Catalytic Regioselective C-H Acetoxylation of Arenes Using 4,6-Dimethoxy-1,3,5-triazin-2-yloxy as a Removable/Modifiable Directing Group

Article abstract of DOI:10.1021/acs.organomet.7b00314

One of the major current challenges in the field of C-H functionalization is the development of new removable/modifiable directing groups (DGs). We report here the 4,6-dimethoxy-1,3,5-triazin-2-yloxy group as a new readily removable/modifiable DG for the regioselective acetoxylation of 2-(aryloxy)-4,6-dimethoxy-1,3,5-triazine. This developed phenol-derived DG can be easily removed to offer synthetically versatile pyrocatechols or converted into a useful biphenyl skeleton. In addition, the acetoxylation of 2-(aryloxy)-4,6-dimethoxy-1,3,5-triazine offers a new avenue to synthesize polysubstituted s-triazine derivatives.

Full text of DOI:10.1021/acs.organomet.7b00314

Article
pubs.acs.org/Organometallics
Catalytic Regioselective C−H Acetoxylation of Arenes Using 4,6-
Dimethoxy-1,3,5-triazin-2-yloxy as a Removable/Modifiable
Directing Group
Zhihua Peng,* Zhi Yu, Tian Li, Na Li, Yilei Wang, Linhua Song, and Cuiyu Jiang
Department of Chemistry, China University of Petroleum, Qingdao 266580, People’s Republic of China
*
S Supporting Information
ABSTRACT: One of the major current challenges in the field
of C−H functionalization is the development of new
removable/modifiable directing groups (DGs). We report
here the 4,6-dimethoxy-1,3,5-triazin-2-yloxy group as a new
readily removable/modifiable DG for the regioselective
acetoxylation of 2-(aryloxy)-4,6-dimethoxy-1,3,5-triazine. This
developed phenol-derived DG can be easily removed to offer
synthetically versatile pyrocatechols or converted into a useful
biphenyl skeleton. In addition, the acetoxylation of 2-(aryloxy)-4,6-dimethoxy-1,3,5-triazine offers a new avenue to synthesize
polysubstituted s-triazine derivatives.
INTRODUCTION
corresponding phenol, installing the synthetically useful boryl
functional group. However, for arenes bearing an oxygen-
■
13
The coordinating directing group (DG) strategy has been
extensively utilized to achieve the regioselective functionaliza-
tion of C−H bonds in metal-catalyzed reactions. Accordingly,
a wide range of DGs have been developed for the selective
tethered DG, it is nontrivial to form a new carbon−carbon
1
bond by the cleavage of the C -O bond. Given the prevalence
Ar
of hydroxyl groups in organic molecules, it is highly desirable to
develop novel removable/modifiable phenol-derived DGs for
the selective functionalization of C−H bonds. Herein, we
report that the 4,6-dimethoxy-1,3,5-triazin-2-yloxy group
serving as a new easily removable and modifiable directing
group allows for a Pd-catalyzed C−H acetoxylation reaction of
arenes. Importantly, this phenol-derived DG can be cleaved by
Suzuki−Miyaura coupling reaction to construct a new carbon−
carbon bond (Scheme 1).
construction of new C−C and C−X bonds through C−H
2
activation. However, the removal or further transformation of
the DGs from C−H functionalized products often represents a
challenging synthetic task, thus limiting the diverse utilities of
the products. One approach for improving the structural
diversity of the products entails the use of removable/
modifiable or traceless DGs which can be conveniently
removed from the products or undergo further versatile
3
transformations after C−H functionalization. In recent years,
4
the disclosed functional groups involving carboxylic acid,
Scheme 1. 4,6-Dimethoxy-1,3,5-triazin-2-yloxy Group as a
Removable/Modifiable DG for C−H Functionalization and
Its Subsequent Transformations
5
6
7
picolinamide, 2-pyridinyloxy, 8-aminoquinoline, 2-pyridyl-
8
9
methyl ether, 2,6-dimethoxylbenzaldoxime, (2-pyridyl)-
1
0
11
sulfonyl group, and triazolyldimethylmethyl (TAM) group
could serve as DGs for various C−H bond functionalization
reactions and then could be easily removed from C−H
functionalized products. Despite the outstanding advances that
have been made in this still-growing field, to date, very few DGs
can be applied to a broad range of further transformations. An
elegant manifestation from Gevorgyan and colleagues illus-
trated that a silicon-tethered pyridyldiisopylsilyl group as a
modifiable DG in Pd-catalyzed C−H ortho acryloxylation and
ortho halogenation of arenes could undergo diverse trans-
formations such as protonation, halogenation, and hydrox-
ylation, as well as Hiyama−Denmark cross-coupling reac-
tions. In addition, Chatani and co-workers performed a one-
pot, catalytic borylative cleavage of the 2-pyridyloxy (OPy)
group, which is an extremely effective DG for a number of
selective C−H functionalization reactions and is normally
removed by the cleavage of the C(pyridinium)−O to give the
Metal-catalyzed C−H acetoxylation reactions of aryl 2,4-
dimethoxy-1,3,5-triazin-6-yl ethers are among the most
attractive transformations because (1) they allow the direct
formation of s-triazine derivatives, which are of potential
biological importance, and (2) the oxygen-tethered DG can be
easily attached to the starting materials and also undergo
further versatile transformations after the C−H bond
1
2
Received: April 24, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00314
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Organometallics
Article
functionalization. Despite the fact that the s-triazine core is a
prevalent structure in a vast array of bioactive organic
compounds, C−H functionalization reactions using the 4,6-
dimethoxy-1,3,5-triazin-2-yloxy group as a DG have not yet
been exploited. We hypothesized that the use of 4,6-dimethoxy-
Scheme 2, in the presence of Pd(OAc) (5 mol %), a broad
range of 2-(aryloxy)-4,6-dimethoxy-1,3,5-triazines smoothly
2
Scheme 2. Substrate Scope of Pd-Catalyzed C−H
a
Acetoxylation of Arenes
1
,3,5-triazin-2-yloxy as a DG should be viable for arene C−H
oxidation, as the selective C−H activation of the aryl 2,4-
dimethoxy-1,3,5-triazin-6-yl ethers could be realized through a
14
six-membered metallacycle.
