Organometallic reactions. Part IV. The preparation of bistrialkyltin derivatives of ureas and biurets by the decarboxylation of bistrialkyltin oxide–isocyanate adducts

Abstract

Under appropriate conditions of temperature and structure, bistributyltin oxide will react with isocyanates to yield carbon dioxide and the bistributylstannyl-NN′-dialkylureas; these ureas will react further with isocyanate giving bistributylstannyl-NN′N″-trialkylbiurets. By reactions of this type, mixed biurets of the composition RHN·CO·NR′·CO·NR″H have been prepared for the first time.

It is suggested that the decarboxylation, and the alternative reaction in which an isocyanurate is formed, involve the allophanate, Bu₃Sn·NR″·CO·OSnBu₃, as a common intermediate.