An inexpensive catalyst, Fe(acac)3, for regio/site-selective acylation of diols and carbohydrates containing a 1,2-: Cis -diol

Article abstract of DOI:10.1039/c8gc00428e

This work describes the [Fe(acac)₃] (acac = acetylacetonate)-catalyzed, regio/site-selective acylation of 1,2- and 1,3-diols and glycosides containing a cis-vicinal diol. The iron(iii) catalysts initially formed cyclic dioxolane-type intermediates with substrates between the iron(iii) species and vicinal diols, and the efficient and selective acylation of one hydroxyl group was subsequently achieved by adding acylation reagents in the presence of diisopropylethylamine (DIPEA) under mild conditions. This reaction generally produced high selectivities and highly isolated yields with the same protection pattern as that achieved with dibutyl tinoxide-mediated schemes.

Full text of DOI:10.1039/c8gc00428e

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An Inexpensive Catalyst, Fe(acac)3, for Regio/Site-Selective
Acylation of Diols and Carbohydrates Containing a 1,2-cis-diol
Received 00th January 20xx,
Accepted 00th January 20xx
Jian
Lv,
Jian-Tao
Ge,
Tao
Luo
and
Hai
Dong*
DOI: 10.1039/x0xx00000x
www.rsc.org/
This work describes the [Fe(acac)3] (acac = acetylacetonate)- selectivities originated from complex stannylene dimer or
catalyzed, regio/site-selective acylation of 1,2- and 1,3-diols and polymer by mechanism studies and proposed that the
glycosides containing a cis-vicinal diol. The iron(III) catalysts selectivity is more likely controlled by stereoelectronic effects
initially formed cyclic dioxolane-type intermediates with of the parent substrate structure.5 Guided by this principle, we
substrates between the iron(III) species and vicinal diols, and the have developed several methods based on nontoxic
efficient and selective acylation of one hydroxyl group was alternatives to organotin6 or reduced amount of organotin
subsequently achieved by adding acylation reagents in the species7 for selective protection. Particularly, in 2016, our
presence of diisopropylethylamine (DIPEA) under mild conditions. group identified an iron(III)-catalyst, [Fe(dibm)3] (dibm=
This reaction generally produced high selectivities and highly diisobutyrylmethane), which yielded high regio/site-
isolated yields with the same protection pattern as that achieved selectivities with very broad substrate scope in the alkylation
with dibutyl tinoxide-mediated schemes.
of diols and polyols.8 As iron is inexpensive, highly abundant,
nontoxic, and generally environmentally benign, we wished to
Regio/site-selective protection strategy under mild and expand the use of this iron(III)-based catalyst to selective
sustainable conditions remains central challenge in acylation. This challenge has been addressed in the present
carbohydrate chemistry due to the requirements for the
a
study, where an iron(III)-based catalyst was used for selective
preparation of value-added carbohydrate chemicals and for acylation of 1,2-diols, 1,3-diols, and glycosides containing a cis-
the construction of building blocks for oligosaccharide vicinal diol (Scheme 1), leading to highly selective acylation of
synthesis.1 Previously, organotin reagents, which play key roles primary and equatorial hydroxyl groups. Comparison of this
in selective protection strategies, were identified as the best method with all previous reported selective acylation methods
reagents and were thus widely used.2 These strategies used that avoided the use of stoichiometric amounts of dibutyl
stoichiometric amounts of dibutyl tinoxide, and the origin of tinoxide, including methods using reduced amounts of
organotins,9 heavy metal-based complexes,10 chiral catalysts11
the resulting selectivities was attributed to stannylene
intermediates through mechanism studies. However, and other nonmetallic catalysts4b,12 and reagents,13 the
organotin compounds are potentially inherently toxic,
a
reported [Fe(acac)3] (acac = acetylacetonate) catalyst herein
significant drawback.3 For this reason, protection strategies can be more easily acquired from commercial sources at a
involving reduced amounts of organotin species or nontoxic lower cost, and the method is environment-friendly and
alternatives are attractive, assuming that good selectivities can associated with more convenient manipulation, higher
be achieved. In 2011, Taylor and colleagues reported an efficiency and selectivity, better yields and broad substrate
organoboron catalyst, a diarylborinic acid derivative (Taylor’s scope.
catalyst).4 This nontoxic catalyst has since been successfully
acac =
used for the selective acylation and alkylation of
O
O
OH
HO
carbohydrates. In 2012, we challenged the conception that the
OH
Fe(acac)3 (10 mol%)
O
O
O
R
O
RCOX (1.2 equiv) DIPEA
(1.2 equiv) , CH3CN, r.t.
