Current societies demand sustainable synthetic procedures and accordingly the combination of two photocatalytic reactions in a one-pot process is a very appealing chemical tool.In the present work,we report on the dev...Current societies demand sustainable synthetic procedures and accordingly the combination of two photocatalytic reactions in a one-pot process is a very appealing chemical tool.In the present work,we report on the development of new Ir(Ⅲ)bis-cyclometallated photosensitizers with β-carboline ligands and disclose a simple and unprecedented photocatalytic one-pot two-step protocol for the chemoselective and C-3 regioselective oxidative thiocyanation of indolines to produce the corresponding 3-thiocyanato-indoles.The procedure is performed in THF at room temperature,in the presence of NH_(4)SCN,O_(2)and the Ir(Ⅲ)photocatalysts under blue light exposure.Moreover,this methodology combines important advantages such as an outstanding efficiency,based on good yields for low catalyst loadings,along with an excellent sustainability founded on the use of O_(2)as a green oxidant and light as the energy source.In addition,DFT studies have allowed a clear interpretation of the photophysical and electrochemical properties of the Ir(Ⅲ)complexes and transient absorption experiments,along with other experimental proof,have demonstrated that the two photocatalytic processes are mediated by ^(1)O_(2).Our results pave the way for future developments in the field of photocatalysis using Ir(Ⅲ)biscyclometallated complexes as photosensitizers.展开更多
Photocatalysis is an expanding tool designed to synthesize organic molecules in a very efficient and selective way,using mild and environmentally friendly conditions.Thus,the development of new photosensitizers and ph...Photocatalysis is an expanding tool designed to synthesize organic molecules in a very efficient and selective way,using mild and environmentally friendly conditions.Thus,the development of new photosensitizers and photocatalytic protocols can further boost the applicability of photocatalysis in preparative chemistry.In this paper,we have conceived a family of Ru(Ⅱ)polypyridyl complexes of general formula[Ru(bpy)_(2)(N^N)]Cl_(2)(bpy=2,2’-bipyridine)bearing the 2-pyridylbenzimidazole(Hpybim)scaffold in the ancillary ligands(N^N=R-pybim).Moreover,using these Ru(Ⅱ)derivatives as photosensitizers we have described a protocol for the synthesis of imines from primary and secondary amines and also a simple,efficient and selective methodology for the one-pot preparation of α-amino nitriles from primary and secondary amines involving the consecutive photooxidation of the amine substrate and the cyanation of the imine intermediate.In addition,we have formulated a mechanism for the afore-mentioned transformations based on the participation of singlet oxygen.展开更多
基金support provided by the Spanish Ministerio de Ciencia,Innovación y Universidades(RTI2018-100709-B-C21,CTQ(QMC)-RED2018-102471-T and PID2019-111215RB-I00),Junta de Castilla y León(BU087G19,Grant BU263P18)Junta de Comunidades de Castilla-La Mancha-FEDER(JCCM)(grant SBPLY/19/180501/000260)+1 种基金support received from the Consejería de Educación-Junta de Castilla y León-FEDER(BU042U16-BU305P18)for the postdoctoral grantfinanced by FEDER(Fondo Europeo de Desarrollo Regional).
文摘Current societies demand sustainable synthetic procedures and accordingly the combination of two photocatalytic reactions in a one-pot process is a very appealing chemical tool.In the present work,we report on the development of new Ir(Ⅲ)bis-cyclometallated photosensitizers with β-carboline ligands and disclose a simple and unprecedented photocatalytic one-pot two-step protocol for the chemoselective and C-3 regioselective oxidative thiocyanation of indolines to produce the corresponding 3-thiocyanato-indoles.The procedure is performed in THF at room temperature,in the presence of NH_(4)SCN,O_(2)and the Ir(Ⅲ)photocatalysts under blue light exposure.Moreover,this methodology combines important advantages such as an outstanding efficiency,based on good yields for low catalyst loadings,along with an excellent sustainability founded on the use of O_(2)as a green oxidant and light as the energy source.In addition,DFT studies have allowed a clear interpretation of the photophysical and electrochemical properties of the Ir(Ⅲ)complexes and transient absorption experiments,along with other experimental proof,have demonstrated that the two photocatalytic processes are mediated by ^(1)O_(2).Our results pave the way for future developments in the field of photocatalysis using Ir(Ⅲ)biscyclometallated complexes as photosensitizers.
基金the financial support provided by the Spanish Ministerio de Ciencia,Innovación y Universidades(RTI2018-100709-B-C21 and CTQ(QMC)-RED2018-102471-T)Junta de Castilla y León(BU087G19)the European Social Fund+2 种基金Consejería de Educación de la Junta de Castilla y León(EDU/1100/2017)the financial support received from the Consejería de Educación-Junta de Castilla y León-FEDER(BU042U16-BU305P18)for the postdoctoral grantMinisterio de Ciencia,Innovación y Universidades(RTI2018-102040-B-100).
文摘Photocatalysis is an expanding tool designed to synthesize organic molecules in a very efficient and selective way,using mild and environmentally friendly conditions.Thus,the development of new photosensitizers and photocatalytic protocols can further boost the applicability of photocatalysis in preparative chemistry.In this paper,we have conceived a family of Ru(Ⅱ)polypyridyl complexes of general formula[Ru(bpy)_(2)(N^N)]Cl_(2)(bpy=2,2’-bipyridine)bearing the 2-pyridylbenzimidazole(Hpybim)scaffold in the ancillary ligands(N^N=R-pybim).Moreover,using these Ru(Ⅱ)derivatives as photosensitizers we have described a protocol for the synthesis of imines from primary and secondary amines and also a simple,efficient and selective methodology for the one-pot preparation of α-amino nitriles from primary and secondary amines involving the consecutive photooxidation of the amine substrate and the cyanation of the imine intermediate.In addition,we have formulated a mechanism for the afore-mentioned transformations based on the participation of singlet oxygen.
