Fast and Chemoselective Addition of Highly Polarized Lithium Phosphides Generated in Deep Eutectic Solvents to Aldehydes and Epoxides

• Published in: ChemSusChem 2020-09, Vol.13 (18), p.4967-4973
• Main Authors: Cicco, Luciana, Fombona‐Pascual, Alba, Sánchez‐Condado, Alba, Carriedo, Gabino A., Perna, Filippo M., Capriati, Vito, Presa Soto, Alejandro, García‐Álvarez, Joaquín
• Format: Article
• Language: English
• Subjects: Aldehydes; deep eutectic solvents; Eutectic reactions; Lithium; organolithium; Organometallic compounds; organophosphorus; Phosphides; phosphine oxide; Phosphines; Room temperature; Solvents; sustainable chemistry
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202001449

Highly polarized lithium phosphides (LiPR2) were synthesized, for the first time, in deep eutectic solvents as sustainable reaction media, at room temperature and in the absence of protecting atmosphere, through direct deprotonation of both aliphatic and aromatic secondary phosphines (HPR2) by n‐BuLi. The subsequent addition of in‐situ generated LiPR2 to aldehydes or epoxides proceeded quickly and chemoselectively, thereby allowing the straightforward access to the corresponding α‐ or β‐hydroxy phosphine oxides, respectively, under air and at room temperature (bench conditions), which are traditionally considered as textbook‐prohibited conditions in the field of polar organometallic chemistry of s‐block elements. A robust constitution: α‐ and β‐hydroxy phosphine oxides are synthesized by a fast and chemoselective one‐pot addition of the in‐situ generated highly polarized lithium phosphides (LiPR2) to both aldehydes and epoxides using eutectic mixtures as biorenewable reaction media. Despite the well‐known air and moisture sensitivity of organolithium compounds, the proposed synthetic protocol enables all reactions (preparation and reactivity of LiPR2) to be performed at room temperature, in protic solvents, and under air atmosphere.