Progress Towards the Syntheses of Cajanusine and Long-Chain Hydroxy Acids

Abstract

Strategies leading to concise syntheses were developed and pursued for two sets of natural products: (–) Cajanusine and C18, C20 and C22 tetra-deuterated hydroxy acids. Palladium-catalyzed C–H activation was explored as a method to arylate a mono-substituted cyclobutane in progress towards Cajanusine. A flouroamide transient directing group with a methyl pyridine ligand was found to be the most successful in producing a mono-arylated product. However, difficulties with scalability and yield led to the project being set aside. Meanwhile, two strategies towards the production of C18, C20 and C22 alkyne hydroxy acids were explored: molybdenum-catalyzed alkyne metathesis and alkyne substitution. Alkyne substitution was found to be the most straightforward method to achieve the hydroxy acid, which is expected to be smoothly deuterated. In the future, more work needs to be done to improve the yield of the alkyne substitution reaction, and a potential alternate strategy is proposed for achieving the product.