Collect. Czech. Chem. Commun. 1987, 52, 1305-1314

Reaction of some nucleophiles with 2,6-di-tert-butylpyrylium perchlorate

Stanislav Böhma, Renata Prantováa, David Šamanb, Petr Trškaa and Josef Kuthana

a Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6
b Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


The title compound IV reacted with sodium borohydride to give the 4H-pyran VIIa and the dienone VIIIa whereas its reaction with sodium cyanide afforded exclusively the dienone VIIIb. Reaction of the salt IV with tert-butylmagnesium chloride or bromide gave a mixture of the 4H-pyran VIIa and the corresponding 4-tert-butyl derivative V. Upon treatment with hydrogen sulfide and hydrogen chloride, this mixture afforded 2,4,6-tri-tert-butyl-4H-thiopyran XI whereas aromatization with chloranil and subsequent reaction with ammonium acetate resulted in 2,4,6-tri-tert-butylpyridine (X). Analogously, the perchlorate IV reacted with ammonium acetate to give 2,6-di-tert-butylpyridine (VI). Addition of triphenylphosphine and potassium phthalimide to IV afforded exclusively the 4H-pyran derivatives XII and XIII. A similar reaction of nitromethyl anion led to the 4,4'-bis(4H-pyran) derivative XIV. Mechanism of the studied reactions and the reasons for the low reactivity of the sterically hindered pyridine derivative VI with electrophilic reagents are discussed.