RESULTS AND DISCUSSION
Next, we tested our hypothesis. Initially, 2-(2,4-dimethylphe-
noxy)-4,6-dimethoxy-1,3,5-triazine (2a), readily prepared from
■
2
-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and 2,4-dime-
15
thylphenol, was used as the model substrate to investigate Pd-
catalyzed C−H acetoxylation of arenes. Pleasingly, in the
presence of 5 mol % Pd(OAc) and 2.0 equiv of PhI(OAc) ,
2
2
the expected ortho-acetoxylated product 3a was obtained in
AcOH/Ac O (1/1) at 100 °C within 24 h in 68% isolated yield
2
(Table 1). In the absence of either the Pd catalyst or the
a
Table 1. Optimization of Reaction Conditions
yield
b
entry
change from the “standard conditions”
(%)
1
2
3
4
5
6
7
8
9
none
68
without Pd(OAc)2
0
no PhI(OAc)2
0
K S O (2 equiv) instead of PhI(OAc)
2
trace
trace
trace
33
2
2
8
a
Reaction conditions: 1.0 mmol of 2, Pd(OAc) (5 mol %), and 2.0
2
(NH ) S O (2 equiv) instead of PhI(OAc)
2
4
2
2
8
mmol of PhI(OAc) in AcOH/Ac O (8 mL) at 100 °C for 24 h.
Isolated yields are given.
2
2
benzoxyl peroxide (2 equiv) instead of PhI(OAc)2
PIFA (2 equiv) instead of PhI(OAc)2
PhI(OPiv) (2 equiv) instead of PhI(OAc)
62
2
2
underwent C−H acetoxylation using PhI(OAc) (2 equiv) as
an oxidant in AcOH/Ac O (1/1 v/v) at 100 °C within 24 h,
2
in air
150 °C instead of 100 °C
RuCl (p-cymene) (2.5 mol %), AgSbF (20 mol %), DCE/ trace
AcOH (3/1 v/v), PhI(OAc) (2 equiv), 100 °C, 24 h
32
2
1
0
1
65
providing the expected ortho-acetoxylated products in moder-
ate to good yields. The efficiency of this transformation was
related to the electron density and the position of substituents
on the phenyl ring. Substrates bearing an electron-donating
group afforded relatively good yields in comparison to those
substrates with an electron-withdrawing group. For substrates
bearing two electron-donating groups such as methyl, neo-
pentyl, and methoxy at the ortho and para positions of the
phenyl ring, the reactions gave the desired products 3a−c in
47−68% yield. The substrate bearing one electron-donating
group at the ortho position of phenyl groups smoothly
underwent Pd-catalyzed C−H acetoxylation, providing the
desired product 3d in 43% yield. The yield decreased slightly in
comparison to those substrates activated by two electron-
donating groups. Steric hindrance influence was observed for
meta-substituted phenoxytriazine which even bore electron-
donating groups such as a methoxy group, and the reaction
occurred at the less sterically hindered site, affording the
product 3e in a yield of 31%. Under similar conditions, Pd-
catalyzed C−H acetoxylation of substrates bearing two ortho
C−H bonds such as 2-(4-methylphenoxy)-4,6-dimethoxy-1,3,5-
triazine, 2-(4-ethylphenoxy)-4,6-dimethoxy-1,3,5-triazine, 2-(4-
1
2
2
6
2
a
Reaction conditions: all the reactions were run on a 0.5 mmol scale
with 4 mL of solvents. Isolated yield.
b
oxidant PhI(OAc) , an ortho-acetoxylated product was not
detected (Table 1, entries 2 and 3). The use of other oxidants
instead of PhI(OAc), such as K S O , (NH ) S O , and
2
2
2
8
4 2
2
8
benzoxyl peroxide, gave only a trace of the desired product
3
a (Table 1, entries 4−6). Moreover, by using other
hypervalent iodine compounds such as [bis(trifluoroacetoxy)-
iodo]benzene and bis(tert-butylcarbonyloxy)iodobenzene, the
isolated yield of 3a can reach 33−63% (Table 1, entries 7 and
8
). When the reaction proceeded in air or at 150 °C, the yields
of 3a decreased to 32% and 65%, respectively (Table 1, entries
9
and 10). When 2.5 mol % of RuCl (p-cymene) was used as a
metal catalyst, traces of product were formed in the presence of
0 mol % of AgSbF and PhI(OAc) (2 equiv) (Table 1, entry
1).
