Morita-Baylis-Hillman Reaction Mediated By Organocatalyst And Acid

Carbon-carbon bond formation is one of the most fundamental reactions in organic chemistry. Selective construction of carbon-carbon bond at required position among a number of competing sites is challenging and fascinating.Morita-Baylis-Hillman?MBH? reaction is shown to be highly efficient in the coupling of activated alkenes at their a-positions with carbon electrophiles, to provide densely functionalized organic compounds with enormous synthetic application in pharmaceutical and fine chemical industries. In this thesis, intermolecular MBH reaction of ?,?-unsaturated ketones with allylic alcohols and their esters have been developed. In addition, domino reaction of ?,?-unsaturated ketones with activated alkenes has also been developed. The dissertation mainly contains the following section.The first chapter is a mini review on MBH reaction according to the essential three components, including a wide range of activated alkenes, electrophiles and catalysts. While a variety of electrophiles, such as aldehydes, aldimines, ?,?-unsaturated compounds, epoxides, and triarylbismuth?V? dichlorides, alkyl halides, allylic alcohols and their esters have been emphatically introduced.The second chapter is about Morita-Baylis-Hillman reaction of ?,?-unsaturated ketones with allylic acetates by the combination of transition-metal catalysis and organomediation. Under the catalysis of 10 mol% Pd?PPh₃?₄ and mediation of P?n-Bu?₃ and AcOH, affording the desired a-coupling products in moderate to good yields. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity. A plausible mechanism via phosphonium salt was also proposed.The third chapter is about Morita-Baylis-Hillman reaction of ?,?-unsaturated ketones with allylic alcohols. Under the catalysis of 10 mol% Pd?PPh₃?₄ and mediation of P?n-Bu?₃ in the mixed solvent of toluene/?CF₃?₂CHOH, affording the desired ?-allylated products. A plausible mechanism using ?CF₃?₂CHOH to both form phosphonium salt and activate allylic alcohols was also proposed. The MBH reaction has many advantages, such as easy availability of starting materials, atom-economical and environmentally benign process as water is the sole side product, good tolerance to many functional groups, excellent regioselectivities and E-stereoselectivities, and satisfactory yields. Thus the MBH reaction of aryl vinyl ketones with allylic alcohols may have practical applications in organic synthesis or industry in the future.The fourth chapter is about domino reaction by combining vinylogous MBH reaction and Wittig reaction of ?,?-unsaturated ketones with activated alkenes. Under the mediation of P?n-Bu?₃ and AcOH, affording the desired ?,?-unsaturated ketones in moderate to good yields. Vinylogous MBH byproduct of dimer is decreased remarkably and Wittig reaction is facilitated effectively in the presence of acetic acid. A plausible mechanism via phosphonium salt and phosphorus ylide intermediate was also proposed.The fifth chapter is about direct N-alkylation of amines with alcohols using AlCl₃ as a Lewis acid. Using inexpensive AlCl₃ without any ligand or additive to afford various N-alkylated amines in satisfactory yields. Either aromatic or aliphatic amines and primary or secondary alcohols perform the AlCl₃-mediated reaction smoothly.