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DOI: 10.1055/s-2003-42464
The Reaction of Dialkyl Carbonates with o-Aminophenol Catalysed by K2CO3: A Novel High-Yield Synthesis of N-Alkylbenzoxazol-2-ones
Publikationsverlauf
Publikationsdatum:
04. November 2003 (online)
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Abstract
At 130-150 °C 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 BAc2/BAl2 sequence. Moreover, compounds 2a-c serve also as solvents. In the case of 2d, 1,2-dimethoxyethane (DME) is the reaction medium.
Key words
alkylations - allylations - benzylations - carbonylations - catalysis
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References
The alkylation reaction with 2 takes place only at a high temperature [≥ 120 °C; Scheme [2] , path (a)]. Under these conditions, the alkylation is the sole possible process because of the reversibility of path (b).