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Synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives via direct decarboxylative coupling of α,β-unsaturated carboxylic acids with benzyl boronic acid pinacol ester
Tetrahedron Letters 58 (2017) 2255–2257
Contents lists available at ScienceDirect
Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet
Synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives via direct decarboxylative coupling of a,b-unsaturated carboxylic acids with benzyl boronic acid pinacol ester Mingxiang Zhu a, Zhenjiang Qiu a, Yun Zhang a, Hongli Du a, Jingya Li b,c, Dapeng Zou a,b,⇑, Yangjie Wu a,⇑, Yusheng Wu b,d,⇑ a
The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450052, PR China Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, PR China c Tetranov Biopharm, LLC., No. 75 Daxue Road, Zhengzhou 450052, PR China d Tetranov International, Inc., 100 Jersey Avenue, Suite A340, New Brunswick, NJ 08901, USA b
a r t i c l e
i n f o
Article history: Received 15 March 2017 Revised 15 April 2017 Accepted 24 April 2017 Available online 26 April 2017
a b s t r a c t The first copper-catalyzed cross-coupling reaction between benzyl boronic acid pinacol ester and a,bunsaturated carboxylic acids was described. The ready availability of the starting materials and excellent E selectivity make this protocol a safe and operationally convenient strategy for the efficient synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives. Ó 2017 Published by Elsevier Ltd.
Keywords: Decarboxylative cross-coupling Cinnamic acid derivatives Benzyl boronic acid pinacol ester
Introduction Allylic derivatives are one of the most widely available building blocks for modern organic synthesis and drug discovery research.1 Active allylic substrates bearing functional groups are commonly used in allylic substitution reactions and evolved as powerful tools for organic synthesis.2 Various synthetic methods were developed for the synthesis of allylic compounds. In general, allylic derivatives have been obtained by the following methods: (a) allylic substitution reactions of allylic ethers with Grignard reagents.3 (b) Allyl-aryl coupling reaction of allylic carbonates with arylboronic acids.4 (c) Cross-dehydrogenative-coupling reaction of toluol with cinnamylic acids.5 Although these well-developed methods usually give the target products in moderate to good yields, the discovery of new methods or new catalytic system for the synthesis of these compounds is still a demand. Aryl and alkyl boronic acids are amongst the most widely available building blocks for modern organic synthesis. Among them, benzyl boronic acid pinacol esters are regarded as a kind of important organic boron reagents.6 In 2013, Sueki and Kuninobu reported the first Cu-catalyzed cross⇑ Corresponding authors at: Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, PR China (D. Zou and Y. Wu). E-mail addresses: [email protected] (D. Zou), [email protected] (Y. Wu), yusheng. [email protected] (Y. Wu). http://dx.doi.org/10.1016/j.tetlet.2017.04.084 0040-4039/Ó 2017 Published by Elsevier Ltd.
coupling reaction between benzyl boronic acid pinacol ester with amines to get the corresponding secondary and tertiary amines.7 Suzuki and coworkers reported the Pd-catalyzed cross-coupling reaction between benzyl- and cinnamyl boronic acid pinacol esters with methyl iodide at the same year.8 However, benzyl boronic acid pinacol esters in these reactions are considered to be more challenging due to its lack of stability under the reaction conditions.7 Recently, the decarboxylative cross-coupling reaction has attracted much more attentions and it opens a new avenue for the formation of carbon-carbon and carbon-heteroatom bonds.9 Carboxylic acids are always used as alternatives to halides and organometal reagents in decarboxylative synthetic strategies. Advanced progresses in decarboxylative bond formation (e.g. C– C, C–N) have been reported by the groups of Goossen,10 Fu11 and others.12 As to the decarboxylative cross-coupling reaction of cinnamic acids and organoboronic acids, only limited examples were reported.13,14 In 2010, Miura and co-workers reported the Pd-catalyzed decarboxylative coupling reaction between cinnamic acids and arylboronic acids in good to excellent yields.14 Herein, we report the first copper-catalyzed cross-coupling reaction between benzyl boronic acid pinacol ester and a,b-unsaturated carboxylic acids to get the corresponding (E)-prop-1-ene-1,3-diyldibenzene derivatives in moderate to good yields.
