# Sonochemistry and Biocatalysis: Two-Step Green Asymmetric Synthesis of Optically Active Dialkyl(4-(hydroxyalkyl)phenyl)phosphates

## TL;DR

This paper presents a two-step green method to synthesize optically active dialkylphenylphosphates using ultrasound and biocatalysis.

## Contribution

A novel metal-free, eco-friendly two-step synthesis combining sonochemistry and enzymatic reduction for optically active phosphates.

## Key findings

- Ketophosphonate intermediates were obtained in 70–97% yields using ultrasound and diphenyl ditelluride.
- Chiral phosphonates were formed with 50–98% yields and up to 99% enantiomeric excess via bioreduction.
- A telescoping approach reduced waste, cost, and time in the synthesis process.

## Abstract

A green and practical synthetic route for obtaining chiral O,O-dialkyl-O-phenylphosphonate
compounds is described here. The two-step synthetic strategy combines
sonochemistry with an enzymatic asymmetric reduction. In the first
step, aromatic hydroxyketones react with dialkyl H-phosphonates employing diphenyl ditelluride as an organocatalyst
under ultrasound irradiation for 2 h at 25 °C. The ketophosphonate
intermediates were obtained in satisfactory yields (70–97%).
In the second step, bioreduction was performed employing Daucus carota bits in water at 25 °C for 72
h. The chiral O,O-dialkyl-O-phenylphosphonates were formed in good to excellent yields
(50–98%) with satisfactory enantiomeric excesses (up to 99%).
This eco-friendly and metal-free synthetic route can also be performed
using a two-step sequential synthesis protocol (telescoping approach),
reducing waste, cost, and time. The enantiomeric excess of the products
was determined by a 31P NMR chiral discrimination protocol
based on the racemic hydroxyphosphonates using a simple and rapid
procedure.