JOURNAL OF CHEMICAL RESEARCH 2008 485
7.08–7.64 (m, 10H), 7.78–7.82 (m, 4H), 8.50 (d, Jꢀ ꢀꢅꢁꢌꢀ+]ꢂꢀꢇ+ꢉꢁꢀ
Anal. Calcd. for C27H17NO3: C, 80.38; H, 4.25; N, 3.47. Found: C,
80.12; H, 4.40; N, 3.65%.
Having established the optimum experimental conditions,
various 14-aryl-14H-dibenzo[a,j]xanthenes were synthesised
in good to excellent yields by the reaction of different
aromatic aldehydes with 2-naphthol. Representative examples
are summarised in Table 1. As shown in Table 1, present
PHWKRGRORJ\ꢀ ZRUNHGꢀ HI¿FLHQWO\ꢀ ZLWKꢀ Dꢀ ZLGHꢀ YDULHW\ꢀ RIꢀ
substrates. In all cases, the 14-aryl-14H-dibenzo[a,j]xanthene
was the sole product and no by-products were observed.
Aromatic aldehydes with electron-withdrawing groups reacted
faster than the aromatic aldehydes with electron-releasing
groups as would be expected. Sterically hindered aromatic
aldehydes such as 2-chloro (1i) and 2-nitro (1n) bezaldehydes
required long reaction times. 2-Naphthalene-carbaldehyde
(1r) was also examined under these conditions and gave the
corresponding product in excellent yield. Another important
aspect is that various functionalities such as halide, nitro, and
hydroxyl, survived under the present reaction conditions.
Recycling of the catalyst was also investigated. After
completion of the model reaction, the mixture was washed
ZLWKꢀHWK\OꢀDFHWDWHꢀDQGꢀWKHꢀFDWDO\VWꢀZDVꢀ¿OWHUHGꢂꢀDQGꢀDFWLYDWHGꢀ
at 100°C for 2 h and reused in another reaction with the same
substrates. The catalyst could be reused at least three times
without appreciable decrease in yield and reaction rate.
In summary, an environmentally friendly procedure for the
synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives
by one-pot condensation of 2-naphthol and aryl aldehydes
catalysed by expanded graphite has been developed. This
method has several merits, involving a simple experimental
procedure, solvent-free conditions, short reaction times,
high yield of product, general applicability and it uses an
inexpensive and recyclable catalyst.
4-(14H-Dibenzo[a,j]xanthen-14-yl)-benzonitrile (3q): IR (KBr):
ꢇꢅꢎꢈꢀꢃ&+ꢉꢂꢀꢇꢇꢇꢋꢀꢃ&Ł1ꢉꢂꢀꢌꢋꢄꢈꢀꢃ& &ꢉꢂꢀꢌꢋꢈꢋꢀꢃ& &ꢉꢂꢀꢌꢇꢏꢍꢀꢃ&±2±&ꢉꢀ
1
cm-1. H NMR (CDCl3, 300 MHz) G ppm: 6.55 (s, 1H), 7.40–7.82
(m, 14H), 8.25 (d, Jꢀ ꢀꢅꢁꢎꢀ+]ꢂꢀꢇ+ꢉꢁꢀ$QDOꢁꢀFDOFGꢁꢀ)RUꢀ&28H17NO: C,
87.71; H, 4.47; N, 3.65. Found: C, 87.81; H, 4.65; N, 3.56%.
14-Naphthalen-2-yl-14H-dibenzo[a,j]xanthene (3r): IR (KBr):
1
ꢍꢈꢏꢊꢀꢃ &±+ꢉꢂꢀꢌꢋꢅꢅꢀꢃ& &ꢉꢂꢀꢌꢇꢏꢏꢀꢃ&±2±&ꢉꢀFP-1. H NMR (CDCl3,
300 MHz) G ppm: 7.08 (s, 1H), 7.18–7.48 (m, 9H), 7.68–8.46 (m,
9H), 9.10 (d, Jꢀ ꢀꢅꢁꢎꢀ+]ꢂꢀꢌ+ꢉꢁꢀ$QDOꢁꢀFDOFGꢁꢀ)RUꢀ&31H20O: C, 91.15; H,
4.93. Found: C, 91.06; H, 4.84%.
7KLVꢀUHVHDUFKꢀZDVꢀ¿QDQFLDOO\ꢀVXSSRUWHGꢀLQꢀSDUWꢀE\ꢀWKHꢀ6FLHQFHꢀ
and Technology Research and Development Program from
Hebei Province (06213507D-2).
Published online: 26 August 2008
References
1
2
3
4
5
G. Sartori and R. Maggi, Chem. Rev., 2006, 106, 1077.
6
7
8
Z.-H. Zhang, T.-S. Li, T.-S. Jin and J.-X. Wang, J. Chem. Res. (S), 1998, 152.
9
Experimental
IR spectra were obtained as KBr pellets with a Thermo Nicolet
FT-IR200 spectrometer. NMR spectra were recorded on a Bruker
AV 300 spectrometer in CDCl3 using TMS as an internal standard.
