Iron-catalyzed alkenylation of cyclic ethers via decarboxylative sp 3(C)-sp2(C) coupling

Article abstract of DOI:10.1016/j.tetlet.2013.09.082

An efficient Fe(acac)₃-catalyzed decarboxylative C(sp ²)-C(sp³) coupling reaction via oxidation of C-H bond adjacent to an oxygen atom has been developed successfully, in which cyclic ethers are selectively transformed into the corresponding alkenylation products with good chemical yields and excellent stereoselectivities. The mechanism was studied and the reaction was supposed to proceed through a radical oxidative coupling process.

Full text of DOI:10.1016/j.tetlet.2013.09.082

Accepted Manuscript
Iron-catalyzed alkenylation of cyclic ethers via decarboxylative sp3(C)-sp2(C)
coupling
Jincan Zhao, Wei Zhou, Jianlin Han, Guigen Li, Yi Pan
PII:
S0040-4039(13)01647-X
DOI:
http://dx.doi.org/10.1016/j.tetlet.2013.09.082
TETL 43582
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
22 July 2013
7 September 2013
19 September 2013
Please cite this article as: Zhao, J., Zhou, W., Han, J., Li, G., Pan, Y., Iron-catalyzed alkenylation of cyclic ethers
via decarboxylative sp3(C)-sp2(C) coupling, Tetrahedron Letters (2013), doi: http://dx.doi.org/10.1016/j.tetlet.
2013.09.082
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Iron-catalyzed alkenylation of cyclic ethers via
decarboxylative sp3(C)-sp2(C) coupling
Jincan Zhao,a Wei Zhou,a Jianlin Han,a,b,* Guigen Li,b,c Yi Pana,
a School of Chemsitry and Chemical Engineering, State of Key Laboratory of
Coordination, Nanjing University, Nanjing, 210093, China
b Institute for Chemistry & BioMedical Sciences, Nanjing University, Nanjing, 210093,
China
c Department of Chemsitry and Biochemistry, Texas Tech Unviersity, Lubbock, Texas,
79409-1061, USA
Abstract An efficient Fe(acac)3-catalyzed decarboxylative C(sp2)–C(sp3) coupling
reactions via oxidation of C–H bond adjacent to an oxygen atom has been developed
successfully, in which cyclic ethers are selectively transformed into the corresponding
alkenylation products with good chemical yields and excellent stereoselectivities. The
mechanism was studied and the reaction was supposed to proceed through a radical
oxidative coupling process.
Keywords: Fe(acac)3; Alkenylation; Coupling; Decarboxylative; Oxidation
Direct C–H transformation has attracted continuous interest since early 1970s
because it avoids prefunctionalization of starting materials and can maximize atom
economy.1 Numerous efforts have been devoted to the unactivated sp3(C)–H alkyl groups,
however, this process still remains a major challenge until now. In the previous studies,
several transition metal catalyzed processes, such as Pd,2 Cu,3 Ru,4 Rh,5 Co,6 Au,7 Ir,8
Fe,9 and some other metals,10 have been developed in the sp3(C)–H activation reactions.
 Corresponding author. Tel: +86-25-83592846; Fax: +86-25-83593153. Email address: hanjl@nju.edu.cn (J. L. Han);
yipan@nju.edu.cn (Y. Pan).

In addition, metal-free methodologies using TBHP, PhI(OAc)2, TBAI, I2, or
Lewis/Brønsted acids have also been employed for the cross dehydrogenative-coupling
reactions.11
Transition metal-catalyzed decarboxylative cross-coupling is of great interest in
synthetic organic chemistry, because this method uses cheap carboxylic acids to replace
expensive and often sensitive organometallic reagents.12 Several groups have recently
found that Pd or Cu could catalyze decarboxylative coupling of various aromatic, alkenyl,
and alkynyl carboxylic acids.13 Especially, Liu group reported a copper-catalyzed
decarboxylative coupling of vinylic carboxylic acids with simple alcohols, ethers, and
hydrocarbons with broad substrate scope and low catalyst loading.14 However, only one
report of direct decarboxylative C–H functionalization for C(sp2)–C(sp3) bond formation
catalyzed by iron was found until now.15
Cyclic ethers are important basic chemical feedstocks. Large number of natural
products, which have five- or six-membered cyclic ethers as the key structural features,
show a wide range of biological activities.16 Owing to their lack of reactivity under many
conditions, to construct cyclic ether derivatives in complex organic molecules is
sometiomes challenging. Therefore, many attentions have been attracted in developing
direct C–H transformation of cyclic ethers. Just recently, Lei et al. developed a novel
nickel–catalyzed oxidative arylation of the ortho-C(sp3)–H bond adjacent to the oxygen
atom of THF or 1,4-dioxane.17 Traditionally, alkenylation of cyclic ethers can be prepared
by methods such as direct addition of cyclic ethers to alkynes via TBHP as oxidation18 or
under microwave conditions (Scheme 1 a),19 however, these two methods suffered from
low stereoselectivities and low chemical yields. Therefore, a selective and efficient
method for alkenylation of cyclic ethers is highly desirable. To our delight, we found that
Fe(acac)3 can catalyze alkenylation of cyclic ethers via oxidation of C(sp3)–H bond
adjacent to an oxygen atom with good yields and highly stereoselectivities (Scheme 1 b).

