A High Yield Procedure for the Preparation of 2‐Hydroxynitrostyrenes: Synthesis of Imines and Tetracyclic 1, 3‐Benzoxazines. Issue 15 (21st March 2014)

• Record Type: Journal Article
• Authors: Tena Pérez, Víctor; Fuentes de Arriba, Ángel L.; Monleón, Laura M.; Simón, Luis; Rubio, Omayra H.; Sanz, Francisca; Morán, Joaquín R.
• Is Part Of: European journal of organic chemistry. Issue 15(2014)
• Page Start: 3242
• Page End: 3248
• Publication Date: 2014-03-21
• Subjects: Synthetic methods -- Heterocycles -- Schiff bases -- Nucleophilic addition -- Elimination; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201402016
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: Attempts to synthesize 2‐hydroxynitrostyrenes by a Knoevenagel condensation of salicylaldehyde and subsequent elimination were unsuccessful because of the formation of a stable imine. This could be easily prevented by using secondary amines to catalyze the reaction, which then afforded 2‐hydroxynitrostyrenes in high yields. In addition, the stable imine that was formed by employing ammonium acetate underwent a reaction with phosgene to allow the preparation of benzoxazines in good yields. Abstract : The reaction of salicylaldehyde, nitromethane, and ammonium acetate yields a surprisingly stable imine, which hinders the synthesis of 2‐hydroxynitrostyrene. Herein, we present a procedure to overcome this drawback and report the reaction of this stable imine with phosgene to afford benzoxazines in good yields.