Amine arenesulfonamide

The reactivity of amines and imidazolide anions with aryl 4-toluenesulfonates (310) in 80% aqueous DMSO has been studied and Bronstcd [lmlc values of ca 0.7 and ca 1.0, respectively, were found.284 The points for botii die amines and die imidazolides can all be accommodated on die same Bronsted plot. S—O rather than C—O cleavage occurs in the reaction, hi a useful aside to tiiis work die authors have shown that plots of pKA data in water are linear witii tiiose in DMSO or 80% DMSO and tiiese can be used to obtain unknown pA, values. The same Ukrainian group has obtained deviations from Bronsted plots for the reaction of (310) witii highly basic nucleophiles such as imidazoles and arenesulfonamides. The /Jnuc value goes from 0.79 for pA/<11 to 0-0.1 for pKa>11.0.285... 

Aryl tellurium trichlorides and secondary amines or dialkyl(trimethylsilyl)amines formed aryl dialkylamino tellurium dichlorides. A,A -Bis[trimethylsilyl]arenesulfonamides reacted similarly producing aryl arenesulfonimide tellurium chlorides (p. 345, 358). 

The utility of acid chlorides as effective activating species has been reestablished, in conjunction with other protecting groups for the a-amino function. For example, acid chlorides of derivatives containing hetero-arenesulfonamide iV -protecting groups [180,181] as well as azido acids [182] coupled efficiently without significant racemization. In the latter, the azido function acts as a precursor of the amine. 

David Crich, now at CNRS de Gif-sur-Yvette, found (J. Org. Chem. 2009, 74, 3886) that the enantiomerically-pure thioanhydride 22 could be coupled sequentially first with an amine 23 and then with an arenesulfonamide 24 to give the unsymmetrical diamide 25. This approach was used to prepare diastereomerically-pure glycodipeptides. 

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