US EPA

7447433 

Journal Article 

Intramolecular Schmidt Reaction of Alkyl Azides with Pentafluorophenyl Esters 

Cao Zhiqi; Li Rui; Su Yan; Gu Peiming 

2020 

1 

Youji Huaxue / Chinese Journal of Organic Chemistry
ISSN: 0253-2786 

Science Press 

40 

8 

2555-2562 

Chinese 

10.6023/cjoc202003017 

WOS:000581125800037 

The intramolecular Schmidt reaction of alkyl azides with pentafluorophenyl esters was investigated. The perfluorophenyl 5-azido-2-phenylpentanoate was employed as the model substrate, and the acid promoter, the solvent and the temperature were scanned. Then the titanium tetrachloride in the refluxing 1,2-dichloroethane was effective for the reaction of perfluorophenyl 5-azido-2-phenylpentanoate. Eleven 5-azido-pentanoates were designed and prepared for exploration, where different aryl, benzyl and alkyl groups were introduced at the α-carbon of perfluorophenyl ester. This type substrate would mainly give isocyanate ion as the primary product from Schmidt rearrangement. Then the scope of substrate was examined, and the experiment results indicated that the substrate with an electron-rich aryl or a benzyl group at the α-carbon of perfluorophenyl ester would afford a lactam via an intramolecular nucleophilic addition of arene to the isocyanate ion, and the substrate with an electron-deficient aryl or an alkyl group at the α-carbon of perfluorophenyl ester would give perfluorophenyl carbamate through an intermolecular capture of isocyanate ion with pentafluorophenol anion. The good leaving apptitude of pentafluorophenol anion should be accounted for inititating the Schmidt reaction, where the nucleophilic attack of azide onto perfluorophenyl ester would proceed very easy. © 2020 Chinese Chemical Society & SIOC, CAS. 

Schmidt reaction; N-heterocycle; azides; pentafluorophenyl esters; rearrangement