Nontoxic, Commercial, Inexpensive, High selectivity
Scheme 1. Iron(III)-catalyzed regioselective acylation of carbohydrates
containing a cis-vicinal diol.
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mL) used instead of BzCl and MeCN.
Initially, we expected Fe(dibm)3 would also catalyze acylation
as it catalyzed alkylation reported by us.8 Therefore, methyl-6-
The scope of this method was further evaluated using other
substrates containing a cis-diol moiety with AcCl as the
acylation reagent (Table 2). TEA as a base was initially excluded
O-(tertbutyldimethylsilyl)-α-D-mannopyranoside
as the first substrate with which to verify this hypothesis
(Table 1). As expected, compound was treated with 1.2 equiv.
1 was chosen
in the method due to the low conversions of substrates
3 and
1
5
. To our delight, when using DIPEA as the base, all tested
of BzCl in the presence of 0.1 equiv. of Fe(dibm)3 and 1.5 equiv.
of diisopropylethylamine (DIPEA) in acetonitrile at room
temperature, leading to high regioselectivity for the 3-O-
substrates were selectively acylated at the equatorial hydroxyl
groups in yields of 70–85%. High yields (82-85%) were
obtained for the acylation of galacto-type compounds
3,
5, and
benzoated product
2 (Entry 1, 85% isolated yield). Compared
7
(Entries 1–3). However, the benzoylation of the galacto-type
with Fe(dibm)3, Fe(acac)3 is more easily acquired from
commercial sources and is less expensive. However, the use of
Fe(acac)3 for alkylation is inefficient due to the instability of the
compound
9 and manno-type compounds 11 and 13 yielded
more side-products with acylated axial hydroxyl groups
(Entries 4–6, 13-21% yields). The method using stoichiometric
amounts of organotin gives much better regioselectivity for
some of these compounds.14
Table 2. [Fe(acac)3]-catalyzed regioselective acylation of substrates containing
cis-diol. a
o
acetylacetonate ligand at high reaction temperature (80 C).8
To our delight, the use of 0.1 equiv. of Fe(acac)3, instead of
Fe(dibm)3, led to an identical result for acylation (Entry 2, 85%
isolated yield of
of Fe(acac)3 led to an 86% isolated yield of
a decrease in the catalyst load to 0.05 equiv. of Fe(acac)3 still
produced an 80% yield of (Entry 4). Little or no conversion
2). An increase in the catalyst load to 0.2 equiv.
2
(Entry 3), whereas
Entry
Substrate
Product
Isolated
Yields %
2
4a: R=Bz 85
4b: R=Ac 83
was observed with no catalyst or when FeCl3 was used as the
catalyst (Entries 5 and 6). Various bases, including K2CO3, Ag2O,
TEA, TMEDA, DEA and pyridine, were also tested in the
acylation reaction with 0.1 equiv. of Fe(acac)3 (Entries 7 - 12).
A good result was also observed with the use of TEA (Entry 9,
1
6a: R=Bz 82
6b: R=Ac 85
2
3
83% isolated yield of
2). The use of Bz2O as the acylation
8a: R=Bz 83
8b: R=Ac 84
reagent produced a 76% isolated yield of
2
(Entry 13).
Replacement of the solvent acetonitrile by DMF, along with
the use of Bz2O as the acylation reagent, produced a 55%
10a: R1=Bz R2=H
isolated yield of
selectivity indicated that Fe(acac)3 mainly improved the
acylation rate of compound
2
(Entry 14). The results of conversion and
76
10b: R1=H R2=Bz
13
4
1.
12a: R1=Bz R2=H
Table 1. Comparison of results achieved under various conditions.a
73
12b: R1=H R2=Bz
21
5b
TBSO
TBSO
OH
OH
14a: R1=Bz R2=H
O
Cat., BzX
O
HO
HO
HO
BzO
70
14b: R1=H R2=Bz
20
6b
1
MeCN, r.t., 4 h.
