Reaction of diazomethane with quaternary nitrogen compounds to form betaines
Abstract
The reaction of diazomethane with 3-carboxy-4-fluorophenyltrimethylammonium iodide (1) affords, not the methyl ester, but the betaine 2-fluoro-5-trimethylammoniobenzoate (2). However, when the iodide anion is replaced by a weaker nucleophile, tetrafluoroborate, the methyl ester is obtained. A mechanism for the betaine reaction is outlined.