Transition Metal Catalyzed Reactions Of O-Substituted Aromatic Aldehydes

o-Substituted aromatic aldehydes with various functional groups are important building blocks in organic synthesis. A variety of heterocyclic compounds were synthetized using o-Substituted aromatic aldehydes. Among them, transition metal-mediated cyclization attracted much attention in recent years. However, the synthesis of heterocyclic compounds with o-Substituted aromatic aldehydes by environmental friendly metals is rare. This thesis focus on the preparation of O- or N-containing heterocycles mediated by copper, iron or silver, including the following four parts:1. A Cu(â… )-catalyzed highly efficient and general synthetic method for 2,3-disubstituted benzo[b]furans was established. These reactions were realized by the three-component coupling/annulation using salicylaldehyde, amine, and alkyne in the presence of Cuâ… . And the 2,3-disubstituted benzo[b]furans were obtained in 46% to 86% yields in one-pot. The structure of benzo[b]furans was fully confirmed by X-ray crystallographic analysis. A number of functional groups such as chloro, bromo, nitro, amino, and pyridyl groups are tolerated under the reaction conditions.2. An efficient one-pot procedure for the synthesis of multisubstituted xanthenes derivatives through Fe(â…¢)-catalyzed reactions of 2-aryloxybenzaldehydes with electron-rich arenes has been developed. This method offers several advantages such as high selectivities, mild reaction conditions, and easily accessible starting materials. A mechanistic study revealed that a C-C bond cleavage of a triarylmethane intermediate might be involved in the domino process. The yields of the xanthenes were from 48% to 95%. The structure of xanthenes was confirmed by X-ray crystallographic analysis.3. Iron-catalyzed cascade Michael addition-cyclization of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones, and o-aminobenzyl alcohols with ynones for the synthesis of 3-carbonyl quinolines was developed. The reactions proceed to afford 3-carbonyl quinoline derivatives with or without substituent at the C-4 position using Iron(â…¢) chloride hexahydrate as the catalyst in the air.3-carbonyl quinoline derivatives were obtained with the yields from 34%-94%. 4. Silver-catalyzed, aniline mediated cascade hydroamination/cycloaddition of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones with alkynes for the synthesis of 2- or 2,4-substituted quinolines was developed. The reactions proceed with high regioselectivity to afford mono- or disubstituted quinoline derivatives using AgOTf as the catalyst in the air.2- or 2,4-substitued quinoline derivatives could be prepared with the yields from 55% to 84%.In this thesis,43 new compounds were synthetized. Among of them,16 designed 2,3-disubstituted benzo[b]furans,16 multisubstiuted xanthenes,9 3-carbonyl quinolines,2 2-substitued quinolines. Meanwhile,16 foregone compounds were synthetized with our new methonds, there were 5 3-carbonyl quinolines,9 2-substitued quinolines,2 3-substitued quinoline compounds were synthesized. All new compounds were characterized by 1H,13C NMR spectroscopy and mass spectroscopy.