关键词: 自由基, 串联环化, 中环化合物, 催化, 机理研究

Medium-sized ring (7- to 12-membered) compounds possess unique molecular structures and biological activities. Widely distributed in natural products and pharmaceutically active molecules, they hold an important position in the research of organic chemistry and medicinal chemistry. In addition, in the field of materials science, medium-sized ring compounds offer numerous possibilities for the efficient synthesis of novel functional materials by virtue of their distinctive electronic distribution and spatial configuration. However, due to unfavorable entropic and enthalpic factors, as well as high transannular strain and strong conformational flexibility, the synthesis of medium-sized ring compounds is plagued by problems such as tedious procedures, low yields and poor functional group compatibility, which severely restricts the exploration, development and application of such compounds. Therefore, it is imperative to develop efficient, economical and structurally diverse synthetic strategies for medium-sized ring compounds. In recent years, the construction of medium-sized ring compounds via radical cascade cyclization has achieved considerable progress. This strategy generates highly reactive intermediates through radical pathways to trigger multiple consecutive transformations and forge multiple chemical bonds in one step, thus enabling the efficient synthesis of medium-sized ring compounds. It boasts numerous advantages including concise procedures, green and high efficiency, excellent functional group compatibility, high atom economy, and unique regio- and stereoselectivity, thereby providing a variety of strategies for the construction, development and application of medium-sized ring compounds. This paper summarizes the recent research advances in the synthesis of nitrogen/oxygen-containing medium-sized heterocyclic compounds via the radical cascade cyclization strategy, with a focus on the following two aspects: (1) Separately summarizing the synthetic strategies for 7-membered, 8-membered, and 9- to 12-membered ring compounds; (2) Focusing on the elaboration of the reaction mechanisms, substrate scopes and practical applications of representative reactions. This thesis aims to provide new synthetic insights for the construction of nitrogen/oxygen-containing medium-sized heterocyclic compounds through the radical cascade cyclization strategy and facilitate its applications in the fields of new drug research and development, chemical engineering, materials science and other related areas.

Key words: radical, cascade cyclization, medium-sized ring compounds, catalysis, mechanism study