Synthesis Of Trisubstituted Allenyl-phosphine Oxide And Their Derivation Under Metal-free Conditions

Allenes are three-carbon functional groups possessing a 1,2-diene moiety.The substituents on the carbon at the end of allene can affect the electron cloud density and stereoselectivity,increase the reaction center and regulate the reaction site.Phosphonate(phosphine)is a kind of functional phosphorous compound,which contains both the properties of the allene and the characteristics of organophosphorus group.The introduction of phosphine oxygen groups can effectively regulate the chemical,biological,medical and material functions of organic compounds.In chemical synthesis,the phosphine group can effectively change the regional selectivity and stereoselectivity of the chemical reaction.There is a broad prospect in organic transformation,which is conducive to the construction of natural or synthetic compounds with potential bioactivity.Therefore,a simple and efficient method for synthesizing allenyl-phosphine oxide is necessary.Previously,our group has studied a lot about the reactions of tetrasubstituted allenyl-phosphine oxide,which promoted us to conduct further investigations about trisubstituted allenyl-phosphine oxide.This paper focuses on the synthesis of trisubstituted allenyl-phosphine oxide and developing their new applications under metal-free conditions,which is divided into the following three aspects:1.Synthesis of trisubstituted allenyl-phosphine oxideThere are limited methods for synthesizing trisubstituted allenes,and these methods have certain limitations.They require high catalyst costs,harsh reaction conditions,multi-steps,and some need to use toxic reagents,which are contrary to the concept of green chemistry.Therefore,it is of great significance to develop new methods for the synthesis of trisubstituted allenyl-phosphine oxide with high efficiency and convenience.This paper researched on developing a new method for constructing trisubstituted allenyl-phosphine oxide with different substituents.Synthesis of alkyne ethers started from 2,6-dimethylphenol.The ether alkyne reacted with the different aldehydes to synthesize the corresponding alkyneol.Under the catalysis of copper trifluoromethylate,the trisubstituted allenyl-phosphine oxide with different substituted groups were synthesized from alkyneol and diphenyl.The products were isolated in good yield.2?Synthesis of phosphinoyl conjugated enyneConjugated enyne is a valuable structure,which is widely found in bioactive molecules and functional materials.Most of its synthesis requires complicated reaction steps?complex reaction systems?metal catalysts and various additives.This paper used trisubstituted allenyl-phosphine oxide as the substrate,and obtained phosphinoyl conjugated enyne under basic condition.The products were isolated in good yield and had broad substrat scope.3?The[4+1]cyclization of trisubstituted allenyl-phosphine oxide with cyclic 1,3-dionesSpiral structure molecular skeleton widely exists in many biologically active drug molecules and natural products.It is the core skeleton of many excellent chiral ligands.Its synthesis need multi-step or expensive transition metal catalysts.This paper studied on the synthesis of spiro products by the[4+1]cyclization of cyclic 1,3-diketone with trisubstituted allenyl-phosphine oxide as starting materials under metal-free conditions.The structure of the products was confirmed by NMR,X-ray.And a possible mechanism of reaction was suggested:the nucleophilic substitution reaction of 1,3-diketone core carbon atoms and nucleophilic addition reaction at the end of allene were formed to form the spiral ring skeleton.