2
OMe
OMe
a
X stands for Cl, OBz
Reactant (100 mg), BzCl or AcCl (1.2 eq.), Fe(acac)3 (0.1 eq.), DIPEA (1.5 eq.),
MeCN (1 mL), r.t., 4-8 h. b Reaction at 15 oC.
Entry
Various Conditions IsolatedYield %
Conversion
(2
/side-product)
85/-
85/-
86/-
80/-
29/6
-
%
>95
>95
>95
>90
38
Acyl group migration is often found in carbohydrate
chemistry.5,15 For carbohydrates containing a cis-diol, an
equatorial acyl group equilibrates with its axial counterpart
under basic conditions and axial substitution is preferred.5,15b
Accordingly, we suspected that the poor selectivities for the
1
2
0.1 eq. Fe(dibm)3, DIPEA
0.1 eq. Fe(acac)3, DIPEA
0.2 eq. Fe(acac)3, DIPEA
0.05 eq. Fe(acac)3, DIPEA
Without cat., DIPEA
3
4
5
6
0.1 eq. FeCl3, DIPEA
0
acylation of 9, 11, and 13 originated from acyl group
7
0.1 eq. Fe(acac)3, K2CO3
0.1 eq. Fe(acac)3, Ag2O
0.1 eq. Fe(acac)3, TEA
0.1 eq. Fe(acac)3, TMEDA
0.1 eq. Fe(acac)3, DEA
0.1 eq. Fe(acac)3, Pyridine
0.1 eq. Fe(acac)3, DIPEA
0.1 eq. Fe(acac)3, DIPEA
32/-
47/15
83/-
45/-
-
39
migrations in the presence of excess amounts of DIPEA. Acetyl
group is more prone to acyl migration. Thus, with acetyl
chloride as the acylation reagent instead of benzoyl chloride
(73/21 selectivity, entry 5 in Table 2), a poorer selectivity
8
65
9
>90
49
10
11
12
13b
14c
0
(57/38) was obtained from the acetylation of 11
hypothesis was further confirmed, as shown in Table 3. The
selectivities for the acylation of 11, and 13 improved
. This
43/
50
76/8
85
9
,
55/8
64
considerably when the amounts of DIPEA were reduced to 1.2
equiv (Entries 1 – 3). As most of the base DIPEA may form acyl
a Reactant (100 mg), BzCl (1.2 eq.), catalyst (0.05 – 0.2 eq.), base (1.5 eq.), MeCN
(1 mL), r.t., 4 h. b Bz2O (1.2 eq.) used instead of BzCl. Bz2O (1.2 eq.) and DMF (1
c
2 | J. Name., 2012, 00, 1-3
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ammonium intermediate with equimolecular amount of acyl Fe(dibm)3 catalyzed regioselective alkylation.8 Once the
chloride instantly, the acyl group migration was suppressed intermediate has formed between the cis-diol and Fe(acac)3
due to the lack of base catalysis. To further verify the effects in the presence of DIPEA, would further react with the
of acyl group migrations on the reaction, the benzoylation of acylating reagent to yield intermediate , where the equatorial
13 was compared at various reaction temperatures (Entries 4- position is acylated and the axial position is occupied by the Fe
6). Accordingly, the ratio of 14a 14b decreased to 56/33 at species. The intermediate would subsequently undergo
a
a
b
/
b
25oC, 48/45 at 50 oC and 36/62 at 70 oC, indicating the ligand exchange with a second cis-diol in the presence of
migration accelerates as the reaction temperature is increased. DIPEA, either directly or via acac, thus regenerating the cyclic
The yield of 14a only increased to 85% in the presence of 1.2 intermediate
a and a product with an acylated equatorial
equiv of DIPEA when 1.5 equiv of BzCl was used in the position. However, in the presence of excess DIPEA, the acyl
benzoylation of 13 (Entry 7). To minimize the effect of benzoyl group is favored to migrate from the equatorial to the axial
group migration on the selectivity, a mixture of 1.2 equiv of position via the five-membered ring tetrahedral intermediate
DIPEA and 1.2 equiv of BzCl was added dropwise into the c,5 thereby decreasing the selectivity of acylation.
