to C.-F. Liang).
Supporting information Available: CCDC1555466, 1828908 and 1828910 contain the
supplementary crystallographic data for complexes A·HOTf·2THF, A·(CH3)2CO and B·2HOTf,
respectively.
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References
[1] (a) F. Fringuelli, F. Pizzo, L. Vaccaro, J. Org. Chem. 2001, 66, 4719-4722; (b) R. F. Childs, D. L.
Mulholland, A. Nixon, Can. J. Chem. 1982, 60, 801-808; (c) C.-C. Lin, M.-D. Jan, S.-S. Weng,
C.-C. Lina, C.-T. Chen, Carbohydr. Res. 2006, 341, 1948-1953.
[2] (a) S. Kobayashi, M. Sugiura, H. Kitagawa, W. W.-L. Lam, Chem. Rev. 2002, 102, 2227-2302;
(b) M. Adinolfi, G. Barone, A. Iadonisi, L. Mangoni, M. Schiattarella, Tetrahedron Lett. 2001,
42, 5967-5969; (c) M. Adinolfi, G. Barone, L. Guariniello, A. Iadonisi, Tetrahedron Lett. 2000,
41, 9005-9008; (d) L. T. Padiyar, Y.-S. Wenzc, S.-C Hung, Chem. Commun. 2010, 46, 5524-
5526; (e) C.-C. Wang, S.-Y. Luo, C.-R. Shie, S.-C. Hung, Org. Lett. 2002, 4, 847-849; (f) S.
Kobayashi, S. Nagayama, T. Busujima, J. Am. Chem. Soc. 1998, 120, 8287-8288; (g) A. G. M.
Barrett, D. C. Braddock, Chem. Commun. 1997, 0, 351-352; (h) K. Shen, X. Liu, L. Lin, X.
Feng, Chem. Sci. 2012, 3, 327; (i) W. Chen, L. Lin, Y. Cai, Y. Xia, W. Cao, X. Liu, X. Feng,
Chem. Commun. 2014, 50, 2161; (j) X. Liu, H. Zheng, Y. Xia, L. Lin, X. Feng, Acc. Chem. Res.
2017, 50, 2621-2631; (k) H. Yu, S. Dong, Q. Yao, L. Chen, D. Zhang, X. Liu, X. Feng, Chem.
Eur. J. 2018, 24, 1-8.
[3] (a) A. Dzudza, T. Marks, Tetrahedron Lett. 2008, 49, 2163-2165; (b) S. Kobayashi, K. Manabe,
ACS Symp. Ser. 2002, 819, 151-165; (c) C.-J. Li, Chem. Rev. 1999, 93, 2023-2035.
[4] (a) A. T. Tran, S. Deydier, D. Bonnaffe, C. L. Narvor, Tetrahedron Lett. 2008, 49, 2163-2165; (b)
Y.-X. Li, Y.-W. Li, W. Zhang, H.-S. Guan, Chin. J. Chem. 2004, 22, 117-118.
[5] (a) X. Zhu, R. R. Schmidt, Angew. Chem. Int. Ed. 2009, 48, 1900-1934; (b) S. Sabesan, S. Neira,
Carbohydr. Res. 1992, 223, 169-185; (c) P. J. Meloncelli, A. D. Martin, T. L. Lowary,
Carbohydr. Res. 2009, 344, 1110-1122.
[6] (a) G. Excoffier, D. Gagnaire, J.-P. Utille, Carbohydr. Res. 1975, 39, 368-373; (b) K. Watanbe,
21
This article is protected by copyright. All rights reserved.

10.1002/asia.201801652
Chemistry - An Asian Journal
Submitted to
K. Itoh, Y. Araki, Y. Ishido, Carbohydr. Res. 1986, 154, 165-176; (c) T. Sambaiah, P. E.
Fanwick, M. Cushman, Synthesis 2001, 10, 1450-145.
[7] (a) A. K. Smith, J. M. Basset, J. Mol. Catal., 1977, 2, 229-241; (b) G. Duca, Homogeneous
Catalysis with Metal Complexes. Springer Series in Chemical Physics. Springer Berlin,
Heidelberg, 2012, Vol. 102; (c) X. Jiang, S. Ma, J. Am. Chem. Soc. 2007, 129, 11600-11607.
[8] (a) K. Binnemans, Chem. Rev. 2009, 109, 4283-4374; (b) S. Faulkner, L. Natrajan, S. William, D.
Sykes, Dalton Trans. 2009, 3890-3899; (c) J.-C. Bünzli, C. Piguet, Chem. Soc. Rev. 2005, 34,
1048-1077.