Having established the optimized reaction conditions, we set
out to investigate the scope of this reaction. As shown in
2
2
2
1
6 2
B
DOI: 10.1021/acs.organomet.7b00314
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Article
tert-butylphenoxy)-4,6-dimethoxy-1,3,5-triazine, and 2-(4-me-
thoxyphenoxy)-4,6-dimethoxy-1,3,5-triazine gave the monoace-
toxylated products 3f−i in 48−59% yield. The acetoxylation of
Scheme 4. Cleavage of the Directing Group
2
-(3,5-dimethylphenoxy)-4,6-dimethoxy-1,3,5-triazine gave the
product 3j in a yield of 36% due to the steric hindrance
influence. Pd-catalyzed C−H acetoxylation of 2-(phenoxy)-4,6-
dimethoxy-1,3,5-triazine without any substitute led to the
expected product 3k in a moderate yield. Under similar
conditions, substrates bearing electron-withdrawing groups
such as halogen and carboxylate could also undergo Pd-
catalyzed C−H acetoxylation reactions, providing the desired
products 3l−q in 20−39% yields. In contrast to those
substrates bearing electron-donating groups, the yields were
comparatively low, probably due to the low electron density on
the phenyl ring which would reduce the tendency of C−H
oxidative addition. Additionally, it is worth mentioning that a
variety of functional groups such as OMe (3c,e,i), Cl (3l,q), Br
substituted pyrocatechol 4 instead of the expected coupling
product 5 was afforded, suggesting that the hydrolysis of the
acetoxy group and protection of the furnished phenol are
required prior to the coupling step. The selective hydrolysis of
the acetoxy group in 3g with Cs CO in methanol, followed by
2
3
the protection of the generated 2-((4,6-dimethoxy-1,3,5-triazin-
-yl)oxy)-5-methylphenol with MeI under basic conditions,
2
(3m), F (3n), and ester (3o,p) were tolerated well under the
gave the intermediate 2c in 62% yield in two steps. It was found
reaction conditions.
that compound 2c underwent an efficient Suzuki−Miyaura
16
According to previous reports, a plausible mechanism for
the DMT-directed acyloxylation of C−H bonds is proposed.
Initially, the reaction of palladium acetate with 2k affords the
six-membered palladacycle intermediate A. The subsequent
oxidation of palladacycle intermediate A with PhI(OAc)2
generates the intermediate B. Finally, the intermediate B
undergoes reductive elimination, providing the product 3k and
regenerating the Pd(II) catalyst (Scheme 3).
15b
cross-coupling with o-tolylboronic acid, providing the C −
Ar
O bond cleavage product 6 in 93% yield (Scheme 5).
Scheme 5. Cleavage of Directing Group via C −O
Ar
Activation
Scheme 3. Proposed Mechanism for the Pd-Catalyzed
Acyloxylation
CONCLUSION
In conclusion, we have developed a new readily removable/
modifiable directing group for regioselective acetoxylation of 2-
■
(
aryloxy)-4,6-dimethoxy-1,3,5-triazine. Using the developed
method, a variety of s-triazine derivatives can be synthesized
in moderate to good yields. In addition, the 4,6-dimethoxy-
1
,3,5-triazin-2-yloxy group proved to be a highly efficient DG,
which can be removed to offer synthetically versatile
pyrocatechols or act in a modifiable fashion to give the
corresponding Suzuki−Miyaura coupling product.
Next, we explored the further conversion of the 4,6-
dimethoxy-1,3,5-triazin-2-yloxy group from the products after
the development of the directed C−H acyloxylation of 2-
(
aryloxy)-4,6-dimethoxy-1,3,5-triazine. The 4,6-dimethoxy-
EXPERIMENTAL SECTION
■
1
,3,5-triazin-2-yloxy group could be readily removed by the
All reactions were carried out under a nitrogen atmosphere in flame-
dried glassware. Syringes which were used to transfer anhydrous
solvents or reagents were purged with nitrogen prior to use. Yields
refer to isolated yields of compounds estimated to be >95% pure as
cleavage of the C(DMT)−O bond. Herein, the acyloxylated
product 3a was converted into substituted pyrocatechols 4 in
71% yield in two steps by the treatment of 3a with MeOTf in
1
determined by H NMR (25 °C). NMR spectra were recorded on
dry toluene and subsequent addition to a refluxing Na/MeOH
6
a
solutions in deuterated chloroform (CDCl ) with residual chloroform
3
solution (Scheme 4).
1
13
(
δ 7.25 ppm for H NMR and δ 77.0 ppm for C NMR).
