Chiral Phosphorothioate Synthons for Scalable Stereocontrolled Synthesis
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Solution Overview
Problem
Existing methods for synthesizing P-chiral phosphorothioates are limited by the use of labile P(III) intermediates, multiple-step processes, scale limitations, and poor coupling efficiency, which hinder efficient large-scale production and flexibility in nucleotide synthesis.
Innovation Solution
Development of novel P(V)-based orthogonally protected chiral phosphorothioates, bearing a fluorenylmethyl group and a pyridinyl group on a chiral alcohol, which serve as synthons for the stereoselective synthesis of P-chiral phosphorothioates, allowing for simple operation and easy scale-up without the need for column chromatography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If P(III)-based phosphoramidite intermediates are used for synthesis, then chiral phosphorothioates can be formed, but the intermediates are labile and require multiple-step synthesis with poor coupling efficiency
Solution Approach 1:
The patent changes the oxidation state parameter of phosphorus from P(III) to P(V), transforming labile phosphoramidite intermediates into stable phosphorothioate intermediates. This parameter change maintains reliability while improving coupling efficiency and enabling scale-up.
Solution Approach 2:
The patent replaces stable but inefficient P(III) intermediates with P(V) intermediates that are stable yet can be easily manipulated. The new intermediates act as disposable building blocks that can be coupled efficiently and then transformed into final products without requiring complex purification.
2Manufacturing precision
If traditional multi-step synthesis methods are used, then chiral phosphorothioates can be synthesized, but the process is complex and difficult to scale up
Solution Approach 1:
The patent performs preliminary oxidation of phosphorus from P(III) to P(V) state before coupling reactions. This preliminary action stabilizes the intermediate structures, allowing for simpler, fewer synthesis steps while maintaining stereochemical control through the stable P(V) configuration.
Solution Approach 2:
The patent segments the synthesis process into distinct modular steps using stable P(V) intermediates with orthogonal protecting groups. Each intermediate can be prepared independently and then coupled in a streamlined sequence, reducing overall process complexity while maintaining precision.
3Measurement precision
If conventional synthesis approaches are used, then oligonucleotides can be synthesized, but column chromatography is required which is impractical for large scale production
Solution Approach 1:
The patent extracts the purification step (column chromatography) from the synthesis process by designing P(V) intermediates with orthogonal protecting groups that enable selective deprotection and purification through simpler methods such as precipitation or filtration, making the process scalable to large production volumes.
Solution Approach 2:
The patent changes the chemical state parameters of the phosphorus intermediates to P(V) with specific protecting group configurations that inherently favor product formation and enable straightforward purification without requiring chromatographic separation, thus improving both purity and scalability.
4Productivity
If strong base DBU is used for chain elongation, then phosphorus-sulfur incorporation is achieved, but flexibility of protecting group choice is limited
Solution Approach 1:
The patent applies local quality by using orthogonal protecting groups with different stability characteristics at different positions on the molecule. This allows selective deprotection at specific sites using mild conditions, maintaining protecting group flexibility even in the presence of strong base DBU required for phosphorus-sulfur incorporation.
Solution Approach 2:
The patent introduces orthogonal protecting groups as intermediary elements that mediate between the strong base conditions required for coupling and the need for protecting group stability. These intermediaries allow the strong base to perform its function while the protecting groups remain intact or can be selectively removed under controlled conditions.
Data Source
AI summary
This invention relates to compounds of Formula (I) useful as synthons for a general synthetic method for making chiral phosphorothioates, to their preparation and to their use in a robust large scale process for making P-chiral phosphorothioates.