156969-34-5Relevant articles and documents
The Pyrolytic Rearrangement of 1-Alkynoyl-3-methylpyrazoles: Synthesis of Pyrazolopyridin-5-ols and Related Compounds
Brown, Roger F. C.,Eastwood, Frank W.,Fallon, Gary D.,Lee, Swee Choo,McGeary, Ross P.
, p. 991 - 1008 (2007/10/02)
Flash vacuum pyrolysis of 1-(alkyn-2'-oyl)-3-methylpyrazoles at 650 deg/0.03 mm forms pyrazolopyridin-5-ols, often in high yield, which may bear substituents at C2, C3 or C7.In the absence of a 3-methyl group in the precursor, N-ethynylpyrazoles are formed in low yield.The formation of both types of product is interpreted as involving 3-(N-pyrazolyl)propadienones formed by N1 --> N2 migration of the N-alkynoyl group with inversion of the three-carbon chain.The fused-ring structure of 2-methylpyrazolopyridin-5-ol (25) was established by X-ray crystallography of the O-benzoyl derivative (27).