Smiles rearrangement as a tool for the preparation of 5-[(2-hydroxyacyl)amino]-2,4,6-triiodo-1,3-benzenedicarboxamides: Main pathway and side reactions

✍ Scribed by Pier Lucio Anelli; Marino Brocchetta; Luisella Calabi; Secchi Carlo; Fulvio Uggeri; Sandra Verona

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 565 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)00764-3

✦ Synopsis

In the preparation of 5-[(2-hydroxyacyl)amino]-2,4,6-triiodo-l,3-benzenedicartmxamides la-h from 2a-h two conditions using stoichiometric amounts of base (method A -aq NaOH at 50 °C; method B -MeONa in DMF at r. t.) were used. Yields are good to excellent provided that the right conditions are chosen. Primary amides 2a,b give la,b with method B only, whereas with method A extensive hydrolysis of the CONH 2 moiety is observed. N-Methyl derivatives 2¢,d afford lc,d with either method. However, with method B long reaction times lead to the formation of large amounts of benzoxazinones, 4c,d. Under the same conditions, the pattern of side products which are formed from N-(hydroxyalkyl)phenoxyacetamides 2e-g is furtherly complicated by: i) intramolecular cyclizations leading to bicyclic (7f, g) and tricyclic structures (5) ii) N-deacylation; iii) double Smiles rearrangement reactions.