关键词: 金属有机化学, 过渡金属催化, 反应机理, 机理认知转变, 有机化学教学

Abstract: As organometallic chemistry continues to gain prominence in modern organic synthesis, transition metal-catalyzed reactions have been progressively incorporated into undergraduate organic chemistry curricula. However, pedagogical experience reveals that students frequently struggle to make the conceptual transition from traditional organic reaction mechanisms to those involving transition metal catalysis. While conventional organic reactions predominantly involve homolytic or heterolytic bond cleavage processes typically explained through radical or polar reaction pathways, transition metalcatalyzed reactions introduce distinct mechanistic characteristics including metal-carbon bond formation, substrate coordination, and catalytic cycles. These fundamental differences in mechanistic paradigms present significant learning challenges. To address this issue, we examine the cognitive models of undergraduate students and analyze the conceptual gaps between traditional organic reaction mechanisms and transition metal-catalyzed processes. We propose a teaching strategy specifically designed to facilitate this mechanistic cognitive transition. Through systematic comparison of traditional polar reactions with transition-metal-catalyzed reactions in terms of electronic structure, substrate activation modes, and catalytic cycles, we highlight the essential differences between Pd–C bond reactivity and conventional organometallic reagents. This approach prevents students from making oversimplified analogies between Pd–C bonds and classical carbanion structures, while establishing a proper conceptual framework for understanding transition-metal-catalyzed reaction mechanisms. Using representative cross-coupling reactions (Suzuki, Heck, and Sonogashira) as teaching examples, we demonstrate the practical implementation of this pedagogical approach in undergraduate organic chemistry courses. Classroom assessments indicate that this method effectively helps students develop a comprehensive understanding of transition metal-catalyzed reaction mechanisms, facilitating their transition from linear mechanistic thinking to catalytic cycle-based reasoning, thereby improving overall teaching outcomes.

Key words: Organometallic chemistry, Transition metal catalysis, Reaction mechanisms, Mechanistic cognitive transition, Organic chemistry teaching