The reaction of dialkyl carbonates with o-aminophenol catalysed by K2CO3: A novel high-yield synthesis of N-alkylbenzoxazol-2-ones

摘要

At 130-150 degreesC and in the presence of catalytic K2CO3, o-aminophenol (1) readily reacts with dialkyl carbonates (2: ROCO2R; 2a: R = Me, 2b: Et, 2c: Allyl, 2d: Bn) to give the corresponding N-alkylbenzoxazol-2-ones (3a-d) in high yields (88-98%). This reaction is a rare example where dialkyl carbonates may simultaneously act as carbonylating and alkylating agents likely through a B(Ac)2/B(Al)2 sequence. Moreover, compounds 2a-c serve also as solvents. In the case of 2d, 1,2-dimethoxyethane (DME) is the reaction medium. [References: 20]