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Please login to access the full content or check if you have access via20.5.1.2.1.2 Variation 2: Dicyclohexylcarbodiimide Activation of Acids
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Jain, N. F.; Masse, C. E., Science of Synthesis, (2007) 20, 712.
Perhaps the most common approach to the synthesis of esters involves activation of the carboxylic acid component by treatment with a carbodiimide reagent followed by subsequent nucleophilic acyl substitution with the neutral alcohol component. The most commonly employed diimide activating reagent is dicyclohexylcarbodiimide; however, the use of dicyclohexylcarbodiimide alone in these esterification protocols has traditionally suffered from variable yields due to the formation of N-acylurea side products. This limitation has been overcome by the addition of catalytic amounts of 4-(dimethylamino)pyridine. A representative example of this approach involves treatment of (E)-cinnamic acid with dicyclohexylcarbodiimide, catalytic 4-(dimethylamino)pyridine (3–10 mol%), and methanol or tert-butyl alcohol in dichloromethane at 0°C to afford the desired esters 3 (R1 = Me, t-Bu) in 98 and 68% yield, respectively (Scheme 2).[2]
Meeeee 8 Meeeeeeeeeeeee ee ee Meee Meeeeeeee eeee Meeeeeeeeeeeeeeeeeeeeeee[8]
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Meeeeeeeeeee Meeeeeeee
(M)-Meeeeeeee Meeeee 8; Meeeeee Meeeeeeee:[8]
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References
[2] | Meeeee, M.; Meeeeeee, M., Meeee. Meee., (8888) 88, 888; Meeee. Meee. Mee. Me. Meee., (8888) 88, 888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 8-8, 888.
- 8.Meeeee-Meee, (8888) M 88e, 888.