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Photolytic Cleavage and Condensation Reactions of Cyclohexa-2,4-dienones with Diamines

Young Mee Kim
Suk Jin Song
Tae Woo Kwon
1,* and
Sung Kee Chung
Department of Chemistry, Kyungsung University, Pusan 608-736, Korea
Department of Chemistry, Pohang University of Science Technology, Pohang 790-784, Korea
Author to whom correspondence should be addressed.
Molecules 2000, 5(7), 961-966;
Submission received: 29 April 2000 / Accepted: 29 June 2000 / Published: 23 July 2000


Cyclohexa-2,4-diene-1-one sulfone derivative undergoes ring cleavage to afford bis-amides containing a diene moiety on irradiation with visible light in the presence of vari- ous diamines.


We previously reported that the photochemical ring cleavage of cyclohexa-2,4-dienones represents a new and high yielding method for labeling the terminal amino functionality of amino acids and peptides [1]. Since the pioneering work of Barton and Quinkert [2], it has been established that the cleavage of cyclohexa-2,4-dien-1-ones by photolysis using UV light generates ketenes [3]. For the cleavage of the dienones of type 1, it was found that UV light can be replaced by visible light, a highly desirable feature for ketene generation in the presence of light sensitive chromophores in peptides or in DNA [4].
We have also shown that the photolysis of 1 in EtOH in the presence of amines resulted in the for-mation of amides [5]. However, one drawback of the parent dienones 1 and 2 is their sensitivity to acid and, resultant conversion to the aromatic compounds 4 and 5 [6] (Scheme 1). Oxidation of sulfone 3 obviated the stability problem. We have been interested in the synthesis of symmetrical bis-cyclohexadienones of the type 6, in which two units of chromophores are linked via varying lengths of carbon tether. These type of compounds may be envisaged as a molecular measuring rod for nucleo-philic functionalities on a polypeptide or DNA fragment. The photolytic coupling reactions of 3 were studied with dibasic functionality such as diamines, in order to test whether ketenes derived from 3 could react with diamines to produce symmetrical bis-amides without any problems such as polymeriza-tion. Herein we wish to report the results of the photochemical coupling reactions (Scheme 2).

Results and Discussion

The sulfone 3 was prepared by treating mesitol with Me2S-N-chlorosuccinimide followed by oxida- tion using m-chloroperbenzoic acid [5,7 and 8]. Photolysis of 3 with a tungsten lamp in the presence of diamines afforded the corresponding bis (amide) products 8 from the reaction of two molecules of the ketene from 3 in ethanol or ethanol-DMSO below 38°C and the results are summarized in Table 1.
The reactions were over within 5-8 hr and the major products (8) were obtained in 43-70%. Longer reaction time did not increase the yields. The ring cleavage led to both cis and trans isomers which were difficult to separate by flash column chromatography. A trace amount of terminal amine products (9; n=2, 3, 4, 8 and 10) from monoacylation were also detected by TLC and compared with authentic sam- ples (n=3) [7]. For the preparation of 8d and 8e, we carried out the reaction in EtOH/DMSO, which provided enough solubility for the diamines.


In summary, photolytic cleavage and condensation reactions between sulfone 3 and various diamines were found to yield the corresponding bis-amide products in moderate yields. These results augur well for the potential utility of the symmetric bichromophoric cyclohexadienones (6) as molecular measuring rods. Additional studies on the preparation and uses of 6 are in progress and results will be communi-cated in due course.



A typical experimental procedure for the photolysis of 3 is as follows: A tungsten lamp (220 W) was employed to irradiate 3 (345 mg, 1.51 mmo0le) in 5 mL of absolute ethyl alcohol in the presence of 1,2- diaminoethane (39 mg, 0.66 mmole) under argon atmosphere. The solution was irradiated at a distance of 2 cm and the temperature kept below 38 °C with a water cooling bath. The reactions were monitored by TLC. Irradiation was continued for 5 hr. The volatiles were removed in vacuo and the crude product was diluted with 20 mL of CH2Cl2. The organic layer was washed with 10% HCl (2×10mL) and dried over MgSO4, filtered and evaporated in vacuo. The residue was subjected to flash chromatography (MeOH : Et2O = 5 : 95) over silica gel to give 8a (540 mg, 1.04 mmol, 69%) as an oil.