Precious work:
O
O
O
O
TBHP or microwave
+
a)
O
This work:
O
O
COOH
O
Fe(acac)3
DTBP
+
b)
Scheme 1 Alkenylation of cyclic ethers.
With these motivations, we initiated our investigation by reacting cinnamic acid (0.3
mmol) with 1,4-dioxane (2 mL) in the presence Iron(II) chloride tetrahydrate (20
o
mol %) and 2.0 equiv of di-tert-butyl peroxide (DTBP) as oxidant at 120 C under
nitrogen, which provided the expected (E)-2-styryl-1,4-dioxane (5a) but in a mere yield
of 47% (entry 1, Table 1). The use of aqueous TBHP as oxidantat instead of DTBP,
resulted in lower yield (26%, entry 2). Furthermore, with the help of 1,10-phenanthroline
(30 mol %) as the ligand, the yields can be slightly improved to 56% (entry 3). The
Iron(III) acetylacetonate provided a superior yield (80%) compared to other Fe salts such
as FeCl3, Ferrocene, Fe2O3 and Fe3O4 tested (entries 4–8). The use of other oxidants such
as K2S2O8 and H2O2 (30% aqueous solution) did not afford better results (entries 9–10).
Decreasing loading of Fe(acac)3 to 10 mol %, increasing loading of DTBP to 5.0 equiv or
o
lowering the reaction temperature to 110 C, dramatically lower yields were obtained for
these reactions (52%, 65% and 72%, respectively, entries 11–13). Furthermore, no
reaction was observed when the iron catalyst or DTBP was not used in the reaction
(entries 14–15). Finally, the chemical yield will be reduced to 67% when only 1 mL of
1,4-dioxane was added (entry 16).
Table 1 Optimization of typical reaction conditions.a
O
O
COOH
Cat., Oxidation
120 oC, 24 h, N2
O
+
O
5a
2
1a
Entry
Catalyst (mol %)
Oxidation
Yield (%)b

1
2
FeCl2·4H2O (20)
FeCl2·4H2O (20)
FeCl2·4H2O (20)
FeCl3 (20)
DTBP
TBHP
DTBP
DTBP
DTBP
DTBP
DTBP
DTBP
K2S2O8
47
26
56c
Trace
63
3
4
5
Ferrocene (20)
Fe2O3 (20)
6
60
7
Fe3O4 (20)
70
8
Fe(acac)3 (20)
Fe(acac)3 (20)
Fe(acac)3 (20)
Fe(acac)3 (10)
Fe(acac)3 (20)
Fe(acac)3 (20)g
Fe(acac)3 (20)
-
80
9
N.R.
18
d
10
11
12
13
14
15
16
H2O2
DTBPe
DTBP
DTBP
-
52
65f
72
N.R.
N.R.
67h
DTBP
DTBP
Fe(acac)3 (20)
a
Catalytic conditions: Cinnamic acid (0.3 mmol), 1,4-dioxane (2 mL), iron catalyst (20
mol %), oxidant (2.0 equiv), 120 °C, 24 h, N2.
b Isolated yields based on cinnamic acid.
c Using 1,10-phenanthroline (30 mol %) as the ligand.
d 30% aqueous solution.
e 5 equiv.
f 12 h.
g 110 oC.
h Reaction done in 1 mL 1,4-dioxane.
Once the viability of the method was established, this approach was then applied to
alkenylation of 1,4-dioxane with a variety of cinnamic acids and the results of which are
shown in Table 2. The process tolerated a broad scope substrates with functional groups,
such as halide (5i, 5j and 5l), methyl (5b–5d), methoxyl (5e, 5f and 5h),
trifluoromethoxyl (5g), and trifluoromethyl (5k) functional groups. Different substitution
patterns on the aryl ring were tolerated. All of the ortho-, meta-, and para-substituted

