Research Advances in Electrochemical Synthesis of Spirocyclic Skeleton Compounds

Abstract

Spirocyclic compounds have attracted the interest of synthetic chemists because of their unique ring systems and utility in drug discovery. Many natural compounds contain spirocyclic moieties in their skeleton, which are effective in the pharmaceutical industry. For many redox processes, electroorganic synthesis is considered an environmentally friendly method, since the use of reagents with significant toxicity is replaced by electric current, so the amount of waste is often greatly reduced. Therefore, this review summarizes the construction of spirocyclic skeleton compounds via electrochemical synthesis strategies, which were published mainly in the past two decades.

A Sulfonic Acid Polyvinyl Pyridinium Ionic Liquid Catalyzes the Multi-Component Synthesis of Spiro-indoline-3,5′-pyrano[2,3-d]-pyrimidines and -Pyrazines

“…Recent advances in the synthetic chemistry of spirooxindoles in recent years have made this interesting substance class available for drug development in various medical fields such as antibiotics and cancer [1][2][3][4][5][6][7][8]. Among them, spirooxindole-pyranes are not part of established drugs.…”

“…It showed promising activity against hemorrhagic fever and weak acetylcholinesterase inhibition [9,10]. This has triggered enormous synthesis efforts to make the general class of spirooxindole pyranes available for drug development [1][2][3][4][5][6][7][8][11][12][13]. Recently, spiro-indoline-3,4 -pyrano [2,3-c]pyrazoles were also tested as corrosion inhibitors [14].…”

“…Recently, spiro-indoline-3,4 -pyrano [2,3-c]pyrazoles were also tested as corrosion inhibitors [14]. One option for the synthesis of spiroindoline-3,4 -pyranes is the three-component reaction of 1-alkylindoline-2,3-diones with malonitrile derivatives and an activated enolate (Scheme 1B) [2,[4][5][6]8,[11][12][13][15][16][17][18][19][20][21][22]. Using such procedures, reactions of N-alkyl-1-(methylthio)-2-nitroethenamines, barbituric acid, and isatin (1H-indole-2,3-dione) in water produced spiroindoline-3,4 -pyrano [2,3-c]pyrimidines [15], the three-component reaction of barbituric acids, isatin, and cyclohexane-1,3-diones catalyzed by para-toluene sulfonic-acidproduced spiro[chromeno [2,3-d]pyrimidine-5,3-indoline]-tetraones [16], and spiroindoline-3,4 -pyrano [2,3-c]naphthalenes were obtained from isatin or its N-methyl derivative and 1or 2-naphthol in reactions catalyzed by InCl 3 under microwave conditions [21].…”

Scalable Diastereoselective Electrosynthesis of Spiro[benzofuran-2,2′-furan]-3-ones

“…In recent years, electrochemistry as an appealing technique for achieving spirocyclic products of indoles, thiophenes, furans, phenols, and other aromatic rings has been used elegantly. − Particularly, the fascinated works of Ackermann and Ye showed the excellent ability of electrochemistry for the preparation of spirocyclic compounds (see Scheme a). While in recent years many efforts have been made to develop new electrochemical methods for achieving spirocyclic scaffolds, the methods introduced for the synthesis of these valuable structures are still scarce.…”