Organically Gaining Synthetic Expertise

I started teaching Karty’s textbook in my first full-time teaching position, and I am not looking back. At the end of each semester as I review my course plan and think about what worked that semester and what didn’t, I always notice new ways in which this textbook design is smart, student-centered, and ultimately makes my job easier. The way the textbook addresses synthesis problems is just the latest example. Karty devotes two chapters at strategic points in the book to teaching synthesis, but this is really just the start of how his design is perfect for this topic.

As an organic chemistry professor, one of the end goals that I set for my students is that they will be able to propose a multi-step total synthesis for a moderately complex molecule. This skill is one many organic professors strive for because it allows our students to showcase a broad understanding of a variety of reactions. To be proficient in this skill, students have to know a large number of organic transformations, and more importantly, they need to recognize the advantages and limitations for each. For example, if our goal is to synthesize a primary alcohol, we have to know that oxymercuration/reduction or acid catalyzed hydration are poor choices (these lead to secondary or tertiary alcohols), while hydroboration/ oxidation is a likely tool that will be used.

In my courses, I often reach Karty’s first organic synthesis chapter (Chapter 13) towards the start of the second semester (Organic II), so I largely ignore the concept of a multi-step synthesis until that point. For my students, this pace actually works out perfectly because when they return from winter break we get to take time reviewing their first semester reactions while putting them into the context of useful tools towards building molecules. This initial taste of synthesis also helps to reinforce the importance of the content the students are learning. They realize that the reactions they are seeing are not just there to fill pages of a textbook, but instead can be used in meaningful applications.

Teaching synthesis at the mid-point in organic chemistry can have some challenges. The biggest issue is that students have really only begun to learn the practical reactions that are useful in a multi-step synthesis. This limits the examples we can provide to reinforce the concept. However, with Karty’s text, students do get exposed to some of the more “interesting” transformations earlier. For example, in chapter 10 students see alpha alkylations and halogenations, practical applications of an SN2 reaction. This topic often shows up in the middle of Organic II if you follow a functional group approach. I find that by that first synthesis chapter there is actually a breadth of material to work with to begin building an understanding of complex syntheses. Rather than an introduction in functional groups one at a time, typically confined to one or two chapters, students see these functional groups in different settings at various points of the semesters. This helps to bridge the relationships between functional groups and students start to think of groups not just as a starting material or a product, but also as a useful intermediate.

Later in the semester, once the students have really built up their “organic toolbox,” we get to revisit the concept of synthesis again as a separate chapter and learn additional strategies to apply synthesis in practice. Karty’s approach to introducing synthesis through these two chapters is unique and I have found that this is an excellent approach to ease my students into the topic. I see a growing appreciation for the reactions the students are learning as we move through the semester. They enjoy the “break” of the synthesis chapters where the amount of “new” content is low. Instead of absorbing new reactions, they get to practice what they’ve learned already.

I think for most students, developing a multi-step synthesis will always be one of the toughest parts of an organic class. However, with cleverly timed introductions to this skill and reinforcement throughout multiple chapters as in Joel’s book, our students often surprise themselves with their synthetic expertise.

-Jamie Ludwig, Rider University

Click here to learn more about Prof. Ludwig

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