[9] (a) D. I. Alexandropoulos, S. Mukherjee, C. Papatriantafyllopoulou, C. P. Raptopoulou, V.
Psycharis, V. Bekiari, G. Christou, T. C. Stamatatos, Inorg. Chem. Commun. 2011, 50, 11276-
11278; (b) K. Binnemans, Handbook on the Physics and Chemistry Lanthanides of Rare-Earth.
2005, 35, 107-272; (c) X. Feng, J. S. Zhao, B. Liu, L. Y. Wang, S. Ng, G. Zhang, J. G. Wang, X.
G. Shi, Y. Y. Liu, Cryst. Growth Des. 2010, 10, 1399-1408; (d) J. Long, B. G. Shestakov, D Liu,
L. F. Chibotaru, Y. Guari, A. V. Cherkasov, G. K. Fukin, A. A. Trifonov, J. Larionova, Chem.
Commun. 2017, 53, 4706-4709.
[10] (a) M. Gustafsson, A. Bartoszewicz, B. Martin-Matute, J. L. Sun, J. Grins, T. Zhao, Z. Y. Li, G.
S. Zhu, X. D. Zou, Chem. Mater. 2010, 22, 3316-3322; (b) Y. Zhu, Y. Wang, P. Liu, C. Xia, Y.
Wu, X. Lu, J. Xie, Dalton Trans. 2015, 44, 1955-1961; (c) X.-M. Lin, J.-L. Niu, P.-X. Wen, Y.-N.
Lu, L. Hu, D.-L. Zhang, Y.-P. Cai, RSC Adv. 2016, 6, 63425-63432; (d) C.-H. Ho, H.-J. Chuang,
P.-H. Lin, B.-T. Ko, J. Polym. Sci. A Polym. Chem. 2017, 55, 321-328; (e) C.-J. Kuo, R. J.
Holmberg, P.-H. Lin, Dalton Trans. 2015, 44, 19758-19762; (f) S-Y. Tosaki, K. Hara, V.
Gnanadesikan, H. Morimoto, S. Harada, M. Sugita, N. Yamagiwa, S. Matsunaga, M. Shibasaki,
J. Am. Chem. Soc. 2006, 128, 11776-11777; (g) J. R. Robinson, X. Fan, J. Yadav, P. J. Carroll, A.
J. Wooten, M. A. Pericꢀs, E. J. Schelter, P. J. Walsh, J. Am. Chem. Soc. 2014, 136, 8034-8041; (h)
22
This article is protected by copyright. All rights reserved.

10.1002/asia.201801652
Chemistry - An Asian Journal
Submitted to
K.-C. Lee, H.-J. Chuang, B.-H. Huang, B.-T. Ko, P.-H. Lin, Inorg. Chim. Acta. 2016, 450, 411-
417; (i) I. J. Gray, R. Kluger, Carbohydr. Res. 2007, 342, 1998-2002; (j) N. K. Jalsa, Catal.
Commun. 2012, 18, 32-36; (k) T. Stahlberg, M. G. Sorensen, A. Riisager, Green Chem. 2010, 12,
321-325.
[11] (a) K. Nie, X. Gu, Y. Yao, Y. Zhang, Q. Shen, Dalton Trans. 2010, 39, 6832-6840; (b) K. Nie,
L. Fang, Y. Yao, Y. Zhang, Q. Shen, Y. Wang, Inorg. Chem. 2012, 51, 11133-11143; (c) S.
Yang, Z. Du, Y. Zhang, Q. Shen, Chem. Commun. 2012, 48, 9780-97822.
[12] (a) K. C. Gupta, A. K. Sutar, C.-C. Lin, Coord. Chem. Rev. 2009, 253, 1926-1946; (b) H. C.
Aspinall, Chem. Rev. 2002, 102, 1807-1850; (c) V. Alexander, Chem. Rev. 1995, 95, 273-342;
(d) F.-B. Han, Y.-L. Zhang, X.-L. Sun, B.-G Li, Y.-H. Guo, Y. Tang, Organometallics 2008, 27,
1924-1928; (e) X.-H. Yang, X.-L. Sun, F.-B. Han, B. Liu, Y. Tang, C. Wang, M.-L. Gao, Z. Xie,
S.-Z. Bu, Organometallics 2008, 27, 4618-4624; (f) C. Wang, Z. Ma, X.-L. Sun, Y. Gao, Y.-H.
Guo, Y. Tang, L.-P. Shi, Organometallics 2006, 25, 3259-3266.
