S-Ethylcarbamoyl group

The S-ethylcarbamoyl group was found to be unaffacted by 4.5N-hydrogen bromide in acetic acid, IN-hydrochloric acid, or refluxing trifluoroacetic acid [9]. 

Removal of the S-ethylcarbamoyl group was accomplished with 4N-ammonia, liquid ammonia-methanol (1 1) or liquid ammonia alone [9]. The group was also cleaved with IN-aqueous sodium hydroxide, sodium methoxide in methanol, or hydrazine in methanol. Wittinghofer [114] has utilized the S-ethylcarbamoyl group in the synthesis of the A. ij segment of ovine insulin, (32). The group was readily removed using... 

N-ammonia in methanol. Upon oxidation to the cyclic disulphide Wittinghofer noted the formation of small amounts of di o-nitrophenyl disulphide which may have resulted from -> S-o-nitrophenylsulphenyl group migration during the alkaline removal of the S-ethylcarbamoyl group. 

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