Copper-catalyzed acyloxylation of the C(sp3)-H bond adjacent to an oxygen by a cross-dehydrogenative coupling approach

Article abstract of DOI:10.1039/c4ra06233g

The acyloxylation of the C(sp³)-H bond adjacent to oxygen by adopting a copper catalyzed dehydrogenative cross-coupling reaction between simple ethers and benzyl alcohols has been disclosed. The advantages of the dehydrogenative cross-coupling reaction are the adoption of unactivated ethers as substrates and good tolerance of many functional groups. This journal is

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COMMUNICATION
Copper-Catalyzed Acyloxylation of C(sp3)-H bond Adjacent to Oxygen
by Cross-Dehydrogenative Coupling Approach
Kammari Bal Raju, a Bejjanki Naveen Kumara and Kommu Nagaiah*a
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
Acyloxylation of C(sp3)-H bond adjacent to oxygen by
Previous works
adopting copper catalyzed dehydrogenative cross-coupling
reaction between simple ethers and benzyl alcohols has been
disclosed. The advantages of dehydrogenative cross-coupling
10 reaction are adoption of unactivated ethers as a substrates
and good tolerance of many functional groups.
O
O
O
O
TBAI (20 mol%)
O
O
Wan (2011)
Duan (2013)
Patel (2014)
TBHP (2.2 equiv.)
OH
O
O
(a)
(b)
(c)
EtOAc
O
O
O
O
OH
TBAI (20 mol%)
O
O
The construction of carbon–carbon (C–C) and carbonꢀheteroatom
(C–O & C–N) bond using transitionꢀmetal catalyzed C–H bond
functionalization has emerged as an attractive and powerful tool
15 in modern organic chemistry.1,2 In particular, functionalization of
C(sp3) –H bonds under oxidative condition has fascinated much
attention among synthetic chemists, since it eliminates the
prefunctionalization step and thus make synthetic schemes more
shorter and straight forward. In recent years, tremendous efforts
20 have been made for the formation of these bonds through
oxidative C–H bond functionalization adjacent to heteroatoms by
cross dehydrogenative coupling approach (CDC).3,4,6 Moreover,
the majority of reported methods have focused on
functionalization of C(sp3)–H bond (via reactive iminium ion
25 intermediates) adjacent to nitrogen atom under oxidative
O
TBHP (2.2 equiv.)
O
O
O
O
Cu(OAc)2 (20 mol%)
TBHP (6 mmol)
O
O
Present work
X
O
X
n
Cu Catalyst (5mol%)
n
O
O
OH
(d)
Oxidant (4 equiv.)
100 °C, 8 h
O
X = C, O
n = 0, 1
Scheme 1: CDC approach for C–O bond forming reaction via C–
H bond functionalization
alkylbenzenes and simple ethers (Scheme 1, c).
50
Traditionally, benzyl alcohols are known to be
acylation7 and acyloxylation reagents.8 Since benzyl alcohols are
naturally abundant, stable, and easy to handle and readily
oxidized into aldehydes, acids and thus can be likely to be used as
ideal acyl and acyloxylating sources. αꢀAcyloxy ethers appear as
55 structural motif in biologically active, pharmaceutical and natural
products compounds.9 Herein, we report a copper–catalyzed
oxidative CDC reaction between benzyl alcohols and simple
cyclic and acyclic ethers in the presence of tertꢀButyl hydrogen
peroxide (TBHP) as an oxidant (scheme 1, d), affording the
60 acyloxylated products in moderate to good yields.
conditions with various proꢀnucleophiles.4
However, the
functionalization of C(sp3)–H bond (via reactive oxonium ion
intermediates) adjacent to oxygen atom is relatively inert due to
its higher oxidation potential and required strong hydrogen
30 acceptor. In this regard, most of the reported methods were
devoted to allylic and benzylic C–H bonds αꢀposition to the
oxygen with different carbon based proꢀnucleophiles.5
In contrast, to our knowledge, there have been scarce
reports exist on αꢀC–H bond functionalization on simple alkyl
35 ethers for construction of C–O, C–N and C–S bond using oxygen,
nitrogen and sulphur based pro–nucleophiles via CDC reaction.6
For example, Wan and coꢀworkers6c first described a Bu4NIꢀ
catalyzed C–O bond formation by adopting CDC reaction
between carboxylic acids and unactivated simple ethers using
40 tertꢀButyl hydrogen peroxide as an oxidant (scheme 1, a).