Another synthetic utility of the 4,6-dimethoxy-1,3,5-triazin-2-
yloxy group as a removable/modifiable DG lies in the cleavage
Abbreviations for signal coupling are as follows: s, singlet; d, doublet; t,
triplet; q, quartet; m, multiplet, br, broad. Column chromatographic
purifications were performed using SiO2 (200−300 mesh ASTM)
from Branch of Qingdao Haiyang Chemical Co., Ltd., if not indicated
otherwise.
of the DG through C −O activation. The cleavage of the DG
Ar
in 3a using a direct nickel-catalyzed Suzuki−Miyaura coupling
15b
reaction with phenylboronic acid was tested first. However,
C
DOI: 10.1021/acs.organomet.7b00314
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Organometallics
Article
TP: Typical Procedure for the Direct Ortho Acetoxylation of
Ar-O-DMT Ethers. A solution of Ar-−O-DMT ether (1 mmol),
Pd(OAc) (11 mg, 0.05 mmol), and PhI(OAc) (644 mg, 2 mmol) in
2-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-5-ethylphenyl Acetate
(3g). According to TP, 2-(4-ethylphenoxy)-4,6-dimethoxy-1,3,5-
triazine (261 mg, 1 mmol) gave the desired product 3g (152 mg,
2
2
1
AcOH (4.0 mL) and Ac O (4.0 mL) was stirred in a 25 mL Schlenk
48%) as a colorless oil. H NMR (400 MHz, CDCl ): δ (ppm) 7.14−
2
3
tube at 100 °C for 24 h. The solvent was evaporated to dryness in
vacuo. The residue was purified by column chromatography
7.10 (m, 1 H), 7.06−6.99 (m, 2 H), 3.93 (s, 6 H), 2.62 (q, J = 7.6 Hz,
2 H), 2.12 (s, 3 H), 1.210 (t, J = 7.6 Hz, 3 H). 13C NMR (100 MHz,
(
petroleum ether/ethyl acetate) to give the desired product.
-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-3,5-dimethylphenyl Ac-
etate (3a). According to TP, 2-(2,4-dimethylphenoxy)-4,6-dimethoxy-
CDCl ): δ (ppm) 173.8, 172.9, 168.3, 143.0, 141.8, 140.8, 125.9,
3
2
122.8, 122.7, 55.5, 28.2, 20.7, 15.0. IR (KBr): 3248, 2965, 1775, 1567,
−1
1506, 1470, 1362, 1266, 1212, 1189, 1129, 935, 820 cm . HRMS
+
1
6
,3,5-triazine (261 mg, 1 mmol) gave the desired product 3a (217 mg,
(C H N O + H): calcd, 320.1246; found, 320.1248 (M + H).
15
17
3
5
1
8%) as a white solid (mp 78.2−79.5 °C). H NMR (400 MHz,
5-(tert-Butyl)-2-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)phenyl Ac-
etate (3h). According to TP, 2-(4-(tert-butyl)phenoxy)-4,6-dime-
CDCl ): δ (ppm) 6.91 (s, 1 H), 6.83 (s, 1 H), 3.96 (s, 6 H), 2.30 (s, 3
H), 2.15 (s, 3 H), 2.12 (s, 3 H). C NMR (100 MHz, CDCl ): δ
3
13
thoxy-1,3,5-triazine (289 mg, 1 mmol) gave the desired product 3h
3
1
(
ppm) 173.9, 172.8, 168.5, 141.9, 139.6, 136.2, 131.5, 128.9, 121.4,
(205 mg, 59%) as a pale yellow oil. H NMR (400 MHz, CDCl ): δ
3
5
1
5.5, 20.9, 20.7, 16.1. IR (KBr): 3129, 1766, 1568, 1400, 1357, 1216,
(ppm) 7.30−7.26 (m, 1 H), 7.21−7.17 (m, 2 H), 3.99 (s, 6 H), 2.18
−1
13
122, 816, 693 cm . HRMS (C H N O + H): calcd, 320.1246;
(s, 3 H), 1.32 (s, 9 H). C NMR (100 MHz, CDCl ): δ (ppm) 173.7,
15
17
3
5
3
+
found, 320.1246 (M + H).
172.8, 168.2, 149.9, 141.4, 140.5, 123.4, 122.3, 120.5, 55.4, 34.5, 31.2,
−1
2
-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-3,5-dineopentylphenyl
20.6. IR (KBr): 3129, 1775, 1562, 1400, 1208, 1180, 817 cm . HRMS
+
Acetate (3b). According to TP, 2-(2,4-dineopentylphenoxy)-4,6-
dimethoxy-1,3,5-triazine (373 mg, 1 mmol) gave the desired product
3
(C H N O + H): calcd, 348.1559; found, 348.1562 (M + H).