OTBS
OTBS
OTBS
OTBS
HO
reaction solution of 13, which yielded the best selectivity
(Entry 8, 14a 14b: 90/-). These experiments indicate that the
HO
HO
HO
O
O
O
O
/
i_
Pr
SEt
S
SPh
SBn
RO
RO
RO
RO
OH
15: R = H
85% 16a: R = Bz
OH
17: R = H
18a: R = Bz
OH
OH
9: R = H
85% 10c: R = Ac
regioselectivity in this method can be improved by suppressing
acyl group migration via reducing the amount of DIPEA,
decreasing the reaction temperature, and improving the DIPEA
7: R = H
93% 8a: R = Bz
8b: R = Ac 86%
89%
18b: R = Ac 91%
16b: R = Ac 86%
OTBS
O
OTBS
HO
OTBS
OTBS
O
HO
RO
HO
HO
RO
feed method.
Table 3. Selectivities affected by acyl group migration.a
O
O
SMeb
STol
OPh
OAll
RO
RO
OH
19: R = H
93% 20a: R = Bz
OH
OH
21: R = H
83% 22: R = Ac
OH
23: R = H
Entry Substrate
Various Conditions
Isolated Yield %
10b (91/-c)
25: R = H
26: R = Bz
92%
24: R = Bz
86%
1
2
3
4
5
6
7
8b
9
1.2 eq. DIPEA, 1.2 eq. BzCl, 25 o
1.2 eq. DIPEA, 1.2 eq. BzCl, 25 o
1.2 eq. DIPEA, 1.2 eq. BzCl, 25 o
1.5 eq. DIPEA, 1.2 eq. BzCl, 25 o
1.5 eq. DIPEA, 1.2 eq. BzCl, 50 o
1.5 eq. DIPEA, 1.2 eq. BzCl, 70 o
1.2 eq. DIPEA, 1.5 eq. BzCl, 25 o
1.2 eq. DIPEA, 1.2 eq. BzCl, 25 o
C
C
C
C
C
C
C
C
10a/
20b: R = Ac
89%
OMeb
OTBS
OTBS
HO
11
13
13
13
13
13
13
12a
14a
/
12b (81/13)
14b (83/11)
OH
O
O
Ph
O
O
O
O
O
OH
SPh
/
RO
HO
RO
15
SPh
OR
HO
31: R = H
80% 32a: R = Bz
OH
OH
14a/14b (56/33)
27: R = H
87% 28a: R = Bz
29: R = H
30: R = Bz
14a
14a
14a
/
/
/
14b (48/45)
14b (35/62)
14b (85/10)
81%
32b: R = Ac 76%
28b: R = Ac 83%
OMeb
OR
O
OH
O
HO
OH
O
O
HO
RO
O
OMec
HO
OR
RO
14a/
14b (90/-c)
OMeb
35: R = H
OR
OH
39: R = H
80% 40a: R = Bz
OH
33: R = H
HO
a Reactant (100 mg), Fe(acac)3 (0.1 eq.), MeCN (1 mL), 4 h. b The mixture of DIPEA
and BzCl added dropwise over 2 h. c No or trace amount.
37: R = H
78% 38: R = Bz
86% 34: R = Bz
73% 36: R = Bz
40b: R = Ac
78%
OR
HO
45: R = H
84% 46: R = Bz
OR
HO
RO
OH
HO
OR
O
O
HO
RO
After comprehensive consideration of reaction efficiency and
manipulation methodology, further tests of our method were
RO
ORb
OMec
43: R = H
44: R = Bz
HO
OMec
41: R = H
42a: R = Bz
42b: R = Ac
OH
Ph
47: R = H
HO
81% 48: R = Bz
conducted with the following substrates containing cis-diols
7,
49: R = H
89% 50: R = Bz
74%
76%
68%
9,
15, 17 19 21 23 25, 27 29, 31, 33, 35, and 37, DIPEA and
,
,
,
,
,
OH
OH
OH
ORb
PhO
ORb
acylation reagents were simply mixed with the acetonitrile
solution of the substrate in the presence of 0.1 equiv of
Fe(acac)3 catalysts. These reactions were then allowed to
proceed at room temperature for 2 – 8 h (Figure 1). Most
tested substrates were selectively acylated at the equatorial
hydroxyl groups in high yields (> 80%). The acylation of the
O
ORb
53: R = H
ORb
51: R = H
80% 52: R = Bz
55: R = H
81% 56: R = Bz
57: R = H
76% 58: R = Bz
94% 54: R = Bz
Fig. 1 [Fe(acac)3]-catalyzed regioselective acylation of substrates containing cis-,
1,2-, and 1,3-diols.a Reaction conditions: a BzCl or AcCl (1.2 eq.), Fe(acac)3 (0.1
eq.), DIPEA (1.2 eq.), MeCN (1 mL), r.t., 2-8 h., b BzCl or AcCl (1.5 eq.), Fe(acac)3
(0.1 eq.), DIPEA (1.5 eq.), MeCN (1 mL), r.t., 2-8 h. c BzCl or AcCl (4 eq.), Fe(acac)3
(0.1 eq.), DIPEA (4 eq.), MeCN (1 mL), r.t., 2-8 h.