Recently, Duan’s6e group also described a decarboxylative
acyloxylation of C(sp3)–H bond adjacent to oxygen atom with αꢀ
oxocarboxylic acids in the presence of TBAI and TBHP as an
oxidant (scheme 1, b). Most recently, Patel et al.,6i developed a
45 copper catalyzed synthesis of α–acyloxy ethers from
At the outset of our study, copper catalyzed oxidative
C(sp3)–H bond acyloxylation was investigated with 4–
methylbenzyl alcohol (1a) and 1,4–dioxane (2a) as the model
substrates (Table 1). The initial reaction was carried out with 10
65 mol % Cu(OAc)2 in presence of 70% aqueous solution of TBHP
(2 equiv) at 80 °C for 8 h and we perceived the desired product
3a in 15% yield (Table 1, entry 1). Next we examined with
different Cu sources like Cu(acac)2, CuCl2, CuBr2, CuCl, CuI and
Cu(OAc)2.H2O. However, the expected product was not observed
70 in all the cases (Table 1, entries 3ꢀ6) except Cu(OAc)2.H2O
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Table 1 Optimization of reaction conditions.a
substrates 1 for the C(sp3)–H bond acyloxylation with different
unactivated ethers 2. For example, substrates bearing electron–
rich groups like a methyl, isopropyl, methoxy, benzyloxy on
35 aromatic ring showed good active with 1,4ꢀdioxane to offered the
desired products (3a–e) in good yields. Orthoꢀsubstituted benzyl
alcohol did not affect the reaction and undergoes efficient
coupling with 1,4–dioxane and gave the desired product 3f in
73% yield. The electron–poor groups containing benzyl alcohols
40 such as CN, NO2 and F are worked well under the optimized
Entry
Catalyst
(mol%)
Oxidant (equiv.)
T [°C] Yields
3a [%]c
1
2
Cu(OAc)2(10)
Cu(acac)2(10)
CuCl2(10)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (2)
TBHP in H2O (3)
O2
80
80
15
d
–
d
3
80
–
d
4
CuBr2(10)
80
–
d
5
CuCl(10)
80
–
d
6
CuI(10)
80
–
7
Cu(OAc)2H2O
Cu(OAc)2(10)
Cu(OAc)2(10)
Cu(OAc)2(10)
Cu(OAc)2(10)
Cu(OAc)2(10)
Cu(OAc)2(5)
Cu(OAc)2(5)
Cu(OAc)2(2)
–
80
12
35
8
100
100
100
100
100
100
100
100
100
100
100
d
9
–
d
10
11
12
13
14
15
16
17
18
H2O2 e(3)
–
DTBPe
–
d
TBHP in decane (3)
TBHP in decane (3)
TBHP in decane (4)
TBHP in decane (4)
TBHP in decane (4)
–
57
68
82
80b
d
–
d
Cu(OAc)2(5)
Cu(OAc)2(5)
–
TBHP in decane (4)
12f
a Reaction conditions: Unless specified, the reaction was carried out with:
1a (1 mmol), 2a (2 mL), Cu catalyst (5 mol%), oxidant (4 equiv), T [°C],
b
c
d
5
8 h. Reaction time was 18 h. Yield of isolated product. Product not
observed by TLC eH2O2 = hydrogen peroxide, eDTBP = Diꢀtertꢀbutyl
peroxide. f 2a (1mmol)
catalyst, which gave only 12% yield (Table 1, entry 7). Then, it is
necessary to check the quantity of TBHP and temperature role.
10 Accordingly, the aq. TBHP amount was raised to 3 equiv and
temperature from 80 °C to 100 °C (Table 1, entry 8) then, the
product yield was increased from 15% to 35%. We have
evaluated the role of oxidant by screening different oxidants such
as O2, H2O2, Diꢀtertꢀbutyl peroxide (DTBP). However, we could
15 not able to see the required product (Table 1, entries 9–11).
