Integrating Retrosynthetic Analysis into the Undergraduate Laboratory: A Reverse-Planning Approach for the Multiroute Synthesis of Cinnamic Acid

Traditionally, undergraduate organic chemistry laboratory courses typically rely on “recipe-based” teaching approaches─where students simply follow predefined steps from textbooks or teachers─limiting the development of their synthetic design thinking and critical reasoning. To address this limitation, we describe a comprehensive laboratory module centered on retrosynthetic analysis, using the synthesis of cinnamic acid─a classic target molecule in organic chemistry curricula─as a case study. Through a reverse-planning approach within an integrated “preclass, in-class, and postclass” framework, students first independently propose synthetic routes based on their own retrosynthetic analyses, then defend and refine their designs in a flipped-classroom setting, and finally execute one of several viable pathways. Multiple distinct routes emerge from this process, including the Heck, Perkin, Wittig, and Knoevenagel reactions as the most frequently selected options. Each route engages different synthetic principles and incorporates three Nobel Prize-winning advances (1979, 1990, and 2010) into green, small-scale experiments. Quantitative assessment and student feedback collected over 7 years (N = 213) indicate that this teaching reform enhances students’ understanding of reaction mechanisms, retrosynthetic logic, and green chemistry principles, while fostering critical comparison of synthetic strategies. The modular design of the module enables flexible use in standard organic chemistry laboratory courses, providing a reproducible template for transforming recipe-based laboratories into inquiry-driven learning environments.