Spectral Data

7-Methanesulfonyl-2,4,6-trimethylhepta-3,5-dienoic acid [2-(7-methanesulfonyl-2,4,6-trimethylhepta- 3,5-dienoylamino)-ethyl]-amide, 8a
1H NMR (300 MHz, CDCl3) 6.75 (2H, two NH, broad t), 6.00 (2H, two =CH, s), 5.32-5.28 (2H, two =CH, d, J=9.54 Hz), 3.76 (4H, two CH2SO2, s), 3.24 (4H, two NCH2, m), 3.03 (2H, two CHCO, m), 2.97 (6H, two SO2CH3, s), 1.79 (6H, two CH3C=, s), 1.75 (6H, two CH3C=, s), 1.13 (6H, two CH3-CH, d); IR (neat); 3392.3 (amide), 2980.2, 1644.0, 1540.3, 1448.4, 1380.1, 1297.6, 1131.6 cm-1 HRMS; m/z Calcd for C24H40N2O6S2; [M+H]+=517.3582 /Found 517.3578.
7-Methanesulfonyl-2,4,6-trimethylhepta-3,5-dienoic acid [3-(7-methanesulfonyl-2,4,6-trimethylhepta- 3,5-dienoylamino)-propyl]-amide, 8b
1H NMR (300 MHz, CDCl3) 6.63 (2H, two NH, broad t), 6.05 (2H, two =CH, s), 5.37-5.34 (2H, two =CH, d, J=9.60 Hz), 3.78 (4H, two CH2SO2, s), 3.16 (4H, two NCH2, m), 3.03 (2H, two CHCO, m), 2.94 (6H, two SO2CH3, s), 1.84 (6H, two CH3C=, s), 1.78 (6H, two CH3C=, s), 1.54 (4H, -CH2-, m), 1.17 (6H, two CH3-CH, dd); IR (neat); 3390.4, 2975.1, 2933.6, 1646.9, 1540.1, 1448.4, 1378.8, 1297.0, 1131.6 cm-1 HRMS; m/z Calcd for C25H42N2O6S2; [M+H]+=531.3743 /Found 531.3735.
7-Methanesulfonyl-2,4,6-trimethylhepta-3,5-dienoic acid [4-(7-methanesulfonyl-2,4,6-trimethylhepta- 3,5-dienoylamino)-butyl]-amide, 8c
1H NMR (300 MHz, CDCl3) 6.43 (2H, two NH, broad t), 5.99 (2H, two =CH, s), 5.37-5.33 (2H, two =CH, d, J=9.78 Hz), 3.77 (4H, two CH2SO2, s), 3.15 (4H, two NCH2, m), 3.14 (2H, two CHCO, m), 2.99 (6H, two SO2CH3, s), 1.82 (6H, two CH3C=, s), 1.75 (6H, two CH3C=, s), 1.43 (4H, two - CH2-, m), 1.16 (6H, two CH3-CH, d); IR (neat); 3375.4, 2977.0, 2933.9, 1648.9, 1542.6, 1448.2, 1378.4, 1299.6, 1128.3, 1097.5 cm-1 HRMS; m/z Calcd for C26H44N2O6S2; [M+H]+=545.3897 /Found 545.3871.
7-Methanesulfonyl-2,4,6-trimethylhepta-3,5-dienoic acid [8-(7-methanesulfonyl-2,4,6-trimethylhepta- 3,5-dienoylamino)-octyl]-amide, 8d
1H NMR (300 MHz, CDCl3) 6.23 (2H, two NH, broad t), 5.96 (2H, two =CH, s), 5.35-5.32 (2H, two =CH, d, J=9.68 Hz), 3.74 (4H, two CH2SO2, s), 3.10 (4H, two NCH2, m), 3.10 (2H, two CHCO, m), 2.96 (6H, two SO2CH3, s), 1.79 (6H, two CH3C=, s), 1.73 (6H, two CH3C=, s), 1.38 (12H, - (CH2)6-, m), 1.16, 1313 (6H, two CH3-CH, d, J=6.80 Hz); IR (neat); 3393.2, 2933.3, 2874.1, 1654.0, 1540.1, 1437.5, 1378.6, 1298.5, 1139.4cm-1 HRMS; m/z Calcd for C28H48N2O6S2; [M+H]+=573.4096/Found 573.4075.
7-Methanesulfonyl-2,4,6-trimethylhepta-3,5-dienoic acid [10-(7-methanesulfonyl-2,4,6-trimethylhepta- 3,5-dienoylamino)-decyl]-amide, 8e
1H NMR (300 MHz, CDCl3) 6.16 (2H, two NH, broad t), 5.99 (2H, two =CH, s), 5.38-5.35 (2H, two =CH, d, J=9.82 Hz), 3.74 (4H, two CH2SO2, s), 3.13 (4H, two NCH2, m), 3.05 (2H, two CHCO, m), 2.98 (6H, two SO2CH3, s), 1.83 (6H, two CH3C=, s), 1.76 (6H, two CH3C=, s), 1.45 (4H, two - CH2-, m), 1.24 (12H, -(CH2)6-, m), 1.19-1.16 (6H, two CH3-CH, d, J=6.81 Hz); IR (neat); 3295, 3368.4, 2930.2, 2856.0, 1649.7, 1540.8, 1448.3, 1375.3, 1301.0, 1132.6, 1083.2 cm-1 HRMS; m/z Calcd for C32H56N2O6S2; [M+H]+=629.4837 /Found 629.4912.

