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Mark Gandelman - One of the best experts on this subject based on the ideXlab platform.
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Enantioselective Suzuki cross-couplings of unactivated 1-fluoro-1-haloalkanes: synthesis of chiral β-, γ-, δ-, and ε-Fluoroalkanes.
Journal of the American Chemical Society, 2015Co-Authors: Xiaojian Jiang, Mark GandelmanAbstract:The incorporation of fluorine atom into a stereogenic center is a highly challenging transformation with current methodologies offering access mainly to chiral α- and β-Fluoroalkanes. In this article, the development of a novel general approach to construct β-, γ-, δ-, and e- Fluoroalkanes with good enantioselectivity is described. Different directing groups, such as benzyl, ketone, and sulfonyl, were shown to give good enantioselectivity under Suzuki cross-coupling conditions in the presence of a Ni catalyst and chiral diamine ligand. It includes the first examples of enantioselective synthesis of chiral fluorine-containing centers at as distant as δ or e positions from the functional groups.
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efficient synthesis of secondary alkyl fluorides via suzuki cross coupling reaction of 1 halo 1 Fluoroalkanes
ChemInform, 2015Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:The title reaction is found to be very efficient for a large variety of 1-halo-1-Fluoroalkanes (syntheses described), where in most cases the bromo substrate is used.
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Efficient Synthesis of Secondary Alkyl Fluorides via Suzuki Cross‐Coupling Reaction of 1‐Halo‐1‐Fluoroalkanes.
ChemInform, 2015Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:The title reaction is found to be very efficient for a large variety of 1-halo-1-Fluoroalkanes (syntheses described), where in most cases the bromo substrate is used.
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efficient synthesis of secondary alkyl fluorides via suzuki cross coupling reaction of 1 halo 1 Fluoroalkanes
Journal of the American Chemical Society, 2014Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:Organofluorine compounds have found extensive applications in various areas of science. Consequently, the development of new efficient and selective methods for their synthesis is an important goal in organic chemistry. Here, we present the first Suzuki cross-coupling reaction which utilizes dihalo compounds for the preparation of secondary alkyl fluorides. Namely, an unprecedented use of simple 1-halo-1-Fluoroalkanes as electrophiles in Csp3-Csp3 and Csp3-Csp2 cross-couplings allows for the formal site-selective incorporation of F-group in the alkyl chain with no adjacent activating functional groups. Highly effective approach to the electrophilic substrates, 1-halo-1-Fluoroalkanes, via iododecarboxylation of the corresponding α-fluorocarboxylic acids is also presented. The conceptually new route to organofluorides was used for the facile preparation of biomedically valuable compounds. In addition, we demonstrated that an asymmetric version of the developed reaction for the stereoconvergent synthesis of ...
Douglas W. Stephan - One of the best experts on this subject based on the ideXlab platform.
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P(v) dications: carbon-based Lewis acid initiators for hydrodefluorination.
Chemical communications (Cambridge England), 2019Co-Authors: Alexander E. Waked, Saurabh S. Chitnis, Douglas W. StephanAbstract:The P(III) dication [(terpy)PPh]2+ is oxidized by reaction with o-chloranil or 9,10-phenanthrenequinone to give the P(V) dications [(terpy)(C6Cl4O2)PPh]2+ and [(terpy)(C14H8O2)PPh]2+, respectively. These species are coordinatively saturated at phosphorus and yet display the ability to effect Lewis acid initiation of hydrodefluorination of Fluoroalkanes. Experimental and computational data support the notion that the P(V) dications are Lewis acidic at the para-carbon of the central ring of the terpy ligand.
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Interactions of C-F Bonds with Hydridoboranes: Reduction, Borylation and Friedel-Crafts Alkylation.
Chemistry (Weinheim an der Bergstrasse Germany), 2018Co-Authors: Karlee L. Bamford, Saurabh S. Chitnis, Douglas W. StephanAbstract:The stoichiometric reactions of the alkylfluorides 1-fluoroadamantane (Ad-F), fluorocyclohexane (Cy-F), 1-fluoropentane (Pent-F) and benzyl fluorides with secondary boranes pinacolborane (HBpin), catecholborane (HBcat), 9-borabicyclo(3.3.1)nonane (9-BBN) and Piers' borane (HB(C6 F5 )2 ) are described. While HBcat, 9-BBN and HB(C6 F5 )2 reduce Ad-F to Ad-H, the latter borane was shown to react with secondary and primary Fluoroalkanes, affording C-F borylation, while benzyl fluorides undergo Friedel-Crafts chemistry.
