The Direct Phosphorylation Of 2-, 3-, and 4-Methylstyrenes and 2,4,6-Trimethylstyrene with Elemental Phosphorus VIA Trofimov–Gusarova Reaction

GRAPHICAL ABSTRACT

Abstract

3- and 4-Methylstyrenes react with red phosphorus in the superbase system KOH/DMSO (110 °C, 2 h) to afford tertiary phosphine oxides in 20–25% total yield. Under microwave irradiation (600 W) this reaction proceeds for 5 min giving in the case of 2-, 3-, and 4-methylstyrenes mixtures of tris[2-(methylphenyl)ethyl]phosphines and their oxides. Subsequent treatment of these products with H₂O₂ (acetone/H₂O, r.t., 5 min) allowed the phosphine oxides to be isolated in 45–68% yields. 2,4,6-Trimethylstyrene reacts with red phosphorus (KOH/DMSO 600 W, 5 min) in a similar manner to furnish tris[2-(2,4,6-trimethylphenyl)ethyl]-phosphine oxide (40% yield) along with 2-(2,4,6-trimethylphenyl)ethylphosphinic acid (21% yield).

Keywords:

• Elemental phosphorus
• phosphine oxides
• phosphines
• phosphinic acids
• styrenes
• superbase systems