An improved synthesis of captopril

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Pharmaceutical Synthesis

Background:

• Captopril is a vital angiotensin-converting enzyme (ACE) inhibitor used to treat hypertension and heart failure.
• Existing synthesis routes for captopril can be complex and may require optimization for efficiency and yield.
• Developing alternative synthetic pathways is crucial for cost-effective pharmaceutical production.

Purpose of the Study:

• To describe an improved and efficient synthesis of captopril.
• To utilize methacrylic acid as a readily available starting material.
• To optimize intermediate steps for higher overall yield.

Main Methods:

• Synthesis initiated with methacrylic acid treated with hydrogen halide to form 3-halogeno-2-methylpropanoic acids.
• Conversion of acids to acyl chlorides using thionyl chloride.
• Coupling of acyl chlorides with L-proline to form N-(R,S-3-halogeno-2-methylpropanoyl)-L-prolines.
• Separation of diastereoisomers using dicyclohexylamine.
• Final conversion to captopril using methanolic ammonium hydrosulfide.

Main Results:

• Successfully synthesized captopril from methacrylic acid.
• Achieved a 28% overall yield for captopril.
• Demonstrated the utility of diastereoisomer separation for purification.

Conclusions:

• The described method provides an improved synthesis of captopril.
• Methacrylic acid is a viable starting material for captopril production.
• This pathway offers a potentially more accessible route for captopril synthesis.