[13] (a) P.-H. Lin, I. Korobkov, T. J. Burchell, M. Murugesu, Dalton Trans. 2012, 41, 13649-13655;
(b) F. B. Tamboura, O. Diouf, A. H. Barry, M. Gaye, A. S. Sall, Polyhedron 2012, 43, 97-10; (c)
A. J. Hutchings, F. Habib, R. J. Holmberg, I. Korobkov, M. Murugesu, Inorg. Chem. 2014, 53,
2102-21122; (d) F. Piccinelli, A. Melchior, A. Speghini, M. Monari, M. Tolazzi, M. Bettinelli,
Polyhedron 2013, 57, 30-38; (e) M. Albrecht, S. Mirtschin, O. Osetska, S. Dehn, D. Enders, R.
Frohlich, T. Pape, E. F. Hahn, Eur. J. Inorg. Chem. 2007, 3276-32877; (f) X. Yang, R. A. Jones,
J. H. Rivers, W.-K. Wong, Dalton Trans. 2009, 10505-10510; (g) T. Nankawa, M. Watanabe, M.
Murata, H. Nishihara, Chem. Lett. 2003, 32, 286-287; (h) M. Albrecht, Y. Yulia, A. Exarchos, P.
Nachev, R. Frohlich, Dalton Trans. 2009, 7421-7427; (i) M. W. Loble, P. Ona-Burgos, I.
Fernandez, C. Apostolidis, A. Morgenstern, O. Walter, F. Bruchertseifer, P. Kaden, T. Vitova, J.
Rothe, K. Dardenne, N. L. Banik, A. Geist, M. A. Denecke, F. Breher, Chem. Sci. 2013, 4,
23
This article is protected by copyright. All rights reserved.

10.1002/asia.201801652
Chemistry - An Asian Journal
Submitted to
3717-3724.
[14] M. Takhi, A. H. Adel, R. R. Schmidt, Tetrahedron Lett. 2001, 42, 4053-4056.
[15] P.-H. Lin, T. J. Burchell, R. Clérac, M. Murugesu, Angew. Chem. Int. Ed. 2008, 47, 8848-8851.
[16] (a) M. G. Pérez, M. S. Maier, Tetrahedron Lett. 1995, 36, 3311-3314; (b) R. Yanada, N. Negoro,
K. Bessho, K Yanada, Synlett. 1995, 12, 1261-1263.
[17] (a) S. Alvarez, P. Alemany, D. Casanova, J. Cirera, M. Llunell, D. Avnir, Coord. Chem. Rev.
2005, 249, 1693-1708; (b) A. Ruiz-Martínez, D. Casanova, S. Alvarez, Chem. Eur. J. 2008, 14,
1291-1303.
[18] G. Bartoli, R. Dalpozzo, A. D. Nino, L. Maiuolo, M. Nardi, A. Procopio, A. TagarelliGreen
Green Chem. 2004, 6, 191-192.
[19] (a) K. V. N. S. Srinivas, I. Mahender, B. Das, SYNLETT. 2003, 15, 2419-2421; (b) O. Houllle, T.
Schmittberger, D. Uguen, Tetrahedron Lett. 1996, 37, 625-628.
[20] C. Y. Liu, H. L. Chen, C. M. Ko, C. T. Chen, Tetrahedron 2011, 67, 872-876.
[21] (a) R. B. Deval, R. S. Assary, E. Nikolla, M. Moliner, Y. R. Leshkov, S. J. Hwang, A. Palsdottir,
D. Silverman, R. F. Lobo, L. A. Curtiss, M. E. Davis, PNAS. 2012, 109, 9727-9732; (b) J. Tang,
X. Guo, L. Zhu, C. Hu, ACS Catal. 2015, 5, 5097-5103.
[22] P. van der Sluis, A. L. Spek, Acta Cryst. 1990, A46, 194-201.
[23] D.H.R. Barton, R. K. Haynes, G. Leclerc, P. D. Magnus, I. D. Menzies, J. Chem. Soc., Perkin
Trans. 1975, 1, 2055-2065.
24
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Table of Contents:
Dinuclear dysprosium complex as air-stable and recyclable catalyst:
application in deacetylation of carbohydrate, aliphatic and aromatic
molecules
Ting-Yu Chiu, Wei Chin, Jiun-Rung Guo, Chien-Fu Liang, and Po-Heng Lin*
Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
Disarmed glycosyl trichloroacetimidates can be activated by dinuclear dysprosium complex,
[Dy2(hmb)2(OTf)2(H2O)4]·HOTf·2THF (A·HOTf·2THF), in the synthesis of 1,2-trans glycosides involving
primary and secondary acceptors. This method offers an efficient solution for selectively deacetylated
saccharides with high yields as well as a green catalyst which could be easily recycled and reused.
25
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