cinnamic acids can react with 1,4-dioxane to give the corresponding products with good
chemical yields. Electronic effects of the cinnamic acids hardly influenced the reactivity,
giving the desired products in good yields. Furthermore, when heterocyclic acrylic acids,
such as thiophene, and furan were reacted, the corresponding products were also obtained
in good yields (5m–5n). In addition, the 1-naphthylacrylic acid gave the desired product
(5o) with 73% yield.
Table 2 Fe(acac)3-catalyzed alkenylation of 1,4-dioxane.a,b
Fe(acac)3 (20 mol %)
O
O
O
DTBP(2.0 eq)
120 oC, 24 h
COOH
O
+
Ar
Ar
1a-1o
5a-5o
2

O
O
O
O
O
O
5b, 77%
5a, 80%
5c, 79%
O
O
O
O
O
O
MeO
OMe
5f, 81%
5d, 72%
5e, 76%
MeO
O
O
O
MeO
O
O
F
O
F3CO
5h, 78%
5i, 74%
5g, 78%
O
O
O
O
O
O
F3C
Cl
F
5j, 73%
5k, 71%
5l, 76%
O
O
O
O
O
O
S
O
5m, 81%
5n, 79%
5o, 73%
a
Catalytic conditions: Cinnamic acid 1 (0.3 mmol), 1,4-dioxane (2 mL), Fe(acac)3 (20
mol %), DTBP (2.0 equiv), 120 °C, 24 h, N2.
b Isolated yields based on cinnamic acid.
After testing the coupling reaction of 1,4-dioxane with cinnamic acids, other target
ethers were investigated. As shown in Table 3, other cyclic ethers, tetrahydrofuran and
tetrahydropyran were found to be suitable coupling partners and the desired products
were formed in good yields. They also can tolerate a variety of functional groups. The
decarboxylative cross-coupling with tetrahydropyran showed relatively lower efficiency
than 1,4-dioxane or tetrahydrofuran.
Table 3 Fe(acac)3-catalyzed alkenylation of tetrahydrofuran and tetrahydropyran.a,b

Fe(acac)3 (20 mol %)
DTBP (2 eq)
COOH
n
n
Ar
+
O
120 oC, 24 h
O
Ar
6
3, 4
1
n = 1
n = 2
3
4
O
O
O
O
O
MeO
6c, 75%
6a, 79%
6b, 77%
6e, 73%
O
Cl
F
OMe
6d, 78%
6f, 74%
O
O
OMe
6h, 70%
6g, 65%
a
Catalytic conditions: Cinnamic acid (0.3 mmol), tetrahydrofuran or tetrahydropyran
(2.0 mL), Fe(acac)3 (20 mol%), DTBP (2 equiv), 120 °C, 24 h, N2.
b Isolated yields based on cinnamic acid.
Then, several control experiments were performed to probe the reaction mechanism
(Scheme 2). Addition of the radical scavenger 2,2,6,6-tetramethylpiperidine N-oxide
(TEMPO) (Scheme 2a) or azobisisobutyronitrile (AIBN) (Scheme 2b) can completely
inhibit the reaction, and almost no desired products were obtained at all. The results
indicate that the current transformation may proceed via a radical course.

O
Fe(acac)3 (20 mol %)
DTBP (2.0 equiv)
O
O
O
COOH
a)
b)
+
TEMPO (1.0 equiv)
120 oC, 24 h
Trace
O
Fe(acac)3 (20 mol %)
DTBP (2.0 equiv)
O
O
O
COOH
+
AIBN (1.0 equiv)
120 oC, 24 h
Trace
Scheme 2 Investigation of the reaction mechanism.
On the basis of the above results and literature reports,15,20 a plausible mechanism
containing a radical oxidative coupling process is illustrated in Scheme 3 for the reaction.
At the beginning, Fe-catalyzed cleavage of DTBP by Fe3+ in the presence of cinnamic
acid, gives a tert-butoxy radical A, intermediate B and one acac. Cyclic ether radical C is
generated by the reaction between tert-butoxy radical A and cyclic ether. Subsequently,
addition of cyclic ether radical C to the α-position of the double bond of intermediate B
gives intermediate D. Finally, D proceeds via elimination of carbon dioxide to generate
the product 5a and the catalyst Fe(II). The Fe(II) catalyst is then reformed via DTBP
oxidation.

