LpxC Analog Intermediates Process for Scalable Chiral Synthesis
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Solution Overview
Problem
Existing processes for producing the LpxC inhibitor (R)-4-(4-(2H-1,2,3-triazol-2-yl)phenyl)-2-oxopyridin-1(2H)-yl)-N-hydroxy-2-methyl-2-(methylsulfonyl)-butanamide are not scalable, yield low enantiomerically pure intermediates, and require expensive and dangerous reagents, making them inefficient and hazardous.
Innovation Solution
A novel scalable process is developed using safer reagents and stable intermediates, involving specific reaction conditions and chiral chromatography to produce higher yields of the enantiomerically pure intermediate compounds, such as 3-methyl-3-(methylsulfonyl)dihydrofuran-2(3H)-one and 4-(4-chloro-2-oxopyridin-1(2H)-yl)-2-methyl-2-(methylsulfonyl)butanoic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the existing process using expensive and dangerous reagents (Cs2CO3, NaH) is used, then the LpxC inhibitor can be prepared, but the process is not scalable with low yield (13%) and high costs
Solution Approach 1:
The patent replaces expensive reagents (Cs2CO3) and dangerous reagents (NaH) with cheaper and safer alternatives (K2CO3, CsF). This substitution maintains the desired chemical transformation while significantly reducing cost and improving safety, enabling scalable manufacturing. The new reagents achieve the same intermediate preparation but with 31% yield compared to the previous 13% yield.
2Reliability
If the existing multi-step process with unstable intermediates is used, then the LpxC inhibitor can be prepared, but the process requires extra synthetic steps and unstable intermediates
Solution Approach 1:
The patent eliminates the unstable intermediate (ethyl 4-bromo-2-methyl-2-(methylsulfonyl)butanoate) from the synthetic pathway by using a different reaction sequence. The new process directly converts stable starting materials to stable intermediates through controlled reactions, removing the need to handle and store unstable compounds, thereby simplifying the overall process and improving reliability.
Solution Approach 2:
The patent performs preliminary protection of functional groups and prepares stable intermediates before the key transformation steps. By pre-establishing stable molecular structures with protected functional groups, the process avoids forming unstable intermediates during the synthesis, allowing for fewer steps and better overall process reliability.
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
The new process achieves a 31% yield of the enantiomerically pure intermediate, reducing costs and hazards while enabling large-scale production of the LpxC inhibitor.
Implementation Method 1
reacting 3-bromotetrahydrofuran-2(3H)-one (a) with sodium methanesulfinate in the presence of solvent A, a phase transfer catalyst and optionally, a dehydrating agent, at a temperature of 40-100°C for 1-24 hours to prepare intermediate 3-(methylsulfonyl)-dihydrofuran-2(3H)-one (b)
Implementation Method 2
reacting the solids with a base in the presence of a phase transfer catalyst, a methylating agent, solvent B, and optionally, a dehydrating agent, at a temperature of 40-100°C for a period of 4-48 hours
Implementation Method 3
reacting the solids with a base in the presence of a phase transfer catalyst, a methylating agent, solvent B, and optionally, a dehydrating agent, at a temperature of 40-100°C for a period of 4-48 hours
Implementation Method 4
cooling further to induce crystallization, filtering and washing the crystals with solvent A to afford the final product, 3-methyl-3-(methylsulfonyl)-dihydrofuran-2(3H)-one (rc1)
Data Source
Figure 1
AI summary
The application relates to the novel intermediates (rc1) and (rc2) and to processes for their preparation. The intermediates are useful for preparing the LpxC hydroxamic acid inhibitor (R)-4-(4-(4-(2H-1,2,3-triazol-2-yl)phenyl)-2-oxopyridin-1 (2H)- yl)-N-hydroxy-2-methyl-2-(methylsulfonyl)butanamide (1).