| In this thesis, some novel synthetic protocols for the preparation of chromone and phenol derivativesbased on the diverse reactivity of allenic ketones have been developed. It includes the following two parts:In the first part, the preparation and reaction of3-(2-buta-2,3-dienoylphenoxy)acrylates were studied.It was found that upon treatment with Cs2CO3,3-(2-buta-2,3-dienoylphenoxy)acrylates underwent aMichael addition cyclization/ring opening/ring closure cascade to give3-(4-oxo-4H-chromen-3-yl)acrylatederivatives with high efficiency. Notably, the synthesis did not involve a chromone precursor and wasrealized in the presence of catalytic amount of base without using any expensive transition metal catalyst.Compared with literature procedures toward C-3functionalized chromones, this strategy showedremarkable advantages such as readily available starting materials, simple procedure, high efficiency, andextremely mild reaction conditions.In the second part, the reaction of allenic ketones with pentane-2,4-dione was studied. It was foundthat upon treating with a base in DMF, allenic ketones and pentane-2,4-dione underwent a Michaeladdition/intramolecular aldol condensation cascade to give1-(2-hydroxyphenyl)ethanone derivatives inhigh efficiency. On the other hand, when the mixture of allenic ketones and pentane-2,4-dione was treatedwith a base in ethanol, a more sophisticated cascade incuding Michael addition/intramolecular aldolcondensation/deacylation occurred to give substituted phenols with good yields.In summary, this thesis is mainly about the development of new synthetic methodologies for thepreparation of chromone and phenol derivatives. Compared with literature methods, the protocolsdeveloped herein showed advantages such as readily available starting materials, high efficiency, simplerprocedure and environmental benigncy. It is expected that these methods will find broad applications insynthetic organic chemistry and related areas. |
PDF Full Text Request