Preparation of adamantylidene enol ethers by Wittig-Horner reaction

Abstract

A practical synthetic pathway of adamantylidene enol ethers by Wittig-Horner reaction has been developed. In this route, acetals were obtained by reaction of trimethyl orthoformate and benzaldehyde derivatives with tetrabutylammonium tribromide in methanol at room temperature. Trimethyl phosphite was converted into phosphonates with acetals in the presence of titanium (Ⅳ) tetrachloride in dichloromethane, followed by utilization of 2-adamantanone and lithium diisopropylamide (LDA) in anhydrous tetrahydrofuran under argon atmosphere at −78 °C to form adamantylidene enol ethers. Total yields are up to 66%.

Keywords

• Adamantylidene enol ether
• Wittig-Horner reaction
• 2-adamantanone