A new method for the reaction of cross-coupling: Preparation of 5,5′-bi(1,10-phenanthroline)

Article abstract of DOI:10.1515/hc-2016-0225

Synthesis and characterization of 5,5′-bi(1,10-phenanthroline) (3) are described. Compound 3 was obtained by treatment of 5-chloro-1,10-phenanthroline (1) with 4-hydroxy- phthalonitrile (2) in the presence of K₂CO₃ as a base in DMF at room temperature for 25 h.

Full text of DOI:10.1515/hc-2016-0225

Heterocycl. Commun. 2017; aop
Preliminary Communication
Mehmet Salih Ağırtaş*
A new method for the reaction of cross-coupling:
preparation of 5,5′-bi(1,10-phenanthroline)
DOI 10.1515/hc-2016-0225
N
Received November 8, 2016; accepted December 8, 2016
N
HO
CN
Cl
Abstract: Synthesis and characterization of 5,5′-bi(1,10-
phenanthroline) (3) are described. Compound 3 was
obtained by treatment of 5-chloro-1,10-phenanthroline (1)
with 4-hydroxy- phthalonitrile (2) in the presence of K2CO3
as a base in DMF at room temperature for 25 h.
N
CN
2
N
N
1
DMF, K2CO3
3
N
Scheme 1ꢀ
Keywords: catalysis; cross-coupling; phenanthroline;
synthesis.
4HPN
Ar-X
Ar-4HPN-X
Introduction
Ar-Ar′
Ar-4HPN-Ar′
1,10-Phenanthroline and its derivatives are valuable com-
pounds for metal complexation, due to their high coordina-
tion numbers and flexible coordination modes [1, 2]. This
class of compounds has found extensive utility as chelating
ligands in coordination chemistry and as building blocks
in supramolecular chemistry [3]. Metal complexes of phen-
anthroline and its derivatives have also found interesting
biological applications, in particular, as agents for recogni-
tion and cleavage of DNA [4, 5] and as inhibitors of telom-
erase [6]. We report here the synthesis and characterization
of 5,5′-bi(1,10-phenanthroline) (3 in Scheme 1) using a new
method that is an alternative to Suzuki-Miyaura cross-cou-
pling reactions. To the best of our knowledge, compound 3
has not been described previously [7, 8].
5-Chloro-1,10-phenanthroline (1) was allowed to react
with 4-hydroxyphthalonitrile (2) in the presence of K2CO3
in dry DMF under nitrogen atmosphere at room temper-
ature for 25 h. Product 3 was obtained by using a con-
ventional workup that did not involve chromatography.
Currently, we are studying the scope and limitations of
this new methodology that is more convenient and uses
less expensive reagents than the classical Suzuki-Miyaura
approach.
K2CO3
KCl
K2CO3
KCl
Ar-4HPN-CO3
Figure 1ꢀCatalytic cycle for cross-coupling of phenanthroline 1 (Ar-X)
and 4-hydroxyphthalonitrile 2 (4HPN).
The reaction of Suzuki-Miyaura cross-coupling of phe-
nylboronic acid and bromoaryl substrates requires the use
of palladium complexes [9–13] that are difficult to prepare
and handle. By contrast, the preparation of 4-hydroxyph-
thalonitrile is easy, and it is a commercial reagent.
A mechanism for this new cross-coupling reaction
is suggested in Figure 1. As can be seen, the initial step
involves the oxidative addition of 1 to 2. In the final step
product 3 is formed with a concomitant release of sub-
strate 2. As a result, compound 2 acts as a catalyst.
Experimental details
5-Chloro-1,10-phenanthroline, K2CO3, CH2Cl2, THF, DMF and
4-hydroxyphthalonitrile were purchased from Merck (Istanbul,
Turkey) and Sigma (Interlab A.S., Istanbul, Turkey). Solvents were
purified according to standard procedures [14] and stored over 4Å
*Corresponding author: Mehmet Salih Ağırtaş, Department of
Chemistry, Faculty of Science, Yuzuncu Yıl University, 65080 Van,
Turkey, e-mail: salihagirtas@hotmail.com
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ꢀꢀꢀꢂ
ꢁM.S. Ağırtaş: A new method for the reaction of cross-coupling
2ꢁ
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A mixture of 5-chloro-1,10-phenanthroline (1, 1 g, 4.66 mmol) and
4-hydroxyphthalonitrile (2, 0.67 g, 4.66 mmol) in N,N-dimethyl-
formamide (DMF, 25 mL) was stirred at room temperature under nitro-
gen atmosphere. After stirring for 15 min, K2CO3 (2.5 g, 18 mmol) was
added portion-wise to the mixture over a period of 2 h. After stirring the
reaction mixture for an additional 25 h, the mixture was poured into
water (150 mL) and extracted with dichloromethane. The extract was
washed with 10% NaHCO3 and then with water, dried over anhydrous
sodium sulfate and concentrated to give analytically pure product
1
3: yield 1.0 g (60%); mp 129–132ꢀ°C; H NMR (300 MHz, DMSO-d6): δ
9.18 (dd, Jꢀ=ꢀ1.7 Hz and 4.3 Hz, 2H), 9.10 (dd, Jꢀ=ꢀ1.7 Hz and 4.3 Hz, 2H),
8.65 (dd, Jꢀ=ꢀ1.7 Hz and 8.4 Hz, 2H), 8.46 (dd, Jꢀ=ꢀ1.7 Hz and 8.1 Hz, 2H),
8.25 (s, 2H), 7.90 (dd, Jꢀ=ꢀ4.3 Hz and 8.4 Hz, 2H), 7.78 (dd, Jꢀ=ꢀ4.3 Hz and
8.1 Hz, 2H); IR: υmax 3020, 1589, 1554, 1481, 1400, 1373, 1284, 1037, 933,
+
906, 794, 736 cmꢀ−ꢀ1; MS: m/z 358.10 [M] . Anal. Calcd for C24H14N4: C,
80.43; H, 3.94; N, 15.63. Found: C, 80.61; H, 4.03; N, 15.56. Compound 3
is soluble in acetonitrile, dichloromethane, chloroform and DMF.
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Acknowledgements: The author thanks the Yüzüncü Yıl
University Office of Scientific Research Projects for the
financial support to his research laboratory.
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