The melting points are uncorrected and were recorded on a WRR
melting point instrument. Elemental analyses were performed on a
PE 2400 CHNS/O Analyser.
The preparation of expanded graphite: A mixture of concentrated
VXOIXULFꢀ DFLGꢀ ꢃꢄꢅꢆꢂꢀ ꢇꢈꢀ Jꢉꢂꢀ QLWULFꢀ DFLGꢀ ꢃꢊꢋꢆꢂꢀ ꢌꢈꢀ Jꢉꢂꢀ QDWXUDOꢀ ÀDNHꢀ
graphite (10 g) and potassium permanganate (0.7 g) was stirred at
URRPꢀWHPSHUDWXUHꢀIRUꢀꢍꢈꢀPLQꢁꢀ7KHꢀH[SDQGHGꢀJUDSKLWHꢀZDVꢀ¿OWHUHGꢂꢀ
ZDVKHGꢀZLWKꢀZDWHUꢀXQWLOꢀS+ꢀ ꢀꢊ±ꢎꢀDQGꢀGULHGꢀDWꢀꢊꢀ&ꢀIRUꢀꢌꢀKꢁ9
13 Y.-Q. Zhang, C. Wang, G.-S. Li, J.-C. Li, H.-M. Liu and Q.-H. Wu, Chin.
J. Org. Chem., 2005, 25, 1265.
3107.
General procedure for the synthesis of 14-aryl-14H-
dibenzo[a,j]xanthene derivatives: 2-Naphthol (2 mmol), aldehydes
(1 mmol) and expanded graphite (50 mg) were ground well and
WUDQVIHUUHGꢀWRꢀDꢀꢇꢋꢀPOꢀÀDVNꢀDQGꢀWKHꢀPL[WXUHꢀZDVꢀLQVHUWHGꢀLQꢀDQꢀRLOꢀEDWKꢀ
and heated at 120°C for an appropriate time (monitored by TLC).
After completion of the reaction, the mixture was cooled to room
WHPSHUDWXUHꢂꢀZDVKHGꢀZLWKꢀHWK\OꢀDFHWDWHꢀDQGꢀWKHꢀFDWDO\VWꢀZDVꢀ¿OWHUHGꢁꢀ
7KHꢀVROYHQWꢀZDVꢀHYDSRUDWHGꢀDQGꢀWKHꢀFUXGHꢀSURGXFWVꢀZHUHꢀSXUL¿HGꢀE\ꢀ
recrystallisation from aqueous ethanol to afford the pure product.
14-(4-Methoxy-phenyl)-14H-dibenzo[a,j]xanthene (3c): IR (KBr):
ꢍꢈꢏꢌꢀꢃ &±+ꢉꢂꢀꢇꢄꢇꢍꢀꢃ&+ꢉꢂꢀꢌꢊꢈꢋꢀꢃ& &ꢉꢂꢀꢌꢋꢈꢅꢀꢃ& &ꢉꢂꢀꢌꢇꢏꢄꢀꢃ&±2±&ꢉꢀ
cm-1. 1H NMR (CDCl3, 300 MHz) G ppm: 3.63 (s, 3H), 6.60 (s, 1H),
6.70 (d, Jꢀ ꢀꢅꢁꢎꢀ+]ꢂꢀꢇ+ꢉꢂꢀꢎꢁꢍꢅ±ꢎꢁꢏꢅꢀꢃPꢂꢀꢊ+ꢉꢂꢀꢎꢁꢋꢊ±ꢎꢁꢅꢇꢀꢃPꢂꢀꢊ+ꢉꢂꢀꢅꢁꢍꢅꢀ
(d, Jꢀ ꢀꢅꢁꢎꢀ+]ꢂꢀꢇ+ꢉꢁꢀ$QDOꢁꢀ&DOFGꢁꢀIRUꢀ&28H20O2: C, 86.57; H, 5.19.
Found: C, 86.35; H, 5.42%.
28 J.V. Madhav, V.N. Kumar, P. Someshwar and B. Rajitha, J. Heterocyclic
Chem., 2008, 45, 119.
29 S. Kantevari, M.V. Chary, A.P.R. Das, S.V.N. Vuppalapati and
14-(2-Nitro-phenyl)-14H-dibenzo[a,j]xanthene (3n): IR (KBr):
ꢍꢍꢄꢅꢀ ꢃ &±+ꢉꢂꢀ ꢌꢋꢄꢇꢀ ꢃ& &ꢉꢂꢂꢀ ꢌꢋꢇꢌꢀ ꢃ1ꢀ ꢀ 2ꢉꢂꢀ ꢌꢍꢏꢅꢀ ꢃ1ꢀ ꢀ 2ꢉꢂꢀ ꢌꢇꢋꢏꢀ
1
(C–O–C) cm-1. H NMR (CDCl3, 300 MHz) G ppm: 7.50 (s, 1H),