Studies On The Atom Economy C-P,C-S Bond Cleavage And Rearrangement Reaction Via Free Radicals

Free radical chemistry can be used to construct molecular skeletons rapidly in drug discovery,agrochemistry,materials science and other fields due to its practicability and chemoselectivity.These intermediates have potential transformation capabilities and can be widely used in scientific research to improve human life.From agriculture to industry,many fields of social needs depend on the development of organic chemistry.Free radical chemistry can shorten the reaction time,have higher atomic economy and step economy,and create opportunities for ideal synthesis.In recent years,high-efficiency clean photocatalytic and electro-oxidative reduction and other free radical chemical reactions have conformed to the green chemistry concept of sustainable development in the 21st century,and have renewed the nascent of free radical chemistry.Free radical conversion has become one of the most active research hotspots in the field of organic synthetic chemistry.Based on the molecular characteristics of allenylphosphine oxides,functionalized thioether isonitrile compounds,a free radical conversion strategy,combined with the green chemical concept of atom economy,chemically selective synthesis of novel phosphine oxides,benzothiazole derivatives.Specifically,it mainly introduces from the following two aspects:1.A novel visible-light-driven alkenyl C-P bond cleavage under metal-free conditions is reported.Allenylphosphine oxides,in the presence of light,erythrosin B,and air,participate in a radical pathway initiated by singlet oxygen,affording diverse alkynyl phosphinates with high regioselectivity and broad group tolerance in good to excellent yields.Formally speaking,this transformation is a retro Homer-Mark rearrangement,but it differs from this classical[2,3]-sigmatropic rearrangement in that redox is involved.Mechanistic studies indicated that the reaction follows an intramolecular pathway,i.e.,the formation of a five-membered ring intermediate and subsequent radical-mediated alkenyl C-P bond cleavage.2.A new method for the synthesis of 2-substituted benzothiazole derivatives was found by studying the intramolecular free radical reaction of thioether isocyanide molecules.A mechanism has been proposed to use the free radical initiator di-tert-butyl peroxide(DTBP)to initiate intramolecular tandem cyclization of o-methylthioisonitrile to produce R radicals,which are then applied to the R radicals.Another molecule of the functionalized isonitrile is cascaded to continue to produce R radicals,which ultimately achieves the goal of "turning waste into treasure".