The mechanism of the Wittig reaction is not without controversy. Two principal researchers, Prof. Edwin Vedejs (a former personal mentor) from the University of Wisconsin – Madison (now at the University of Michigan) and Prof. Manfred Schlosser from the Université of Lausanne, had very different points of view. The entire “argument” was based upon whether betaines are observed in the absence of lithium salts, i.e. under “salt-free” conditions.
The alkene functionality is a fundamental building block in synthetic organic chemistry. It is practically ubiquitous, and can be found in a variety of natural products such as beta carotene, the precursor to Vitamin A. Alkenes are known to form under conditions of E1 and E2 elimination. Although an integral part of Organic Chemistry, elimination reactions are not always synthetically appropriate given the delicate functionality often present in complex organic molecules. The more versatile Wittig reaction through which they may be synthesized lies in chemistry pioneered by Nobel Laureate George Wittig (University of Heidelberg).
Many times at larger universities professors do not review proper study skills for success in Organic Chemistry. The presumption is that the student has made it past general chemistry, and thus has learned the proper skills. This is not always so. Statistically, professors at smaller universities place a much higher emphasis upon teaching vs. research, and are more likely to review such skills. My years of experience teaching and tutoring have led me to develop a set of 9 Golden Rules for Success in Organic Chemistry.
Thus far we’ve looked at both thermodynamic and kinetic control in the Aldol Condensation. This is typically where most undergraduate Organic Chemistry professors conclude discussing the reaction. The topic of stereochemistry, however, is left mostly unexamined due to time constraints. The man pictured to the right, Professor Howard Zimmerman (1926-2012), University of Wisconsin – Madison was an exception to this rule. This article takes the Aldol Condensation one step further by discussing one of the most interesting aspects of the reaction. The article is dedicated to Professor Howard Zimmerman, one of my former mentors who helped shape me as a both a scientist and a teacher, and as a person who pursues the meaning in everything through deductive reasoning.