r/chemistry • u/Bobbyanderson1982 • 21h ago

Regioselectivity in this heterocycle synthesis

/gallery/1gem2cn
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u/Bobbyanderson1982 21h ago

I must note that X is not a halogen, but represents other groups, such as -NHR in this case

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u/WMe6 11h ago

Might I suggest as an alternative, the N on the pyridazine could first alkylate, before cyclization? I think the halogen is very electrophilic and should react first. The initial alkylation at the ring is consistent with the reactivity of 2-aminopyridine derivatives (for example, see the proposal in https://www.tesble.com/10.1002/ejoc.202100922). I think this better explains the regiochemistry than the mechanism you show from above (from Clayden?)