M. Mekhael, Richard J. Smith, S. Bienz
Sep 17, 2002
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ChemInform
Abstract
via Amidinium-Intermediates: A New Synthetic Approach to 2,3-Dihydro-1,3,3-trimethylindol-2-one [1]* Maged K. G. Mekhaela,b, Richard J. Smitha, Stefan Bienza, Anthony Lindena, and Heinz Heimgartnera a Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland b Mubarak City for Scientific Research and Technology Applications (MCSRTA), Alexandria, Egypt Reprint requests to Prof. Dr. H. Heimgartner. Fax: 0041-16356836. E-mail: heimgart@oci.unizh.ch Z. Naturforsch. 57b, 444Ð452 (2002); received January 11, 2002 2H-Azirin-3-amines, Ring Enlargement, 2,3-Dihydroindol-2-ones 2,2,N-Trimethyl-N-phenyl-2H-azirin-3-amine (1a) was prepared by successive treatment of 2,N-dimethyl-N-phenylpropanamide (18) with phosgene, triethylamine, and sodium azide. Reaction of 1a in THF solution with boron trifluoride gave 2-amino-1,3,3-trimethyl-3H-indolium tetrafluoroborate (19) in high yield. The latter reacted with acetic anhydride in pyridine to give a mixture of N-(2,3-dihydro-1,3,3-trimethylindol-2-yliden)acetamide (22) and 2,3-dihydro-1,3,3-trimethylindol-2-one (21). On hydrolysis with aqueous HCl, 22 was converted to 21. The molecular structures of 19 and 22 were established by X-ray crystal structure determination.