Protected Organoboronic Acids with Rigid Groups
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Solution Overview
Problem
Current methods for protecting boronic acids in synthetic reactions, such as the Suzuki-Miyaura reaction, face challenges due to the harsh conditions required for deprotection of boronic esters and amides, which can cause undesirable side reactions and lack selectivity, while trifluoroboronate anions are unreactive and non-selective.
Innovation Solution
Development of protected organoboronic acids with a boronate group having sp3 hybridization and a conformationally rigid protecting group, allowing for mild deprotection and selective Suzuki-Miyaura cross-coupling reactions, using specific organic groups and protecting reagents like N-methyliminodiacetic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boronic esters or boronic amides are used as protecting groups, then the boronic acid can be protected from chemical transformations, but harsh deprotection conditions are required which cause undesirable side reactions
Solution Approach 1:
The patent changes the chemical parameters of the protecting group by using fluorinated alkyl groups (such as CF3) instead of traditional ester or amide groups. This parameter change allows the protecting group to be stable during synthesis but removable under mild basic conditions, resolving the contradiction between protection stability and deprotection harshness.
Solution Approach 2:
The patent introduces a specific intermediary structure - the fluorinated alkyl boronic acid derivative - that acts as a mediator between the protected boronic acid and the deprotection conditions. This intermediary allows controlled deprotection under mild conditions while maintaining stability during the synthesis process.
2Reliability
If trifluoroboronate anions are used, then the boronic acid is protected from chemical transformations, but the protecting group is unreactive and non-selective
Solution Approach 1:
The patent applies local quality by using different fluorinated alkyl groups at specific positions on the boronic acid molecule. The CF3 groups provide the necessary electronic effects for stability, while the specific arrangement and substitution pattern maintain the reactivity and selectivity needed for Suzuki-Miyaura reactions.
3Duration of action of stationary object
If conventional protecting groups are used, then boronic acid can be carried through multiple steps, but the deprotection conditions are incompatible with complex molecule synthesis
Solution Approach 1:
The patent changes the deprotection parameter from harsh acidic or basic conditions to mild basic conditions by using fluorinated alkyl boronic acid derivatives. This parameter change enables the protecting group to withstand multiple synthetic steps while allowing deprotection under conditions compatible with sensitive functional groups in complex molecules.
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
Enables the protection of boronic acids under mild conditions with high yields, expanding the versatility of the Suzuki-Miyaura reaction and other boronic acid reactions by maintaining the organic group's reactivity while preventing boron transformation during chemical transformations.
Implementation Method 1
protected organoboronic acids with a boronate group having sp3 hybridization
Data Source
AI summary
A protected organoboronic acid includes a boron having an sp3 hybridization, a conformationally rigid protecting group bonded to the boron, and an organic group bonded to the boron through a boron-carbon bond. A method of performing a chemical reaction includes contacting a protected organoboronic acid with a reagent, the protected organoboronic acid including a boron having an sp3 hybridization, a conformationally rigid protecting group bonded to the boron, and an organic group bonded to the boron through a boron-carbon bond. The organic group is chemically transformed, and the boron is not chemically transformed.