- Thermodynamic Resolution and Enantioselective Synthesis of C2-Symmetric Bis-sulfoxides Based on Chiral Iridium(III) Complexes
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Enantiopure λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) (where dfppy is (4,6-difluoropheny)pyridine) were demonstrated to preferentially react with (S,S)-1,2-bis(arylsulfinyl)
- Li, Li-Ping,Peng, He-Long,Ye, Bao-Hui
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p. 12245 - 12253
(2019/10/11)
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- Carbazole-triazine based donor-acceptor porous organic frameworks for efficient visible-light photocatalytic aerobic oxidation reactions
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We report the synthesis of a series of carbazole-triazine based donor-acceptor (D-A) POFs and their photocatalytic activities for aerobic oxidation reactions. The simultaneous introduction of a carbazole-based electron donor and a triazine-based electron acceptor in D-A POFs stabilizes the charge transfer state and enables an efficient triplet-triplet energy transfer to generate 1O2. Meanwhile, systematic variation of the D-A distance results in the tunable photoredox properties and consequently the efficiency for generation of reactive oxygen species (ROSs). Upon visible light excitation, all three D-A POFs exhibit excellent capability to promote three aerobic oxidations: sulfide oxidation, oxidative amine coupling, and Mannich reactions. This systematic study validates the design principle of D-A POFs as high-performance photo-oxidation catalysts with wide substrate scope and excellent stability and recyclability.
- Luo, Jian,Lu, Jingzhi,Zhang, Jian
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supporting information
p. 15154 - 15161
(2018/08/17)
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- Metal- and additive-free oxygen-atom transfer reaction: an efficient and chemoselective oxidation of sulfides to sulfoxides with cyclic diacyl peroxides
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Metal- and additive-free oxidation of a series of sulfides/thioketones has been achieved using cyclic diacyl peroxides as mild oxygen sources. This protocol features simple manipulation, high chemo- and diastereoselectivity, and a broad substrate scope (up to 42 examples), tolerates many common functional groups, and is scalable and applicable to the late-stage sulfoxidation strategy. A preliminary mechanistic study by quantum mechanical calculations suggests that a single two-electron transfer process is energetically more favorable, and indicates the reactivity of cyclic diacyl peroxides distinct from conventional acyclic acyl peroxides.
- Gan, Shaoyan,Yin, Junjie,Yao, Yuan,Liu, Yang,Chang, Denghu,Zhu, Dan,Shi, Lei
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supporting information
p. 2647 - 2654
(2017/04/03)
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- A Bulky Disulfoxide Ligand for Pd-Catalyzed Oxidative Allylic C-H Amination with 2,2,2-Trichloroethyl Tosyl Carbamate
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Challenging substrates and conditions in homogeneous catalysis pose stringent demands on the ligands used. A novel, bulky, 1-adamantyl-substituted disulfoxide ligand designed after a systematic evaluation of the electronic and steric properties of disulfoxide substituents permits the allylic oxidative C-N coupling reaction to proceed at lower catalyst loading while requiring a smaller excess of reagents. Additionally, this ligand improves the yields when TsNHCOOCH2CCl3, a novel reagent that permits deprotection of the products under both acidic and basic conditions, is used.
- Li, You-Gui,Li, Li,Yang, Ming-Yue,He, Gang,Kantchev, Eric Assen B.
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p. 4907 - 4917
(2017/05/12)
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- Synthesis of C3- and C2-symmetric tris- and bis-sulfoxide ligands by asymmetric oxidation
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A series of tris- and bis-sulfoxides were synthesized by multiple asymmetric oxidation of the corresponding sulfides. High enantioselectivities were obtained based on Horeau-type amplification of selectivity. Naphthyl-substituted sulfoxides allowed for higher selectivity and greater ease of purification. These sulfoxides were tested as ligands in rhodium-catalyzed olefin hydroacylation and 1,4-addition of phenyl boronic acid to 2-cyclohexen-1-one. While no enantioinduction was observed in hydroacylation, up to 80% ee was obtained for a tris-sulfoxide and a bis-sulfoxide ligand in the 1,4-addition. Bis-sulfoxides with flexible backbones gave lower and inversed enantioselectivity, suggesting backbone rigidity plays a key role in enantioinduction.
- Dornan, Peter K.,Leung, Priscilla L.,Dong, Vy M.
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experimental part
p. 4378 - 4384
(2011/08/04)
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- Synthetic versatility in C-H oxidation: A rapid approach to differentiated diols and pyrans from simple olefins
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Conventionally, C-H oxidation reactions are used to install functional groups. The use of C-H oxidation to transform simple starting materials into highly versatile intermediates, which enable rapid access to a range of complex target structures, is a new area with tremendous potential in synthesis. Herein we report a Pd(II)/sulfoxide-catalyzed allylic C-H oxidation to form anti-1,4-dioxan-2-ones from homoallylic oxygenates. These versatile building blocks are rapidly elaborated to differentiated syn-1,2-diols, stereodefined amino-polyols, and syn-pyrans, structures ubiquitous in medicinally important complex molecules found in Nature. We also demonstrate that a C-H oxidation approach to the synthesis of these motifs is orthogonal and complementary to other state-of-the-art methods.
