Visible-Light Promoted P(O)-H And C(sp~2)-H Functionalization

Visible light,a sustainable green energy,is abundant and renewable.In recent years,the visible light promoted reaction has been developed into a practical and effective strategy in organic synthesis,which has many advantages such as mild reaction conditions,simple operation,green and high efficiency.P?O and C?S bonds are widely presented in biologically active molecules such as natural products,living organisms and drugs.The construction of P?O and C?S bonds has important research significance in organic synthesis.The direct P(O)? H/C ? H functionalization,avoiding pre-functionalization of the substrate,has the characteristics of step and atomic economy.It is an ideal way to construct P?O and C?S bonds.However,the traditional P(O)?H/C?H functionalization requires the toxic reagents,expensive transition metal catalysts,or high temperature and harsh conditions.Therefore,developing the green and efficient methods for P(O)? H/C ? H functionalization and constructing new P?O and C?S bonds have scientific significance and potential application value.The main work of this paper includes the following two parts: Part ?: Visible light-mediated phosphorylation of phosphine oxides with alcohols and phenols.Base on the systematic research,we developed a novel,visible light-promoted method for synthesis of phosphoric acid esters via oxidative cross-coupling of phosphorus oxides,and alcohols or phenols.With bengal rose as the photosensitizer,DBU as the base,THF as the solvent,the reaction can proceed smoothly under white LED irradiation for 8-16 hours at room temperature in air atmosphere,corresponding products can be obtained in moderate to good yields.Based on experimental research,a possible catalytic reaction mechanism was proposed.The method has a wide substrate scope,avoiding the use of transition metals,external oxidants,highly toxic solvents CCl4,and water-sensitive phosphorus oxyhalides.It is a mild,green and novel method for the synthesis of phosphate compounds.Part ?: Visible-light induced palladium-catalyzed ortho-C(sp2)?H bonds thiolation / oxidation of acetanilides via disulfides.Based on the analysis and prediction of the reaction mechanism,we designed a strategy merging visible light and palladium catalysis to study the ortho-C(sp2)?H thiolation/ oxidation reaction of acetanilide,which has not been reported before.Through systematicly preliminary study,the optimal conditions for the reaction of acetanilide and aryl disulfides were established.Using palladium acetate as the catalyst,and avoiding external photosensitizer,the sulfenylated products were obtained in moderate yields under fluorescent lamp irradiation and room temperature.Which laid a foundation for further research of establishing a new method for visible light induced,palladium-catalyzed ortho-C(sp2)?H sulfenylation of acetanilide.