Methylation of carboxylic acids with streptozotocin

The clinically used DNA-alkylating drug streptozotocin (STZ) was investigated using a simple work-up as an O -methylating agent to transform various carboxylic acids, sulfonic acids and phosphorous acids into corresponding methyl esters, and did so with yields of up to 97% in 4 h at room temperature. Good substrate tolerance was observed, and benefited from the mild conditions and compatibility of the reaction with water. Streptozotocin (STZ), DNA-alkylating agents in clinical, was newly explored as an agent for O -methyl esterification. With STZ, carboxylic acids, sulfonic acids and phosphorous acids were transformed into methyl esters in 4 hours at RT with good yield after simple workup.