A new route to 1,5-disubstituted 4-arylsulfonylpyrazoles by lithiation of 1-methyl-4-arylsulfonylpyrazoles
摘要:
The arylsulfonylvinamidinium salts 1 reacted with hydrazine in refluxing ethanol to give rise to 4-arylsulfonylpyrazoles 2 in reasonable yield. Regioselective lithiation of N-methylpyrazoles 3 with LDA followed by treatment with various electrophiles afforded the corresponding 1,5-disubstituted 4-arylsulfonylpyrazoles 5 in good yield.