Hydroxylation of azulenes with tert-butylhydroperoxide active nucleophile, also reacts with unsubstituted azulene. A variety of transformations of 6-hydroxyazulenes, such as proceeds efficiently at the 6-position when the former contain electron-withdrawing substituents in the five-substitution of the corresponding sulfonates with nitrogen, oxygen, sulfur, carbon nucleophiles and halogens, and the membered ring. Similarly, VNS amination of azulenes proceeds with 4-amino-1,2,4-triazole; its anion, being an Claisen rearrangement of allylic ethers, is reported.
ence of potassium tert-butoxide in liquid ammonia gave
Results and Discussion
Hydroxylation of Azulenes
The hydroxylation of nitroarenes proceeds smoothly by reaction with tert-butyl or cumyl hydroperoxides in the presence of strong bases. [9] [10] However, the first attempts Scheme 1 at hydroxylation of azulene (1a) with tBuOOH in the pres-In all these reactions we observed the formation of only [a] Institute of Organic Chemistry, Polish Academy of Sciences, one product of the hydroxylation in the 6-position; forma-Kasprzaka 44, 01-224 Warsaw, Poland tion of 4-or 8-hydroxyazulenes was not observed.