FAPI Synthesis Intermediate for Lower-Polarity Industrial Purification

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Solution Overview

Problem

The existing synthesis methods for Evans blue modified FAPI (LNC1004) face challenges such as increased polarity leading to difficult separation and purification, instability of DOTA-NHS resulting in low yield and high cost, and unsuitability for industrial production.

Innovation Solution

A novel synthesis method using a key intermediate with a specific structure, involving steps like coupling, deprotection, and hydrolysis, and replacing DOTA-NHS with a more stable and less polar tri-tert-butyl DOTA-TRIS-TBU-ESTER NHS, reducing polarity and cost, and optimizing the reaction sequence for efficient large-scale production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional synthesis route using Evans blue fragment with sulfonic acid group is used, then the target product LNC1004 can be obtained, but the polarity of intermediate is increased making separation and purification difficult

Engineering Contradiction:

Improveseparation and purification difficultyVSAvoidpolarity of intermediate

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by introducing a hydrophobic protecting group (tert-butyl ester) on the DOTA ring before coupling reactions. This protecting group reduces the polarity of intermediates during synthesis, enabling effective separation and purification by traditional methods such as extraction and column chromatography. The protecting group is removed in a final deprotection step to yield the desired product.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a hydrophobic protecting group as an intermediary substance that temporarily modifies the polarity characteristics of the DOTA intermediate. This intermediary allows subsequent coupling reactions to proceed while maintaining separability, and is later removed to reveal the final product with the required polar properties for biological activity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If DOTA-NHS is used for coupling of final fragments, then the coupling reaction can proceed, but DOTA-NHS is unstable at high temperature causing decomposition and ring opening

Engineering Contradiction:

Improvestability of DOTA-NHSVSAvoidyield and side reactions

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs the coupling reaction with the protected DOTA derivative (lower polarity, more stable) before removing the protecting group. This preliminary coupling step avoids the instability issues of DOTA-NHS at high temperatures, as the protected intermediate is more stable and less prone to decomposition and ring-opening side reactions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The hydrophobic protecting group acts as a cushioning element that protects the DOTA ring structure from thermal decomposition and ring-opening during the coupling reaction. This prior protection prevents harmful side reactions that would otherwise occur with unstable DOTA-NHS under elevated temperatures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If DOTA-NHS is used for coupling, then the reaction can proceed, but DOTA-NHS is expensive resulting in high overall cost

Engineering Contradiction:

Improvecost of reagentsVSAvoidoverall production cost

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent employs a more cost-effective DOTA derivative with hydrophobic protecting groups instead of expensive DOTA-NHS. The protected DOTA intermediate is more stable, easier to handle, and significantly cheaper, enabling cost-effective large-scale production while maintaining product quality.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 method significantly improves yield and reduces production costs, making the synthesis suitable for industrial production with higher efficiency and lower side reactions.

Implementation Method 1

step a: subjecting (S)—N-(2-(2-cyanopyrrolidin-1-yl)-2-oxoethyl)-6-(3-(piperazin-1-yl) propoxy)quinolin-4-formamide (that is, a compound II) to a reaction with succinic anhydride to obtain a compound III

Methodology Applied

Scientific EffectCoupling reaction: Chemical Bonding

Implementation Method 2

step c: subjecting the compound V to a deprotection reaction to obtain a compound VI

Methodology Applied

Scientific EffectDeprotection reaction: Hydrolysis

Implementation Method 3

step d: subjecting the compound VII to a hydrolysis reaction and treatment to obtain the intermediate having the structure of Formula I

Methodology Applied

Scientific EffectHydrolysis reaction: Hydrolysis

Data Source

PatentUS20250382329A1Intermediate used for FAPI synthesis, preparation method therefor and application thereof

Publication Date: 2025.12.18 YANTAI LANNACHENG BIOTECHNOLOGY CO LTD

AI summary

The present invention provides an intermediate used for Evans blue modified FAPI synthesis, a method for preparing the intermediate, and an application of the intermediate in the synthesis of an Evans blue modified FAPI. The use of the intermediate provided by the present invention to synthesize Evans blue modified FAPI can improve the production efficiency and reduce the production cost, and the intermediate is suitable for industrial production.