(3,5-Dimethyl-3-methylsulfonylmethyl-4-oxo-cyclohexa-1,5-dienyl)-acetic acid, 2

Rf=0.18 (50% hexane/50% Ethyl acetate). 1H NMR (300 MHz, D2O/CDC3OD) 6.95 (1H, s), 6.01 (1H, s), 3.04 (2H, s, CH2C=O), 2.84 (1H, d), 2.61 (1H, d), 1.91 (3H, s, CH3-S), 1.75 (3H, s, CH3-C=), 1.08 (3H, s, CH3) ppm; IR(neat); 3650-2700, 1628, 1560, 1379, 1250 cm-1 HRMS; m/z Calcd for C12H16O3S; [M+H]+=241.0609 /Found 241.0621.

(4-Hydroxy-3,5-dimethylphenyl)-acetic acid, 5

1H NMR (300 MHz, CDCl3) 6.85 (2H, s, Ar-H), 3.49 (2H, s, Ar- CH2-), 2.21 (6H, s, two CH3); 13CNMR (300 MHz, CDCl3) ; 178.10, 151.64, 129.61, 124.90, 123.42, 39.98, 15.59 ppm; IR(neat); 3440, 2997, 2970, 1680, 1290, 1189, 923 cm-1. mp = 145-147°C.


Dedicated to the memory of Sir Derek H. R. Barton (deceased March 16th, 1998). This research was supported by the Non Directed Research Fund, Korea Research Foundation (1998) and the Kyungsung University Research Grants in 2000.

References and Notes

  1. Barton, D. H. R.; Kwon, T. W.; Taylor, D. K.; Tajbakhsh, M. Bioorg. Med. Chem. 1995, 3, 79–84. [CrossRef]
  2. Barton, D. H. R.; Quinkert, G. Proc. Chem. Soc. 1958, 197–198. [CrossRef] Barton, D. H. R.; Quinkert, G. J. Chem. Soc. 1960, 1, 1–9.
  3. Quinkert, G. Angew. Chem. Int. Ed. Engl. 1975, 14, 790–802. Quinkert, G. Angew. Chem. Int. Ed. Engl. 1972, 11, 1072–1087. Quinkert, G. Pure Appl. Chem. 1973, 33, 285–316.
  4. Barton, D. H. R.; Chung, S. K.; Kwon, T. W. Tetrahedron Lett. 1996, 37, 3631–3634.
  5. Barton, D. H. R.; Chung, S. K.; Kim, Y. M.; Kwon, T. W. Bioorg. Med. Chem. Lett. 1997, 7, 733–738. [CrossRef]
  6. For example, saponification of dienone 10 with aqueous NaOH afforded the carboxylate salt quan-titatively. However, neutralization attempts with 10% aqueous HCl gave the phenol 5, although compound 2 could be obtained by careful neutralization with NH4Cl; Molecules 05 00961 i001
  7. Kim, Y. M.; Kwon, T. W.; Chung, S. K.; Barton, D. H. R. Bioorg. Med. Chem. Lett. 1999, 9, 1175–1178. [CrossRef]
  8. Katayama, S.; Watanabe, T.; Yamauchi, M. Chem. Pharm. Bull. 1993, 41, 439–444. [CrossRef]
  • Sample Availability: Not available.
Scheme 1.
Scheme 1.
Molecules 05 00961 sch001
Scheme 2.
Scheme 2.
Molecules 05 00961 sch002
Table 1. Photolysis of cyclohexa-2,4-dienone (3, 2.3 equiv.) in the presence of diamine (1equiv.).
Table 1. Photolysis of cyclohexa-2,4-dienone (3, 2.3 equiv.) in the presence of diamine (1equiv.).
Product No.DiaminesaReaction TimeProduct (8)
8a1,2-Diaminoethane5 hrEtOH0.26c269%
8b1,3-Diaminopropane8 hrEtOH0.13d343%
8c1,4-Diaminobutane5 hrEtOH0.12d461%
8d1,8-Diaminooctane5 hrEtOH/DMSO 1:10.15d670%
8e1,10-Diaminodecane7 hrEtOH/DMSO 1:10.17d847%
aDiamines were purchased from Aldrich and used without further purification. bTLC plates were made with E. Merck AB Darmstadt Silica gel 60 F254. c90% Et2O/10% MeOH. d95% Et2O / 5% MeOH. eYields of isolated product based on 3 after flash column chromatography.

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MDPI and ACS Style

Kim, Y.M.; Song, S.J.; Kwon, T.W.; Chung, S.K. Photolytic Cleavage and Condensation Reactions of Cyclohexa-2,4-dienones with Diamines. Molecules 2000, 5, 961-966.

AMA Style

Kim YM, Song SJ, Kwon TW, Chung SK. Photolytic Cleavage and Condensation Reactions of Cyclohexa-2,4-dienones with Diamines. Molecules. 2000; 5(7):961-966.

Chicago/Turabian Style

Kim, Young Mee, Suk Jin Song, Tae Woo Kwon, and Sung Kee Chung. 2000. "Photolytic Cleavage and Condensation Reactions of Cyclohexa-2,4-dienones with Diamines" Molecules 5, no. 7: 961-966.

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