Moving from aqueous TBHP to a commercially available TBHP
in decane solution, the product yield could be increased from
35% to 57% (Table 1, entry 12).10 By decreasing the Cu(OAc)2
quantity from 10 mol% to 5 mol% (Table 1, entry 13), the yield
20 was further enhanced from 57% to 68%. Further optimization
studies revealed that, the product yield was increased to 82%
(Table 1, entry 14), when the reaction has carried out with 5
Scheme 2 Cu(OAc)2–catalyzed coupling of 1,4–dioxane with
variety of benzyl alcohols.
a
Reaction conditions: benzyl alcohol (1 mmol), 1,4–dioxane (2 mL),
45 Cu(OAc)2 (5 mol%), TBHP in decane (4 equiv), 100 0C, 8 h.
reaction conditions (3g–3i). The present protocol well tolerated
for the halogen bearing benzyl alcohols (Cl & Br) without any
difficulties (3j & 3k). The catalytic system showed good activity
in the case of fused ring (naphthalene) containing benzyl alcohol
50 and the product (3l) yield was obtained in 68%. Our efforts to
activate hetero aromatic benzyl alcohols were not successful;
instead of the acyloxylation product (3m) we observed the
alcohol attack at carbon atom (adjacent to oxygen) (3n, 3o) (see
Supporting Information). In addition, the acyloxylation of 1,4ꢀ
55 dioxane 2a was also unsuccessful with allyl alcohol and aliphatic
alcohol (3p, 3q, 3r) (Scheme 2) under optimized reaction
conditions.
mol% Cu(OAc)2 and
4 equiv. of TBHP. No significant
improvement in the product yield was observed with a loading of
25 2 mol% of Cu(OAc)2 and prolonging the reaction time (Table 1,
entry 15). The lack of product formation in control experiments
in the absence of metal or oxidant clearly showed the significance
of both metal catalyst and oxidant for this transformation (entry
16, 17).
30
Having the optimized reaction conditions in our hand
(Table 1, entry 14), we screened different benzyl alcohol
2
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To evaluate the role of ethers we carried out the
carbons, we have carried out the reaction with 1,2–
reactions with cyclic (2bꢀ2e) and acyclic (2f, 2g) (Table 2) ethers
dimethoxyethane (2f) under standard conditions and we observed
under standard reaction conditions. Cyclic ethers like THP (2b) 15 the two products (4fa–4fc') with their respective combined good
and THF (2c) reacted smoothly with benzyl substituted alcohol to
provide the corresponding products (4b, 4c) in 68% &63% good
yields. In the entire cases acyloxylation products at internal
methylene carbon were slightly higher. Next, we carried out the
reaction of 1a with diethylether (b.p 35 °C) (2g) but we couldn’t
scrutinize the acyloxy ether (4g) under standard reaction
20 conditions.
5
Table 2 Reaction of Benzyl alcohols with ethers a
To explore the mechanism of the reaction several
control experiments were performed. In this process, we observed
that, the coupling product 3a was obtained in <5% yield7a,c when
4–methylbenzoic acid was used instead of benzyl alcohol under
25 the optimum reaction conditions (scheme 3, equation 1) from this
it is apparent that the transformation did not proceed via an acid
intermediate.11 Surprisingly, no product observed when reaction
was carried out between 2–(4–methylbenzyloxy)–1,4–dioxane
(i.e, protected alcohol) and 2a (scheme 3, equation 2) in our
30 catalytic system. The acyloxylated product 3a was obtained in
80% yield when the reaction was performed with 4ꢀmethyl
benzaldehyde (scheme 3, equation 3). Additionally, 2,2,6,6ꢀ
Tetramethylpiperidinyloxy (TEMPO), a radical scavenger, added
to the reaction mixture of 1a and 1,4–dioxane(2a) under
35 optimized reaction conditions, no coupling product 3a was
observed (Scheme 3, equation 4). On the basis of these
observations and in line with earlier reports6b,12 it suggests that,
mechanism of the dehydrogenative cross–coupling reaction may
undergo a radical pathway in presence of Cu(OAc)2 and TBHP in
40 decane as an oxidant, which is depicted in scheme 3.
Scheme 3 Investigation of reaction mechanism
The mechanism involve five steps: Initially, tert–
butoxyl and tert–butyl peroxyl radicals which are formed through
45 interaction of TBHP with the Cu (II)–Cu (I) redox couple
(Scheme 4, step a).13 Next activate the C–H bonds adjacent to
oxygen atom of benzyl alcohol to produce aldehyde.
