16205-98-4

3-Oxo-1-cyclohexanecarboxylic acid (3-oxocyclohexanecarboxylic acid) may be used in the preparation of 9-(4-chlorobenzoyl)-6-methoxy-2,3,4,9-tetrahydro-1H-carbazole-2-carboxylic acid by reacting with 4-chloro-N-(4-methoxyphenyl)benzohydrazide hydrochloride via Fischer indolization.

3-Oxo-1-cyclohexanecarboxylic acid is a cyclic keto acid that can be prepared starting from 2-acetoxy-1,4-ethoxycarbonylcyclohex-1-ne.

Preparation of Jones oxidizing reagent: Jones reagent was prepared by mixing sulfuric acid (30 mL), CrO3 (8.1 g) and H2O (30 mL) under ice/water bath conditions. The prepared Jones reagent was slowly added dropwise to a solution of 3-hydroxycyclohexane-1-carboxylic acid (11 g, 76.3 mmol, 1.00 eq.) in acetone (150 mL) over 30 min at 0 °C. After the dropwise addition was completed, the reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the solid impurities were removed by filtration. The filtrate was extracted with dichloromethane (3 x 100 mL). The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give the crude 3-oxocyclohexane-1-carboxylic acid (8.7 g) as a yellow oil.

[1] Patent: WO2014/11902, 2014, A1. Location in patent: Paragraph 00282-00283
[2] Patent: WO2014/194242, 2014, A2. Location in patent: Paragraph 00353; 00355