Reaction of N-(Alkoxycarbonyl)saccharins with Nucleophiles

Abstract

The reaction of N-(methoxycarbonyl)saccharin [1a] with various nucleophiles proceeded through two reaction paths, A and B: path A involved the attack of nucleophiles to the ring carbonyl carbon to yield sulfonamide derivatives [3a∼e] and the nucleophilic substitution took place in path B at the carbonyl carbon of the methoxycarbonyl group to form carbonic ester derivatives [4 d∼h] along with saccharin C 61. The selectivity for the reaction paths depended on the nature of nucleophiles: ( 1 ) alkoxide and ethanethiolate ions reacted exclu- sively via path A, ( 2 ) amines reacted both via paths A and B, and ( 3 ) phenoxide, benzenethiolate and carboxylate ions reacted via path B. The use of [1 a] and N-(isopropoxycarbonyl)saccharin [1 b] for the synthesis of amide and peptides was examined. The mechanisms for these reactions were discussed in terms of the specific interactions such as a CT interaction between [1 a] and the nucleophiles in solution.