In the presence of onium salts, at 140-170 °C, methyl alkyl carbonates [1a-c, ROCO2Me, R ) MeO(CH2)2[O(CH2)2]n; n ) 2-0, respectively] react with primary aromatic amines (XC6H4NH2, X) p-OMe, p-Me, H, p-Cl, p-CO2Me, o-Et, and 2,3-Me2C6H3NH2) to yield the corresponding N,N-dimethyl derivatives (ArNMe2) with high selectivity (up to 96%) and good isolated yields (78-95%). Phosphonium salts (e.g., Ph3PEtI and n-Bu4PBr) are particularly efficient catalysts. Overall, a solventfree reaction is coupled with safe methylating agents (1a-c) made from nontoxic dimethyl carbonate.
|Titolo:||Selective N,N-Dimethylation of Primary Aromatic Amines with Methyl Alkyl Carbonates in the Presence of Phosphonium Salts|
|Data di pubblicazione:||2006|
|Appare nelle tipologie:||2.1 Articolo su rivista |