Novel α-hydroxy phosphonic acids via castor oil

Hydroxy fatty acids (HFAs) have found a number of uses in today's market, with uses ranging from materials to pharmaceuticals. Castor oil has served as a source of a versatile HFA; its principle component, ricinoleic acid, can be isolated from castor oil and has been modified extensively for a number of applications. Additionally, α-hydroxy phosphonates and their corresponding phosphonic acids are a functional moiety that have been shown to display a wide variety of biological activities, as enzyme inhibitors, pesticides, antibiotics and anti-cancer therapeutics. We were interested in combining these two functionalities, HFAs modified to produce α-hydroxy phosphonates and phosphonic acids, as potentially biologically active molecules. We have accomplished the synthesis of two families of α-hydroxy phosphonic acids based on ricinoleic acid: a family that retains the cis alkene found in ricinoleic acid to produce an unsaturated α-hydroxy phosphonic acid and one where the alkene has undergone hydrogenation to produce a saturated α-hydroxy phosphonic acid. These compounds have been produced in high yields and high purity, and the synthesis of these compounds is reported in this manuscript.

► Castor oil is a source of a widely used hydroxy fatty acid.
► α-Hydroxy phosphonic acids are known for interesting biological properties.
► Ricinoleic acid was synthetically modified to produce α-hydroxy phosphonic acids.
► Two families of ricinoleic acid derivatives have been produced in high yields.