COOH
Fe(acac)3
Ph
COOFe(acac)2
+
acac
O
+
+
Ph
O
B
O
A
O
COOFe(acac)2
O
Ph
B
+
O
O
O
C
A
O
O
O
Fe(acac)2
CO2
+
+
COOFe(acac)2
O
Ph
5a
D
DTBP
COOH
COOFe(acac)2
Fe(acac)2
Ph
B
Ar
Scheme 3 Possible mechanism.
In conclusion, we have described a direct alkenylation of cyclic ether via
decarboxylative C(sp2)–C(sp3) coupling process catalyzed by Fe(acac)3 and using TBHP
as oxidant. This catalytic system is suitable for the coupling reactions between a wide
range of cinnamic acid and cyclic ethers. Based on the control experiments, a radical
mechanism was proposed. Further studies to elucidate the mechanism and to expand the
synthetic scope of this reaction are currently underway in our laboratory.
Acknowledgments
We gratefully acknowledge the financial support from the National Natural Science
Foundation of China (No. 21102071) and the Fundamental Research Funds for the
Central Universities (No. 1107020522 and No. 1082020502).
References and notes
1. For selected reviews, see: (a) Chen, X.; Engle, K. M.; Wang, D. H.; Yu, J. Q. Angew.
Chem., Int. Ed. 2009, 48, 5094; (b) Daugulis, O.; Do, H. Q.; Shabashov, D. Acc.
Chem. Res. 2009, 42, 1074; (c) Li, C. J. Acc. Chem. Res. 2009, 42, 335; (d) Coperet,
C. Chem. Rev. 2010, 110, 656; (e) Werner, H. Angew. Chem., Int. Ed. 2010, 49, 4714;

(f) Sun, C. L.; Li, B. J.; Shi, Z. J. Chem. Rev. 2011, 111, 1293; (g) Campbell, A. N.;
Stahl, S. S. Acc. Chem. Res. 2012, 45, 851; (h) Kozhushkov, S. I.; Ackermann, L.
Chem. Sci. 2013, 4, 886.
2. (a) Guin, S.; Rout, S. K.; Banerjee, A.; Nandi, S.; Patel, B. K. Org. Lett. 2012, 14,
5294; (b) Rousseaux, S.; Liégault, B.; Fagnou, K. Chem. Sci. 2012, 3, 244; (c) Solé,
D.; Mariani, F.; Fernández, I.; Sierra, M. A. J. Org. Chem. 2012, 77, 10272; (d) Wasa,
M.; Chan, K. S. L.; Zhang, X. G.; He, J.; Miura, M.; Yu, J. Q. J. Am. Chem. Soc.
2012, 134, 18570; (e) Yin, Z. W.; Sun, P. P. J. Org. Chem. 2012, 77, 11339; (f) Saget,
T.; Perez, D.; Cramer, N. Org. Lett. 2013, 15, 1354; (g) Zhang, S. Y.; He, G.; Nack, W.
A.; Zhao, Y. S.; Li, Q.; Chen, G. J. Am. Chem. Soc. 2013, 135, 2124.
3. (a) Li, Z. P.; Li, C. J. J. Am. Chem. Soc. 2004, 126, 11810; (b) Xie, J.; Huang, Z. Z.
Angew. Chem., Int. Ed. 2010, 49, 10181; (c) Yang, F.; Li, J.; Xie, J.; Huang, Z. Z.
Org. Lett. 2010, 12, 5214; (d) Rout, S. K.; Guin, S.; Ghara, K. K.; Banerjee, A.; Patel,
B. K. Org. Lett. 2012, 14, 3982; (e) Xia, R.; Niu, H. Y.; Qu, G. R.; Guo, H. M. Org.
Lett. 2012, 14, 5546.
4. (a) Pastine, S. J.; Gribkov, D. V.; Sames, D. J. Am. Chem. Soc. 2006, 128, 14220; (b)
Rankin, M. A.; Schatte, G.; McDonald, R.; Stradiotto, M. J. Am. Chem. Soc. 2007,
129, 6390; (c) Deng, G.; Zhao, L.; Li, C. J. Angew. Chem., Int. Ed. 2008, 47, 6278; (d)
Wang, M. Z.; Zhou, C. Y.; Wong, M. K.; Che, C. M. Chem. Eur. J. 2010, 16, 5723.
5. (a) Shi, L.; Tu, Y. Q.; Wang, M.; Zhang, F. M.; Fan, C. A.; Zhao, Y. M.; Xia, W. J. J.
Am. Chem. Soc. 2005, 127, 10836; (b) Jo, E. A.; Lee, J. H.; Jun, C. H. Chem.
Commun. 2008, 5779; (c) Rakshit, S.; Patureau, F. W.; Glorius, F. J. Am. Chem. Soc.
2010, 132, 9585; (d) Kuninobu, Y.; Nakahara, T.; Takeshima, H.; Takai, K. Org. Lett.
2013, 15, 426.
6. (a) Harden, J. D.; Ruppel, J. V.; Gao, G. Y.; Zhang, X. P. Chem. Commun. 2007, 4644;
(b) Hung-Low, F.; Krogman, J. P.; Tye, J. W.; Bradley, C. A. Chem. Commun. 2012,
48, 368; (c) Lu, H. J.; Hu, Y.; Jiang, H. L.; Wojtas, L.; Zhang, X. P. Org. Lett. 2012,
14, 5158.
7. (a) Horino, Y.; Yamamoto, T.; Ueda, K.; Kuroda, S.; Toste, F. D. J. Am. Chem. Soc.
2009, 131, 2809; (b) Bhunia, S.; Ghorpade, S.; Huple, D. B.; Liu, R. S. Angew.
Chem., Int. Ed. 2012, 51, 2939.

