Molecules 2019, 24, 4453
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1,3-Dicyano-2-(4-biphenyl)benzene 1d: White solid, m.p. 180–181 ◦C; IR (KBr, cm−1) 3060, 2227; 1H
NMR (500 MHz, CDCl3) 8.01 (d, J = 8.0 Hz, 2H), 7.78 (d, J = 8.0 Hz, 2H), 7.67 (d, J = 7.4 Hz, 2H),
δ
7.63–7.60 (m, 3H), 7.50–7.47 (m, 2H), 7.42–7.39 (m, 1H); 13C{1H} NMR (125 MHz, CDCl3)
δ 148.6, 143.1,
140.0, 137.2, 132.9, 129.7, 128.9, 128.4, 127.9, 127.7, 127.3, 116.7, 114.4; HRMS (FAB) calcd. for (M + H)+
C20H13N2: 281.1079, found: 281.1068.
1,3-Dicyano-2-(2-biphenyl)benzene 1e: White solid, m.p. 187–188 ◦C; IR (KBr, cm−1) 3065, 2238; 1H
NMR (500 MHz, CDCl3)
δ
7.80–7.77 (m, 2H), 7.63–7.60 (m, 1H), 7.55–7.52 (m, 2H), 7.47–7.44 (m, 1H),
149.5, 141.9, 139.5, 137.2, 136.3,
7.40–7.39 (m, 1H), 7.22–7.16 (m, 5H); 13C{1H} NMR (125 MHz, CDCl3)
δ
133.1, 130.8, 130.5, 129.8, 129.7, 129.1, 128.2, 128.0, 127.8, 127.3, 123.4, 118.2, 116.3, 115.6; HRMS (FAB)
calcd. for (M + H)+ C20H13N2: 280.1079, found: 280.1068.
General procedure for the photoreaction of 4, 5, and 6 with 1
An aqueous CH3CN solution (CH3CN 45 mL, H2O 5 mL) of 1 (10 mM), 4 (20 mM), NaOH (20 mM)
in Pyrex vessels (18 mm x 180 mm) was purged with Ar for 10 min. The mixture was irradiated with a
100 W high-pressure mercury lamp for 10 h and then the solvent was removed under reduced pressure.
The crude product was purified by silica-gel column chromatography using hexane/EtOAc = 9:1 as
the eluent to yield alcohol
7 along with dimer 8. Similar photoreactions of 5 and 6 were carried out
under the similar conditions to yield 10 and 11.
2-Hydroxyindane 7: Compound
has been previously reported [16]. White solid, 1H NMR (500 MHz,
CDCl3) 7.21 (m, 4H), 4.70 (s, 1H), 3.22 (dd, J = 8.3, 3.0 Hz, 2H), 2.92 (dd, J = 8.3, 1.2 Hz, 2H), 1.68 (d,
J = 5.2 Hz, 1H); 13C{1H} NMR (125 MHz, CDCl3) δ 140.8, 126.7, 125.0, 73.2, 42.7
Cyclobutadiindene 8: Compound
has been previously reported [16]. White solid, 1H NMR (500 MHz,
CDCl3)
9
δ
8
δ
7.41 (d, J = 7.4 Hz, 2H), 7.31 (d, J = 6.9 Hz, 2H), 7.29–7.22 (m, 4H), 3.70 (d, J = 5.2 Hz, 2H), 3.19
(dd, J = 8.5, 3.8 Hz, 1H), 2.94 (d, J = 8.3 Hz, 2H), 2.78–2.76 (m, 2H); 13C{1H} NMR (125 MHz, CDCl3)
δ
146.6, 144.0, 126.9, 126.8, 125.5, 125.2, 54.0, 43.2, 39.4
5-Hydroxy-4,4,5-trimethylhexanenitrile 10: Compound 10 has been previously reported [18]. Colorless
oil, 1H NMR (500 MHz, CDCl3):
δ 2.41 (t, J = 8.0 Hz, 2H), 1.80 (t, J = 8.0 Hz, 2H), 1.39 (s(br), 1H), 1.20
(s, 6H), 0.92 (s, 6H); 13C{1H} NMR (125 MHz, CDCl3): δ 121.2, 75.5, 39.9, 33.8, 25.9, 21.9, 13.6.
1,2-Di(4-methoxyphenyl)ethane 11: Compound 11 has been previously reported [27]. White solid, 1H
NMR (500 MHz, CDCl3)
δ 7.08 (d, J = 8.2 Hz, 4H), 6.82 (d, J = 8.2 Hz, 4H), 3.80 (s, 6H), 2.83 (s, 4H);
13C{1H} NMR (125 MHz, CDCl3): δ 157.9, 134.1, 129.4, 113.8, 55.3, 37.4.
4. Conclusions
This study has led to the development of PET-promoted reactions using a new class of organic
photoredox catalysts
1
wherein donor and acceptor arenes are directly linked. The intramolecular
, and in an aqueous
exciplex of functions as a photoredox catalyst for the photoreactions of
1
4,
5
6
acetonitrile solution, even at low concentrations. Further investigations on the application of catalyst
to other PET-promoted reactions and the elucidation of the detailed mechanism are underway.
1
Supplementary Materials: 1H and 13C{1H} NMR spectra for all compounds 1, 2, 7, 8, 9, 10, and 11.
Author Contributions: Conceptualization, M.Y. and Y.Y.; methodology, Y.Y.; formal analysis, T.M.; investigation,
M.Y., A.A., T.F., Y.I., Y.T. and K.O.; data curation, M.Y.; writing—original draft preparation, M.Y.; writing—review
and editing, Y.Y.; funding acquisition, Y.Y.
Funding: This work was partially supported by the Japan Society for the Promotion of Science (JSPS), Grant-in-Aid
no. 17K05779, for scientific research.
Conflicts of Interest: The authors declare no conflict of interest.