| Research Abstract |
exo-Ureas, endo-ureas, exo-sulfonamides, and exo-carbamates readily undergo aminocarbonylation by the catalysis of PdC12 in methanol under 1 atm of carbon monoxide at room temperature. O-Allyl-endo-carbamates, on the other hand, do not undergo the aminocarbonylation under the similar conditions. This makes sharp contrast to the fact that endo-ureas are more reactive toward aminocarbonylation than exo-ureas. After experimentations, we found that aminocarbonylation of endo-carbamates proceed smoothly in the presence of sodium acetate and methyl orthoacetate (MOA). MOA can be utilized as an additive (in MeOH as a solvent) or as a solvent. In the latter case, MOA serves not only as a solvent but also as a reactant (a nucleophile) and much higher stereoselectivities are observed then the case undertaken in MOA/MeOH.Diamines possessing endo-carbamate and exo-carbamate (exo-urea or exo-sulfonamide) moieties in the same molecules were found to undergo chemoselective amination : the endo-carbamate moieties in MOA and the exo-carbamate, exo-urea, and exo-sulfonamide moieties in MeOH undergo the selective aminocarbonylation under 1 atm of CO by the catalysis of PbC12.
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