title: Concise routes to pyrazolo[1,5-a]pyridin-3-yl pyridazin-3-ones.
abstract: Cycloaddition of pyridine N-imine with 6-alkyl-4-oxohex-5-ynoates followed by condensation with hydrazine provides concise access to pharmacologically active 6-(pyrazolo[1,5-a]pyridin-3-yl)pyridazinones. For the first time alkynyl heterocycles are also shown to be effective dipolarophiles for pyridine N-imine, and analogous compounds can be accessed directly in modest yields through the reaction of 6-(alkyn-1-yl)pyridazin-3-one derivatives.
authors: Chemistry Department, School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, UKEH14 4AS. D.R.Adams@hw.ac.uk
authors: Karen A
authors: KA
authors: Johnston
authors: Robert W
authors: RW
authors: Allcock
authors: Zhong
authors: Z
authors: Jiang
authors: Ian D
authors: ID
authors: Collier
authors: Haakon
authors: H
authors: Blakli
authors: Georgina M
authors: GM
authors: Rosair
authors: Patrick D
authors: PD
authors: Bailey
authors: Keith M
authors: KM
authors: Morgan
authors: Yasushi
authors: Y
authors: Kohno
authors: David R
authors: DR
authors: Adams
mesh_terms: D018360:Crystallography, X-Ray; D006834:Hydrazines / Q000737:chemistry; D007097:Imines / Q000737:chemistry; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D006834:Hydrazines; D007097:Imines; D011720:Pyrazoles; D011725:Pyridines; C447480:pyrazolo(3,4-b)pyridine; C527298:pyridine N-imine; C029424:hydrazine