Subsequently, this aldehyde undergoes a similar hydrogen
abstraction to form acyl radical, which is coupled with tert butyl
50 peroxy radical provides per ester intermediate (Scheme 4, step
b).14 The intermediacy of tertꢀbutyl perbenzoate in this
transformation (step b) has been supported by a control
experiment, where the treatment of commercially available tertꢀ
butyl perbenzoate with 1,4–dioxane 2a under optimized reaction
55 conditions afforded the coupling product 3e in moderate yields
(Scheme 3, equation 5).6i From this we can predict, the plausible
a
Reaction conditions: Benzyl alcohol 1a (1 mmol), 2b–2g (2 ml),
0
b
Cu(OAc)2 (5 mol%), TBHP in decane (4 equiv.), 100 C, 8 h. Yield of
isolated product.
10 yields. But 2ꢀmethyl THP (2d) and 1,3ꢀdioxolane (2e) were both
inactive for coupling reaction with benzyl alcohols. To compare
the reactivity between internal methylene and terminal methyl
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1) For selected reviews of C–C coupling from C–H bonds, see; (a) B.
A. Arndtsen, R. G. Bergman, T. A. Mobley, T. H Peterson, Acc.
Chem. Res. 1995; (b) A. E. Shilov, G. B. Shulpin, Chem. Rev. 1997,
97, 2879; (c) G. Dyker, Angew. Chem. Int. Ed. 1999, 38, 1698; (d)
V. Ritleng, C. Sirlin, M. Pfeffer, Chem. Rev. 2002, 102, 1731; (e)
Metal–Catalyzed Cross–Coupling Reactions, (Eds: A. de Meijere, F.
Diederich), Wiley–VCH, Weinheim, 2004; (f) G. Dyker, Ed.; Wiley
VCH: Weinheim, 2005; 28, 154; (g) C. J. Li, Acc. Chem. Res. 2009,
42, 335; (h) X. Chen, K. M. Engle, D. H. Wang, J. Q. Yu, Angew.
Chem. 2009, 121, 5196; Angew. Chem. Int. Ed. 2009, 48, 5094; (i)
T. W. Lyons, M. S. Sanford, Chem. Rev. 2010, 110, 1147; (j) C–H
Activation (Eds.: J. Q. Yu, Z. J. Shi, Top. Curr. Chem. 2010, 292, 1;
(k) R. Jana, T. P. Pathak, M. S. Sigman, Chem. Rev. 2011, 111,
1417; (l) T. Xiong, Y. Li, X. H. Bi, Y. H. Lv, Q. Zhang, Angew.
Chem. Int. Ed. 2011, 50, 7140; (m) X. S. Wang, D. S. Leow, J. Q.
Yu, J. Am.Chem Soc. 2011, 133, 13864; (n) S. Rakshit, C.
Grohmann, T. Besset, F. Glorius, J. Am. Chem. Soc. 2011, 133,
2350; (o) W. Shi, C. Liu, A. Lei, Chem. Soc. Rev. 2011, 40, 2761;
(p) C. L. Sun, B. J. Li, Z. J. Shi, Chem. Rev. 2011, 111, 1293; (q) M.
Klussmann, D. Sureshkumar, Synthesis. 2011, 353; (r) L.
Ackermann, Chem. Rev. 2011, 111, 1315;
2) For selected reviews of C–heteroatom coupling, see; (a) B. A.
Arndtsen, R. G. Bergman, T. A. Mobley, T. H. Peterson, Acc.
Chem. Res. 1995, 28, 154; (b) I. P. Belskaya, A. V. Cheprakov,
Coord. Chem. Rev. 2004, 248, 2337; (c) Echavarren, A. Angew.
Chem. Int. Ed. 2004, 116, 4808; (d) B. Marciniec, M. Majchrzak,
W. Prukala, M. Kubicki, D. Chadyniak, J. Org. Chem. 2005, 70,
8550; (e) A. R. Dick, M. S. Sanford, Tetrahedron. 2006, 62, 2439;
(f) D. Fiedler, H. V. Halbeek, R. G. Bergman, J. Am. Chem. Soc.
