Synthesis of Esters via FGI

Fischer esterification similar leaving group abilities gives equiibrium 

Methyl esters can be prepared with the reagent diazomethane (CH2N2). When reacted with a carboxylic acid, diazomethane becomes protonated and serves as an extremely reactive electrophile since it contains an extremely good leaving group (N2). A rapid and irreversible Sn2 displacement by the carboxyl-ate nucleophile gives the methyl ester product. 

Esters can also be formed upon oxidation of ketones with a peroxyacid oxidizing agent (such as mCPBA or CF3CO3H). This Baeyer-Villiger oxidation is especially useful in the preparation of cyclic esters (called lactones) from cyclic ketones. 

Synthesis of Esters via Baeyer-VUhger Oxidation of Ketones 

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