Studies on organophosphorus compounds XXIII synthesis of salicylthioamides and 4H-1,3,2-benzoxaphoshorine derivatives from the dimer of p-methoxyphenylthionophosphine sulfide and salicylamides

✍ Scribed by S. Scheibye; B. S. Pedersen; S.-O. Lawesson

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 383 KB
• Volume: 87
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19780870408

✦ Synopsis

Abstract

By heating secondary O‐hydroxybenzamides at 110‐120 °C with the dimer of p‐methoxyphenylthionophosphine sulfide, 1, in HMPA, the main product is the corresponding thioamide (15‐51 %) but in addition two phosphorheterocyclic systems are isolated, namely 2,3‐dihydro‐2‐(4‐methoxyphenyl)‐4H‐1,3,2‐benzooxazaphosphorine‐4‐thione 2‐sulfide, 4 (5‐23 %) and the corresponding 2‐oxide, 5 (13‐21 %). Cyclohexylsalicylamide at somewhat elevated temperature (∼ 120°C), only gives one phosphorus containing product besides the thioamide. This product is not a benzoxazaphosphorine derivative but a ring opened phosphonthioamidate, 6. A mechanism is suggested. The structures are determined by ^1^ H, ^13^ C, and ^31^ P NMR spectroscopy, as well as UV, IR, and MS spectrometry, and elemental analyses.