8. (a) DeBoef, B.; Pastine, S. J.; Sames, D. J. Am. Chem. Soc. 2004, 126, 6556; (b) Pan,
S.; Endo, K.; Shibata, T. Org. Lett. 2011, 13, 4692; (c) Obora, Y.; Ogawa, S.;
Yamamoto, N. J. Org. Chem. 2012, 77, 9429.
9. (a) Wang, Z.; Zhang, Y. M.; Fu, H.; Jiang, Y. Y.; Zhao, Y. F. Org. Lett. 2008, 10, 1863;
(b) Zhang, S. Y.; Tu, Y. Q.; Fan, C. A.; Zhang, F. M.; Shi, L. Angew. Chem. 2009, 121,
8917; (c) Pan, S. G.; Liu, J. H.; Li, H. R.; Wang, Z. Y.; Guo, X. W.; Li, Z. P. Org. Lett.
2010, 12, 1932; (d) Bloom, S.; Pitts, C. R.; Woltornist, R.; Griswold, A.; Holl, M. G.;
Lectka, T. Org. Lett. 2013, 15, 1722; (e) Yoshikai, N.; Mieczkowski, A.; Matsumoto,
A.; Ilies, L.; Nakamura, E. J. Am. Chem. Soc. 2010, 132, 5568; (f) Qian, B.; Xie, P.;
Xie, Y.; Huang, H. Org. Lett. 2011, 13, 2580.
10. (a) Vadola, P. A.; Sames, D. J. Am. Chem. Soc. 2009, 131, 16525; (b) Liu, X.; Sun, B.;
Xie, Z.; Qin, X.; Liu, L.; Lou, H. J. Org. Chem. 2013, 78, 3104–3112.
11. (a) Chen, L.; Shi, E.; Liu, Z.; Chen, S.; Wei, W.; Li, H.; Xu, K.; Wan, X. Chem. Eur.
J. 2011, 17, 4085; (b) He, T.; Yu, L.; Zhang, L.; Wang, L.; Wang, M. Org. Lett. 2011,
13, 5016; (c) Huang, J.; Li, L. T.; Li, H. Y.; Husan, E.; Wang, P.; Wang, B. Chem.
Commun. 2012, 48, 10204; (d) Li, L. T.; Li, H. Y.; Xing, L. J.; Wen, L. J.; Wang, P.;
Wang, B. Org. Biomol. Chem. 2012, 10, 9519; (e) Mai, W. P.; Wang, H. H.; Li, Z. C.;
Yuan, J. W.; Xiao, Y. M.; Yang, L. R.; Mao, P.; Qu, L. B. Chem. Commun. 2012, 48,
10117; (f) Feng, J.; Liang, S.; Chen, S. Y.; Zhang, J.; Fu, S. S.; Yu, X. Q. Adv. Synth.
Catal. 2012, 354, 1287; (g) Shi, E.; Shao, Y.; Chen, S.; Hu, H.; Liu, Z.; Zhang, J.;
Wan, X. Org. Lett. 2012, 14, 3384; (h) Wang, F. F.; Luo, C. P.; Wang, Y.; Deng, G.;
Yang, L. Org. Biomol. Chem. 2012, 10, 8605; (i) Zhu, Y. P.; Jia, F. C.; Liu, M. C.; Wu,
L. M.; Cai, Q.; Gao, Y.; Wu, A. X. Org. Lett. 2012, 14, 5378; (j) Zhu, Y. P.; Liu, M.
C.; Jia, F. C.; Yuan, J. J.; Gao, Q. H.; Lian, M.; Wu, A. X. Org. Lett. 2012, 14, 3392.
12. (a) Gooβen, L. J.; Rodriguez, N.; Gooβen, K. Angew. Chem. Int. Ed. 2008, 47, 3100;
(b) Dzik, W. I.; Lange, P. P.; Gooβen, L. J. Chem. Sci. 2012, 3, 2671.
13. (a) Forgione, P.; Brochu, M. C.; StOnge, M.; Thesen, K. H.; Bailey, M. D.; Bilodeau,
F. J. Am. Chem. Soc. 2006, 128, 11350; (b) Gooßen, L. J.; Rudolphi, F.; Oppel, C.;
Rodríguez, N. Angew. Chem., Int. Ed. 2008, 47, 3043; (c) Kim, H.; Lee, P. H. Adv.
Synth. Catal. 2009, 351, 2827; (d) Wang, Z.; Ding, Q.; He, X.; Wu, J. Org. Biomol.
Chem. 2009, 7, 863; (e) Zhang, F.; Greaney, M. F. Angew. Chem., Int. Ed. 2010, 49,

