Assisted Tandem Catalytic Cross Metathesis–Oxidation: In One Flask from Styrenes to 1,2-Diketones and Further to Quinoxalines

Abstract

1,2-Diketones were synthesized from styrenes by combining a cross metathesis and a Ru-catalyzed alkene oxidation to an assisted tandem catalytic sequence. The synthesis relies on the use of just one metathesis precatalyst, which was in situ converted to the oxidation catalyst by addition of an alkyl hydroperoxide as a chemical trigger and oxidant. The one-flask sequence can be extended beyond 1,2-diketones to quinoxalines, by condensation of the oxidation products with ortho-phenylenediamine.

Transition Metal‐Catalyzed Synthesis of 1,2‐Diketones: An Overview

“…The Ru catalyst reacts with TBHP to form Schmidt and co-workers reported another interesting approach for the synthesis 1,2-diketones 45 starting from styrenes 43 combining a two-step process comprising cross metathesis and Ru-catalyzed alkene oxidation (Scheme 17). [38] In this method, Ru-catalyst 44 acts as a precatalyst for metathesis which was in situ transformed into the oxidation catalyst in the presence of t-butyl hydroperoxide (TBHP). This approach has limited substrate scope that works only for styrenes bearing electron donating substituents (Me, OMe, OBn) and no conversion was observed for electron deficient styrenes bearing NO 2 and CO 2 Me groups.…”

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

“…Assisted tandem catalysis is a method that employs a single catalyst to perform multiple transformations. Ruthenium metathesis catalysts have been utilized in transformations as C-C bond forming agents that can promote additional structural elaborations [162][163][164][165][166][167][168]. CM promoted by 1 followed by dihydroxylation using NaIO4 as an oxidant delivered diol products through rutheniumcatalyzed dihydroxylation.…”

“…CM promoted by 1 followed by dihydroxylation using NaIO4 as an oxidant delivered diol products through rutheniumcatalyzed dihydroxylation. The ruthenium alkylidene functioned as the oxidation catalyst in the presence of NaIO4 [167][168][169][170][171][172]. Dihydroxylation is a stereospecific process, and because the metathesis was under thermodynamic control, the E-olefin was formed in excess leading to syn-diols.…”

KI‐I2‐DMSO: An Improved Microwave‐Assisted Selective Oxidation of Alkenes into 1,2‐Diketones

“…Diverse metal catalysed such as, Pd, Ru, Fe, Cu, Mn, Au, Mo, Hg, used processes that have received considerable attention for the synthesis of α‐diketones from different sources. Despite this progress with transition metals, acid catalysts and oxidizing agents, were used in numerous methodologies by the researchers. Recently, X. Liu et al .…”