Unexpected intramolecular nucleophilic cyclization of ureidoacetamide: A novel route towards the synthesis of 2,4,5-trisubsituted oxazoles |
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| Authors: | Jianhui Liu Yawen Dong Guanglan Li Xiangting Min Mustafa Hussain |
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| Institution: | 1. State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, Liaoning Province 116024, PR China;2. School of Petroleum and Chemical Engineering, Dalian University of Technology, Panjin Campus, Panjin, Liaoning Province 124221, PR China |
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| Abstract: | A variety of N, 2-diaryl-2-ureidoacetamide prepared from the condensation of N-aryl-α-aminoamide with potassium cyanate (KOCN) undergo efficient Hendrickson’s reagent-mediated nucleophilic cyclization to afford 2,5-diamine-4-aryloxazoles. The two-step synthesis provides seven target products in yields of 61–78% under mild conditions. This reaction involves an unusual pathway in which the electrophilic amide carbonyl carbon is activated by Hendrickson’s reagent and attacked by a nucleophilic ureido oxygen in a 5-exo-trig O-cycloisomerization. |
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| Keywords: | Corresponding author at: School of Petroleum and Chemical Engineering Dalian University of Technology Panjin Campus Panjin Liaoning Province 124221 PR China Oxazoles Hendrickson’s reagent Ureidoacetamide |
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