Palladium-catalyzed Heck Reactions Of Allyl Acetate And Ortho Positional C-H Activation Of Isoquinoline N-oxides

Heck-type reaction is highly significant in organic synthesis. Muchattention focus on the versatility of allyl acetate due to its uniqueelimination process. N–Oxides are a special class of heterocycliccompounds, whose chemical properties are significantly different fromthe non-oxidized parent compounds. These distinct differences have beendemonstrated in electrophilic substitution and nucleophilic substitution.The oxygen atom of N–Oxides has been used as a directing group insubstitution and rearrangement reactions. Furthermore, the oxygen atomcan be removed by reduction strategy. This dissertation includes twoparts:（1） palladium-catalyzed Heck reaction of allyl acetate;（2）palladium-catalyzed C–H oxidation of isoquinoline N–Oxides.（1） A selective and general route to （E）-1,3-diaryl-prop-1-enes and（E）-3-arylallyl acetates has been developed by palladium-catalyzedHeck-type reactions of allylic esters with arylboronic acids or potassiumaryltrifluoroborates. In the presence of Pd（OAc）₂, n-Bu₄NCl and KH₂PO₄, aryl boronic acids selectively proceeded the Heck reaction and the β-OAcelimination coupling-reaction with allyl acetate to afford thecorresponding diarylation products in moderate to good yields.Interestingly, only the Heck reaction took place when potassiumaryltrifluoroborates were used as the reaction partners, selectivelyaffording the mono-arylation products in moderate yields.（2） This part focuses on palladium-catalyzed ortho C–H activation ofisoquinoline N–Oxides. Two novel reactions have been developed in thefield of nucleophilic substitution:（1） a novel Pd-catalyzed C–H oxidationof isoquinoline N–Oxides has been developed for regioselectivelysynthesizing substituted isoquinolines. This method represents the firstexample of using dialkylsulfoxides as the alkyl sources for theconstruction of1-alkylated isoquinolines. Moreover, regioselectivehalogenation of isoquinoline N–Oxides was also successfully achieved byusing dihalosulfoxides as the halogen sources.（2） Pd-Catalyzed doubleC–H activation of isoquinoline N–Oxides with benzothiazole is presented.The present method has the advantages of high atom-economy and goodyields.