Phosphorus oxide (P4O10) → 1-ethyl-3,4-dihydroisoquinoline

Participants

Reaction Steps

A mixture of N-(2-phenylethyl)-propionamide (10 g, 56.4 mmol) and phosphorus pentoxide (80 g, 563 mmol) in tetralin (500 ml) was heated at reflux for 15 min, cooled, further phosphorus pentoxide (80 g) was added and reflux was resumed for 15 min. After standing overnight the tetralin was decanted, the residue was decomposed with ice-water, the suspension was filtered through celite and washed with two portions of ether. The aqueous solution was basified with concentrated ammonium hydroxide, extracted with three portions of ether, the extracts were dried (MgSO4) and the solvent was evaporated giving a red solid (5.0 g, 55.7%); MS [M+H]+ 160.

Provenance & Evidence