Chlorosulfonyl isocyanate, reaction with indole

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 reaction of 3,6-di-/ftt-butyl-l,4-dihydropyrrolo[3,2-. ]pyrrole 58 with chlorosulfonyl isocyanate (CSI) giving 59 was investigated (Scheme 1) <1996H(43)2361>. The higher reactivity for electrophilic reaction demonstrated the remarkably electron excessive nature of the system when compared with indole and pyrrole derivatives. 

Reaction of Jt-excessive heterocycles (e.g. thiophene, indole), enol ethers (e.g. dihydropyran) and enol acetates, and carboxylic acids with chlorosulfonyl isocyanate leads in generally excellent yields to A-chlorosulfonylamides. These intermediates are converted into the corresponding nitriles by heating in DMF, although the yields can be somewhat variable. A recent reinvestigation of the N-chlorosulfonylamide to nitrile conversion revealed that treatment of the amides with one equivalent of triethylamine led to formation of the nitriles in excellent yield. Clearly, the mechanisms of the DMF and the EtsN induced transformations are different. 

Electrophilic reaction of heterocycles, such as thiophene or indole, with equimolar amounts of chlorosulfonyl isocyanate in dry ether or acetonitrile at 0-5 °C produces N-chlorosulfonyl-substituted heterocycles (173), which on treatment with DMF gave nitriles in good yields (equations 90 and 91)83. 

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