2256
M. Zhu et al. / Tetrahedron Letters 58 (2017) 2255–2257
Results and discussion Initially, cinnamic acid and benzyl boronic acid pinacol ester were chosen as model compounds to optimize the reaction conditions. After screening various catalytic conditions, an available process to get desired product by copper catalysis conditions was found. A smooth reaction can be achieved by Cu(OAc)2 (50 mol%) and Ag2CO3 (1.5 eq) as catalyst and oxidant in DMSO (0.1 M) at 120 °C under argon atmosphere for 12 h to afford a 38% yield of the desired product. Various silver salts (AgOAc, AgF, AgNO3, AgTFA, Ag2O and Ag2CO3) were screened (Table 1, entries 1–6) and Ag2CO3 could give a better result with 38% yield. The copper salt CuO (Table 1, entry 10) was indispensable to promote the cross-coupling reaction. The yields of 3a were lower when using other copper salts (Table 1, entries 7–16). Finally, the reaction time
Table 1 Decarboxylative coupling of cinnamic acid with benzyl boronic acid pinacol ester: variation of reaction conditions.a
Entry
Catalyst
Oxidant
Solvent
Yield (%)b
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17c 18d 19e 20f 21g 22h 23i 24j 25 26 27 28 29 30
Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OTf)2 CuCO3 CuSO45H2O CuO Cu(OH)2 CuCl2 Cu2O CuCl CuI Cu CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO
AgOAc AgF AgNO3 AgTFA Ag2CO3 Ag2O Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3
DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMF DMA DME t-AmylOH Dioxane Toluene
20 19 Trace Trace 38 37 26 36 41 63 31 34 40 31 25 32 40 45 Trace 35 45 63 40 45 33 Trace Trace Trace Trace Trace
a All reactions were performed with 0.2 mmol of cinnamic acid, 2 equiv of benzyl boronic acid pinacol ester, 40 mol% of catalyst, 1.5 equiv of oxidant, 2 mL of solvent at 120 °C for 12 h under Ar. b Yields were determined by GC–MS using diamyl phthalate as internal standard. c The reaction was performed for 4 h under Ar. d The reaction was performed for 8 h under Ar. e The reaction was performed at 60 °C under Ar. f The reaction was performed at 100 °C under Ar. g The reaction was performed at 110 °C under Ar. h The reaction was performed at 130 °C under Ar. i The reaction was performed under air. j The reaction was performed with 1.5 equiv of benzyl boronic acid pinacol ester.
