A quick and low E-factor waste valorization procedure for CuCl-catalyzed oxidative self-coupling of (hetero)arylboronic acid in pomegranate peel ash extract

Figures & data

Scheme 1. Brief overview on self-coupling reactions of organoboron compounds.

Table 1. Comparison of self-coupling reactions of (H)ABAs using transition metal-based catalysts.

Entry	Catalyst	Conditions	Yield (%)	E-factor	Remarks
1	Ti0.97Pd0.03O1.97 (20)	1.5 eq. K2CO3, 1.5 eq. K2S2O8, 110 °C, Acetone-H2O (3:1), 1.5–4 h	80–>99%	∼56.9	Precious Pd-catalyst, heating, 1.5 eq. each of base and oxidant, high temperature and volatile solvents are required.
2	[{Pd(μ-OH)Cl(IPr)}2] (22)	KOH, EtOH, reflux, 6 h	70–99%	∼10.1	Precious and expensive Pd-complex as catalyst, non-renewable base, refluxing and large reaction times are required.
3	Pd Colloids (23)	Water–CH3CN (1:1), K2CO3 (2 eq.), 80 °C, 24 h	40–96%	∼4.4	Precious catalyst, problematic solvent, 2 eq. of K2CO3, heating and large reactions are necessary.
4	Au/chitosan NPs (27)	Water, RT, 1–3 h	94–99%	∼3.3	Precious Au and chitosan based catalyst and limited substrate scope was reported.
5	[(η^6-benzene)RuCl2(aniline)] (30)	Water, CH3OH, Na2CO3 (2 eq.), Cu(OAc)2 (1.5 eq.), 70 °C, 4–24 h	36–68%	∼7.6	Precious and expensive catalyst, 2 eq. of Na2CO3, 1.5 eq. of Cu(OAc)2, toxic solvent, large reaction times and heating are necessary.
6	RhCl(PPh3)3 (31)	Water, dioxane, TEMPO, 130 °C, 2 h	40–82%	∼10.3	Precious catalyst, organic solvent, oxidant and high temperature are necessary.
7	CuO grafted triazine functionalized covalent organic framework (32)	MeOH, 60 °C, 5 h	59–96%	∼26.8	Tedious preparation of catalyst, toxic solvent, heating, limited substrate scope and large reaction time are reported.
8	[Cu^I(bpy)2] (33)	iso-PrOH, K2CO3 (1 eq.), RT, 4–15 h	54–88%	∼79.3	Unconventional catalyst, 1 eq. of non-renewable base, large reaction times and limited substrate are reported.
9	Cu nanoparticles supported on reduced graphene oxide (CuNPs@rGO) (34)	DMF, microwave (360 W) heating, 12–15 min	86–94%	∼13.0	Tedious preparation of catalyst, microwave heating and problematic solvents are required. Limited number of substrates was studied.
10	[Cu^II(trans-cyclohexane-1,2-diamine)2(H2O)2] [OTf]2 (35)	CH3OH, RT, 2–3 h	40–85%	∼20.2	Un-conventional catalyst and toxic solvents are required. Formation of phenols as bi-products and moderate yields are reported.
11	CuCl (present method)	WEPA, EtOH, RT, 10–45 min	90–99%	∼1.25	Low E-factor, application of waste-derived biorenewable extract, quick reactions, avoid volatile organics, high yields, quick reactions and wide substrate scope.

Table 2. Optimization studies.^a

Entry	Catalyst (mol%)	WEPA (mL)	EtOH (mL)	Time (min)	Isolated yield (%)
1	CuCl (2)	0.5	–	720	20
2	CuCl (2)	0.5	0.5	180	32
3	CuCl (2)	1	0.5	60	39
4	CuCl (3)	1	0.5	60	63
5	CuCl (4)	1	0.5	40	82
6	CuCl (5)	1	0.5	10	99
7	CuCl (6)	1	0.5	10	99
8	CuCl (5)	2	0.5	10	99
9	CuCl (5)	–	0.5	720	–
10	–	1	0.5	720	–
11	CuCl (5)	–^b	0.5	150	72
12	CuCl (5)	–^c	0.5	60	92
13	CuSO4 (5)	1	0.5	720	–
14	FeCl3 (5)	1	0.5	720	–
15	Ni(OAC)2 (5)	1	0.5	720	–
16	NiCl2 (5)	1	0.5	720	–-
17	MnCl2 (5)	1	0.5	720	–

^a Reaction conditions: 1 mmol of phenylboronic acid (1a) at RT.