17
21
3
5
2-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-5-methoxyphenyl Ace-
tate (3i). According to TP, 2,4-dimethoxy-6-(4-methoxyphenoxy)-
1
b (256 mg, 59%) as a colorless oil. H NMR (400 MHz, CDCl ): δ
3
(
ppm) 7.12 (d, J = 2.2 Hz, 1 H), 6.98 (d, J = 2.2 Hz, 1 H), 3.90 (s, 6
1,3,5-triazine (263 mg, 1 mmol) gave the desired product 3i (158 mg,
1
H), 1.97 (s, 3 H), 1.59 (dt, J = 14.6 Hz, 7.3 Hz, 4 H), 1.28 (s, 6 H),
1
52%) as a pale yellow oil. H NMR (400 MHz, CDCl ): δ (ppm) 7.16
3
13
.25 (s, 6 H), 1.59 (ddd, J = 16.0 Hz, 7.5 Hz, 7.3 Hz, 6 H). C NMR
(d, J = 8.8 Hz, 1 H), 6.82−6.75 (m, 2 H), 3.98 (s, 6 H), 3.80 (s, 3 H),
2.17 (s, 3 H). 13C NMR (100 MHz, CDCl ): δ (ppm) 173.8, 173.2,
(
100 MHz, CDCl ): δ (ppm) 173.8, 173.0, 167.9, 146.6, 142.2, 139.8,
3
3
1
8
9
4
39.6, 123.1, 118.9, 55.4, 38.8, 37.9, 36.9, 34.6, 28.3, 28.2, 20.6, 9.3,
.9. IR (KBr): 3129, 1768, 1596, 1558, 1400, 1367, 1230, 1200, 1137,
168.1, 157.7, 142.6, 136.7, 123.4, 111.8, 109.2, 55.7, 55.5, 20.7. IR
(KBr): 3373, 2952, 1774, 1571, 1505, 1470, 1364, 1210, 1124, 819
−
1
−1
77, 816 cm . HRMS (C H N O + H): calcd, 432.2498; found,
cm . HRMS (C14
H
15
N
3
O
6
+ H): calcd, 322.1039; found, 322.1037
23
33
3
5
+
+
32.2502 (M + H).
-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-3-methoxy-5-methyl-
phenyl Acetate (3c). According to TP, 2,4-dimethoxy-6-(2-methoxy-
-methylphenoxy)-1,3,5-triazine (275 mg, 1 mmol) gave the desired
product 3c (158 mg, 47%) as a pale yellow solid (mp 124.5−125.7
(M + H).
2
2-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-4,6-dimethylphenyl Ac-
etate (3j). According to TP, 2-(3,5-dimethylphenoxy)-4,6-dimethoxy-
1,3,5-triazine (261 mg, 1 mmol) gave the desired product 3j (114 mg,
4
1
36%) as a white solid (mp 101.5−102.3 °C). H NMR (400 MHz,
1
°
C). H NMR (400 MHz, CDCl ): δ (ppm) 6.63 (d, J = 1.2 Hz, 1 H),
CDCl ): δ (ppm) 6.93 (s, 1 H), 6.88 (s, 1 H), 3.98 (s, 6 H), 2.30 (s, 3
3
3
13
6
2
1
.58 (d, J = 1.2 Hz, 1 H), 3.93 (s, 6 H), 3.73 (s, 3 H), 2.31 (s, 3 H),
H), 2.18 (s, 3 H), 2.15 (s, 3 H). C NMR (100 MHz, CDCl ): δ
3
.14 (s, 3 H). 13C NMR (100 MHz, CDCl ): δ (ppm) 173.7, 172.8,
(ppm) 173.8, 173.0, 168.2, 143.1, 138.7, 136.2, 131.9, 129.2, 121.0,
3
68.3, 151.8, 142.8, 136.4, 130.5, 115.6, 110.7, 56.1, 55.3, 21.5, 20.6. IR
55.5, 20.9, 20.3, 16.2. IR (KBr): 3130, 1759, 1571, 1400, 1360, 1315,
−1
−1
(
KBr): 3130, 1766, 1585, 1400, 1369, 1216, 1192, 1101, 819 cm .
1189, 1145, 901, 853, 819 cm . HRMS (C15
H
17
N
3
O
5
+ H): calcd,
+
+
HRMS (C H N O + H): calcd, 336.1196; found, 336.1192 (M +
320.1246; found, 320.1248 (M + H).
15
17
3
6
H).
2-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)phenyl Acetate (3k). Ac-
3
-(tert-Butyl)-2-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)phenyl Ac-
cording to TP, 2,4-dimethoxy-6-phenoxy-1,3,5-triazine (233 mg, 1
etate (3d). According to TP, 2-(2-(tert-butyl)phenoxy)-4,6-dime-
mmol) gave the desired product 3k (154 mg, 53%) as a white solid
1
thoxy-1,3,5-triazine (289 mg, 1 mmol) gave the desired product 3d
149 mg, 43%) as a pale yellow oil. H NMR (400 MHz, CDCl ): δ
(mp 49.7−51.5 °C). H NMR (400 MHz, CDCl ): δ (ppm) 7.31−
3
1
13
(
7.21 (m, 4 H), 3.98 (s, 6 H), 2.18 (s, 3 H). C NMR (100 MHz,
3
(
ppm) 7.32−7.28 (m, 1 H), 7.21 (t, J = 8.1 Hz, 1 H), 7.10 (dd, J = 7.9
CDCl ): δ (ppm) 173.8, 172.8, 168.2, 143.1, 142.2, 126.7, 126.5,
3
13
Hz, 1.6 Hz, 1 H), 3.96 (s, 6 H), 2.03 (s, 3 H), 1.34 (s, 9 H). C NMR
123.6, 123.2, 55.5, 20.6. IR (KBr): 3129, 1772, 1573, 1400, 1247, 1208,
−
1
(
100 MHz, CDCl ): δ (ppm) 173.7, 172.9, 167.9, 142.9, 142.7, 142.0,
1120, 938, 911, 820 cm . HRMS (C H N O + H): calcd,
3
13 13 3 5
+
1
1
25.6, 124.2, 121.2, 55.4, 34.8, 30.2, 20.5. IR (KBr): 3457, 1775, 1587,
292.0933; found, 292.0934 (M + H).
