Aims & Objective:
In this work ZnO-nanorod (ZnO-NR) as reusable catalyst
promoted Strecker-type reaction of 2,4-dihydroxyacetophenone, isopropenylacetylene,
trimethylsilyl cyanide (TMSCN), primary amines and isocyanides at ambient temperature under
solvent-free conditions and produced α-amino nitriles benzofuran derivatives in high yields. These
synthesized compounds may have antioxidant ability.
Materials and Methods:
ZnO-NRs in these reactions were prepared according to reported article.
2,4-dihydroxyacetophenone 1 (2 mmol) and isopropenylacetylene 2 (2 mmol) were mixed and
stirred for 30 min in the presence of ZnO-NR (10 mol%) under solvent-free conditions at room
temperature. After 30 min, primary amine 3 (2 mmol) was added to the mixture gently and the
mixture was stirred for 15 min. After this time TMSCN 4 (2 mmol) was added to the mixture and
stirred for 15 min. After completion of the reaction, as indicated by TLC, isocyanides 5 was added
to mixture in the presence of catalyst.
Results:
In the first step of this research, the reaction of 2,4-dihydroxyacetophenone 1,
isopropenylacetylene 2, methyl amine 3a, trimethylsilyle cyanide 4 and tert-butyl isocyanides 5a
was used as a sample reaction to attain the best reaction conditions. The results showed this
reaction performed with catalyst and did not have any product without catalyst after 12 h.
Conclusion:
In conclusion, we investigate multicomponent reaction of 2,4-dihydroxyacetophenone
1, isopropenylacetylene 2, primary amines 3, trimethylsilyl cyanide 4 and isocyanides along with
ZnO-NRs as reusable catalyst at room temperature under solvent-free conditions which generates
α-amino nitrile benzofuran derivatives in high yields. The advantages of our method are high atom
economy, green reaction conditions, higher yield, shorter reaction times, and easy work-up, which
are in good agreement with some principles of green chemistry. The compounds 8c exhibit
excellent DPPH radical scavenging activity and FRAP compared to synthetic antioxidants BHT
and TBHQ.
Microwave-assisted multicomponent reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and their corresponding 2(1H)-thiones using lanthanum oxide as a catalyst under solvent-free conditions