One-Pot Synthetic Research Of Adjacent Quaternary Centers Compounds Via Inter/Intra-Molecular Oxonium Ylide MCRs

Tandem reactions/multi-component reactions(MCRs) are operatively simple, highly efficient,convergent and atom-economic.Tandem reactions/MCRs in diazo chemistry mainly focused on the 1,3-dipolar cycloaddition formed by carbonyl ylide with unsaturated compounds.Our group discovered a new series of multi-component reactions with trapping ammonium/hydroxyl onium ylide.Some new reactions via inter/intra-molecular onium ylide as intermediates will be described in this thesis.The thesis explored the first example of cyclic etheracetates formation from a hydroxyl aryldiazoacetate and an electron-deficient aldehyde or isatins in the presence of Rh(II) or copper catalysts.Cu(HfAcAc)₂ proved to be the best catalyst screened in the research,and gave both high chemo- and diastereo-selectivities,specially for isatins.It was found that the diazo compounds bearing an electron-withdrawing group on the phenyl ring gave better selectivities and electron-deficient carbonyl compounds proceeded more effectively in the addition reactions.At the some time,the onium ylide could also be trapped successfully by some aldimines with electron-withdrawing/donating groups.The new C-C bond was probably formed through intramolecular oxonium ylides,which were trapped by electron-deficient carbonyl compounds.The reaction provides evidence that intramolecular O-H insertion was probably proceed via an alcoholic oxonium ylide as intermediate.In addition,Rh(II) catalyzed three-component reaction of diazoacetates,alcohols and ketimines(formed with isatin and p-methoxyaniline) was explored.This reaction provides a convenient route to synthesis of 3-substituted-3-amidoindolin-2-ones with adjacent quaternary centers with extremely high chemo- and stereo-selectivities.It is the first time to expand the scope of the imine(trapping the hydroxyl onium) from aldimine to ketimine with two adjacent quaternary centers constructed.At the same time,the hydroxyl onium can also be trapped by the acyclic ketimine catalyzed by organic protonic acid successfully with high chemo- and stereo-selectivities,although this kind of acyclic ketimines has lower activity than the cyclic ketimine(isatin imine).