| Tetrasubstituted alkenes are attractive structural units in many natural products,medicine and organic functional materials,and they are also intermediates in the synthesis of many complex molecules.The introduction of phosphonate group into the tetrasubstituted olefin skeleton can realize the transformation of various functional molecules.Therefore,exploring the synthesis method of tetrasubstituted olefins containing phosphonate group has attracted great attention of scientists.However,highly selective and functional synthesis of phosphonates of tetrasubstituted olefin remains a challenging task.Among many synthesis strategies,the electrophilic addition reaction of allenylphosphonates is one of the most effective synthesis methods,which can achieve electrophilic addition and cyclization reaction with highly-selectivity to obtain tetrasubstituted olefins and cyclic olefin through the influence of the electron effect and steric effect of phosphonate groups.On the other hand,ferrocene is an aromatic organic transition metal compound,which is widely used in the fields of catalysts and functional materials.Based on our interest in related reaction of ferrocenylallene,this paper focuses on regio-and stereoselective synthesis of highly-functionalized tetrasubstituted olefins via iodine-mediated electrophilic addition of ferrocene-containing allenylphosphonates.Firstly,the iodine-promoted electrophilic addition reaction of ferrocene-containing allenylphosphonates with oxygen nucleophilic reagents（carboxylic acids,alcohols,phenols）was realized.The E-type tetrasubstituted allyl esters and ethers containing phosphate groups were synthesized at room temperature with t-Bu OLi as the optimal base and dichloromethane as the solvent.The reaction has the advantages of simple operation,highly regio-and stereoselectivity,a broad scope of substrates,and with good functional tolerance.It is believed that the stereoselectivity of reaction may be controlled by the neighboring group participation of the oxygen atom of the phosphonate group.Secondly,the oxygen nucleophilic reagent was replaced by azide nucleophilic reagent,and the three-component reactions of ferrocene-containing allenylphosphonates with sodium azide and iodine were studied in detail.Tetrasubstituted allyl azides were obtained in in moderate to excellent yields without the base was needed,and abroad scope of substrates.In addition to Na N3,trimethylsilyl azides（TMSN3）can also be used as an excellent nitrogen source to participate in the reaction.In addition,a series of tetrasubstituted 1,2-oxaphosphol-3-ene 2-oxide were synthesized by the electrophilic cyclization of ferrocene-containing allenylphosphonates with iodine.In addition to ferrocene group,the substrate containing benzene ring,heterocyclic,alkyl substituted allenylphosphonate also have good universality.Additionally,the electrophilic reagent Ph Se X（Cl,Br）can also react well with ferrocene-containing allenylphosphonates to obtain phenylselenide-substituted oxaphospholenes.This method provides an effective way for the synthesis of multi-substituted functionalized heterocyclic olefins.Finally,we summarized the iodine-promoted electrophilic addition and cyclization of ferrocene-containing allenylphosphonates,which laid the foundation for subsequent related studies. |