(Table 1, entries 10, 17 and 18) and temperature (Table 1, entries 19–22) were tested at last. The best yield was obtained under 120 °C for 12 h. The effect of gaseous environment (Table 1, entry 23) was also studied, and a better yield was get when the reaction was performed under argon atmosphere. Various solvents (DMF, DMA, DME, t-AmylOH, dioxane and toluene) (Table 1, entries 25– 30) were also investigated and DMSO was used as a better solvent with 63% yield. This reaction could only be obtained in a moderate yield due to the esterification of cinnamic acid as well as protonation reaction and the side products including cinnamic esters and styrene were observed by GC–MS. Finally, the optimum reaction condition was obtained as follows: CuO (40 mol%) and Ag2CO3 (1.5 eq) as catalyst and oxidant, in DMSO (0.1 M) at 120 °C under argon atmosphere for 12 h. After the optimized reaction conditions in hand, various cinnamic acids including electron-donating and electron-withdrawing substituents were investigated. Halogenated substrates such as F, Cl, Br were tested and fluorine atom substituted substrate was found to give higher isolated yield (Table 2, entries 2–4). It is worth noting that when Cl group located at meta-position, the yield increased to some degree compared with those at orthoand papa-position. Next, substrates with electron donating groups including methyl- (Table 2, entries 8–11) and methoxy- (Table 2, entries 12–16) groups were tested. Similar to that halogenated substrates, the desired meta-position products with electron donating groups (methyl- and methoxy-) were obtained in higher yields (Table 2, entries 9 and 12). Most of the cinnamic acids with
Table 2 Decarboxylative cross-coupling reactions between several a,b-unsaturated carboxylic acids and benzyl boronic acid pinacol ester.a
Entry
Substrate
Product
Yield (%)b
1
55
2
47
3
41
4
36
5
32
6
50
7
38
8
38
9
58
10
54
M. Zhu et al. / Tetrahedron Letters 58 (2017) 2255–2257 Table 2 (continued) Entry
Substrate
Product
b
Yield (%)
11
Trace
12
60
13
31
14
46
15
22
16
50
17
41
2257
the target product was obtained in moderate yield (Table 2, entry 23). However, the corresponding product was detected with only trace amount by GC–MS when the cinnamic acid containing nitro-substituent group was used. (Table 2, entry 24). Conclusion In conclusion, an efficient and mild synthetic procedure for the synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives starting from a,b-unsaturated carboxylic acids and benzyl boronic acid pinacol ester was described. Our discovered method can easily construct Csp2-Csp3 bond with two nucleophiles by traditional metal catalyzed oxidative cross-coupling reactions. A wide range of substrates could be used in this system and the desired (E)prop-1-ene-1,3-diyldibenzene derivatives will be very useful building blocks in material science and drug discovery. Acknowledgments
18
38
19
26
20
27
21
62
22
43
23
43
24
Trace
We are grateful to the National Natural Science Foundation of China (21172200) and Research Program of Fundamental and Advanced Technology of Henan Province (122300413203) for financial support. References
a All reactions were performed with 0.2 mmol of substrate, 2 equiv of benzyl boronic acid pinacol ester, 40 mol% of CuO, 1.5 equiv of Ag2CO3, 2 mL of DMSO at 120 °C for 12 h under Ar atmosphere. b Isolated yields.