−1
560, 1469, 1357, 1203, 1122, 820 cm . HRMS (C H N O + H):
5-Chloro-2-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)-4-ethylphenyl
Acetate (3l). According to TP, 2-(4-chloro-3-ethylphenoxy)-4,6-
dimethoxy-1,3,5-triazine (296 mg, 1 mmol) gave the desired product
17
21
3
5
+
calcd, 348.1559; found, 348.1559 (M + H).
-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-4-methoxyphenyl Ace-
tate (3e). According to TP, 2,4-dimethoxy-6-(3-methoxyphenoxy)-
2
1
3l (138 mg, 39%) as a pale yellow solid (mp 49.1−50.4 °C). H NMR
1
3
7
,3,5-triazine (526 mg, 2 mmol) gave the desired product 3e (199 mg,
(400 MHz, CDCl ): δ (ppm) 7.22 (s, 1 H), 7.11 (s, 1 H), 3.96 (s, 6
3
1
1%) as a colorless oil. H NMR (400 MHz, CDCl ): δ (ppm) 7.12−
H), 2.71 (q, J = 7.5 Hz, 2 H), 2.13 (s, 3 H), 1.21 (t, J = 7.5 Hz, 3 H).
3
13
.07 (m, 1 H), 6.80−6.75 (m, 2 H), 3.96 (s, 6 H), 3.76 (s, 3 H), 2.11
C NMR (100 MHz, CDCl ): δ (ppm) 173.8, 172.7, 167.9, 141.7,
3
(
s, 3 H). 13C NMR (100 MHz, CDCl ): δ (ppm) 173.8, 172.8, 168.5,
140.3, 140.2, 130.9, 124.4, 123.3, 55.6, 26.3, 20.6, 13.6. IR (KBr):
3
−1
1
2
57.7, 143.5, 135.8, 123.8, 111.9, 108.8, 55.7, 55.5, 20.5. IR (KBr):
952, 1768, 1588, 1568, 1505, 1471, 1362, 1202, 1124, 1031, 819
3129, 1777, 1591, 1400, 1200, 1153, 1020, 901, 813 cm . HRMS
+
(C H ClN O + H): calcd, 354.0857; found, 354.0855 (M + H).
15
16
3
5
−
1
cm . HRMS (C H N O + H): calcd, 322.1039; found, 322.1037
5-Bromo-2-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)phenyl Acetate
(3m). According to TP, 2-(4-bromophenoxy)-4,6-dimethoxy-1,3,5-
14
15
3
6
+
(
M + H).
-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-5-methylphenyl Ace-
tate (3f). According to TP, 2,4-dimethoxy-6-(p-tolyloxy)-1,3,5-triazine
247 mg, 1 mmol) gave the desired product 3f (151 mg, 49%) as a
2
triazine (312 mg, 1 mmol) gave the desired product 3m (94 mg, 25%)
1
as a yellow oil. H NMR (400 MHz, CDCl ): δ (ppm) 7.40−7.36 (m,
3
1
3
(
2 H), 7.15−7.09 (m, 1 H), 3.97 (s, 6 H), 2.15 (s, 3 H). C NMR (100
MHz, CDCl ): δ (ppm) 173.8, 172.6, 167.7, 142.8, 142.4, 129.6, 127.0,
1
white solid (mp 81.5−82.3 °C). H NMR (400 MHz, CDCl ): δ
3
3
(
(
ppm) 7.14−7.10 (m, 1 H), 7.07−7.00 (m, 2 H), 3.96 (s, 6 H), 2.35
124.5, 118.9, 55.6, 20.6. IR (KBr): 3105, 2952, 1780, 1594, 1575, 1471,
s, 3 H), 2.15 (s, 3 H). 13C NMR (100 MHz, CDCl ): δ (ppm) 173.8,
−1
3
1362, 1265, 1201, 1123, 1011, 921, 819 cm . HRMS (C H BrN O
13 12
3
5
+
1
72.9, 168.4, 141.7, 140.7, 136.9, 127.2, 124.1, 122.7, 55.5, 20.9, 20.7.
+ H): calcd, 370.0039; found, 370.0040 (M + H).
−1
IR (KBr): 3129, 1767, 1586, 1552, 1400, 1216, 1136, 1022, 820 cm .
HRMS (C H N O + H): calcd, 306.1090; found, 306.1092 (M +
H).
2-((4,6-Dimethoxy-1,3,5-triazin-2-yl)oxy)-5-fluorophenyl Acetate
(3n). According to TP, 2-(4-fluorophenoxy)-4,6-dimethoxy-1,3,5-
triazine (251 mg, 1 mmol) gave the desired product 3n (65 mg,
+
14
15
3
5
D
DOI: 10.1021/acs.organomet.7b00314
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
2
1%) as a pale yellow oil. H NMR (400 MHz, CDCl ): δ (ppm)
intermediate (419 mg, 1.6 mmol) in acetone (25 mL) was added
3
7
.24−7.17 (m, 1 H), 7.05−6.95 (m, 2 H), 3.97 (s, 6 H), 2.16 (s, 3 H).
