An Efficient Synthesis of Thio- and Thiazoloquinazolinones by the Electrochemical Oxidation of Catechols in the Presence of 2-Mercapto-4(3H)-quinazolinone

Abstract

Thio-and thiazoloquinazolinones were synthesized efficiently by the anodic oxidation of catechols in the presence of 2-mercapto-4(3H)-quinazolinone in aqueous solution. 4-Methylcatechol and 3-methoxycatechol convert into thioquinazolinones via an EC (E: electron transfer, C: chemical reaction) pathway. Catechol, 3-methylcatechol, and 3,4-dihydroxybenzoic acid convert into thiazoloquinazolinones via an ECEC pathway.Quinazolinone A and its derivatives ( Figure 1) are known to have a broad range of pharmaceutical properties, such as anticancer, anti-inflammatory, anticonvulsant, and antidiuretic activities. 1-7 The presence of the thiazole ring in many natural and synthetic quinazolinones has generated interesting biological properties. 8,9 Moreover, thiazolo[2,3-b]quinazolinones B (Figure 1) are potentially interesting from a biological and synthetic point of view. A number of classic methods for the preparation of thiazoloquinazolinones have been developed. These include the reaction of heteroaromatic 2-aminoesters with 2-(methylthio)-2-thiazoline, 10 solid-phase methods, 11 condensation of o-aminobenzoic acid hydrochloride with the appropriate a-or w-thiocyanato ketone, 12 condensation of substituted anthranilic acids or esters with methyl 2-chlorothiazole-5-carboxylate, 13 reaction of anthranilic acid with 2-chlorobenzothiazole, and the reaction of ethylanthranilate with 2-chlorobenzothiazole. 14,15

Preparation of Fused Tetracyclic Quinazolinones by Combinations of Aza‐Wittig Methodologies and CuI‐Catalysed Heteroarylation Processes

“…These include reactions between heteroaromatic 2-amino esters and 2-(methylthio)-2-thiazoline, [15] solid-phase methods, [16] condensations of substituted anthranilic acids or esters with methyl 2-chlorothiazole-5-carboxylate, [17] and the electrochemical oxidation of catechols in the presence of 2-mercapto-3H-quinazolin-4-one. [18] Scheme 4. Preparation of benzothiazolo [2,3-b]quinazoline-12(5H)-ones 10.…”

Mechanistic study of homogeneous reactions coupled with electrochemical oxidation of catechols

“…The results revealed that the quinones derived from catechols participate in a Michael type addition reaction via an EC mechanism converted to the corresponding catechol derivatives. The electrochemical synthesis of various thiocatechol products (Table 2) has been successfully performed at a carbon rod electrode and in an undivided cell with good yields and high purity [18][19][20][21][22][23][24][25][26].…”

“…According to the obtained results, it seems that the [4 + 2] cycloaddition reaction of 1,3-cyclopentadiene (24) to obenzoquinones (1a) (Scheme 7, Eq. (2)) is faster than the other secondary reactions, leading to the intermediate (25).…”

“…Also the oxidation of C-3 substituted catechols in the presence of 2- [24] mercapto-4-(3H)-quinazolinone (17) proceeds via an ECEC mechanism [24].…”

A novel electrochemical method for the synthesis of 2,4-diamino-6-hydroxybenzofuro[2,3-b]pyridine-3-carbonitrile derivatives

“…Recent reviews focusing on microwave-assisted organic synthesis in water [14], reactions in near-critical water [15], and biocatalysis in water [16] have been published. In addition, electro-organic syntheses in the water environment are also one good way to synthesize organic compounds [17][18][19][20][21][22][23]. In this work, we have developed simple green route for synthesis of benzofuro[2, 3-b]pyridines by using hydroquinones 1 and 2-aminoprop-1-ene-1,1,3-tricarbonitrile 2.…”