Pd-catalysed Direct Dehydrogenative Carboxylation Of Alkenes: Facile Synthesis Of Vinyl Esters

Vinyl ester as an important polymeric monomer is not only used as a mildacylation agent to synthesize esters and amides, but also involved in the cycloadditionreactions which has been utilized in polymer chemistry, chemical industry andpharmaceutical sciences.There are two types traditional synthetic methods: one is the ester exchangereaction, the other is the oxidative coupling reaction of transition-metal catalyzedcarboxylic acids with alkynes or alkenes. In the latter method, the substrate is usuallyalkyne or allylic substituted derivative, which leads to various highly functionalizedproducts. To the best of our knowledge, the direct synthesis of2-substituted vinylester by using carboxylic acids and terminal alkenes adjacent to which there areelectron deficient substitutes has not yet been reported.In this thesis, we successfully synthesized19representative2-substituted vinylesters using carboxylic acids and terminal alkenes in the condition: palladium ascatalyst, silver carbonate as oxidant, acetonitrile as solvent, oxygen atmosphere andrefluxing reaction. Under our optimal conditions, our products were formed in highyields (up to91%) with good regioselectivity (98:2). All novel compounds have beenfully characterized by1H NMR,13C NMR and HRMS. In addition, the initialmechanistic studies of the reaction were also carried out.This new transformation features simple operation, easily available substratesand reagents, mild reactions conditions with wide product scope and goodregioselectivity.