BIBS Protected Nucleoside for Borane-Stable Oligonucleotide Synthesis
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Solution Overview
Problem
Current methods for oligonucleotide synthesis face challenges in selectively removing exocyclic amine protecting groups, particularly under mild conditions, and are unsuitable for borane-containing oligonucleotide analogs due to instability with borane reagents and side reactions during capping steps.
Innovation Solution
The use of sterically hindered silyl protecting groups, such as bis-tert-butylisobutylsilyl (BIBS), which are stable to oligonucleotide synthesis conditions, including borane reagents and strongly basic conditions, and can be selectively removed under mild fluoride treatment, allowing for the synthesis of longer oligonucleotides, including boranephosphonate DNA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If amide based protecting groups are used on exocyclic amines, then deprotection can be achieved under mild basic conditions, but the protecting groups are unstable to borane reagents and undergo side reactions during capping steps
Solution Approach 1:
The patent changes the chemical parameter of the protecting group from amide-based to silyl-based, which fundamentally alters its stability profile. Silyl protecting groups are stable to borane reagents and basic capping conditions while still allowing mild deprotection, thus resolving the contradiction between ease of operation and reliability
Solution Approach 2:
The silyl protecting group acts as an intermediary that mediates between the conflicting requirements of mild deprotection and stability to borane reagents. It provides a stable protecting group that can be selectively removed under mild fluoride conditions without interfering with borane-containing oligonucleotide analogs
2Adaptability or versatility
If synthesis methods are developed for base sensitive modifications, then alternate protection strategies are enabled, but the methods have limitations in stability and compatibility with standard oligonucleotide synthesis procedures
Solution Approach 1:
The patent changes the protecting group chemistry from amide-based to silyl-based, which provides both the versatility needed for base-sensitive modifications and the stability required for standard oligonucleotide synthesis procedures, resolving the contradiction between adaptability and 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
This approach enables the stable synthesis of DNA and boranephosphonate oligomers up to 24 nucleotides in length with high yields and purity, overcoming previous limitations in length and stability, and is applicable in both solid and solution phase synthesis.
Implementation Method 1
the silyl protecting group is a sufficiently sterically hindered such that it is stable to a typical oligonucleotide synthesis procedures
Implementation Method 2
wherein said silyl protecting group is stable to reaction conditions associated with oligonucleotide synthesis
Implementation Method 3
can be selectively removed under mild fluoride treatment
Data Source
AI summary
The present invention provides nucleosides an exocyclic amine-protected nucleoside of the formula: A-B where A is a 5′-protected ribose, 5′-protected-2-deoxyribose, 5′-protected-3′-phosphoramidite ribose, or 5′-protected-3′-phosphoramidite-2-deoxyribose moiety; and B is a nucleobase having an exocyclic amine group that is protected with di-tert-butylisobutylsilyl (“BIBS”) protecting group. Use of BIBS protecting group provides an exocyclic amine-protected nucleoside that is stable to a wide variety of reaction conditions associated with oligonucleotide synthesis. The present invention also provides, oligonucleotides comprising the same, and methods for producing the same.