Direct diazotization of indoles with 2-Methoxyethyl nitrite

/AcOH. Since MOE-ONO is synthesized from NO gas, oxygen, and 2-methoxyethanol, this diazotization serves as an effective utilization of NO. Furthermore, the diazotization proceeds efficiently even in water, which is important for designing clean chemical processes. The synthesized 3-diazoindoles exhibit broad reactivity, such as Grignard reaction at the C2-position and rhodium-catalyzed cyclopropanation at the C3-position. Such reactions can be practical solutions for synthesizing highly functionalized indoles and indolines, which are important for the design and discovery of pharmacologically active compounds.