Seven membered heterocyclic Azepine and its derivatives have great pharmacological and therapeutic implications. In this review, the literature of the last fifty years has been exploited for the synthesis, reaction, and biological properties of these seven-member heterocyclic compounds. Most of the mechanisms involved the ring expansion of either five or six-membered compounds using various methods such as thermally, photo-chemically, and microwave irradiation. The systematically designed schemes involve the synthesis of different derivatives of azepine, azepinone, azepane, etc. using similar moieties by the different researchers. However, there is much work yet to be done in the biological section, as it is not explored and reported in the literature; therefore, N-containing seven-membered heterocycles still have much scope for the researchers.

1,4‐Dihydropyridines shows good to excellent activity against various microbial strains and their activity can be moulded to the desired extent. Electron withdrawing aromatic groups at position C‐4, esters on C‐3 & C‐5, and small alkyl groups on C‐2 & C‐6 are the best substitutions to achieve potent anti‐microbial drug. Understanding this concept a new age anti‐microbial agents can be synthesized with next level of potency.

Syntheses of new bispyrazolines 4a, 4b, 4c, 4d, 4e, 4f, 4g built around the aliphatic linkers of varying lengths have been described. The intermediate bischalcones and final bishetrocyclics were also evaluated for their antimicrobial activities.

The bispyranopyrazoles (4a, 4b, 4c, 4d, 4e, 4f, 4g) were synthesized from the reactions of dibenzaldehydes (2a, 2b, 2c, 2d, 2e, 2f, 2g) with 3‐methylpyrazole‐5‐one 3 and malononitrile by refluxing under alcoholic medium. The dibenzaldehydes were obtained from the O‐alkylation of 3‐hydroxybenzaldehyde with suitable 1,ω‐dibromoalkanes under the alkaline conditions in the presence of dry EtOH/DMF. The structures of bisheterocyclics were determined from rigorous analysis of their spectral parameters (IR, 1H‐NMR, 13C‐NMR, and ESI‐MS). The newly prepared compounds were screened for their antimicrobial activity against seven bacterial and five fungal strains. The DNA photo cleavage potential of these compounds was also evaluated by using agarose gel electrophoresis, and bispyranopyrazoles 4b, 4d and 4e exhibited significant level of DNA photocleavage activity.

Background: Heterocyclic compounds have gained attention due to their growing demand against various infectious diseases, but their synthesis with hazardous chemicals, costly catalysts, and costly purification methods encourage researchers to explore alternative sources. The electrochemical method offers a powerful and versatile approach for assembling different heterocyclic structures. Moreover, it gives a highly proficient and green methodology that avoids harmful oxidants and reductants. Objective: In this review, we aim to compile the different types of reaction i.e. Curtin-Hammet, Michael addition, Wittig reaction, Henry, Diels-Alder, Friedel-crafts, Kolbe, Heck, Benzoin condensation reaction taking place in case of electrochemical synthesis in the last 3 years from 2017-2020. So, to the best of our knowledge, after 2017 there is no such report present that can explain the present scenario in the field of electrochemical synthesis. So, this encouraged us to write a review on this interesting topic. Result: From this study, we concluded that the electrochemical methods provide a green and proficient methodology for radical intermediate’s age utilizing electrons as traceless reagents, which could avoid the use of harmful oxidants and reductants.