4,5,6,7-Tetrahydrothieno pyridine (THTP) and their derivatives are an important heterocyclic compounds that exhibits various biological activities viz.,antimicrobial activity, antileishmanial activity, antiarrhythmic activity, antiinflammatory activity, antihyperlipidemic activity, antidepressant activity, anticancer activity, antiplatelet activity and antidiabetic etc. The present study describes the synthesis, characterization and in vitro cytotoxic potential against human lung carcinoma of some novel derivatives of 4,5,6,7-tetrahydrothieno[3,2-c]pyridine (7A-M) with benzylic and amide substitution on the nitrogen atom of tetrahydro theino pyridine ring. The synthetic steps involves (i) Vilsmeyer protocol in step 1 (ii) formation of tetrahydothieno[3,2-c]pyridine ring in presence of 2-mercaptoacetate in step 2 (iii) alkaline hydrolysis followed by amide coupling with tetrahydro-2H-pyran-4-amine in step 3 and step 4. The newly synthesized compounds 7A-M was sufficiently characterized by 1 H NMR, IR and mass techniques. Furthermore, these derivatives were screened for their in vitro cytotoxic potential against human lung carcinoma (HCT-116) cell line using the MTT assay. Compound 7B (IC50: 69.52 µg) and compound 7K (IC50: 66.35 µg) exhibited significant activity at micro molar concentration when compared to standard drug camptothecin.This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, which allows others to copy and redistribute the material in any medium or format, remix, transform, and build upon the material, as long as appropriate credit is given and the new creations are licensed under the identical terms. tert-Butyl 3-formyl-4-oxopiperidine-1-carboxylate (2):To a stirred solution of tert-butyl 4-oxopiperidine-1-carboxylate (1) (40 g, 0.20 mol) in dichloromethane (500 mL) was added DMF (30.9 mL, 0.40 mol) followed by POCl3 (30 mL, 0.32 mol) at 0 °C and the reaction mixture was stirred at room temperature for 4 h. After completion of the reaction (monitored by TLC), the reaction mixture was quenched with aqueous sodium acetate solution (at 0 °C), diluted with water and extracted with ethyl acetate (2 × 100 mL). The organic layer was washed with water (3 × 50 mL), brine solution, dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to obtain compound 2. The crude compound was used in the next step without any purification. Yellow oil; Yield: 30 g, 65 %; Elemental analysis, C11H17NO4, calcd. (found) %: C 58.14 (58.11), H 7.54 (7.56), N 6.16 (6.12). IR (KBr, νmax, cm -1 ): 2926 (-CH str.), 1695, 1635 (-C=O str.), 1122 (-C-OCstr.); 1 H NMR (500 MHz, CDCl3) δ: 10.14 (s, 1H), 4.15 (d, J = 7.0 Hz, 2H), 3.72 (t, J = 6.0 Hz, 2H), 2.44 (t, J = 6.0 Hz, 2H), 2.09 (brs, 2H), 1.45 (s, 9H); MS: calcd. for C15H21NO4S [m/z] 311.40; found: 312.6 [M+H] + . 5-tert-Butyl 2-ethyl-6,7-dihydrothieno[3,2-c]pyridine-2,5-(4H)-dicarboxylate (3):To a stirred solution of compound 2 (30 g, 0.13...

The present investigation describes the overall preparation of 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide-hydrazone subsidiaries (7a-r) from industrially accessible ethyl-4,6-dichloronicotinate as starting material. The synthesis of these derivatives involve some prominent reactions such as (i) NaBH4 reduction of ethyl ester group (ii) MnO2 oxidation of 1º alcohol (iii) cyclization of aldehyde with ethylmercapto acetate leading to thieno[3,2-c]pyridine ring (iv) hydrazinolysis of the ethyl group (v) condensation of selected aldehydes with 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide leading to the desired 6-chlorothieno[3,2-c]pyridine-2-carbohydrazide-hydrazone derivatives (7a-r). The structure of the derivatives was characterized by elemental analysis, NMR, infrared and mass spectroscopic analysis. These compounds were screened for their antibacterial property towards Gram positive and Gram negative bacterial strains using agar diffusion method with reference to norfloxacin as reference antibiotic.

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