Polyphosphoric acid is an effective reagent for bringing about the ring closure of 3- aryloxypropionic acids into 4-chromanones, 3-arylmercaptopropionic acids into 4- thiochromanones and r\ i', r\'-diaryl-P-alanines into 2, 3-dihydro-l-aryl-4 (1H)-quinolones. Phosphoryl chloride causes cyclization of Sp-chloro-and Sp-bromophenyl-Sp-tolylsulfonyl- L3-alanine into 6-halo-2, 3-dihydro-lp-tolylsulfonyl-4 (1H)-quinolone but the yields are low ...