- Gormisky, Paul E.,White, M. Christina
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supporting information; experimental part
p. 12584 - 12589
(2011/10/05)
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- Allylic C-H amination for the preparation of syn-1,3-amino alcohol motifs
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A highly selective and general Pd/sulfoxide-catalyzed allylic C-H amination reaction en route to syn-1,3-amino alcohol motifs is reported. Key to achieving this reactivity under mild conditions is the use of electron-deficient N-nosyl carbamate nucleophil
- Rice, Grant T.,White, M. Christina
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supporting information; experimental part
p. 11707 - 11711
(2009/12/08)
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- Catalytic intermolecular allylic C-H alkylation
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The first electrophilic Pd(II)-catalyzed allylic C-H alkylation is reported, providing a novel method for formation of sp3-sp3 C-C bonds directly from C-H bonds. A wide range of aromatic and heteroaromatic linear (E)-α-nitro-arylpent
- Young, Andrew J.,White, M. Christina
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supporting information; experimental part
p. 14090 - 14091
(2009/03/11)
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- Sequential hydrocarbon functionalization: Allylic C-H oxidation/vinylic C-H arylation
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A Pd(II)/sulfoxide-catalyzed sequential allylic C-H oxidation/vinylic C-H arylation of α-olefins to furnish E-arylated allylic esters in high regio- and E:Z selectivities (>20:1) is reported. The broad scope of this method with respect to the α-olefin, ca
- Delcamp, Jared H.,White, M. Christina
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p. 15076 - 15077
(2007/10/03)
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- Macrolactonization via hydrocarbon oxidation
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A novel Pd/sulfoxide-catalyzed macrolactonization reaction of linear ω-alkenoic acids is reported that proceeds via serial ligand-catalyzed allylic C-H oxidation. The scope of this macrolactonization appears to be very broad. Aryl, alkyl, and (Z)-α,β-unsaturated acids are all competent nucleophiles for this reaction, with the latter undergoing macrolactonization with no olefin isomerization. High functional group compatibility is observed that includes biologically and medicinally relevant functionality such as ortho-substituted salicylate esters, bis(indoyl)maleimides, and peptides. Evidence is provided to support the hypothesis that macrolactonization proceeds via inner-sphere functionalization from a templated π-allylPd carboxylate intermediate. Copyright
- Fraunhoffer, Kenneth J.,Prabagaran, Narayanasamy,Sirois, Lauren E.,White, M. Christina
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p. 9032 - 9033
(2007/10/03)
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- Serial ligand catalysis: A highly selective allylic C-H oxidation
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We are reporting a mild, chemo-, and highly regioselective Pd(II)-catalyzed allylic oxidation of α-olefins to furnish branched allylic esters that proceeds via a novel serial ligand catalysis mechanism in which two different ligands (i.e., vinyl sulfoxide 2 and BQ) interact sequentially with the metal to promote distinct steps of the catalytic cycle (i.e., C-H cleavage and π-allyl functionalization, respectively). Copyright
- Chen, Mark S.,Prabagaran, Narayanasamy,Labenz, Nathan A.,White, M. Christina
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p. 6970 - 6971
(2007/10/03)
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- Vanadium catalyzed enantioselective oxidation of sulfides: Easy transformation of bis(arylthio)alkanes into C2 symmetric chiral sulfoxides
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A facile and selective method for the title transformation is described. The two-phase oxidation of bis-sulfides with hydrogen peroxide catalyzed by vanadium complex of chiral Schiff base leads to the corresponding chiral mono- and bis-sulfoxides. In the
- Skarzewski, Jacek,Ostrycharz, Elzbieta,Siedlecka, Renata
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p. 3457 - 3461
(2007/10/03)
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- Facile oxidation of sulfides to sulfoxides using sodium hypochlorite and oxoammonium salt as a catalyst: Chemo- and diastereoselective transformation of bis(phenylthio)alkanes into sulfoxides
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A facile and selective method for the title transformation is described. The two-phase oxidation of disulfides with one or two equivalents of sodium hypochlorite mediated by TEMPO and cocatalyzed by potassium bromide and PTC leads to the corresponding mon
- Siedlecka,Skarzewski
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p. 401 - 404
(2007/10/02)
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- High-pressure Synthesis, Structure and Novel Photochemical Reactions of 7,7,8,8-Tetramethyl-7,8-disilabicycloocta-2,5-diene
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7,7,8,8-Tetramethyl-7,8-disilabicycloocta-2,5-diene 1, prepared by the high-pressure reaction (10000 bar) of 1,1,2,2-tetramethyl-1,2-disilacyclohexa-3,5-diene and phenyl vinyl sulphoxide followed by elimination of benzenesulphenic acid, gave tetramethyldisilene (Me2Si=SiMe2) upon photolysis which underwent a photochemical reaction with benzene at 10 K in an argon matrix to regenerate the precursor.
- Sekiguchi, Akira,Maruki, Ikutaro,Ebata, Keisuke,Kabuto, Chizuko,Sakurai, Hideki
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p. 341 - 343
(2007/10/02)
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