substituents at ortho-position gave lower yields than those at paraand meta-position, demonstrating the steric hindrance likely has a negative effect on the coupling reaction (Table 2, entries 12, 14 vs 13, and 11). Next, the substrates with electron withdrawing groups such as trifluoro- (Table 2, entries 18–20) and cyano- (Table 2, entries 21 and 22) were tested. To our delight, a good yield was obtained when m-cyano-cinnamic acid was used (Table 2, entry 21). When (E)-3-(thiophen-2-yl) acrylic acid was used as substrate,
1. (a) Weaver JD, RecioIII A, Grenning AJ, Tunge JA. Chem Rev. 2011;111:1846; (b) Lu Z, Ma S. Angew Chem Int Ed. 2008;47:258; (c) Han F. Chem Soc Rev. 2013;42:5270. 2. (a) Chen F, Qin C, Cui Y, Jiao N. Angew Chem Int Ed. 2011;50:11487; (b) Moorthy JN, Senapati K, Singhal N. Tetrahedron Lett. 2009;50:2493; (c) Qiu J, Zhang R. Org Biomol Chem. 2013;11:6008; (d) Gieshoff TN, Villa M, Welther A, et al. Green Chem. 2015;17:1408. 3. Qi L, Ma E, Jia F, Li Z. Tetrahedron Lett. 2016;57:2211. 4. Xu J, Zhai X, Wu X, Zhang YJ. Tetrahedron. 2015;71:1712. 5. Yang H, Yan H, Sun P, et al. Green Chem. 2013;15:976. 6. Crudden CM, Glasspoole BW, Lata CJ. Chem Commun. 2009;44:6704. 7. Sueki S, Kuninobu Y. Org Lett. 2013;15:1544. 8. Koyama H, Zhang Z, Ijuin R, et al. RSC Adv. 2013;3:9391. 9. Borah AJ, Yan G. Org Biomol Chem. 2015;13:8094. 10. (a) Gooßen LJ, Deng G, Levy LM. Science. 2006;313:662; (b) Gooßen LJ, Rodríguez N, Lange PP, Linder C. Angew Chem Int Ed. 2010;49:1111. Angew Chem 2010, 122, 1129; (c) Fromm A, van Wüllen C, Hackenberger D, Gooßen LJ. J Am Chem Soc. 2014;136:10007; (d) Tang J, Biafora A, Gooßen LJ. Angew Chem Int Ed. 2015;54:13130. Angew Chem 2015, 127, 13324. 11. (a) Shang R, Fu Y, Wang Y, Xu Q, Yu HZ, Liu L. Angew Chem Int Ed. 2009;48:9350; (b) Zhang SL, Fu Y, Shang R, Guo QX, Liu L. J Am Chem Soc. 2010;132:638; (c) Shang R, Ji DS, Chu L, Fu Y, Liu L. Angew Chem Int Ed. 2011;50:4470. 12. (a) Ma JJ, Yi WB, Lu GP, Cai C. Adv Synth Catal. 2015;357:3447; (b) Zhang L, Hang Z, Liu ZQ. Angew Chem Int Ed. 2016;55:236; (c) Zhang Y, Du H, Zhu M, et al. Tetrahedron Lett. 2017;58:880; (d) Yang H, Sun P, Zhu Y, et al. Chem Commun. 2012;48:7847. 13. Bazin MA, Kihel LE, Lancelot JC, Rault S. Tetrahedron Lett. 2007;48:4347. 14. Yamashita M, Hirano K, Satoh T, Miura M. Chem Lett. 2010;39:68.
Contents lists available at ScienceDirect
Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet
Synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives via direct decarboxylative coupling of a,b-unsaturated carboxylic acids with benzyl boronic acid pinacol ester Mingxiang Zhu a, Zhenjiang Qiu a, Yun Zhang a, Hongli Du a, Jingya Li b,c, Dapeng Zou a,b,⇑, Yangjie Wu a,⇑, Yusheng Wu b,d,⇑ a
The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450052, PR China Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, PR China c Tetranov Biopharm, LLC., No. 75 Daxue Road, Zhengzhou 450052, PR China d Tetranov International, Inc., 100 Jersey Avenue, Suite A340, New Brunswick, NJ 08901, USA b
a r t i c l e
i n f o
Article history: Received 15 March 2017 Revised 15 April 2017 Accepted 24 April 2017 Available online 26 April 2017
a b s t r a c t The first copper-catalyzed cross-coupling reaction between benzyl boronic acid pinacol ester and a,bunsaturated carboxylic acids was described. The ready availability of the starting materials and excellent E selectivity make this protocol a safe and operationally convenient strategy for the efficient synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives. Ó 2017 Published by Elsevier Ltd.
