Coumarin-6-sulfonyl chloride

S. M. Z. Al-Kindy, F. E. O. Suhnan, and A. A. Al-Hamadi, Fluorescence enhancement of coumarin-6-sulfonyl chloride amino acid derivatives in cyclodextrin media, Anal. Sci. 17 (2001), 539. 

Chloride [10543-42-7]. 2-Oxo-2H-l-benzopyran-6-sulfonyl chloride, 9CI. 6- Chlorosulfonyl)coumarin, SCI. Coumarin-6-sulfonyl chloride C9H5CIO4S M 244.655... 

Coumarin 4, see H-00283 Coumarin 120, see A-00237 Coumarin 153, C-00304 Coumarinic acid, in H-00500 Coumarin-6-sulfonic acid, see 0-00057 Coumarin-6-sulfonyl chloride, in 0-00057 Cpida, see B-00276... 

This approach has been shown to work with a number of different fluorescent probes such as the short-wavelength fluorophores dansyl sul-fonyl chloride and coumarin chloride and the long-wavelength fluorophores tetramethylrhodamine-5-(and-6)-isothiocyanate [5(6)-TRITC], 5-(and-6)-carboxytetramethylrhodamine, succinimidyl ester [5(6)-TAMRA, succin-imidyl ester] and lissamine rhodamine B sulfonyl chloride (each in conjunction with different binding functionalities on the SAM surface. 

Coumarin 101 by heating with excess chlorosulfonic acid (five equivalents) at 100 °C for 4 hours afforded the 6-sulfonyl chloride 102, 58% (Equation 28). ... 

In coumarin 101 ° "studies have shown that sulfonation generally occurs in the 3- and 6- positions which is in agreement with the polar mesomeric structures of 101 also the presence of a 4-methyl group appears to inhibit 3-sulfonation probably as a result of steric hindrance. The 6-position would be expected to be the most favoured site for sulfonation since it is para to the electron-donating hetero oxygen atom. Coumarin 101 with chlorosulfonic acid (two equivalents) at 100 °C (2 hours) yields a mixture of the 6-sulfonic acid and the 6-sulfonyl chloride 102, while at 130-140 °C (3 hours), the reaction gives the 3,6-disulfonic acid and the 3,6-disulfonyl chloride." ... 

In the sulfonation of 7-hydroxy- and 7-methoxycoumarins, the 6-position was more reactive than the 3- or 8-positions and for coumarins generally the 6-position was the favoured site of sulfonation. The 8-position appeared unfavourable for the formation of sulfonyl chlorides, probably because the 7-sulfonic acid is stabilized by 0-H- O hydrogen bonding between the sulfonic acid group and the hetero oxygen atom. 

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