Concise routes to pyrazolo[1,5-a]pyridin-3-yl pyridazin-3-ones.
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.
Johnston
Karen A
KA
Chemistry Department, School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, UKEH14 4AS. D.R.Adams@hw.ac.uk
Allcock
Robert W
RW
Jiang
Zhong
Z
Collier
Ian D
ID
Blakli
Haakon
H
Rosair
Georgina M
GM
Bailey
Patrick D
PD
Morgan
Keith M
KM
Kohno
Yasushi
Y
Adams
David R
DR
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*
D006834:Hydrazines; D007097:Imines; D011720:Pyrazoles; D011725:Pyridines; C447480:pyrazolo(3,4-b)pyridine; C527298:pyridine N-imine; C029424:hydrazine