Arylboronic acids as versatile coupling partners in fast microwave promoted oxidative Heck chemistry

Abstract

The useful and selective reactivity of arylboronic acids makes them favourite building blocks for many modern organic chemistry applications like the metal-mediated formation of C-C, C-O, C-N, and C-S bonds. This report describes oxidative Heck coupling reactions of arylboronic acids and olefins, which were conveniently and rapidly (5-30 min) carried out under air with temperature-controlled microwave heating. Different reaction conditions were investigated with regard to both microwave heating capability and chemical productivity. Copper(II) acetate was identified as a microwave compatible reoxidant of Pd(0). The scope and limitations of this high-speed chemistry protocol with diverse olefins and organoboronic acids are discussed.

Ligand‐free palladium‐catalyzed tandem pathways for the synthesis of 4,4‐diarylbutanones and 4,4‐diaryl‐3‐butenones under microwave conditions

“…Our approach, presented in this paper, was based on a tandem process involving two arylation steps with the same catalyst, without the isolation of the first aryl ketone (Figure ). The second modification consisted in the application of MW irradiation instead of conventional heating . It was expected that this would shorten the reaction time and save energy.…”

Efficient Palladium(II) Catalysis under Air. Base-Free Oxidative Heck Reactions at Room Temperature or with Microwave Heating

“…26 In contrast, arylboronic acids are comparatively air and moisture stable, relatively nontoxic, and easily accessible. 11, 13,14,18,19,27,28 Another reason for the rising interest in the oxidative Heck transformation stems from the advancements made in environmentally benign reoxidation systems, mainly driven by the development of novel Pd(II)-catalyzed oxidation protocols. 17,29,30 In modern synthetic organic chemistry laboratories, protocols for convenient and rapid transformations are highly desired.…”

Toward Truly Water‐Soluble Rodlike Polyelectrolytes: Synthesis of Poly(para‐phenylenes) Wrapped in Ethylene Oxideand Amino Side Groups

“…Microwave heating may offer advantages compared to conventional heating: higher reaction rates, lower extent of side reactions, and higher yields have been reported. Such improvements have been shown also for some transition‐metal catalyzed cross‐coupling reactions, including Heck, Sonogashira, Suzuki, and Stille procedures. Therefore, microwave heating was applied in the synthesis of model PPP 35 (Scheme ): equimolar amounts of 21 and 22 were heated in THF/aqueous Na 2 CO 3 in the presence of 1 mol% palladium catalyst.…”