10.1016/S0040-4039(00)76652-4
The research focuses on the asymmetric protonation of silyl enol ethers using a chiral proton donor supported on a polymer, aiming to address challenges in asymmetric synthesis. The purpose was to achieve improved asymmetric induction by supporting the proton donor on a polymeric chain, which could potentially allow for the recovery and recycling of the chiral inductor, reducing synthesis costs, and enabling reactions at more convenient temperatures without compromising enantiomeric excess. The study concluded that this approach resulted in higher chemical yields, significantly reduced reaction times, and a considerably higher optimum enantiomeric excess (up to 94%) compared to the 21% achieved in homogeneous solutions. The chemicals used in the process included silyl enol ethers, lithium enolates, pantothenic acid bound on Merrifield resin as the polymer-supported chiral proton donor, and various chiral alcohols such as pantothenol and methyl marzipate. The research demonstrated the advantages of using a polymer-supported chiral proton donor over its analogues, including the ability to recycle the chiral resin without a decrease in the degree of asymmetric induction.