Hindered internal rotation in alkyl N‐[(Arylsulfonyl)‐methyl]‐N‐Methylcarbamates. A total line shape NMR study

Abstract

AbstractThe kinetic parameters of hindered internal rotation around the carbonyl carbon to nitrogen bond in three alkyl N‐[(arylsulfonyl)methyl]‐N‐methylcarbamates and in methyl N‐methyl‐N‐[(p‐tolylthio)methyl]carbamate have been determined using the NMR total line shape technique and an iterative computer programme.The lifetimes of both rotamers were evaluated from the temperature‐dependent signals of the ester alkyl groups. The choice of the input line‐width parameters was found to be critical. Activation parameters for the exchange reactions are discussed in terms of the structures of the carbamates and are compared with those of structurally related compounds.