Copper-Catalyzed Sequential Silylation/Cyclization Of N-Allylanilines And Silanes

Indoleline is an aromatic heterocyclic compound with a co-cyclic structure.As an important intermediate in organic synthesis,its skeleton structure is widely present in alkaloids and drug molecules.In this thesis,copper-catalyzed direct C-H silylation of N-allylanilines with silanes was developed.The main contents of this thesis are as follows:1.The model reaction of N-(2-methyl-allyl)-N-phenylacetamide and triethylsilane was studied by optimizing the solvent,catalyst,oxidant,base and other conditions.The optimal reaction conditions were determined as follows:N-(2-methyl-allyl)-Nphenylacetamide(0.5 mmol,1.0 equiv.),triethylsilane(8.0 equiv.),DTBP(2.0 equiv.),Cu(OAc)2(5 mol%),KOAc(0.5 equiv.)in t-Butanol(3.0 mL)at 130℃ for 12 h under Ar.The corresponding product was obtained in 80%isolated yield(Scheme 1).Scheme 1 The silylation/cyclization of N-(2-methyl-allyl)-N-phenylacetamide with triethylsilane2.Under the optimized reaction conditions,the applicability of N-allylaniline compounds and silane reagents was investigated.The results indicated that substrates with electron-donating groups gave the desired products in higher yields than those with electron-withdrawing groups.For alkyl containing substrates,the steric hindrance has a negative effect on the reaction.Other silanes were also applicable for this reaction condition.This protocol,which is distinguished by its readily available starting materials,simple operation,atomic economy and broad scope,provides a new avenue for the synthesis of diverse indolines(Scheme 2).Scheme 2 The silylation/cyclization of N-allyl anilines with silanes...