The Synthetic Routes of 6-cyclobutylpyridazin-3(2H)-one

6-Cyclobutylpyridazin-3(2H)-one, also known as 6-substituted pyridazin-3-one, is a synthetic organic compound that has garnered much attention in recent years due to its unique properties and diverse range of applications.
The synthetic routes to 6-cyclobutylpyridazin-3(2H)-one have been extensively studied, and many different methods have been developed to synthesize this compound.

The synthetic routes to 6-cyclobutylpyridazin-3(2H)-one can be broadly classified into two main categories: direct synthesis routes and indirect synthesis routes.
The direct synthesis routes involve the synthesis of 6-cyclobutylpyridazin-3(2H)-one from simple starting materials through a series of chemical reactions, while the indirect synthesis routes involve the synthesis of intermediate compounds that are eventually transformed into 6-cyclobutylpyridazin-3(2H)-one.

Direct Synthesis Routes

One of the most popular direct synthesis routes to 6-cyclobutylpyridazin-3(2H)-one involves the sulfonation of 2-cyanopyridine, followed by condensation with 3,4-dihydro-2H-pyran.
This route starts by the synthesis of 2-cyanopyridine from sodium cylindrate and hydrogen cyanide, followed by the sulfonation of the resulting compound using sulfuric acid.
The sulfonated 2-cyanopyridine is then treated with 3,4-dihydro-2H-pyran in the presence of a weak acid catalyst, such as hydrochloric acid, to form 6-cyclobutylpyridazin-3(2H)-one.

Another direct synthesis route to 6-cyclobutylpyridazin-3(2H)-one involves the use of 2-bromopyridine and 2-fluoropyridine in the presence of a Lewis acid catalyst, such as aluminum chloride.
The reaction is carried out in an inert solvent, such as ether or hexane, at a temperature of around 80-90°C.
The resulting compound can then be purified by recrystallization or chromatography.

Indirect Synthesis Routes

An indirect synthesis route to 6-cyclobutylpyridazin-3(2H)-one involves the synthesis of 2,3-dihydro-1H-pyrazolo[4,3-d]pyrimidin-4-amine, followed by its condensation with 2-chloro-6-fluoro-phenyl-acetamide.
The synthesis of 2,3-dihydro-1H-pyrazolo[4,3-d]pyrimidin-4-amine involves the reduction of 2,3-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-one using hydride reducing agents, such as lithium aluminum hydride or hydrogen in the presence of a solvent, such as N,N-dimethylformamide.
The resulting compound is then treated with 2-chloro-6-fluoro-phenyl-acetamide in the presence of an acid catalyst, such as sulfuric acid, to form 6-cyclobutylpyridazin-3(2H)-one.

Another indirect synthesis route to 6-cyclobutylpyridazin-3(2H)-one involves the synthesis of 3-fluoro-4-nitro-phenyl-acetate, followed by its condensation with 2-amino-5-bromopyridine.
The synthesis of 3-fluoro