Synthesis of High Value 4-hydroxy and 4-oxo Pipecolic Acid Derivatives from a Process Byproduct

Abstract

Functional transformations of4-substituted pipecolic acid derivatives are described. Many 4-substituted pipecolic acid derivatives are found throughout nature and within many pharmaceutical targets. The goal of this research involved recycling a pipecolic acid byproduct in order to make useful, marketable compounds. The highlight ofthe transformations includes an oxidation reaction with a TEMPO radical catalyst. Overall yields were 20% in three steps and 55% in two steps to the respective ketone products. Additionally, a Wittig reaction followed by a selective reduction on a 4- oxopipecolic acid product to produce a protected carboxylic acid at position-4 was explored.