A General and Efficient Catalyst System for a Wacker-Type Oxidation Using TBHP as the Terminal Oxidant: Application to Classically Challenging Substrates

Abstract

Utilizing the rapidly synthesized Quinox ligand and commercially available aqueous TBHP, a Wacker-type oxidation has been developed, which efficiently converts the traditionally challenging substrate class of protected allylic alcohols to the corresponding acyloin products. Additionally, the catalytic system is general for several other substrate classes, converting terminal olefins to methyl ketones, with short reaction times. The system is scalable (20 mmol) and can be performed with a reduced catalyst loading of 1 mol%. Enantioenriched substrates undergo oxidation with complete retention of enantiomeric excess.

Catalyst-Controlled Wacker-Type Oxidation of Homoallylic Alcohols in the Absence of Protecting Groups

“…12 This system successfully oxidizes substrates bearing protected allylic and homoallylic alcohols with high selectivity for the Markovnikov (i.e. methyl ketone) product (Eq.…”

ChemInform Abstract: Peroxide‐Mediated Wacker Oxidations for Organic Synthesis

“…57,58,60,61 As a result of these investigations, a highly selective oxidation system was developed and will be discussed below.…”

“…Through empirical optimizations, a highly active catalyst system was developed, which oxidized terminal olefins selectively to their methyl ketone products (Table 4). 57,58,61 The Quinox ligand is readily prepared from simple starting materials (Scheme 4) 57,58 and is also commercially available. Substrates, such as protected allylic alcohols 57 and amines, 58 as well as unprotected homoallylic alcohols 61 are selectively oxidized with catalyst-control using the Pd(quinox)-TBHP system.…”

Practical and General Palladium‐Catalyzed Synthesis of Ketones from Internal Olefins

“…Finally, we briefly evaluated the ability of this system to perform the oxidation of terminal olefins. Dodecene, a substrate classically prone to isomerization in Wacker chemistry, [14] afforded the desired product in high yield. Allylic phthalimides were recently shown by Feringa and co-workers to afford regioselective formation of the aldehyde, [15] and this outcome was also obtained using our conditions.…”