K CO3 (2.2 g, 16 mmol) and MeI (2.3 g, 16 mmol) at room
temperature. The reaction mixture was stirred at room temperature for
2
1
3
C NMR (100 MHz, CDCl ): δ (ppm) 173.8, 172.8, 167.8, 159.9 (d,
3
J = 247 Hz), 142.8 (d, J = 11 Hz), 139.3 (d, J = 4 Hz), 123.8 (d, J = 10
Hz), 113.3 (d, J = 23 Hz), 111.5 (d, J = 26 Hz), 55.6, 20.7. IR (KBr):
20 h. Water (20 mL) was added, and the resulting mixture was
extracted with CH (3 × 20 mL). The combined organic layers
were dried over MgSO . After filtration and evaporation of the solvents
4
Cl
2
2
3
8
3
467, 2922, 1776, 1590, 1561, 1501, 1469, 1358, 1250, 1205, 1013,
−1
90, 818 cm . HRMS (C H FN O + H): calcd, 310.0839; found,
in vacuo, the residue was purified by column chromatography on silica
13
12
3
5
+
gel (petroleum ether/ethyl acetate) to yield 2c (343 mg, 62%) as a
10.0838 (M + H).
1
white solid (mp 130.2−131.5 °C). H NMR (400 MHz, CDCl ): δ
Ethyl 3-Acetoxy-4-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)-
3
benzoate (3o). According to TP, ethyl 4-((4,6-dimethoxy-1,3,5-
(ppm) 7.01−6.95 (m, 1 H), 6.79−6.70 (m, 2 H), 3.95 (s, 6 H), 3.74
(s, 3 H), 2.33 (s, 3 H). 13C NMR (100 MHz, CDCl
): δ (ppm) 173.8,
triazin-2-yl)oxy)benzoate (305 mg, 1 mmol) gave the desired product
3
1
3
o (74 mg, 20%) as a yellow oil. H NMR (400 MHz, CDCl ): δ
173.4, 150.7, 138.6, 136.9, 121.9, 121.2, 113.5, 55.8, 55.3, 21.4. IR
(KBr): 3130, 1571, 1510, 1468, 1400, 1376, 1210, 1154, 1124, 1029,
3
(
ppm) 7.97 (dd, J = 8.6 Hz, 1.9 Hz, 1 H), 7.89 (d, J = 1.9 Hz, 1 H),
−
1
7
.32 (d, J = 8.6 Hz, 1 H), 4.36 (q, J = 7.3 Hz, 2 H), 3.96 (s, 6 H), 2.18
932, 817 cm . HRMS (C13
H
15
N
3
O
4
+ H): calcd, 278.1141; found,
s, 3 H), 1.37 (t, J = 7.3 Hz, 3 H). 13C NMR (100 MHz, CDCl ): δ
+
(
(
278.1138 (M + H).
3
ppm) 173.8, 172.4, 168.0, 165.0, 146.7, 142.1, 129.2, 128.1, 125.2,
2-Methoxy-2′,4-dimethyl-1,1′-biphenyl (6). In a Schlenk tube
were placed in turn 2,4-dimethoxy-6-(2-methoxy-4-methylphenoxy)-
1,3,5-triazine (2c; 277 mg, 1.0 mmol), 2-methylboronic acid (540 mg,
1
23.3, 61.4, 55.6, 20.6, 14.3. IR (KBr): 3347, 3148, 1775, 1728, 1590,
−1
1369, 1224, 820 cm . HRMS (C H N O + H): calcd, 364.1145;
16
17
3
7
+
found, 364.1141 (M + H).
4.0 mmol), NiCl (dppf) (35 mg, 0.05 mmol), and K PO (1,5 g, 7.0
2
3
4
mmol) under an N atmosphere. Toluene (7 mL) was injected by
Ethyl 4-Acetoxy-3-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)-
benzoate (3p). According to TP, ethyl 3-((4,6-dimethoxy-1,3,5-
2
syringe. The mixture was stirred in a preheated oil bath (110 °C) for
24 h. The reaction mixture was cooled to room temperature. Water
(20 mL) was added, and the resulting mixture was extracted with
EtOAc (3 × 20 mL). The combined organic layers were dried over
triazin-2-yl)oxy)benzoate (305 mg, 1 mmol) gave the desired product
1
3
p (101 mg, 28%) as a pale yellow oil. H NMR (400 MHz, CDCl ): δ
3
(
ppm) 7.99−7.93 (m, 2 H), 7.31 (d, J = 8.6 Hz, 1 H), 4.36 (q, J = 7.1
13
Hz, 2 H), 3.97 (s, 6 H), 2.18 (s, 3 H), 1.37 (t, J = 7.1 Hz, 3 H).