free methyl glycosides 39, 41, and 43 with 1.2 equiv. of DIPEA
and 1.2 equiv. of acylation reagents led to mixtures of 3-
OBz/OAc, 6-OBz/OAc and 3,6-di-OBz/OAc products. Therefore,
4 equiv. of DIPEA and 4 equiv. of acylation reagents were
allowed to react with 39
equiv of Fe(acac)3, which produced moderate yields of 3,6-di-
OBz/OAc products 40 42, and 44 (Figure 1, 68 - 80%). This
method was also tested using the 1, 2- and 1, 3-diols 45 47 49
51 53 55, and 57, where the primary hydroxyl groups were
selectively acylated in high yields (Figure 1, 76 - 94%).
, 41, and 43 in the presence of 0.1
,
,
,
,
,
,
The cyclic dioxolane/dioxane-type intermediates play key
roles in the catalytic mechanism of the regio/site-selective
Figure 2. Proposed catalytic mechanism.
acylation (Figure 2), analogous to the proposed mechanism of
The selective protection of carbohydrates containing a trans-
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diol is a challenge when using alternatives to stoichiometric
amounts of dibutyl tinoxide, because a trans-diol is difficult to
form a cyclic dioxolane-type intermediate with catalysts.7a As
Fe(dibm)3 was found to be able to catalyze the selective
benzylation of carbohydrates containing a trans-diol,8 we
expected that Fe(III) catalysts would also catalyze the selective
acylation of these type of compounds. Unfortunately, our
attempt failed, possibly due to the same reason, the formation
of a cyclic dioxolane-type intermediate being difficult.
2 (a) T. B. Grindley, Adv. Carbohydr. Chem. Bi., 1998, 53, 17-
142; (b) S. David, A. Thieffry, A. Forchioni, Tetrahedron Lett,
1981, 22, 2647-2650.
3 (a) M. M. Whalen, B. G. Loganathan, K. Kannan, Environ.
Res., 1999, 81, 108–116; (b) S. M. Jenkins, K. Ehman, S. J.
Barone, Brain Res, 2004, 151, 1–12; (c) W. Seinen, J. G. Vos,
R. van Krieken, A. Penninks, R. Brands, H. Hooykaas, Toxicol.
Appl. Pharmacol., 1977, 42, 213–224.
4 (a) D. Lee, C. L. Williamson, L. Chan, M. S. Taylor, J. Am.
Chem. Soc., 2012, 134, 8260-8267; (b) D. Lee, M. S. Taylor, J.
Am. Chem. Soc., 2011, 133, 3724-3727; (c) L. N. Chan, M. S.
Taylor, Org. Lett., 2011, 13, 3090-3093.
In conclusion, Fe(acac)3 was successfully applied as a catalyst
for regio/site-selective acylation of 1,2-diols, 1.3-diols, and
carbohydrates containing cis-diols. The acylation reaction is
5 (a) H. Dong, Y. X. Zhou, X. Pan, F. Cui, W. Liu, J. Liu, O.
