Synthesis of 6-chloro-2-oxo-1,2-dihydroquinoline-4-carbohydrazide

In previous works we have shown that hydrazides are highly useful starting materials and intermediates in the synthesis of several heterocyclic compounds^1-3 of potential biological activities.

The aim of this work is to describe the preparation of a novel compound entitled 6-chloro-2-oxo-1,2-dihydroquinoline-4-carbohydrazide.

To a solution of ethyl 2-oxo-1,2-dihydroquinoline-4-carboxylate 1 (1g, 3.9 mmol) in ethanol, was added hydrazine hydrate 80 % (0.22 mL, 4.6 mmol). The mixture was refluxed for 24h and ice-water was added. The precipate was filtered and recrystallised from ethanol to afford 0.73 g (70 % yields) of product 2.

Melting point: > 250 °C.

¹H-NMR (300 MHz, DMSO): δ= 4.67 (NH₂); 6.54 (s, 1H, =CH); 7.35-7.78 (m, 3H, H_Ar); 9.93 (NH).

¹³C-NMR (300 MHz, DMSO): δ= 121.8 (=CH); 118.0, 125.4, 131.2 (CH_Ar); 114.8, 126.3, 139.3, 139.9 (Cq); 161.3 (C=O); 165.0 (CON₂H₃).

MS (EI, m/z): 237.

Elemental analysis: Calculated for C₁₀H₈ClN₃O₂: C, 50.54 %; H, 3.39 %; N, 17.68 %; Found: C, 50.60 %; H, 3.42 %; N, 17.74 %;