Hydrazine → 2-((5-Bromo-3-pyridyl)methyl)-1-azabicyclo[2.2.2]octane

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Reaction Steps

The manner in which 2-((5-bromo-3-pyridyl)methyl)-1-azabicyclo[2.2.2]octane and other analogous compounds possessing substituents at the C-5 position of the pyridine ring are synthesized can vary. In another example, 2-((5-bromo-3-pyridyl)methyl)-1-azabicyclo[2.2.2]octane can be prepared starting with the aldol condensation of 5-bromo-3-pyridinecarboxaldehyde and 3-quinuclidinone hydrochloride (commercially available from Aldrich Chemical Company) which proceeds in 75% yield using potassium hydroxide in methanol. The carbon-carbon double bond of the resulting 2-((5-bromo-3-pyridyl)methylene)-1-azabicyclo[2.2.2]octan-3-one can be selectively reduced with an appropriate reducing agent, such as lithium tri-sec-butylborohydride (L-Selectride®) or potassium tri-sec-butylborohydride (K-Selectride®) (available from Aldrich Chemical Company) in tetrahydrofuran at −78° C. using methodology described by J. M. Fortunato et al., J Org. Chem. 41 (12): 2194-2200 (1976) or with sodium borohydride modified with nickel(1) chloride hexahydrate in an ethanolic or aqueous solution to give 2-((5-bromo-3-pyridyl)methyl)-1-azabicyclo[2.2.2]octan-3-one. The latter ketone can be reduced under Wolff-Kishner conditions with hydrazine and base (or under modified Wolff-Kishner conditions with tosylhydrazine and sodium cyanoborohydride) to yield 2-((5-bromo-3-pyridyl)methyl)-1-azabicyclo[2.2.2]octane.

Provenance & Evidence