Isocyanate, chlorosulfonyl amide synthesis

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

Synthesis of nitriles (2, 70). Lohaus has published two procedures which illustrate the use of chlorosulfonyl isocyanate for the preparation of nitriles. One, the preparation of 2,4-dimethoxybenzonitrile,8 illustrates the reaction of the reagent with aromatic compounds that readily undergo electrophilic substitution. Thus reaction of resorcinol dimethyl ether (1) with chlorosulfonyl isocyanate in methylene chloride gives the amide N-sulfonyl chloride (2), which on treatment with an amide9 gives 2,4-dimethoxybenzonitrile (3) in 95-96% yield with a purity of 98%. 

Azetidin-2-ones are more reactive than y- and <5-lactams because of ring strain. This is true for the alkaline fission to give salts of / amino carboxylic acids, as well as for the acid-catalysed hydrolysis to fi-carboxyethylammonium salts. Starting from alkenes and chlorosulfonyl isocyanate, a stereocontrolled synthesis of / -amino carboxylic acids can be realized. Ammonia and amines react with azetidin-2-ones, also with ring-opening, to produce / -amino carboxylic amides. Hence they are acylated by azetidin-2-ones ... 

Synthesis of a,jS-Unsaturated Primary Amides. Vinylsi-lanes react with chlorosulfonyl isocyanate without the aid of Lewis acid catalysts to form -lactams, e.g. (5), which subsequently undergo hydrolysis to the corresponding trans-a,fi-unsaturated primary amides, e.g. (6) (eq 4). ... 

Anhydrides, Amides and Esters Using Chlorosulfonyl Isocyanate as a Dehydrating Agent. Synthesis 506 (1982). 

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