Alkali-metal-assistent Transfer of the Carbamte Group from Phosphocarbamates to Alkyl Halides: a New Easy Way to Alkali-metal Carbamates and to Carbamate Esters
Phosphocarbamates P(O2CNR2)x(NR2)3-x (R=alkyl; x=1 or 2), easily obtainable by insertion of CO2 in the P-N bond of the corresponding aminophosphines P(NR2)3, have been used as a source of carbamate groups in the reaction with alkyl halides, R'X to afford carbamate esters.The reaction is mediated by alkali-metal halides, MY, and requires the presence of a suitable macrocyclic polyether (L).The overall reaction occurs in two steps: the carbamic group is first tranferred to the alkali-metal cation to give a carbamate salt which then reacts with the alkyl halide affording R2NC(O)OR'.The yield and selectivity to the carbamate ester are remarkably influenced by the nature of MY.The influence of the nature of the alkali-metal salt in the overall process and the role of the macrocyclic ligand in modifying the reactivity of the R2NCO2- anion in akli-metal carbamates are discussed.
Nucleophilic substitution reaction at the nitrogen of arylsulfonamides with phosphide anion
A novel nucleophilic substitution reaction at the nitrogen of arylsulfonamides by means of phosphide anions has been described. This reaction allows for the efficient transformation of arylsulfonamides into synthetically valuable phosphamides, amines, and a variety of protected amines.