Kinetics and mechanism of the unusual insertion reactions of aryl isocyanates into the CC bond of the phosphonium zwitter-ion derived by the reaction of triisopropylphosphine with ethyl 2-cyanoacrylate

✍ Scribed by V. I. Galkin; Yu. V. Bakhtiyarova; Yu. G. Gololobov; N. A. Polezhaeva; R. A. Cherkasov

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 182 KB
• Volume: 9
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/(sici)1098-1071(1998)9:7<665::aid-hc11>3.0.co;2-i

✦ Synopsis

The kinetics of the reactions of aryl isocyanates with the zwitterion formed by the addition of triisopropylphosphine to ethyl 2-cyanoacrylate in acetonitrile solution have been determined by a spectrophotometric method. It was established that the reaction is second order overall, first order with respect to each of the reagents. A mechanism is proposed that consists of an attack of the carbanionoid center of the phosphabetaine on the carbonyl carbon atom of the isocyanate group and nucleophilic attack of the isocyanate nitrogen atom on the carbonyl carbon of the ester group, with rupture of the appropriate C-C bond, within the framework of a cyclic transition state.