To remain globally competitive, education in the United States must focus on retaining students in science, technology, engineering, and mathematics (STEM). As laboratory courses have the potential to be powerful attractors or deterrents to a field, developing effective laboratory pedagogies is important to retain students in STEM. A course-based undergraduate research experience (CURE) is one model for laboratory instruction that has generated an increasing amount of attention. This has been driven by their success, especially in increasing students' self-efficacy and science identity, two long-term indicators of persistence in STEM. Herein is reported a large introductory organic chemistry CURE course framework that focuses on green reaction optimization. Students were given an unoptimized alkene epoxidation procedure, split into small "research" groups, and tasked with improving conversion while minimizing reaction inputs. After three rounds of optimization, groups increased conversion 10-20-fold compared to baseline conditions. Then, students investigated the substrate scope of their conditions and analyzed trends in relative reactivities based on principles learned in lecture and from the literature. Lastly, students summarized their findings in a final slideshow presentation. Surveys were used to evaluate different aspects common to CURE courses and students' sense of project ownership. The scores obtained were consistent with other reported CURE courses. Importantly, students saw large gains in self-efficacy and science identity. Students had an overwhelmingly positive response to the curriculum based on informal and written feedback. This approach is generalizable to a wide range of institutions with different equipment availability, reaction types, and course coverage schedules.