Exploring new avenues in c-c coupling: broadening application of the Heck reaction via in-situ formation of olefins

Since its discovery, the Heck reaction has received great attention from academic research. As a result, many advances have been made, making the Heck reaction one of the most widely adopted methods for the construction of carbon-carbon bonds in modern organic chemistry. Chapter 1 presents a brief history of the Heck reaction, from its initial discovery to current day applications. This is followed by a brief overview of the different classes of cross-coupling reactions catalysed by palladium. Chapter 2 describes the synthesis of alkyl aryl ketones from aryl chlorides and aldehydes by the development of a novel Heck-type acylation reaction. The aldehyde first condenses with pyrrolidine to form an enamine intermediate, which acts as an electron-rich olefin and undergoes a regioselective Heck coupling with the aryl chloride. Additional experiments such as in-situ¬ IR spectroscopy were carried out in order to probe the reaction mechanism. Chapter 3 is an extension of Chapter 2. The scope of the newly developed acylation reaction is extended beyond commercially available aliphatic aldehydes. The palladium catalysed Heck arylation-isomerisation reaction of aryl bromides and allyl alcohol leads to the generation of aldehydes which, by intervention of pyrrolidine and the same palladium catalyst, undergo the acylation reaction with a second aryl bromide. This leads to the one-pot synthesis of functionalised dihydrochalcones from readily available starting materials. Chapter 4 presents the development of a second one-pot methodology, based on the same principle of design, whereby the reactive C=C double bond is generated in situ. A Keggin-type heteropolyacid is employed to catalyse the¬ formation of styrenes from secondary aryl alcohols which, following addition of palladium, base and an aryl bromide, undergo regioselective Heck arylation. Interesting stilbene products are obtained in good to excellent yields

Supramolecular Control of Selectivity in Hydroformylation of Vinyl Arenes: Easy Access to Valuable β-Aldehyde Intermediates

Go against the flow! A rationally designed regioselective hydroformylation catalyst, [Rh/L], in which noncovalent ligand–substrate interactions allow the unprecedented reversal of selectivity from the typical α‐aldehyde to the otherwise unfavored product β‐aldehyde, is reported. This catalytic system opens up novel and sustainable synthetic pathways to important intermediates for the fine‐chemicals industry