|Institution:||Wake Forest University|
|Full text PDF:||http://hdl.handle.net/10339/14680|
Since the birth of organic chemistry in the 19th century, scientists have been discovering new reactions to generate interesting synthetic targets. As these new reactions have emerged, they are constantly tweaked so that an array of substrates can be synthesized and better catalysts can be discovered. The focus of our research is to two-fold: (1) to study the reaction chemistry between allenes and imines, and (2) to discover new catalysis and novel substrates for the ene reaction. Reactions between allenes and imines have been mostly unexplored despite their ability to generate useful synthetic intermediates. Described herein is the initial screening of the reaction conditions for the intended allenyl imino-ene reaction, however the primary focus of this project is on the development of an unexpected aza-Baylis–Hillman-type reaction between ketoallenes and imine-containing electrophiles. This chemistry shows promise for a new single step, atom economical reaction for the generation of unnatural amino acids containing densely functionalized alkenes and allene moieties. In addition to studying new reactions, we have worked on the further development of the established ene reaction. The ene reaction is one of the most powerful carbon–carbon bond-forming reactions in organic chemistry. The resulting products can be used as synthons for natural products, as well as substrates for drug targets. Lewis acid catalyzed ene reactions provide access to homoallylic amines and alcohols. However, the scope of this type of catalysis is limited because of the need for inert conditions, the metal waste generated, and the metal’s stronger chelation to the product than the starting material. As an alternative, we have developed Brønsted acid catalyzed ene reactions. A phosphonic acid has been identified as a viable catalyst for the carbonyl-ene and imino-ene reaction. In addition, this phosphonic acid was shown to promote a cyclization reaction of hydrazones to generate pyrazolidine derivatives. This chemistry shows the potential of a phosphonic acid as a more general catalyst for these types of reactions.