Synthesis of 6H,7H-[1]benzopyrano-[3,4-c][1]benzopyran-6,7-diones [2]

Full text of DOI:10.1007/s10593-006-0102-6

Chemistry of Heterocyclic Compounds, Vol. 42, No. 3, 2006
SYNTHESIS OF 6H,7H-[1]BENZOPYRANO-
[3,4-c][1]BENZOPYRAN-6,7-DIONES
E. M. Poronik, M. P. Shandura, and Yu. P. Kovtun
Keywords: 6H,7H-[1]benzopyrano[3,4-c][1]benzopyran-6,7-dione, coumarinocoumarin, fluorescence.
In an attempt to obtain compound 3a by condensation of coumarin-3-carboxylic acid (1) with
m-diethylaminophenol 2a, from the reaction mixture we isolated, instead of the expected compound, an intensely
fluorescent substance in 36% yield with a 1H NMR spectrum corresponding to structure 4a.
R1
O
O
R1
R2
N
R2
O
O
COOEt
O
R2
1
+
R1
OH
O
N
2a,b
1
R2
R1
3a,b
O
O
O
O
COOEt
R2
+
O
O
R1
N
5
R1
R2
4a,b
a R 1 = Et, R2 = H, b R1R2 = CH2CH2CH2
A compound of similar structure 6 was obtained earlier in a similar type of process [1]. The authors of
that paper hypothesized that oxidation in the last step occurred by means of oxygen in the air.
O
O
O
O
O
O
+
EtO
OEt
OEt
MeO
OH
OMe
MeO
6
__________________________________________________________________________________________
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev 02094; e-mail:
yu_kovtun@svitonline.com. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 460-461,
March, 2006. Original article submitted January 24, 2006.
410
0009-3122/06/4203-0410©2006 Springer Science+Business Media, Inc.

We have conducted additional studies of this cyclization, and we have determined that oxidation of the
intermediates 3 does not occur by the action of oxygen in the air. Coumarinocoumarins 4 are also formed under
an inert atmosphere. We found that in this reaction, coumarin 1 acts as an oxidizing agent. In the presence of
2 equivalents of compound 1, the yield of compounds 4 increased approximately two-fold. The dihydrocoumarin
5 formed in this case was identified in the reaction mixture by TLC by comparing with the compound separately
obtained by the procedure in [2]. The authors of [3] observed similar properties of coumarin as an oxidizing
agent.
Compounds 4a,b were obtained by heating a mixture of coumarin 1 (10 mmol) and aminophenols 2a,b
(5 mmol) for 1.5 h at 140°C. After cooling, the solid residue was recrystallized from an appropriate solvent.
6H,7H-3-Diethylamino[1]benzopyrano[3,4-c][1]benzopyran-6,7-dione
(4a).
Yield
74%;
mp 176-177°C (alcohol). The UV spectrum (Shimadzu UV-3100), λabsorption 455 nm (CH3CN); (Varian Cary
1
Eclipse), λemission 550 nm (CH3CN). H NMR spectrum (300 MHz, CDC3, TMS), δ, ppm (J, Hz): 1.27 (6H, t,
J = 7.2, CH3); 3.49 (4H, q, J = 7.2, NCH2); 6.48 (1H, s, H-4); 6.71 (1H, d, J = 9.3, H-2); 7.33-7.38 (2H, m, H-9
+ H-11); 7.65 (1H, t, J = 8.1, H-10); 8.05 (1H, d, J = 9.6, H-1); 8.20 (1H, d, J = 7.8, H-12). Found, %: C 71.60;
H 5.13; N 4.21. C20H17NO4. Calculated, %: C 71.63; H 5.11; N 4.18.
(6H,7H-[1]benzopyrano[3,4-c][1]benzopyran-6,7-dione)[2,3,4-i,j]-2,3,4,6,7,8-hexahydroquinolizine
(4b). Yield 86%; mp >300°C (DMF). UV spectrum (Shimadzu UV-3100), λabsorption 480 nm (CH3CN); (Varian
Cary Eclipse), λemission 583 nm (CH3CN). 1H NMR spectrum (300 MHz, CF3COOD, TMS), δ, ppm (J, Hz): 2.52
(4H, br. s, NCH2CH2); 3.32 (4H, br. s, NCH2CH2CH2); 3.87 (4H, br. s, NCH2); 7.65-7.80 (2H, m, H-9 + H-11);
8.03 (1H, t, J = 7.8, H-10); 8.42 (1H, s, H-1); 8.50 (1H, d, J = 7.8, H-12). Found, %: C 73.48; H 4.78; N 3.94.
C22H17NO4. Calculated, %: C 73.53; H 4.77; N 3.90.
REFERENCES
1.
T. Högberg, M. Vora, S. D. Drake, L. A. Mitscher, and D. T. W. Chu, Acta Chem. Scand. B, 38, 359
(1984).
2.
3.
H. Wamhoff, G. Schorn, and F. Korte, Chem. Ber., 100, 1296 (1967).
F. Risitano, G. Grassi, F. Foti, and C. Bilardo, Heterocycles, 55, 1311 (2001).
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