Verdazyl Radical Building Blocks: Synthesis, Structure, and Sonogashira Cross‐Coupling Reactions

• Published in: European journal of organic chemistry Vol. 2018; no. 34; pp. 4802 - 4811
• Main Authors: Petunin, Pavel V., Martynko, Ekaterina A., Trusova, Marina E., Kazantsev, Maxim S., Rybalova, Tatyana V., Valiev, Rashid R., Uvarov, Mikhail N., Mostovich, Evgeny. A., Postnikov, Pavel S.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 16.09.2018; Wiley Subscription Services, Inc
• Subjects: Chemical reactions; Chemical synthesis; Chemistry; Chemistry, Organic; Coupling; Cross‐coupling; Crystal structure; Density functional calculations; Nitrogen heterocycles; Physical Sciences; Radicals; Science & Technology; Structural analysis; Verdazyl radicals; OXIDATION; ROUTE; Density functional calculations; POLYMERIZATION; CRYSTAL; Verdazyl radicals; MAGNETIC-INTERACTIONS; Cross-coupling; Nitrogen heterocycles; FUNCTIONAL-GROUP TRANSFORMATIONS; VERSATILE; NITRONYL NITROXIDE; DIRADICALS; DERIVATIVES
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201701783

A general and effective method for the synthesis of 3‐phenylveradzyl radicals bearing a variety of iodophenyl substituents has been developed. The synthesized radicals have been characterized by ESR, UV/Vis spectroscopy, and cyclic voltammetry. Structures of biphenyl‐substituted radicals have been solved by X‐ray crystal structure analysis. The synthesized iodoverdazyls are applicable in the Sonogashira coupling reaction for the preparation of a wide range of ethynyl derivatives. Both N‐2 and C‐6 substituents were functionalized through Sonogashira coupling. Iodine‐substituted verdazyl radicals were synthesized in excellent yields. The first Sonogashira coupling reaction on verdazyl radicals was performed, and optimal reaction conditions were found. Functionalization was carried out not only at C‐6 but also at N‐2‐substituents.