4-Aminoindan Synthesis With Selective Nitration and No Purification
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Solution Overview
Problem
Existing methods for synthesizing 4-aminoindan suffer from low selectivity and yield, making it difficult to mass-produce this compound due to the preferential nitration at the 5-position of indan, leading to separation and purification challenges.
Innovation Solution
A method involving decarboxylation and catalytic hydrogenation reactions using palladium (II) acetate, copper (II) acetate, and Pd/C catalysts to selectively prepare 4-aminoindan from intermediates, bypassing the need for separate purification steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nitration reaction is performed using HNO3/H2SO4 condition, then 4-nitroindan can be obtained, but 5-nitroindan is preferentially formed making separation and purification difficult
Solution Approach 1:
The patent changes the reaction parameters by using a different nitration system (acetyl nitrate generated from NaNO2 and Ac2O) instead of the conventional HNO3/H2SO4 system. This parameter change fundamentally alters the selectivity of the nitration reaction, enabling preferential formation of 4-nitroindan over 5-nitroindan, thereby resolving the contradiction between manufacturing precision and ease of manufacture
Solution Approach 2:
The patent introduces acetyl nitrate as an intermediary reagent that mediates the nitration reaction. This intermediary species, generated in situ from NaNO2 and Ac2O, provides selective nitration at the 4-position of indan, avoiding the formation of 5-nitroindan and eliminating the need for complex separation processes
2Productivity
If conventional nitration method is used, then 4-aminoindan can be synthesized through reduction, but the overall yield is low due to separation losses and mixed products
Solution Approach 1:
The patent performs preliminary selective nitration at the 4-position using acetyl nitrate before reduction. This preliminary action ensures that only the desired 4-nitroindan intermediate is formed with high selectivity, preventing the formation of 5-nitroindan that would require separation. This eliminates time losses associated with purification and maximizes overall yield
Solution Approach 2:
The patent extracts or removes the problematic 5-nitroindan formation pathway by using selective reaction conditions. By taking out the non-selective HNO3/H2SO4 system and replacing it with selective acetyl nitrate nitration, the unwanted byproduct is effectively eliminated, allowing direct reduction to high-yield 4-aminoindan without separation losses
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 achieves a high yield of 4-aminoindan without producing 5-aminoindan, with yields exceeding 70%, enabling mass production and subsequent high-yield preparation of dihydroindenyl-pyrazolo[3,4-b]pyridine amine.
Implementation Method 1
the step (Sa) may include a step of performing a decarboxylation reaction on compound 1 using palladium (II) acetate and copper (II) acetate
Implementation Method 2
the step (Sb) may include a step of performing a catalytic (catalyst) hydrogenation reaction on at least one of compounds 2a and 2b
Data Source
Figure 1
AI summary
The present invention relates to a method for preparing 4-aminoindan and a method for preparing a dihydroindenyl-pyrazolo[3,4-b]pyridine-amine compound, in which the method for preparing 4-aminoindan comprises the steps of: (Sa) preparing at least one of compound 2a and compound 2b using compound 1; and (Sb) preparing 4-aminoindan using at least one of compound 2a and compound 2b.