C
MgSO . After filtration and evaporation of the solvents in vacuo, the
4
NMR (100 MHz, CDCl ): δ (ppm) 173.9, 172.7, 167.7, 165.0, 146.0,
residue was purified by column chromatography on silica gel
3
1
3
1
3
42.9, 129.1, 128.1, 124.8, 123.6, 61.4, 55.6, 20.7, 14.3. IR (KBr):
(petroleum ether/ethyl acetate) to yield 6 (198 mg, 93%) as a
1
540, 2957, 1774, 1721, 1589, 1562, 1472, 1364, 1287, 1205, 1173,
colorless viscous oil. H NMR (400 MHz, CDCl
3
): δ (ppm) 7.49−
−
1
123, 1017, 903, 820 cm . HRMS (C H N O + H): calcd,
7.39 (m, 4 H), 7.27 (d, J = 7.6 Hz, 1 H), 7.05 (d, J = 7.6 Hz, 1 H), 7.00
(s, 1 H), 3.94 (s, 3 H), 2.64 (s, 3 H), 2.39 (s, 3 H). C NMR (100
16
17
3
7
+
13
64.1145; found, 364.1144 (M + H).
-Chloro-2-((4,6-dimethoxy-1,3,5-triazin-2-yl)oxy)phenyl Acetate
3q). According to TP, 2-(3-chlorophenoxy)-4,6-dimethoxy-1,3,5-
triazine (268 mg, 1 mmol gave the desired product 3q (72 mg,
4
MHz, CDCl ): δ (ppm) 156.4, 138.6, 138.4, 136.8, 130.7, 130.1, 129.5,
3
(
127.9, 127.0, 125.3, 121.0, 111.6, 55.2, 21.5, 19.9. IR (KBr): 3129,
1613, 1463, 1402, 1283, 1271, 1165, 1134, 1041, 923, 873, 816, 764,
1
−1
2
2%) as a white solid (mp 93.7−95.0 °C). H NMR (400 MHz,
726 cm . HRMS (C15
H16O + H): calcd, 213.1279; found, 213.1275
+
CDCl ): δ (ppm) 7.31−7.24 (m, 2 H), 7.20−7.16 (m, 1 H), 4.00 (s, 6
H), 2.17 (s, 3 H). C NMR (100 MHz, CDCl ): δ (ppm) 173.8,
(M + H).
3
13
3
1
72.5, 167.9, 143.4, 141.0, 131.3, 126.8, 124.5, 123.7, 55.6, 20.6. IR
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00314.
■
−1
(
KBr): 3129, 1756, 1401, 1368, 1216, 1178, 1015, 892, 818 cm .
*
S
+
HRMS (C H ClN O + H): calcd, 326.0544; found, 326.0539 (M +
H).
13
12
3
5
3,5-Dimethylbenzene-1,2-diol (4). To a solution of 2-((4,6-
dimethoxy-1,3,5-triazin-2-yl)oxy)-3,5-dimethylphenyl acetate (3a; 160
mg, 0.50 mmol) in PhMe (20 mL) under N was added MeOTf (100
NMR spectra and HRMS data of compounds (PDF)
2
μL, 0.88 mmol). The reaction mixture was stirred under N at 100 °C
2
for 2 h. The reaction mixture was cooled to ambient temperature.
Evaporation of the solvent in vacuo yielded a solid. The solid was
AUTHOR INFORMATION
Corresponding Author
E-mail for Z.P.: zpech@upc.edu.cn.
ORCID
Zhihua Peng: 0000-0001-6971-4456
Notes
The authors declare no competing financial interest.
■
*
dissolved in dry methanol (5.0 mL) and was added under N to a
2
solution of Na (294 mg, 12 mmol) in dry methanol (15 mL). The
reaction mixture was heated at 80 °C for 15 min. The reaction mixture
was cooled to ambient temperature, and the solvent was evaporated in
vacuo. H O (75 mL) was added, and the resulting mixture was
2
extracted with EtOAc (3 × 50 mL). The combined organic layers were
dried over MgSO . After filtration and evaporation of the solvents in
4
vacuo, the residue was purified by column chromatography on silica
ACKNOWLEDGMENTS
We thank the Shandong Provincial Natural Science Foundation
ZR2012BQ006), the National Natural Science Foundation of
China (21202205), and the Fundamental Research Funds for
gel (petroleum ether/ethyl acetate) to yield 4 (49 mg, 71%) as a
■
(
1
yellow oil. H NMR (400 MHz, CDCl ): δ (ppm) 6.53 (s, 1 H), 6.51
(
3
13
s, 1 H), 4.85 (br s, 2 H), 2.21 (s, 3 H), 2.20 (s, 3 H). C NMR (100
MHz, CDCl ): δ (ppm) 142.9, 139.6, 129.9, 124.2, 123.3, 113.7, 20.6,
3
−1
1
(
5.5. IR (KBr): 3508, 2935, 1622, 1503, 1308, 1039, 848 cm . HRMS
C H O + H): calcd, 139.0759; found, 139.0753 (M + H).
+
the Central Universities (17CX02069) for financial support.
8
10
2
2
,4-Dimethoxy-6-(2-methoxy-4-methylphenoxy)-1,3,5-tria-
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DOI: 10.1021/acs.organomet.7b00314
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(
7
(
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F
DOI: 10.1021/acs.organomet.7b00314
Organometallics XXXX, XXX, XXX−XXX