Purpose: This paper aims to report a case study in flexible learning with multicomponent blended learning mode in an undergraduate chemistry course. Traditional chemistry courses usually include lectures, tutorials and laboratory sections. For a course "Advances in Organic Synthesis" at undergraduate level, it consists of advanced information in organic chemistry such as reaction mechanisms, asymmetric catalysis, retrosynthesis and applications in synthesis of natural products. This course is a difficult subject and requires deep understanding of contents. After learning this course, students should have comprehensive knowledge in advanced strategies of organic synthesis and have an ability to apply them to real cases. This "flexible learning with multicomponent blended learning mode" was implemented by the authors to enhance student engagement and self-motivation in their studies. Design/methodology/approach: The authors hoped to enhance students' engagement in "flexible learning" -- a mixed concept with "blended learning" and "flipped classroom" -- and called this approach as "multicomponent blended learning mode." Blended learning combines face-to-face and e-learning components with interactive Web-based components and technical experimental videos were developed. The knowledge integrated in different components provides a natural environment to link the different synthetic methods together, which help students to get a better understanding of the complicated knowledge and strengthen their skills. For flipped classroom, students participated in the case studies of the organic synthesis and shared their findings to other classmates in oral presentations. Findings: In this study, both course evaluation score and students' academic performance in the "multicomponent blended learning mode" were increased significantly when comparing with traditional teaching methods in 2011. It was found that students' engagement and their self-motivation in learning were enhanced. Originality/value: The positive feedback from the students and the enhancement of their academic performance supported the value in this research. Besides, most universities in Hong Kong have suspended all face-to-face classes and conducted all teaching in online mode during COVID-19 outbreak. As the multicomponent blended learning mode of this course has already been conducted for eight cohorts, the authors are confident that this feature can minimize the sudden change in the learning habits for the students. As social factors and individual variations in students' learning and study mode may affect the learning outcomes, these interactive multicomponent e-learning components in this special period make students excited when they can study and digest the knowledge according to their own pace.