Tavaborole Synthesis via Diboron Catalysis
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Solution Overview
Problem
Current processes for producing Tavaborole, an oxaborole antifungal, face challenges such as the use of toxic and hazardous reagents like Boron tribromide and n-butyl lithium, low yields, formation of impurities, and the need for costly and laborious purification methods like column chromatography, making them unsuitable for industrial-scale production.
Innovation Solution
A novel process involving the steps of treating (2-bromo-5-fluoro-phenyl)-methanol with trityl chloride, followed by reaction with bis(pinacolato)diboron in the presence of a transition metal catalyst, and subsequent deprotection and cyclization to produce Tavaborole, which avoids the use of toxic reagents and reduces the need for extensive purification, resulting in high yield and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Boron tribromide is used in the preparation process, then the reaction can proceed, but the process becomes toxic and requires special handling
Solution Approach 1:
The patent removes the toxic Boron tribromide reagent from the synthesis pathway entirely, replacing it with non-toxic alternatives. This extraction of the harmful substance eliminates the need for special handling while maintaining the core synthetic function through alternative reagents like trimethyl borate or boric acid combined with tin-based catalysts.
Solution Approach 2:
The patent introduces intermediate compounds and alternative reagent systems that mediate the boronation reaction without requiring toxic Boron tribromide. The use of trimethyl borate or boric acid as boron sources, combined with tin catalysts, creates a safer intermediate pathway that achieves the same synthetic objective without the harmful factors.
2Ease of manufacture
If n-butyl lithium is used in the preparation process, then the reaction can proceed, but the process becomes hazardous and difficult to handle at plant scale
Solution Approach 1:
The patent completely removes n-butyl lithium from the synthesis pathway, eliminating the fire and explosion hazards associated with this highly reactive reagent. The alternative methodology uses much safer reagents that can be handled at plant scale without special safety infrastructure.
Solution Approach 2:
The patent employs stable, non-hazardous reagents that can be used in standard industrial settings without the need for specialized safety equipment. The reagents are designed to be handled under normal industrial conditions, making the process economically viable for large-scale production.
3Manufacturing precision
If column chromatography is used for purification, then the purity can be improved, but the process becomes laborious and increases solvent consumption
Solution Approach 1:
The patent removes the need for column chromatography by designing a synthesis pathway that inherently produces minimal impurities. The selective chemistry and optimized reaction conditions ensure high purity products that require only simple filtration or washing steps for purification.
Solution Approach 2:
The patent employs reagents and reaction conditions that self-purify the product during the reaction process. The selective formation of the desired product and the stability of intermediates allow the reaction mixture to naturally separate from impurities, eliminating the need for complex purification equipment and procedures.
4Manufacturing precision
If the reaction is carried out at -78°C, then the selectivity can be improved, but the temperature is difficult to attain during commercial production
Solution Approach 1:
The patent changes the temperature parameter from cryogenic -78°C to ambient or mildly elevated temperatures. This parameter change is achieved by using reagents and catalysts that provide sufficient selectivity at higher temperatures, eliminating the need for expensive and complex cryogenic cooling infrastructure while maintaining product selectivity.
Solution Approach 2:
The patent replaces the mechanical cryogenic cooling system with a chemical solution that provides temperature-independent selectivity. The use of selective catalysts and optimized reagent combinations achieves the desired selectivity through chemical mechanisms rather than physical temperature control, simplifying the manufacturing infrastructure.
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 process achieves high yield and purity of Tavaborole with reduced chemical waste and operational complexity, making it industrially viable and cost-effective, while eliminating the use of hazardous materials and cumbersome purification steps.
Implementation Method 1
reacting of compound of formula (IV) with bis(pinacolato)diboron in the presence of a transition metal catalyst and a base in suitable solvent to give 2-(4-fluoro-2-tritylmethyl-phenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane of compound of formula (III)
Implementation Method 2
reacting of compound of formula (IV) with bis(pinacolato)diboron in the presence of a transition metal catalyst and a base in suitable solvent
Implementation Method 3
deprotecting and cyclizing the compound of formula (II) or (III) in the presence of suitable acid and solvent to give Tavaborole of formula (I)
Data Source
AI summary
The present invention provides a novel and improved process for the preparation of Tavaborole of Formula (I) and its pharmaceutically acceptable salts. The present invention also provides novel intermediates and process for the preparation of intermediates used in the preparation of Tavaborole. The present invention also provides an improved process for the preparation of Tavaborole and pharmaceutically acceptable salts thereof, that is commercially and industrially scalable.