The Synthetic Routes of 5-Methyl-3(2H)-pyridazinone

The synthesis of 5-methyl-3(2H)-pyridazinone, also known as α-pyridylpropionic acid, is an important goal in the chemical industry for its use as an intermediate in the production of a variety of chemicals, including pharmaceuticals and agrochemicals.
There are several synthetic routes available for the preparation of 5-methyl-3(2H)-pyridazinone, and in this article, we will discuss some of the most commonly used methods.

1. Heck reaction
   One of the most common methods for the synthesis of 5-methyl-3(2H)-pyridazinone is the Heck reaction, which involves the use of a palladium catalyst and a phosphine ligand to form the pyridazinone ring.
   The reaction typically involves the use of 2-iodoxybenzene and 5-methyl-2-styrene as the starting materials, although other combinations of starting materials can also be used.
   The reaction proceeds through a series of steps, including the formation of a carbocation intermediate, which is then attacked by the styrene molecule to form the pyridazinone ring.
   The Heck reaction is a well-established synthetic method and is widely used in the chemical industry.
   
2. Pd/C catalyzed hydrolysis of 3-chloro-2-cyclopentanone
   Another synthetic route to 5-methyl-3(2H)-pyridazinone involves the use of 3-chloro-2-cyclopentanone as the starting material.
   This method involves the use of a palladium catalyst, typically Pd/C, and hydrolysis of the starting material to form the pyridazinone ring.
   The reaction proceeds through the formation of an intermediate carbocation, which is attacked by the water molecule to form the desired product.
   This method is also well-established and is widely used in the chemical industry.
   
3. Other methods
   There are several other methods that can be used for the synthesis of 5-methyl-3(2H)-pyridazinone, including the use of lithium aluminum hydride (LiAlH4) reduction of the 2-nitro-5-methyl-3(2H)-pyridazinone, the reduction of the 3-bromo-2-cyclopentanone using lithium metal, and the reduction of the 2-chloro-5-methyl-3(2H)-pyridazinone using diborane.
   These methods may be less commonly used than the Heck reaction or Pd/C-catalyzed hydrolysis, but they can still be effective routes for the synthesis of 5-methyl-3(2H)-pyridazinone.
   

Overall, the synthesis of 5-methyl-3(2H)-pyridazinone is an important goal in the chemical industry, and there are several effective methods available for its synthesis.
The Heck reaction and Pd/C-catalyzed hydrolysis are two of the most common methods, but there are also other methods that can be used depending on the specific requirements of the synthesis.
These methods allow for the production of 5-methyl-3(2H)-pyridazinone in a variety of scales, from laboratory-scale to industrial-scale production, and they are widely used in the pharmaceutical and agrochemical industries for the synthesis of a variety of chemicals and drugs.