Practical Fischer Indolization Using Bench-Stable Arylhydrazine Sulfonate as the Surrogate of Arylhydrazine
Wenjuan Li
a
School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Shandong, Yantai, 264005, P. R. of China
b
Shanghai Frontiers Science Center of Molecule Intelligent Syntheses & Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P. R. of China
,
Chaoren Shen
b
Shanghai Frontiers Science Center of Molecule Intelligent Syntheses & Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P. R. of China
,
Yanping Zhu∗
a
School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Shandong, Yantai, 264005, P. R. of China
b
Shanghai Frontiers Science Center of Molecule Intelligent Syntheses & Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P. R. of China
› Author AffiliationsWe are grateful for the financial support provided by the National Nature Science Foundation of China (22271094) and the Shanghai Rising-Star Program (21QA1402800) and the Innovation Program of Shanghai Municipal Education Commission (No. 2023ZKZD37).
Fischer indolization using bench-stable sodium arylhydrazine sulfonate as a surrogate of arylhydrazine was developed. The preparation of arylhydrazine sulfonate was also modified by replacing sodium sulfite reductant with Pd-catalyzed hydrogen transfer. The straightforward synthesis of tetrahydrocarbazoles from the corresponding anilines was successfully conducted in a one-pot manner. A practical application of this method was demonstrated in the formal synthesis of pharmaceutical molecules Rizatriptan and Zolmitriptan.
26General Procedure: Ketone (1.0 mmol, 1.0 equiv) was added dropwise into a solution of sodium arylhydrazine sulfonate (1.0 mmol, 1.0 equiv) in AcOH (5 mL) and the mixture was stirred at 70 °C for 1 hour. The reaction mixture was then cooled to room temperature and diluted with water. The mixture was extracted with ethyl acetate (2 × 50 mL), and the combined organic layer was washed with water and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure and the obtained crude product was purified by silica-gel column chromatography using petroleum ether/EtOAc as eluent.