Keywords: Decarboxylative cross-coupling Cinnamic acid derivatives Benzyl boronic acid pinacol ester
Introduction Allylic derivatives are one of the most widely available building blocks for modern organic synthesis and drug discovery research.1 Active allylic substrates bearing functional groups are commonly used in allylic substitution reactions and evolved as powerful tools for organic synthesis.2 Various synthetic methods were developed for the synthesis of allylic compounds. In general, allylic derivatives have been obtained by the following methods: (a) allylic substitution reactions of allylic ethers with Grignard reagents.3 (b) Allyl-aryl coupling reaction of allylic carbonates with arylboronic acids.4 (c) Cross-dehydrogenative-coupling reaction of toluol with cinnamylic acids.5 Although these well-developed methods usually give the target products in moderate to good yields, the discovery of new methods or new catalytic system for the synthesis of these compounds is still a demand. Aryl and alkyl boronic acids are amongst the most widely available building blocks for modern organic synthesis. Among them, benzyl boronic acid pinacol esters are regarded as a kind of important organic boron reagents.6 In 2013, Sueki and Kuninobu reported the first Cu-catalyzed cross⇑ Corresponding authors at: Collaborative Innovation Center of New Drug Research and Safety Evaluation, Henan Province, PR China (D. Zou and Y. Wu). E-mail addresses: [email protected] (D. Zou), [email protected] (Y. Wu), yusheng. [email protected] (Y. Wu). http://dx.doi.org/10.1016/j.tetlet.2017.04.084 0040-4039/Ó 2017 Published by Elsevier Ltd.
coupling reaction between benzyl boronic acid pinacol ester with amines to get the corresponding secondary and tertiary amines.7 Suzuki and coworkers reported the Pd-catalyzed cross-coupling reaction between benzyl- and cinnamyl boronic acid pinacol esters with methyl iodide at the same year.8 However, benzyl boronic acid pinacol esters in these reactions are considered to be more challenging due to its lack of stability under the reaction conditions.7 Recently, the decarboxylative cross-coupling reaction has attracted much more attentions and it opens a new avenue for the formation of carbon-carbon and carbon-heteroatom bonds.9 Carboxylic acids are always used as alternatives to halides and organometal reagents in decarboxylative synthetic strategies. Advanced progresses in decarboxylative bond formation (e.g. C– C, C–N) have been reported by the groups of Goossen,10 Fu11 and others.12 As to the decarboxylative cross-coupling reaction of cinnamic acids and organoboronic acids, only limited examples were reported.13,14 In 2010, Miura and co-workers reported the Pd-catalyzed decarboxylative coupling reaction between cinnamic acids and arylboronic acids in good to excellent yields.14 Herein, we report the first copper-catalyzed cross-coupling reaction between benzyl boronic acid pinacol ester and a,b-unsaturated carboxylic acids to get the corresponding (E)-prop-1-ene-1,3-diyldibenzene derivatives in moderate to good yields.
2256
M. Zhu et al. / Tetrahedron Letters 58 (2017) 2255–2257
Results and discussion Initially, cinnamic acid and benzyl boronic acid pinacol ester were chosen as model compounds to optimize the reaction conditions. After screening various catalytic conditions, an available process to get desired product by copper catalysis conditions was found. A smooth reaction can be achieved by Cu(OAc)2 (50 mol%) and Ag2CO3 (1.5 eq) as catalyst and oxidant in DMSO (0.1 M) at 120 °C under argon atmosphere for 12 h to afford a 38% yield of the desired product. Various silver salts (AgOAc, AgF, AgNO3, AgTFA, Ag2O and Ag2CO3) were screened (Table 1, entries 1–6) and Ag2CO3 could give a better result with 38% yield. The copper salt CuO (Table 1, entry 10) was indispensable to promote the cross-coupling reaction. The yields of 3a were lower when using other copper salts (Table 1, entries 7–16). Finally, the reaction time
Table 1 Decarboxylative coupling of cinnamic acid with benzyl boronic acid pinacol ester: variation of reaction conditions.a
Entry
Catalyst
Oxidant
Solvent
Yield (%)b
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17c 18d 19e 20f 21g 22h 23i 24j 25 26 27 28 29 30
Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OAc)2 Cu(OTf)2 CuCO3 CuSO45H2O CuO Cu(OH)2 CuCl2 Cu2O CuCl CuI Cu CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO CuO
AgOAc AgF AgNO3 AgTFA Ag2CO3 Ag2O Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3 Ag2CO3
DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMSO DMF DMA DME t-AmylOH Dioxane Toluene
20 19 Trace Trace 38 37 26 36 41 63 31 34 40 31 25 32 40 45 Trace 35 45 63 40 45 33 Trace Trace Trace Trace Trace
a All reactions were performed with 0.2 mmol of cinnamic acid, 2 equiv of benzyl boronic acid pinacol ester, 40 mol% of catalyst, 1.5 equiv of oxidant, 2 mL of solvent at 120 °C for 12 h under Ar. b Yields were determined by GC–MS using diamyl phthalate as internal standard. c The reaction was performed for 4 h under Ar. d The reaction was performed for 8 h under Ar. e The reaction was performed at 60 °C under Ar. f The reaction was performed at 100 °C under Ar. g The reaction was performed at 110 °C under Ar. h The reaction was performed at 130 °C under Ar. i The reaction was performed under air. j The reaction was performed with 1.5 equiv of benzyl boronic acid pinacol ester.
