Design Of Diaryl Allenic Substrates And Iron(?)-Promoted Cyclizations

Allene is a class of compounds containing a 1,2-cumulative diene with special reactivity,which has been used for preparing a wide variety of cyclic compounds through cyclization reaction.Especially,the metal-catalyzed cyclization of allenes with highly regio-and stereoselectivity are one of the most valuable methods in organic synthesis.Diaryl allene is a kind of allene with diaryl group attaching at the end of allene.During the reaction,the aryl group may participate in the cyclization to afford the aromatic compound with an extended?-system.Therefore,we developed a method for the synthesis of diaryl allenic substrates using a 1,3,3-triarylalkyne.Iron salts have received considerable attention as promising alternatives over precious-metal catalysts because of their earth-abundance,environmental friendliness,and long-term expediency.Because they can adopt multiple oxidation states,iron complexes are highly versatile catalysts for diverse organic transformations.This thesis mainly studies the FeCl₃-mediated cyclization of diaryl allenes for the synthesis of polycyclic compounds with fluorescent properties,and is divided into the following two parts:Part ?:We studied the FeCl₃-promoted tandem C-O bond cleavage/6?electrocyclization/oxidative aromatization of 1-isochromanones bearing a diaryl allenic moiety at C4-position for the construction of functionalized5H-dibenzo[c,g]chromen-5-ones in high yields.Transformations of obtained polycycles were also achieved to afforded several types of 5H-dibenzo[c,g]chromene derivatives.Moreover,the new fluorophore of compounds and its photophysical properties were investigated.Part ?:We studied the practical tandem Nazarov/oxidative umpolung 4?ring closure of readily available 1,2-allenyl aryl ketones mediated by inexpensive iron?III?chloride furnishing a new family of indanone-fused molecular architectures in moderate to excellent yields.The obtained products can be transformed to the unsymmetrically planar dibenzo[a,e]pentalenes through carbonyl reduction and acid-mediated cationotropic rearrangement.These compounds are useful fluorophores and their photophysical properties were intensively investigated.