Research On The C-C Bond Formation Reaction Via Tertiary Amine N-Oxide Intermediate

Organic amines are versatile elements of bioactive and photoelectric structures. Thus, the development of convenient and efficient methods for the synthesis of organic amines has attracted considerable attention. The functionalization of organic amines is an important method for the synthesis of new organic amines. Recently, the oxidative coupling reaction provides a convenient method for the synthesis of organic amines. However, it requires metal catalysts and the functional group tolerance is limited. In this paper, the oxidative coupling reaction via tertiary amine N-oxide intermediate is developed. This method which exhibits good functional group tolerance and broad substrate scope would provide a useful method for the synthesis of organic amines.In this paper, propargylamines were synthesized by copper-catalyzed oxidative coupling of alkynes with tertiary amine N-oxides. The oxidative coupling reaction could be carried out using Cu(acac)2as a catalyst in the absence of external oxidants. Under the optimized conditions, the oxidative coupling of aromatic or aliphatic alkynes with trimethyl amine N-oxide proceeded smoothly, and the desired products were obtained in47-93%yields. This protocol shows good functional group tolerance, such as methyl, allyl, benzyl, methoxyl, hydroxyl, halide (F, Cl, Br), nitryl, ester, aldehyde, amide, and trifluoromethyl groups.In this work, the oxidative coupling reactions of indoles with glycine esters were studied. The oxidative coupling reactions of glycine esters with N-alkyl protected or N-H free indoles proceeded smoothly in the presence of meta-chloroperoxybenzoic acid under ambient conditions to produce indolylglycines in51-93%yields. This protocol shows good functional group tolerance, such as methyl, allyl, benzyl, methoxyl, bromide, and ester groups. The mechanism study shows that the present oxidative coupling proceeds via tertiary amine N-oxide intermediates. The iminium ion intermediates could generate through the acid-catalyzed decomposition of tertiary amine N-oxides.At last, the oxidative coupling reactions of phenols with glycine esters were studied. The oxidative coupling reactions of glycine esters with phenols/naphthols proceeded smoothly in the presence of meta-chloroperoxybenzoic acid under ambient conditions to produce arylglycines in30-79%yields. The reactivity of naphthols is higher than that of phenols.This method shows good functional group tolerance, such as methyl, methoxyl. phenolic hydroxyl, and ester groups.