Experimental

In dry 100 mL round-bottom flask on hot plate magnet stirrer was dissolved 3 g Na-metallic in 40 ml absolute ethanol. It takes about 1 h, after dissolving half portion of Na reflux (cooler+CaCl₂-tube!) was needed. During obtaining NaOEt is necessary to prepare dry ethyl acetate. AcOEt was treated 30 min with dry Na₂SO₄, then 30 min with P₂O₅. Distillation is desirable, but not necessary.

When Na completely dissolved, hot plate was off, then 15 mL (1.5 equiv) of this dry ethylacetate followed by 11.7 mL (1.0 equiv) of benzyl cyanide were added to reaction flask and its was carefully continue to reflux. After 5 min white precipitate was appear together with foam. Is necessary to control this moment of reaction. When the foam was come down, reflux (with stirring) continued for next 1 h.

After approx one hour reaction mixture was cooled down, dissolved in 70 mL of water, washed twice with CH₂Cl₂, cooled to 5-10°C and neutralized by addition of 8 mL of acetic acid. Obtained precipitate of Bz(COMe)CN was filtered off, washed with water and used on next stage without additional purification and drying.

To a wet (or dry) Bz(COMe)CN in 250 mL round-bottom flask was added cooled to r.t. mixture of 20 mL of H₂SO₄ and 8 mL of water and obtained mixture was carefully warmed on hot plate magnet stirrer. At 70-80°C starting material was dissolved, after 5-10 min was exothermic reaction with temperature rise to boiling. The yellow oil with specific smell of P2P was appeared from flask. 50 mL of water was added carefully via cooler and reflux continued for next 1 h. After cooling, P2P was separated, water phase was extracted with 30 mL of ether, combined organic phases dried with Na₂SO₄ and solvent was removed under reduced pressure. Yield – 10 g of P2P (75%) for two stages. This product can be used on next stage without additional purification with some decrease of yield on next stage.