Synthesis of novel Schiff bases using 2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile and 1,3-Disubstituted pyrazole-4-carboxaldehydes derivatives and their antimicrobial activity

Divyaraj Puthran; Boja Poojary; Nikil Purushotham; Nandam Harikrishna; Soukhyarani Gopal Nayak; Vinuta Kamat

doi:10.1016/j.heliyon.2019.e02233

Synthesis of novel Schiff bases using 2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile and 1,3-Disubstituted pyrazole-4-carboxaldehydes derivatives and their antimicrobial activity

Heliyon. 2019 Aug 26;5(8):e02233. doi: 10.1016/j.heliyon.2019.e02233. eCollection 2019 Aug.

Authors

Divyaraj Puthran^{1

2}, Boja Poojary¹, Nikil Purushotham¹, Nandam Harikrishna³, Soukhyarani Gopal Nayak¹, Vinuta Kamat¹

Affiliations

¹ Department of Studies in Chemistry, Mangalore University, Mangalagangothri, Karnataka, 574199, India.
² Solara Active Pharma Sciences, No. 120 A&B, Industrial Area, Baikampady, New Mangalore, Karnataka, 575011, India.
³ Alivira Animal Health, Plot No.104-109,112,113 JNPC, Special Economic Zone, Paravada Mandal, Visakhapatnam, Andhra Pradesh-531019, India.

Abstract

2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile have been synthesized from 1-(3-fluoro-4-methoxyphenyl)ethanone, malononitrile, a mild base and sulfur powder using Gewald synthesis technique and the intermediate was treated with 1,3-disubstituted pyrazole-4-carboxaldehyde to obtain the novel Schiff bases. 1,3-disubstituted pyrazole-4-carboxaldehyde derivatives have been synthesized by Vilsmeier-Haack reaction in the course of a multi-step reaction. The structure of novel compounds were established on the basis of their elemental analyses IR, ¹H NMR, ¹³C NMR, and mass spectral data and then screened for their in vitro antimicrobial activity. Among them 5a, 5c, 5f and 5h showed excellent activity when compared to other derivatives. Remaining derivatives showed moderate activity.

Keywords: 1-(3-fluoro-4-methoxyphenyl)ethanone; Anti-microbial; Gewald synthesis; Organic chemistry; Schiff bases; Vilsmeier-Haack reaction.