^b 1 mL of water extract of wood ash (WEWA) was employed.

^c 1 mL of water extract of banana peel ash (WEB) was used.

Table 3. Self-coupling reactions of (H)ABAs using CuCl in WEPA.^a

^a Reaction conditions: 5 mol% of CuCl and 1 mmol of (H)ABA (1) in 1 mL of WEPA and 0.5 mL of EtOH at RT.

^b Isolated yield.

^c Pure product was obtained after work-up and no column chromatography is performed.

Scheme 2. Proposed mechanism of CuCl-catalyzed self-coupling of (H)ABAs in WEPA.

Bhat, S.K.; Prasanna, D.J.P.; Hegde, M.S. Catal. Lett 2020, 150, 2911–2927.

 Web of Science ®Google Scholar

Ostrowska, S.; Rogalski, S.; Lorkowski, J.; Walkowiak, J.; Pietraszuk, C. Synlett. 2018, 29, 1735–1740.

 Web of Science ®Google Scholar

Sable, V.; Maindan, K.; Kapdi, A.R.; Shejwalkar, P.S.; Hara, K. ACS Omega 2017, 2, 204–217.

 PubMed Web of Science ®Google Scholar

Reddy, K.P.; Meerakrishna, R.S.; Shanmugam, P.; Satpati, B.; Murugadoss, A. New J. Chem 2021, 45, 438–446.

 Web of Science ®Google Scholar

Tyagi, D.; Binnani, C.; Rai, R.K.; Dwivedi, A.D.; Gupta, K.; Li, P.-Z.; Zhao, Y.; Singh, S.K. Inorg. Chem 2016, 55, 6332–6343.

 PubMed Web of Science ®Google Scholar

Vogler, T.; Studer, A. Adv. Synth. Catal 2008, 350, 1963–1967.

 Web of Science ®Google Scholar

Das, S.K.; Chandra, B.K.; Molla, R.A.; Sengupta, M.; Islam, S.M.; Majee, A.; Bhaumik, A. Mol. Catal 2020, 480, 110650.

 Google Scholar

Long, B.-F.; Qin, G.-F.; Huang, Q.; Xiong, T.; Mi, Y.; Hu, F.-L.; Yin, X.-H. J. Iran. Chem. Soc 2019, 16, 2639–2646.

 Web of Science ®Google Scholar

Hussain, N.; Gogoi, P.; Azhaganand, V.K.; Shelke, M.V.; Das, M.R. Catal. Sci. Technol 2015, 5, 1251–1260.

 Web of Science ®Google Scholar

Agrahari, B.; Layek, S.; Kumari, S.; Anuradha, Ganguly, R.; Pathak, D.D. J. Mol. Struct 2017, 1134, 85–90.

 Web of Science ®Google Scholar

Peixoto, M.L.B.; Silva, C.H.L.; Godoi, M. Environ. Chem. Lett 2021. In Press. https://doi.org/10.1007/s10311-021-01343-3.

 Google Scholar

Naidu, B.R.; Lakshmidevi, J.; Naidu, B.S.S.; Venkateswarlu, K. Mol. Catal 2021, 511, 111719.

 Google Scholar

Appa, R.M.; Naidu, B.R.; Venkateswarlu, D.; Hanafiah, M.M.; Lakkaboyana, S.K.; Lakshmidevi, J.; Venkateswarlu, K. Green Chem. Lett. Rev 2021, 14, 700–712.

 Web of Science ®Google Scholar

Appa, R.M.; Lakshmidevi, J.; Naidu, B.R.; Venkateswarlu, K. Mol. Catal 2021, 501, 111366.

 Google Scholar

Kloss, F.; Neuwirth, T.; Haensch, V.G.; Hertweck, C. Angew. Chem. Int. Ed 2018, 57, 14476–14481.

 PubMed Web of Science ®Google Scholar

Venkateswarlu, K. Environ. Chem. Lett 2021, 19, 3887–3950.

 Web of Science ®Google Scholar