2006, 128, 10240; (g) J. F. Hartwig, Inorg. Chem. 2007, 46, 1936;
(h) J. F. Hartwig, Nature 2008, 455, 314; (i) X. Chen, K. M. Engle,
D. H. Wang, J. Q. Yu, Angew. Chem. Int. Ed. 2009, 48, 5094; (j) T.
W. Lyons, M. S. Sanford, Chem. Rev. 2010, 110, 1147; (k) Y. Lu,
D. H. Wang, K. M. Engle, J. Q. Yu, J. Am. Chem. Soc. 2010, 132,
5916; (l) I. A. Mkhalid, J. H. Barnard, T. B. Marder, J. M. Murphy,
J. F. Hartwig, Chem. Rev. 2010, 110, 890; (m) J. F. Hartwig, Chem.
Soc. Rev. 2011, 40, 1992; (n) D. A. Colby, R. G. Bergman, J. A.
Ellman, Chem. Rev. 2010, 110, 624; (o) C. Liu, H. Zhang, W. Shi,
A. Lei, Chem. Rev. 2011, 111, 1780.
35
40
45
50
55
60
65
70
75
80
85
90
95
100
Scheme 4 Plausible pathway for the reaction
mechanism of the reaction as described in scheme 4. This per
ester intermediate undergo a homolytic cleavage to acyloxy
radical (Scheme 4, step c) which acts as a proꢀnucleophile. Tert–
butoxyl radical generated by the dissociation of t–BuOOH may
abstract α–hydrogen of 1, 4–dioxane to form radical and go
through a single electron transfer15 leads to oxonium species
(Scheme 4, step d). Then, finally acyloxylated product 3a was
5
10 formed by the coupling of α–oxy radical with oxonium species
(Scheme 4, step e).
3) For reviews on dehydrogenative cross–coupling reactions: see; (a)
C. J. Li, Acc. Chem. Res. 2009, 42, 335; (b) C. Scheuermann, Chem.
Asian J. 2010, 5, 436; (c) A. E. Wendlandt, A. M. Suess, S. S. Stahl,
Angew. Chem. Int. Ed. 2011, 50, 11062; (d) A. N. Campbell, S. S.
Stahl, Acc. Chem. Res. 2012, 45, 851; (e) C. Zhang, C. Tang, N.
Jiao, Chem. Soc. Rev. 2012, 41, 3464.
Conclusions
In summary, we disclosed a Cu–catalyzed oxidative C(sp3)–H
bond acyloxylation of unactivated cyclic and acyclic ethers with
15 different substrates of benzyl alcohols by adopting TBHP as an
oxidant. Orthoꢀsubstituted, halogen bearing and fused ring
aromatic substrates are well tolerated under the optimized
reaction conditions. This novel strategy provides a simple,
efficient, and direct access to acyloxylated products. Further
20 investigation towards the scope, mechanism, and synthetic
applications of this reaction are expedited in due course.
4) For some selected reports on CꢀH bond functionalization of Amines,
see; (a) S. I. Murahashi, N. Komiya, H. Terai, T. Nakae, J. Am.
Chem. Soc. 2003, 125, 15312; (b) Z. Li, C. J. Li, J. Am. Chem. Soc.
2004, 126, 11810; (c) Z. Li, C. J. Li, J. Am. Chem. Soc. 2005, 127,
3672; (d) Z. Li, C. J. Li, J. Am. Chem. Soc. 2005, 127, 6968; (e) S. I.
Murahashi, N. Komiya, H. Terai, Angew. Chem. Int. Ed. 2005, 44,
6931; (f) A. J. Catino, J. M. Nichols, B. J. Nettles, M. P. Doyle, J.
Am. Chem. Soc. 2006, 128, 5648; (g) S. I. Murahashi, T. Nakae, H.
Terai, N. Komiya, J. Am. Chem. Soc. 2008, 130, 11005; (h) L.Zhao,
C. J. Li, Angew. Chem. Int. Ed. 2008, 47, 7075; (i) Y. Shen, M. Li,
S. Wang, T. Zhang,Z. Tan, C. C. Guo, Chem. Commun. 2009, 953;
(j) L. Zhao, O. Basle, C. J. Li, Proc. Natl. Acad. Sci. USA. 2009,
106, 4106; (k) J. Xie, Z. Huang, Angew.Chem. Int. Ed. 2010, 49,
10181; (l) M. Ghobrial, K. Harhammer, M. D. Mihovilovic, M.
