Synthesis of trans -N-2-aryl(heteryl)ethenamidines |
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| Authors: | K Nagarajan P Rajagopalan B G Advani V Ranga Rao and G A Bhat |
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| Institution: | (1) Hindustan CIBA-GEIGY Ltd., Research Centre, 400063 Bombay, India;(2) Present address: Bangalore Pharmaceuticals and Research Laboratories Pvt. Ltd., 45th Cross, 9th Block, Jayanagar, 560 069 Bangalore, India;(3) Present address: Medicinal Chemistry Division, Central Research & Development Department, E.I. DuPont de Nemours and Company, Experimental Station, Wilmington, USA |
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| Abstract: | 2-Amino-2-arylethylamides1 carrying electron-donating substituents in thepara position are transformed by hot POC13 to the the title compounds2, presumably via iminochlorides 7 and imidazolium derivatives8. Amides lacking this para-substituent give rise to chloroamidines11 under these conditions.m-Methoxyphenethylamide1t and POCl3 form, besides11f, an isoquinoline derivative3. The involvement of an imidazolium compound8 in the formation of ethenamidines has been verified by the synthesis of2a from10. Reaction of amide1w with PCl5 in the cold leads to, besides the chloroamidine11c, thecis-ethenamidine12 which equilibrates with thetrans-isomer2o in hot toluene. Thienylethyl urea13 converted by hot POCl3 to the imidazoline16, while phenylpropylamide17 forms only the iminochloride18a.
Contribution No. 752 from Research Centre |
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| Keywords: | Ethenamidine α -chloroamidine anomalous Bischler-Napieralski reaction imidazoline 2-azabutadienes |
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