2292-59-3Relevant articles and documents
Iridium-Catalyzed Enantioselective Hydrogenation of Oxocarbenium Ions: A Case of Ionic Hydrogenation
Lin, Zhenyang,Sun, Yongjie,Wang, Heng,Wen, Jialin,Yang, Tilong,Zhang, Xumu
, p. 6108 - 6114 (2020/03/04)
Ionic hydrogenation has not been extensively explored, but is advantageous for challenging substrates such as unsaturated intermediates. Reported here is an iridium-catalyzed hydrogenation of oxocarbenium ions to afford chiral isochromans with high enantioselectivities. A variety of functionalities are compatible with this catalytic system. In the presence of a catalytic amount of the Br?nsted acid HCl, an α-chloroether is generated in situ and subsequentially reduced. Kinetic studies suggest first-order kinetics in the substrate and half-order kinetics in the catalyst. A positive nonlinear effect, together with the half kinetic order, revealed a dimerization of the catalyst. Possible reaction pathways based on the monomeric iridium catalyst were proposed and DFT computational studies revealed an ionic hydrogenation pathway. Chloride abstraction and the cleavage of dihydrogen occur in the same step.
Visible-Light-Induced C-O Bond Formation for the Construction of Five- and Six-Membered Cyclic Ethers and Lactones
Im, Honggu,Kang, Dahye,Choi, Soyeon,Shin, Sanghoon,Hong, Sungwoo
supporting information, p. 7437 - 7441 (2018/11/27)
Visible-light-induced intramolecular C-O bond formation was developed using 2,4,6-triphenylpyrylium tetrafluoroborate (TPT), which allows the regiocontrolled construction of cyclic ethers and lactones. The reaction is likely to proceed through the single-electron oxidation of the phenyl group, followed by the formation of a benzylic radical, thus preventing a competing 1,5-hydrogen abstraction pathway. Detailed mechanistic studies suggest that molecular oxygen is used to trap the radical intermediate to form benzyl alcohol, which undergoes cyclization. This new approach serves as a powerful platform by providing efficient access to valuable five- and six-membered cyclic ethers and lactones with a unified protocol.
Direct Arylation of Benzyl Ethers with Organozinc Reagents
Peng, Zhihua,Wang, Yilei,Yu, Zhi,Zhao, Dezhi,Song, Linhua,Jiang, Cuiyu
, p. 7900 - 7906 (2018/06/22)
A novel C(sp3)-H bond arylation of benzyl ethers with Knochel-type arylzinc reagents has been developed. This transition-metal-catalyst-free reaction proceeds well under mild conditions in a simple and effective manner and enables the synthesis of a wide range of potentially biologically active benzyl ethers by using highly functionalized organozinc reagents as a carbon nucleophile.
Transition-Metal-Free Cross-Coupling of Indium Organometallics with Chromene and Isochroman Acetals Mediated by BF3·OEt2
Gil-Negrete, José M.,Sestelo, José Pérez,Sarandeses, Luis A.
supporting information, p. 4316 - 4319 (2016/10/12)
A transition-metal-free coupling of triorganoindium reagents with benzopyranyl acetals mediated by a Lewis acid has been developed. The reaction of R3In with chromene and isochroman acetals in the presence of BF3·OEt2 afforded 2-substituted chromenes and 1-substituted isochromans, respectively, in good yields. The reactions proceed with a variety of triorganoindium reagents (aryl, heteroaryl, alkynyl, alkenyl, alkyl) using only 50 mol % of the organometallic, thus demonstrating the efficiency of these species. Preliminary mechanistic studies indicate the formation of an oxocarbenium ion intermediate in the presence of the Lewis acid.
Efficient photolytic C-H bond functionalization of alkylbenzene with hypervalent iodine(iii) reagent
Sakamoto, Ryu,Inada, Tsubasa,Selvakumar, Sermadurai,Moteki, Shin A.,Maruoka, Keiji
supporting information, p. 3758 - 3761 (2016/03/25)
A practical approach to radical C-H bond functionalization by the photolysis of a hypervalent iodine(iii) reagent is presented. The photolysis of [bis(trifluoroacetoxy)iodo]benzene (PIFA) leads to the generation of trifluoroacetoxy radicals, which allows the smooth transformation of various alkylbenzenes to the corresponding benzyl ester compounds under mild reaction conditions.
Efficient C(sp3)-H bond functionalization of isochroman by azadol catalysis
Muramatsu, Wataru,Nakano, Kimihiro
, p. 1549 - 1552 (2015/03/30)
A novel organocatalytic C(sp3)-H bond functionalization of isochroman under practical conditions has been developed. In the presence of 5.0 mol % of AZADOL, the catalysis proceeded successfully with a broad range of substrates and nucleophiles in excellent yields.
Organocatalytic approach for C(sp3)-H bond arylation, alkylation, and amidation of isochromans under facile conditions
Muramatsu, Wataru,Nakano, Kimihiro
supporting information, p. 2042 - 2045 (2014/05/06)
A new catalytic approach for the synthesis of isochroman derivatives via direct C(sp3)-H bond arylation is described. The oxidation reaction with [bis(trifluoroacetoxy)iodo]benzene facilitates the regeneration of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the C(sp3)-H bond arylation of isochroman. The reaction conditions can also be used for alkyl Grignard reagents and amides to afford the corresponding isochroman derivatives.
Structurally diverse α-substituted benzopyran synthesis through a practical metal-free C(sp3)-H functionalization
Chen, Wenfang,Xie, Zhiyu,Zheng, Hongbo,Lou, Hongxiang,Liu, Lei
supporting information, p. 5988 - 5991 (2015/01/08)
A trityl ion-mediated practical C-H functionalization of a variety of benzopyrans with a wide range of nucleophiles (organoboranes and C-H molecules) at ambient temperature has been disclosed. The metal-free reaction has an excellent functional group tole
Simple and direct sp3 C-H bond arylation of tetrahydroisoquinolines and isochromans via 2,3-dichloro-5,6-dicyano-1,4- benzoquinone oxidation under mild conditions
Muramatsu, Wataru,Nakano, Kimihiro,Li, Chao-Jun
supporting information, p. 3650 - 3653 (2013/08/23)
The 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated sp3 C-H bond arylation of tetrahydroisoquinolines and isochromans is described. The corresponding products were facilely synthesized via a simple nucleophilic addition reaction betwee
Zeolite-catalyzed simple synthesis of isochromans via the oxa-Pictet-Spengler reaction
Hegedues, Adrienn,Hell, Zoltan
, p. 1220 - 1222 (2007/10/03)
The synthesis of isochromans via oxa-Pictet-Spengler reaction using a modified small pore size zeolite E4 as catalyst was investigated. Ersorb-4 (E4) is a clinoptylolite-type zeolite material with high silicon content. The reaction of 2-phenylethanol deri
