Mild Esterification of Carboxylic Acids via Continuous Flow Diazotization of Amines

A new continuous flow protocol for the diazotization of methylamine with 1,3-propanerlinitrite in THF is reported The synthesis of methyl esters was achieved in high yields from a variety of carboxylic acids in 20 min at 90 degrees C. Additionally, this protocol was extended to other aryl and alkylamines, namely secondary ainines, to produce various substituted esters in: high yield using 2-MeTHF as a solvent. The reaction conditions were-compatible with Many functional groups, namely nitrogen-containing heterocycles, alkynes, alkenes, alcohols, and phenols. Mechanistic investigations reveal that the reaction appears to proceed through a transient diazonium species rather than a diazo intermediate,