Schnurch, Chem. Commun. 2010, 46, 8836; (m) G. Kumaraswamy,
A. Murthy, A. Pitchaiah, J. Org. Chem. 2010, 75, 3916; (n) X. Z.
Shu, Y. F. Yang, X. F. Xia, K. G. Ji, X. Y. Liu, Y. M. Liang, Org.
Biomol. Chem. 2010, 8, 4077; (o) G. Zhang, Y. Zhang, R. Wang,
Angew. Chem. Int. Ed. 2011, 50, 10429; (p) Y. Zhang, H. Peng, M.
Zhang, Y. Cheng, C. Zhu, Chem.Commun. 2011, 47, 2354; (q) E.
Shirakawa, T. Yoneda, K. Moriya, K. Ota, N. Uchiyama, R.
Nishikawa, T.Hayashi, Chem. Lett. 2011, 40, 1041; (r) E. Boess, D.
Sureshkumar, A. Sud, C. Wirtz, C. Fares, M. Klussmann, J. Am.
Chem. Soc. 2011, 133, 8106; (s) L. Huang, T. Niu, J. Wu, Y. Zhang,
J. Org. Chem. 2011, 76, 1759; (t) K. Alagiri, G. S. R. Kumara, K. R.
Prabhu, Chem.Commun. 2011, 47, 11787; (u) K. Alagiri, K. R.
Acknowledgment
We thank the Director, IICT for the generous support. CSIR,
New Delhi for funding through the programme ORIGIN XII FYP
25 (CSC0108). K. B and BNK thanks Council of Scientific and
Industrial Research for CSIRꢀSRF fellowship.
Notes and references
a Organic & Biomolecular Chemistry Division, CSIR–Indian Institute of
Chemical Technology, Tarnaka, Hyderabad, 500007, India. Fax: +91(40)
30 27191659; E–mail: nagaiah@iict.res.in.
† Electronic Supplementary Information (ESI) available: See
DOI: 10.1039/b000000x/
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Prabhu, Org. Biomol. Chem. 2012, 10, 835; (v) J. Xie, H. Li, J.
Zhou, Y. Cheng, C. Zhu, Angew. Chem. Int. Ed. 2012, 51, 1252; (w)
E. Boess, C. Schmitz, M. Klussmann, J. Am. Chem. Soc. 2012, 134,
5317;
5
10
15
20
25
30
35
40
45
5) (a) B. M. Trost, P. E. Strege, L. Weber, T. J. Fullerton, T. J.
Dietsche, J. Am. Chem.Soc. 1978, 100, 3407; (b) B. M. Trost, M. L.
Crawley, Chem. Rev. 2003, 103, 2921; (c) Y. Zhang, C. J, Li,
Angew. Chem., Int. Ed. 2006, 45, 1949; (d) Y. Zhang, C. J. Li, J.
Am. Chem. Soc. 2006, 128, 4242; (e) Z. Li, C. J. Li, J. Am. Chem.
Soc. 2006, 128, 56; (f) Z. Li, L. Cao, C. J. Li, Angew. Chem., Int.
Ed. 2007, 46, 6505.
6) (a) X. Liu, Y. Zhang, L. Wang, H. Fu, Y. Jiang, Y. Zhao, J. Org.
Chem. 2008, 73, 6207; (b) S. Pan, J. Liu, H. Li, Z. Wang, X. Guo,
Z. Li, Org. Lett. 2010, 12, 1932; (c) X. Wan, L. Chen, E. Shi, Z.
Liu, S. Chen, W. Wei, H. Li, K. Xu, Chem. Eur. J. 2011, 17, 4085;
(d) K. R. Reddy, C. O. Kappe, G. S. Kumar, B. Pieber, Chem. Eur.
J. 2012, 18, 6124; (e) S. zhang, L. N. Guo, H. Wang, X. H. Duan,
Org. Biomol. Chem, 2013, 11, 4308. (f) S. Guo, Y. Yuan, J. Xiang,
Org. Lett. 2013, 15, 4654. (g) S. Priyadarshini, P. J. A. Joseph, M.
