Green, Palladium-Catalyzed Synthesis of Benzylic H-phosphinates from Hypophosphorous Acid and Benzylic Alcohols.
Benzylic alcohols cross-couple directly with concentrated H(3)PO(2) using Pd/xantphos (1 or 2 mol-%). Depending on the substrate, DMF at 110°C, or t-AmOH at reflux with a Dean-Stark trap, can be used. A broad range of benzylic alcohols reacted successfully in moderate to good yields. The preparation of other organophosphorus compounds (phosphinic and phosphonic acids) is also demonstrated.Asymmetric reaction with (R)-1-(2-naphthyl)ethanol provided the corresponding H-phosphinic acid in 77% ee. The methodology provides a green, PCl(3)-free, entry into benzylic-H-phosphinic acids.
Department of Chemistry, Texas Christian University, Box 298860, Fort Worth, Texas 76129, USA, Fax: :(+1)-817-257-5851.
Laëtitia
L
Coudray
Jean-Luc
JL
Montchamp