Abstract
The nucleophilic ring opening of epoxides with amines is a well known route for the synthesis of β-amino alcohols. The use of carbonates offers significant advantages over epoxides as they are far less hazardous materials, safe for handling, do not require high-pressure equipment and most notably the possibility of solvent less reactions. In this work, utilization of zeolite as host catalyst in the reaction media for synthesis of β-amino alcohols without using solvent is reported.
Highlights
Introduction βAmino alcohols are used as intermediates in the synthesis of wide range of biologically active natural and synthetic products [1,2,3] unnatural amino acids [4,5] and asymmetric synthesis as chiral auxiliaries [6]
We describe here a practical approach that is highly regio selective for synthesis of 1(phenylamino) propan-2-ol (3) from propylene carbonate and aniline using a solvent less system, and zeolite as recyclable heterogeneous catalyst (Scheme 1)
The Na-Y zeolite as catalyst of the reaction can be reused with fresh aniline and propylene carbonate with a high conversion of aniline ~ 80% and yields of 1-(phenylamino) propan-2-ol ~ 75 % even after 5 recycles
Summary
When aniline and propylene carbonate in a molar ratio of 1:1 was stirred along with Na-Y zeolite (100 mg) in a round bottom flask at 150 ̊C, mono substituted N-alkylated product, 1-(phenylamino) propan-2-ol (Scheme 1) was formed with > 95% selectivity (analyzed by gas chromatographic). The carbonium ion (active intermediate of the reaction formed by route I and II, Scheme 1) formed on basic sites of Na-Y from propylene carbonate attacks the active hydrogen from NH2 group leading the formation of N-(phenylamino) propan-2-ol. The example of this is shown in Scheme 1. The Lewis acid and Lewis base in Na-Y zeolite together play an important role in achieving high conversion and high regioselective ring opening reaction between propylene carbonate and aniline. Few more experiments were carried out separately using non zeolite catalysts With these catalysts lower conversion and lower regio-selectivity for the alkylation reaction is observed and results are shown, Sr.no.
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