The Methodology Research Of Benzoquionone Methide Formation Via Transition Metal Catalyzed Cyclization Of Ynones And Its Application

Known as highly reactive and ephemeral intermediates,o-quinone methide intermediates(o-QMs)are widely harnessed for the synthesis of a variety of biological important structures.However,as subtypes of o-QMs,benzoquinone methides,such as o-naphthoquinone methides(o-NQM)and o-phenanthrenequinone methides(o-PQM),have only a few examples concerning their generation and application in organic synthesis due to the dearth of convenient routes to access the corresponding precursors.Through unprecedented ring-formation strategy of ynone,the methodologies to the generation of benzoquinone methides were developed.These unique methodologies provide not only methodological breakthrough,but also feasible approaches to afford a variety of desiring O-containing polycyclic aromatic compounds.This dissertation is divided into five parts as follows:(1)The o-naphthoquinone methides(o-NQM)generated by Ag-catalyzed ring-formation strategy and its[4+2]reaction with styrenes has developed.The reaction features high efficiency,mild reaction conditions,as well as flexible substitutions and atom economy.The obtained benzo[h]chromane products were further oxidized to afford naphthopyrylium salts,which displayed tunable photophysical properties.(2)The 1,4-addition reaction of o-naphthoquinone methides(o-NQM)induced by Ag-catalyzed ring-formation strategy with electron-rich aromatic compounds and?-methylene ketone has been developed.This reaction provides an efficient method to construct versatile unsymmetrical triarylmethanes and benzo[f]chromenes under mild conditions.This transient intermediate was inseparable due to reversible dimerization but could be stored by forming boric acid adduct to proceed further transformation.(3)The semipinacol rearrangement of o-naphthoquinone methides(o-NQM) induced by Ag-catalyzed ring-formation strategy to the construction of a series of partially protected nonsymmetrical biaryldiols were demonstrated.The implementation of O-silyl-protected fluorenol accompanied with the formation of o-NQM affords partially silyl-protected 2,2'-biarylols,which are building blocks that usually required tedious or low-yielding synthetic pathways.(4)The divergent catalytic approach for the regioselective intramolecular hydroarylation of 2-arylphenyl alkynyl ketones has been developed.Using ZnI₂ as catalyst,the formal?-arylation of the ynone was realized via an addition/elimniation mechanism of I^- to generate the unique o-phenanthrenequinone methides(o-PQM)intermediate,which was then trapped by styrenes to form dibenzo[f,h]chromenes.When IPrAuCl/AgSbF₆ was used as catalyst,the?-arylation of the ynone took place to afford benzocycloheptene-5-ones in moderate to good yields.(5)Based on our continuous effects in the development of oxonium salts chemistry and alkyne cyclization process with intramolecular nucleophiles,the effective gold-catalyzed protocol for the synthesis of full-substituted pyrroles from sulfonamide has been developed.The reaction was designed to interrupt the traditional 1,3-H shift aromatization process through the oxidation of 3-methylene dihydropyrrole and generation of the key intermediate,azafulvenium.