Beta-Eliminative Linkers That Suppress Aza-Michael Addition

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Solution Overview

Problem

Existing β-eliminative linkers for drug conjugation suffer from undesired aza-Michael addition reactions, particularly under physiological conditions, leading to uncontrolled drug release and linker residue activation.

Innovation Solution

Incorporation of a geminally-substituted carbon adjacent to the leaving oxygen in the linker structure, which significantly suppresses nucleophile addition and lowers the equilibrium constant, thereby controlling drug release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If β-eliminative linkers are used for drug conjugation, then controlled drug release is achieved, but undesired aza-Michael addition reactions occur leading to uncontrolled drug release

Engineering Contradiction:

Improvecontrolled drug releaseVSAvoidaza-Michael addition reactions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by introducing a geminally-substituted carbon at the gamma-position to preemptively block the nucleophilic addition pathway. This structural modification creates steric hindrance and electronic effects that prevent aza-Michael addition reactions before they can occur, thereby maintaining controlled drug release without the harmful side reactions.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent changes the chemical structure parameter by modifying the linker molecule to include a geminally-substituted carbon atom. This structural parameter change fundamentally alters the reaction landscape, suppressing the equilibrium constant for aza-Michael addition and preventing the formation of reactive intermediates that would lead to uncontrolled drug release.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If alkyl groups are added to suppress aza-Michael addition, then undesired reactions are reduced, but linker structure complexity increases

Engineering Contradiction:

Improveaza-Michael additionVSAvoidlinker structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies local quality by placing the geminally-substituted carbon specifically at the gamma-position relative to the leaving oxygen. This localized structural modification provides the necessary steric and electronic effects to suppress aza-Michael addition without requiring complex modifications throughout the entire linker structure. The solution is targeted and minimal, adding only the necessary elements at the critical position.

Inventive Principle:

Principle #3Local quality

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 linkers effectively inhibit aza-Michael addition, ensuring controlled drug release and reducing unwanted side reactions, enhancing the stability and efficacy of drug conjugates.

Implementation Method 1

U.S. Pat. Nos. 8,680,315, 8,754,190, and 9,649,385 disclose drug conjugate systems having β-eliminative linkers, which allow drug release through a rate-controlled, beta-elimination mechanism

Methodology Applied

Scientific EffectBeta-elimination: