Electrochemical Oxidation of 2,3-dihydrophthalazine-1,4-dione in the Presence of Indole Derivatives

Abstract

The electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione (1) has been studied in the presence of indole derivatives as nucleophiles in a water/acetonitrile mixture by means of cyclic voltammetry and controlled-potential coulometry. Results indicate that electrogenerated phthalazine-1,4-dione (1ox) participates in a Michael type addition reaction with indole derivatives (2 and 3) via an EC mechanism. In this work, we propose a mechanism for the electrode process. The electrochemical synthesis of indoyl- phthalazines (4 and 5) has been successfully performed at a carbon rod electrode and in an undivided cell.

Oxidative ring cleavage of 2,3-dihydrophthalazine-1,4-dione in aqueous and non-aqueous solutions: Electrochemical and kinetic studies

“…These peaks correspond to the transformation of 2,3-dihydrophthalazine-1,4-dione (DHP) to phthalazine-1,4-dione (diazanaphthoquinone) (PTD) and vice versa, within a quasi-reversible two-electron process with a peak current ratio (I pC1 /I pA1 ) less than unity. 17 This confirms the instability of the generated PTD. The higher reactivity or instability of PTD can be due to the simultaneous presence of both carbonyl and azo moieties.…”

“…16 Furthermore, we recently studied the electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione in the presence and * For correspondence absence of indole derivatives. 17 Cyclic voltammograms of this compound in the absence of indole show one anodic (A 1 ) peak and its corresponding cathodic peak (C 1 ). These peaks correspond to the transformation of 2,3-dihydrophthalazine-1,4-dione (DHP) to phthalazine-1,4-dione (diazanaphthoquinone) (PTD) and vice versa, within a quasi-reversible two-electron process with a peak current ratio (I pC1 /I pA1 ) less than unity.…”

Electrochemically Induced Michael Addition Reaction: An Overview

“…Electrogenerated phthalazine‐1,4‐dione 281 was employed in a Michael type addition reaction with indoles 282 through an EC mechanism. The electrochemical synthesis of indoylphthalazine derivatives 283 was effectively accomplished in an undivided cell at a carbon rod electrode and (Scheme ) …”

“…The electrochemical synthesis of indoylphthalazine derivatives 283 was effectively accomplished in an undivided cell at a carbon rod electrode and (Scheme 80). [92] The electrochemical synthesis of different sulfonamides 287 has been achieved through the electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione 284 using arylsulfinic acids 286a and 286b as nucleophiles. [93] Remarkably, the electrogenerated phthalazine-1,4-dione 285 was used in a Michael type addition reaction with 286a or 286b through an EC mechanism to provide the desired sulfonamides (Scheme 81).…”