C-C And C-N Bond Formation Reactions Via π-Allylpalladium Intermediates Related To Aromatic Rings

Arylamines and diaryl ketones represent interesting structural motifs that are frequently found in various bioactive molecules and functional materials. The development of convenient and efficient methods for the synthesis of arylamines and diaryl ketones has attracted considerable attention. Meanwhile, Five-membered heteroarene moieties such as thiophenes, furans and pyrroles are common skeletons in drug molecules and natural products. Allylation has become an important technique for functionalization of five-membered heteroarenes because of the versatility of the allyl group as a handle to access various functional groups. In this dissertation, π-allyl palladium intermediates related to aromatic rings are used as active species to realize palladium-catalyzed regioselective amination and acylation of chloromethylnaphthalene derivatives, regioselective allylation of five-membered heteroarenes, respectively.In the first part, a novel and general catalytic method for the conversion of chloromethylnaphthalene and chloromethylanthracene derivatives to naphthylamines and anthrylamines was successfully developed using Pd(PPh3)4 as a catalyst. The amination of chloromethylnaphthalene and chloromethylanthracene derivatives with various amines proceeded smoothly in the presence of Pd(PPh3)4 to provide pra-amination products in 38%-86% yields. The commercial availability of the catalyst, mild reaction conditions, experimental simplicity, and broad substrate scope are the features of the catalytic method. The mechanism study showed that the amination proceeded via the nucleophilic substitution/dearomatization procedures.In the second part, regioselective control by a ligand switch in acylation involving 7r-benzyl palladium intermediates was also successfully developed.4-Acylation products were obtained using bulky ligand, on the contrary,2-acylation products were obtained using less bulky ligand. This protocol shows good functional group tolerance, such as methyl, tert-butyl, methoxyl, aryl, and halides (F, Cl and Br). Electron-donating groups were more favorable for this reaction, various phenylacetonitriles gave the terminal products in 28%-86% yields. Mild reaction conditions, and high regioselectivity controlled by ligand are the most important features of the catalytic method. The mechanism study showed that the acylation proceeded via the nucleophilic substitution/dearomatization-inner hydrogen transfer-oxidation procedures.In the last part, a new method for the regioselective allylation of five-membered heteroarenes was successfully developed using palladium as catalyst. Under the optimized conditions, the allylation reactions proceeded smoothly, and the corresponding allylation products of five-membered heteroarenes were obtained in 25%-84% yields. This novel protocol exhibited good tolerance for various functional groups linked to five-membered heteroarenes, such as ester, carbonyl, and alkynyl. The commercial availability of the catalyst, mild reaction conditions, and experimental simplicity are the features of the catalytic method.