2768.
14. Cui, Z.; Shang, X. J.; Shao, X. F.; Liu, Z. Q. Chem. Sci. 2012, 3, 2853.
15. Yang, H.; Yan, H.; Sun, P.; Zhu, Y.; Lu, L.; Liu, D.; Rong, G.; Mao, J. Green Chem.
2013, 15, 976.
16. (a) Malmstrøm, J.; Christophersen, C.; Barrero, A. F.; Oltra, J. E.; Justicia, J.;
Rosales, A. J. Nat. Prod. 2002, 65, 364; (b) Miles, S. M.; Marsden, S. P.;
Leatherbarrow, R. J.; Coates, W. J. J. Org. Chem. 2004, 69, 6874; (c) Kumar, V.;
Shaw, A. K. J. Org. Chem. 2008, 73, 7526; (d) Ghosal, P.; Sharma, D.; Kumar, B.;
Meena, S.; Sinha, S.; Shaw, A. K. Org. Biomol. Chem. 2011, 9, 7372.
17. Liu, D.; Liu, C.; Li, H.; Lei, A. Angew. Chem., Int. Ed. 2013, 52, 4453.
18. Miura, K.; Fujisawa, N.; Saito, H.; Wang, D.; Hosomi, A. Org. Lett. 2001, 3, 2591.
19. Zhang, Y.; Li, C. J. Tetrahedron Lett. 2004, 45, 7581.
20. Liu, Z. Q.; Sun, L.; Wang, J. G.; Han, J.; Zhao, Y. K.; Zhou, B. Org. Lett. 2009, 11,
1437.

Graphical Abstract (for review)
Iron-catalyzed alkenylation of cyclic ethers via decarboxylative sp3(C)-sp2(C)
coupling
Jincan Zhao, Wei Zhou, Jianlin Han,* Guigen Li, Yi Pan*
Fe(acac)3 (20 mol %)
X
X
DTBP (2.0 eq)
120 oC, 24 h
COOH
+
O
Ar
Ar
O
X=C, O-C,C-C
An efficient Fe(acac)3-catalyzed decarboxylative C(sp2)-C(sp3) coupling reactions
has been reported, in which cyclic ethers are selectively transformed into corresponding
alkenylation products with good chemical yields and excellent stereoselectivities.