Studies of sodium azide with tetraphenylcyclopentadienones and various analogs

Abstract

<p>The reaction of sodium azide with 2-p-chloro- and 2-pâ methoxyphenylâ 3,4,5-triphenylâ 2,4-cyclopentadienâ Iâ one was studied to determine if the substituent would have any appreciable effect on the product distribution of the corresponding l,5,7,8â tetraphenyl-2,3,4â triazabicyclo[3.3.0]octa-2,7-dien-6-ones and the 3,4,5,6â tetraphenylâ 2(lH)â pyridinones that were formed by an acid catalyzed rearrangement. It was found that the chloro substituent had no effect on the reaction. The methoxy substituent had a moderate effect in that the product arising from the stabilized intermediate cation was favored by a ratio of approximately 3 to l.</p> <p> The two simple linear analogs studied were l,2,3,3â tetraphenyl-2- propen-l-one and 3,4,4-triphenyl-3â butenâ 2â one. These compounds did not react with azide, presumably due to charge delocalization. Also studied as a cyclic analog was 2,7-diphenyltropone which did not react due to the aromatic character of the tropone ring system. A reaction did occur with diphenylcyclopropenone to give an unidentified product. However, the reaction did not take place in the same fashion as for the tetracyclones.</p>