Ramstrom, J. Org. Chem., 2012, 77, 1457-1467; (b) X. L. Pan,
Y. X. Zhou, W. Liu, J. Y. Liu, H. Dong, Chem. Res. Chin. Univ.,
2013, 29, 551-555.
proposed to proceed through
a cyclic dioxolane-type
intermediate between a diol and Fe(acac)3 under base
conditions. The resulting selectivities exhibited the same
product pattern as for traditional dibutyl tinoxide-mediated
approaches. Despite the effects of acyl group migration during
the reaction, high selectivities were obtained in most cases
through suppressing the migration. Our method proved
straightforward, representing an affordable, green and benign
alternative to Taylor’s catalyst. Additionally, Fe(acac)3 is a
much less expensive catalyst, which at approximately is only
one-fourth (for the price per mole) as expensive as Taylor’s
catalyst.
6 (a) B. Ren, J. Lv, Y. Zhang, J. Tian, H. Dong, ChemCatChem,
2017,
Dong, Tetrahedron, 2016, 72, 1005-1010; (c) B. Ren, M. Y.
Wang, J. Y. Liu, J. T. Ge, H. Dong, ChemCatChem, 2015,
9, 950-953; (b) X. L. Zhang, B. Ren, J. T. Ge, Z. C. Pei, H.
7
,
761-765; (d) B. Ren, M. Rahm, X. L. Zhang, Y. X. Zhou, H.
Dong, J. Org. Chem., 2014, 79, 8134-8142; (e) Y. X. Zhou, M.
Rahm, B. Wu, X. L. Zhang, B. Ren, H. Dong, J. Org. Chem.,
2013, 78, 11618-11622; (f) Y. X. Zhou, O. Ramstrom, H. Dong,
Chem. Commun., 2012, 48, 5370-5372.
7 (a) H. F. Xu, Y. Zhang, H. Dong, Y. C. Lu, Y. X. Pei, Z. C. Pei,
Tetrahedron Lett, 2017, 58, 4039-4042; (b) H. F. Xu, B. Ren,
W. Zhao, X. T. Xin, Y. C. Lu, Y. X. Pei, H. Dong, Z. C. Pei,
Tetrahedron, 2016, 72, 3490-3499; (c) H. F. Xu, Y. C. Lu, Y. X.
Zhou, B. Ren, Y. X. Pei, H. Dong, Z. C. Pei, Adv. Synth. Catal.,
2014, 356, 1735-1740; (d) Y. X. Zhou, J. Y. Li, Y. J. Zhan, Z. C.
Pei, H. Dong, Tetrahedron, 2013, 69, 2693-2700.
Conflicts of interest
The authors declare no competing financial interest.
8
(a) B. Ren, O. Ramstrom, Q. Zhang, J. T. Ge, H. Dong,
Acknowledgements
Chem. Eur. J., 2016, 22, 2481-2486; (b) B. Ren, O. Ramstrom,
Q. Zhang, J. T. Ge, H. Dong, Chem. Eur. J., 2016, 22, 7662
This study was supported by the National Nature Science
Foundation of China (Nos. 21772049, 21272083). The authors
are also grateful to the staffs in the Analytical and Test Center
of School of Chemistry & Chemical Engineering at HUST for
support with the NMR instruments
9
(a) W. Muramatsu, J. M. William, O. Onomura, J. Org.
Chem., 2012, 77, 754-759; (b) Y. Demizu, Y. Kubo, H. Miyoshi,
T. Maki, Y. Matsumura, N. Moriyama, O. Onomura, Org. Lett.,
2008, 10, 5075-5077.
10 (a) I. H. Chen, K. G. M. Kou, D. N. Le, C. M. Rathbun, V. M.
Dong, Chem. Eur. J., 2014, 20, 5013-5018; (b) C. L. Allen, S. J.
Miller, Org. Lett., 2013, 15, 6178-6181; (c) C. Mazet, S.
Notes and references
1 (a) Y. Hu, K.Yu, L.-L. Shi, L. Liu, J.-J. Sui, D.-Y. Liu, B. Xiong,
J.-S. Sun, J. Am. Chem. Soc., 2017, 139, 12736-12744; (b) A. R.
Podilapu, S. S. Kulkarni, Org. Lett., 2017, 19, 5466-5469; (c) Y.
Toda, T. Sakamoto, Y. Komiyama, A. Kikuchi, H. Suga, ACS
Roseblade, V. Kohler, A. Pfaltz, Org. Lett., 2006, 8, 1879-1882;
(d) Y. Matsumura, T. Maki, S. Murakami, O. Onomura, J. Am.
