Chlorosulfonyl isocyanate, chlorination

Chloroperoxidase catalysis by, 58, 302 in chlorination of pyrazoles, 57, 337 Chlorophyll, thioaldehyde synthetic intermediate to, 55, 3 Chlorosulfonyl isocyanate, reaction with 2-arylhydrazono-3-oxobutanoate, 59, 148 Chromatography, of [l,2,4]triazolo[l,5-a]-pyrimidines, 57, 106 Chrom-3-enes, see 2//-l-Benzopyrans Chromium tricarbonyl complexes of 3,5-diphenyl-l-(alkyl- or oxido-)-thiabenzenes, 59, 206, 227 indoles, lithiation of, 56, 181, 184 of pyridine, 58, 160 pyridines, lithiation of, 56, 230, 239 of 2f/-thiopyrans, 59, 227 Chromones, see l-Benzopyran-4-ones Cinnamonitrile, a-cyano-, condensations with thio-, seleno-amides, 59, 184, 186 Cinnoline, nitration, MO calculation, 59, 302... 

The direct chlorination of chlorosulfonyl isocyanate (I) to chloro-sulfonylcarbonimidoyl dichloride (II) by means of phosphorus penta-chloride has been reported f ). However, severe conditions are required and the yield is low. Selective fluorination of II with antimony trifluoride produces the sulfonyl fluoride III (" ). 

The Burgess reagent is a chlorine-free advancement of chlorosulfonyl isocyanate (see also Section 4.5.1), in which the two active sites are reacted with triethyl-amine and methanol, respectively, forming appropriate residues. This achieves the required level of reactivity and the right degree of selectivity, and thus enables consistent reaction mechanisms. 

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