(Table 1, entries 10, 17 and 18) and temperature (Table 1, entries 19–22) were tested at last. The best yield was obtained under 120 °C for 12 h. The effect of gaseous environment (Table 1, entry 23) was also studied, and a better yield was get when the reaction was performed under argon atmosphere. Various solvents (DMF, DMA, DME, t-AmylOH, dioxane and toluene) (Table 1, entries 25– 30) were also investigated and DMSO was used as a better solvent with 63% yield. This reaction could only be obtained in a moderate yield due to the esterification of cinnamic acid as well as protonation reaction and the side products including cinnamic esters and styrene were observed by GC–MS. Finally, the optimum reaction condition was obtained as follows: CuO (40 mol%) and Ag2CO3 (1.5 eq) as catalyst and oxidant, in DMSO (0.1 M) at 120 °C under argon atmosphere for 12 h. After the optimized reaction conditions in hand, various cinnamic acids including electron-donating and electron-withdrawing substituents were investigated. Halogenated substrates such as F, Cl, Br were tested and fluorine atom substituted substrate was found to give higher isolated yield (Table 2, entries 2–4). It is worth noting that when Cl group located at meta-position, the yield increased to some degree compared with those at orthoand papa-position. Next, substrates with electron donating groups including methyl- (Table 2, entries 8–11) and methoxy- (Table 2, entries 12–16) groups were tested. Similar to that halogenated substrates, the desired meta-position products with electron donating groups (methyl- and methoxy-) were obtained in higher yields (Table 2, entries 9 and 12). Most of the cinnamic acids with
Table 2 Decarboxylative cross-coupling reactions between several a,b-unsaturated carboxylic acids and benzyl boronic acid pinacol ester.a
Entry
Substrate
Product
Yield (%)b
1
55
2
47
3
41
4
36
5
32
6
50
7
38
8
38
9
58
10
54
M. Zhu et al. / Tetrahedron Letters 58 (2017) 2255–2257 Table 2 (continued) Entry
Substrate
Product
b
Yield (%)
11
Trace
12
60
13
31
14
46
15
22
16
50
17
41
2257
the target product was obtained in moderate yield (Table 2, entry 23). However, the corresponding product was detected with only trace amount by GC–MS when the cinnamic acid containing nitro-substituent group was used. (Table 2, entry 24). Conclusion In conclusion, an efficient and mild synthetic procedure for the synthesis of (E)-prop-1-ene-1,3-diyldibenzene derivatives starting from a,b-unsaturated carboxylic acids and benzyl boronic acid pinacol ester was described. Our discovered method can easily construct Csp2-Csp3 bond with two nucleophiles by traditional metal catalyzed oxidative cross-coupling reactions. A wide range of substrates could be used in this system and the desired (E)prop-1-ene-1,3-diyldibenzene derivatives will be very useful building blocks in material science and drug discovery. Acknowledgments
18
38
19
26
20
27
21
62
22
43
23
43
24
Trace
We are grateful to the National Natural Science Foundation of China (21172200) and Research Program of Fundamental and Advanced Technology of Henan Province (122300413203) for financial support. References
a All reactions were performed with 0.2 mmol of substrate, 2 equiv of benzyl boronic acid pinacol ester, 40 mol% of CuO, 1.5 equiv of Ag2CO3, 2 mL of DMSO at 120 °C for 12 h under Ar atmosphere. b Isolated yields.
