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Abstract To investigate the catalytic effect of amino-Cu chelates when applying to C-N coupling reaction, leucine-Cu chelate ( Leu-Cu) and methionine-Cu chelate (Met-Cu) were synthesized and identified by copper content test that 19.82% for Leu-Cu and 17.57% for Met-Cu, which were consistent with theory values. XRD results showed that the diffracted primary peak at 2θwere 6.3o and $5.6o shown in Leu-Cu and Met-Cu spectrums respectively that were consistent with reported literature. Leu-Cu and Met-Cu were directly applied to catalyze C-N coupling reaction. Both of them gave better results than corresponding amino acid-Cu catalytic system, and Leu-Cu lead to higher yield 64.7% than Met-Cu in one-step C-N coupling reaction (21.7%), and been well substrate tolerated that 7 aryl amines were obtained and yield up to 91.4% in the present of 20 mol% Leu-Cu, but most gave medium yields mostly. However, when applied to one-pot multi-component reaction for the preparation of heterocycle quinazolinone, 5 mol% of Met-Cu provided 71.2% yield of expected product starting from 2-iodobenzamide with EtOH as solvent, while 2-iodobenzonitril gave 80.5% yield catalyzed by 10 mol% of Met-Cu under 100℃ with DMSO/H2O as solvent. It was indicated that Leu-Cu gave better results than Met-Cu in one-step C-N coupling reaction, while Met-Cu exhibited mild condition, higher yields and less catalyst amounts compared to traditional amino acid-Cu catalytic system in multi-components reaction. This work certified that amino acid-Cu chelates can replace tradition amino acid-Cu catalyst system in Ullmann C-N coupling reaction, and amino acid-Cu chelates presented better results in multi-component reaction in terms of reaction condition and yield.
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Received: 13 March 2024
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2023, Vol. 36 
