Isoxazoles from ketone oximes

Several 3/3-(aryl)-2/3-(3-substituted isoxazol-5-yl)tropanes 375 were synthesized from methyl esters 374 by reaction with the dilithium salt of the appropriate ketone or aldehyde oxime (Scheme 90) <2004JME296>. The same procedure was applied to 7-ethoxycarbonyl-2-azabicyclo[2.2.1]heptanes for the synthesis of novel epibatidine analogues, such as 376 <2004JOC5328>. The reaction of a-bromoketone oximes with isocyanides and sodium carbonate led to 5-aminoisoxazole derivatives in good yields. Probably, isocyanides are involved in a [4-1-1] cycloaddition with nitrosoalkene intermediates <1997TL8027>. 

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