substituents at ortho-position gave lower yields than those at paraand meta-position, demonstrating the steric hindrance likely has a negative effect on the coupling reaction (Table 2, entries 12, 14 vs 13, and 11). Next, the substrates with electron withdrawing groups such as trifluoro- (Table 2, entries 18–20) and cyano- (Table 2, entries 21 and 22) were tested. To our delight, a good yield was obtained when m-cyano-cinnamic acid was used (Table 2, entry 21). When (E)-3-(thiophen-2-yl) acrylic acid was used as substrate,
1. (a) Weaver JD, RecioIII A, Grenning AJ, Tunge JA. Chem Rev. 2011;111:1846; (b) Lu Z, Ma S. Angew Chem Int Ed. 2008;47:258; (c) Han F. Chem Soc Rev. 2013;42:5270. 2. (a) Chen F, Qin C, Cui Y, Jiao N. Angew Chem Int Ed. 2011;50:11487; (b) Moorthy JN, Senapati K, Singhal N. Tetrahedron Lett. 2009;50:2493; (c) Qiu J, Zhang R. Org Biomol Chem. 2013;11:6008; (d) Gieshoff TN, Villa M, Welther A, et al. Green Chem. 2015;17:1408. 3. Qi L, Ma E, Jia F, Li Z. Tetrahedron Lett. 2016;57:2211. 4. Xu J, Zhai X, Wu X, Zhang YJ. Tetrahedron. 2015;71:1712. 5. Yang H, Yan H, Sun P, et al. Green Chem. 2013;15:976. 6. Crudden CM, Glasspoole BW, Lata CJ. Chem Commun. 2009;44:6704. 7. Sueki S, Kuninobu Y. Org Lett. 2013;15:1544. 8. Koyama H, Zhang Z, Ijuin R, et al. RSC Adv. 2013;3:9391. 9. Borah AJ, Yan G. Org Biomol Chem. 2015;13:8094. 10. (a) Gooßen LJ, Deng G, Levy LM. Science. 2006;313:662; (b) Gooßen LJ, Rodríguez N, Lange PP, Linder C. Angew Chem Int Ed. 2010;49:1111. Angew Chem 2010, 122, 1129; (c) Fromm A, van Wüllen C, Hackenberger D, Gooßen LJ. J Am Chem Soc. 2014;136:10007; (d) Tang J, Biafora A, Gooßen LJ. Angew Chem Int Ed. 2015;54:13130. Angew Chem 2015, 127, 13324. 11. (a) Shang R, Fu Y, Wang Y, Xu Q, Yu HZ, Liu L. Angew Chem Int Ed. 2009;48:9350; (b) Zhang SL, Fu Y, Shang R, Guo QX, Liu L. J Am Chem Soc. 2010;132:638; (c) Shang R, Ji DS, Chu L, Fu Y, Liu L. Angew Chem Int Ed. 2011;50:4470. 12. (a) Ma JJ, Yi WB, Lu GP, Cai C. Adv Synth Catal. 2015;357:3447; (b) Zhang L, Hang Z, Liu ZQ. Angew Chem Int Ed. 2016;55:236; (c) Zhang Y, Du H, Zhu M, et al. Tetrahedron Lett. 2017;58:880; (d) Yang H, Sun P, Zhu Y, et al. Chem Commun. 2012;48:7847. 13. Bazin MA, Kihel LE, Lancelot JC, Rault S. Tetrahedron Lett. 2007;48:4347. 14. Yamashita M, Hirano K, Satoh T, Miura M. Chem Lett. 2010;39:68.