Cyclic Alkyl Triphosphoic Anhydride Amide Coupling
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Solution Overview
Problem
Current synthetic processes for ixazomib and its citrate ester rely on expensive and toxic reagents like TBTU and EDCI, which pose challenges for scale-up due to racemization risks and complex workup procedures.
Innovation Solution
A process using cyclic alkyl triphosphoic anhydride as a coupling agent, specifically n-propyl-substituted, to perform amide coupling reactions under mild conditions, minimizing racemization and toxicity, and facilitating easier purification and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TBTU or EDCI/HOBt coupling reagents are used for amide coupling, then the coupling reaction can proceed, but the process becomes expensive, toxic, and prone to racemization
Solution Approach 1:
The patent replaces expensive, toxic coupling reagents (TBTU, EDCI/HOBt) with a cheaper, less toxic alternative: cyclic alkyl triphosphoic anhydride. This reagent is used in stoichiometric amounts and can be removed by simple aqueous workup, eliminating the need for complex purification procedures. The reagent itself is less toxic and does not pose the same racemization risks as the prior art reagents.
Solution Approach 2:
The patent changes the chemical parameters of the coupling reaction by using a different class of coupling reagent (cyclic alkyl triphosphoic anhydride instead of uronium or carbodiimide reagents). This parameter change results in milder reaction conditions that prevent racemization of the chiral center in the ixazomib molecule, while also reducing toxicity and simplifying workup procedures.
2Ease of manufacture
If TBTU or EDCI/HOBt are used for coupling, then amide bonds can be formed, but tedious workup procedures are required
Solution Approach 1:
The cyclic alkyl triphosphoic anhydride reagent is designed to be water-soluble and easily removable by aqueous workup. After the coupling reaction, the reagent and its byproducts can be simply washed away with water or dilute acid/base solutions, eliminating the need for tedious chromatography or multiple extraction steps required when using TBTU or EDCI/HOBt.
3Manufacturing precision
If conventional coupling reagents are used, then coupling can occur, but there is risk of racemization of reactants
Solution Approach 1:
The patent changes the reaction conditions by using cyclic alkyl triphosphoic anhydride, which activates the carboxylic acid without forming highly reactive intermediates that could attack the chiral center. The reagent operates under milder conditions with lower activation energy, preventing racemization while still achieving complete coupling. This has been demonstrated experimentally with retention of optical purity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a more efficient, scalable, and cost-effective synthesis of ixazomib with reduced toxicity and epimerization, enabling higher yields and simpler purification processes.
Implementation Method 1
The process comprising at least one amide coupling reaction in the presence of a cyclic alkyl triphosphoic anhydride
Data Source
AI summary
This invention relates to a process for preparing Ixazomib 1, its trimer 1.trimer, its citrate ester 2 or an intermediate for their synthesis. The process comprising at least one amide coupling reaction in the presence of a cyclic alkyl triphosphonic anhydride 9, wherein the R1 groups in the cyclic alkyl triphosphonic anhydride 9 are C1-C6 alkyl groups, preferably n-propyl groups.