L. Kantam, RSC Advances, 2013, 3, 18283.(h) J. Zhao, H. Fang, W.
Zhou, J. Han, Y. Pan, J. Org. Chem. 2014, 79, 3847. (i) R. S.
Kumar, G. Srimanta, A. Wajid, G. Anupal, K. P. Bhisma, Org. Lett.
2014, 16, 3086.
7) (a) C. Chatgilialoglu, D. Crich, M. Komatsu, I. Ryu, Chem. Rev.
1999, 99, 1991; (b) G. Guillena, D. Ramon, M. Yus, Angew. Chem.
Int. Ed. 2007, 46, 2358; (c) G. Dobereiner, R. Crabtree, Chem. Rev.
2010, 110, 681; (d) F. Xiao, Q. Shuai, F. Zhao, O. Basle, G. Deng,
C. J. Li, Org. Lett. 2011, 13, 1614.
8) (a) L. Liu, L. Yun, Z. Wang, X. Fu, C. Yan, Tetrahedron Letters,
2013, 54, 5383; (b) Y. Zhu, H. Yan, L. Lu, D. Liu, G. Rong, J. Mao,
J. Org. Chem. 2013, 78, 9898; (c) P. Li, J. Zhao, R. Lang, C. Xia, F.
Li. Tetrahedron Letters. 2014, 55, 390.
9) R. Jasti, J. Vitale, S. D. Rychnovsky, J. Am. Chem. Soc. 2004, 126,
9904; b) J. E. Dalgard, S. D. Rychnovsky, J. Am. Chem. Soc. 2004,
126, 15662; c) I. D. Gridnev, S. Kikuchi, A. S. Touchy, I. Kadota,
Y. Yamamoto, J. Org. Chem. 2007, 72, 8371; d) S.Chamberland, K.
A. Woerpel, Org. Lett. 2004, 6, 4739; e) J. Lage Robles, C. G.
Bochet, Org. Lett. 2005, 7, 3545.
10) To our knowledge, the increased yield can be explained as follows.
In presence of aqueous TBHP water may acts as a nucleophile and it
attacks at oxonium ion which leads to lactol or lactone (e.g 1,4ꢀ
dioxanꢀ2ꢀone). But in case of TBHP in decane, decane is not a
nucleophile, so attack of only acyloxy radical/nucleophile to the
oxonium ion and forms the coupling product. From this we can
conclude that a reaction enhancement using waterꢀfree variant).
11) Q. Xia, X. Liu, Y. Zhang, C. Chen, W. Chen, Org. Lett. 2013, 15,
3326.
12) D. Liu, C. Liu, H. Li, A. Lei, Angew. Chem., Int. Ed. 2013, 52,
4453.
50 13) (a) L. Chen, E. Shi, Z. Liu, S. Chen, W. Wei, H. Li, K. Xu, X Wan,
Chem. Eur. J. 2011, 17, 4085; (b) Z. Liu, J. Zhang, S. Chen, E. Shi,
Y. Xu, X. Wan, Angew. Chem. Int. Ed. 2012, 51, 3231.
14) (a) W. Wei, C. Zhang, Y. Xu, X. Wang, Chem. Commun. 2011,
10827; (b) T. He, H. Li, P. Li, L. Wang, Chem. Commun. 2011,
55
8946.
15) (a) S. I. Murahashi, N. Komiya, H. Terai, Angew. Chem., Int. Ed.
2005, 44, 6931; (b) C. Wei, C. J. Li, Green Chem. 2002, 4, 39; (c)
C. J. Li, C. Wei, Chem. Commun. 2002, 268–269; (d) A. E.
Wendlandt, A. M. Suess, S. S. Stahl, Angew. Chem. Int. Ed. 2011,
50, 11062.
60
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DOI: 10.1039/C4RA06233G
Graphical Abstract
We demonstrated an efficient, unprecedented oxidative dehydrogenative cross coupling between a benzyl
alcohol and C(sp3)–H bond adjacent to oxygen atom for the construction of C–O bond, in which benzyl alcohol used
as pronucleophile. Significantly, this method reveals a new strategy for the direct use of benzyl alcohols in the
synthesis of acyloxylated products in moderate to good yields with the use of inexpensive copper as a catalyst and
TBHP as an oxidant.