Chem. Soc., 2003, 125, 2052-2053; (e) R. S. Dhiman, R. Kluger,
Org. Biomol. Chem., 2010, 8, 2006-2008; (f) E. V. Evtushenko,
Catal, 2017, 7, 6150-6154; (d) Z. Huang, G. Dong, Acc. Chem.
Carbohydr. Res., 2012, 359, 111-119; (g) E. V. Evtushenko, J.
Carbohydrate. Chem., 2015, 34, 41-54.
Res., 2017, 50, 465-471; (e) S. J. Danishefsky, Y. K. Shue, M. N.
Chang, C. H. Wong, Acc. Chem. Res., 2015, 48, 643-652; (f) Q.
J. Zhang, E. R. van Rijssel, M. T. C. Walvoort, H. S. Overkleeft,
G. A. van der Marel, J. D. C. Codee, Angew. Chem. Int. Ed.,
2015, 54, 7670-7673; (g) H. Dong, M. Rahm, T. Brinck, O.
Ramstrom, J. Am. Chem. Soc., 2008, 130, 15270-15271; (h) C.
C. Wang, J. C. Lee, S. Y. Luo, S. S. Kulkarni, Y. W. Huang, C. C.
Lee, K. L. Chang, S. C. Hung, Nature, 2007, 446, 896-899.
11 (a) G. Xiao, G. A. Cintron-Rosado, D. A. Glazier, B. Xi, C.
Liu, P. Liu, W. Tang, J. Am. Chem. Soc., 2017, 139, 4346-4349;
(b) X. Sun, H. Lee, S. Lee, K. L. Tan, Nature Chem, 2013, 5,
790-795; (c) E. Mensah, N. Camasso, W. Kaplan, P. Nagorny,
Angew. Chem. Int. Ed., 2013, 52, 12932-12936; (d) M. B.
Lauber, C.-G. Daniliuc, J. Paradies, Chem. Commun., 2013, 49
,
7409-7411;
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12 (a) F. Huber, S. F. Kirsch, Chem.-Eur. J., 2016, 22, 5914-
5918; (b) H. Takeuchi, K. Mishiro, Y. Ueda, Y. Fujimori, T.
Furuta, T. Kawabata, Angew. Chem. Int. Ed., 2015, 54, 6177-
6180; (c) Y. Ueda, K. Mishiro, K. Yoshida, T. Furuta, T.
Kawabata, J. Org. Chem., 2012, 77, 7850-7857; (d) T.
Kawabata, W. Muramatsu, T. Nishio, T. Shibata, H. Schedel, J.
Am. Chem. Soc., 2007, 129, 12890-12895.
13 (a) D. L. Cramer, S. Bera, A. Studer, Chem.-Eur. J., 2016,
22, 7403-7407; (b) M. A. Witschi, J. Gervay-Hague, Org. Lett.,
2010, 12, 4312-4315; (c) A. Francais, D. Urban, J.-M. Beau,
Angew. Chem. Int. Ed., 2007, 46, 8662-8665.
14 (a) C. W. Holzapfel, J. M. Koekemoer, C. F. Marais, South
Afr. J. Chem., 1984, 37, 19-26; (b) S. Langston, B. Bernet, A.
Vasella, Helv. Chim. Acta, 1994, 77, 2341-2353; (c) Y. Tsuda,
M. E. Haque, K. Yoshimoto, Chem. Pharm. Bull., 1983, 31
,
1612-1624.
15 (a) Y. X. Zhou, X. L. Zhang, B. Ren, B. Wu, Z. C. Pei, H.
Dong, Tetrahedron, 2014, 70, 5385-5390; (b) M. U. Roslund,
O. Aitio, J. Warna, H. Maaheimo, D. Y. Murzin, R. Leino, J. Am.
Chem. Soc., 2008, 130, 8769-8772; (c) H. Dong, Z. C. Pei, O.
Ramstrom, Chem. Commun., 2008, 1359-1361; (d) E. A.
Pritchina, N. P. Gritsan, G. T. Burdzinski, M. S. Platz, J. Phys.
Chem. A., 2007, 111, 10483-10489; (e) M. Mastihubova, P.
Biely, Carbohydr. Res., 2004, 339, 1353-1360.
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