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Catalytic Hydrodefluorination of C-F Bonds by an Air-Stable PIII Lewis Acid.
Chemistry (Weinheim an der Bergstrasse Germany), 2018Co-Authors: Saurabh S. Chitnis, Felix Krischer, Douglas W. StephanAbstract:Catalytic hydrodefluorination (HDF) of unactivated Fluoroalkanes or CF3 -substituted aryl species is performed using the PIII Lewis acids, [(bipy)PPh]2+ (12+ ) and [(terpy)PPh]2+ (22+ ) under mild conditions (25 or 50 °C). Mechanistic studies indicate that activation of C-F bond by the PIII center is key. Particularly noteworthy is that the catalyst 2[B(C6 F5 )4 ]2 is air-stable and readily accessible from bench-stable, commercially available reagents in one-step and can be used without isolation.
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The Highly Lewis Acidic Dicationic Phosphonium Salt: [(SIMes)PFPh2][B(C6F5)4]2†
Angewandte Chemie (International ed. in English), 2014Co-Authors: Michael H. Holthausen, Meera Mehta, Douglas W. StephanAbstract:The dicationic imidazolium-phosphonium salt [(SIMes)PFPh2][B(C6F5)4]2 has been prepared and shown to exhibit remarkable Lewis acidity in stoichiometric reactions and acting as an effective Lewis acid catalyst for the hydrodefluorination of Fluoroalkanes and the hydrosilylation of olefins.
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lewis acidity of organofluorophosphonium salts hydrodefluorination by a saturated acceptor
Science, 2013Co-Authors: Christopher B. Caputo, Lindsay J Hounjet, Roman Dobrovetsky, Douglas W. StephanAbstract:Prototypical Lewis acids, such as boranes, derive their reactivity from electronic unsaturation. Here, we report the Lewis acidity and catalytic application of electronically saturated phosphorus-centered electrophilic acceptors. Organofluorophosphonium salts of the formula [(C6F5)(3-x)Ph(x)PF][B(C6F5)4] (x = 0 or 1; Ph, phenyl) are shown to form adducts with neutral Lewis bases and to react rapidly with Fluoroalkanes to produce difluorophosphoranes. In the presence of hydrosilane, the cation [(C6F5)3PF](+) is shown to catalyze the hydrodefluorination of Fluoroalkanes, affording alkanes and fluorosilane. The mechanism demonstrates the impressive fluoride ion affinity of this highly electron-deficient phosphonium center.
Nobutaka Fujii - One of the best experts on this subject based on the ideXlab platform.
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diastereoselective synthesis of highly functionalized fluoroalkene dipeptide isosteres and its application to fmoc based solid phase synthesis of a cyclic pentapeptide mimetic
Tetrahedron, 2008Co-Authors: Tetsuo Narumi, Kenji Tomita, Shinya Oishi, Hiroaki Ohno, Eriko Inokuchi, Kazuya Kobayashi, Nobutaka FujiiAbstract:A diastereoselective and divergent method for synthesis of a highly functionalized (Z)-fluoroalkene dipeptide isosteres has been developed. The key feature of this synthetic method is an efficient one-pot reaction involving reduction/asymmetric alkylation via transmetalation, which produces trans-amide type (Z)-fluoroalkenes flanking two stereogenic centers in high yields, with excellent (Z)-selectivity and diastereoselectivity. Practical Fmoc-based solid-phase synthesis of a specific CXCR4 antagonistic pseudopeptide 25 containing (Z)-fluoroalkene isostere is also described.
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facile synthesis of fluoroalkenes by palladium catalyzed reductive defluorination of allylic gem difluorides
Organic Letters, 2007Co-Authors: Tetsuo Narumi, Kenji Tomita, Shinya Oishi, Hiroaki Ohno, Eriko Inokuchi, Kazuya Kobayashi, Nobutaka FujiiAbstract:Chemo- and stereoselective synthesis of fluoroalkenes was achieved in excellent yields via Pd-catalyzed C-F bond activation. In this transformation, Et3N plays a crucial role to produce reactive hydride species such as Ph(EtO)SiH2 and Ph(EtO)2SiH by promoting dehydrogenative coupling. The reaction proceeds efficiently at 50 degrees C with a variety of substrates and is also useful for the synthesis of fluoroalkene peptidomimetics.
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a novel one pot reaction involving organocopper mediated reduction transmetalation asymmetric alkylation leading to the diastereoselective synthesis of functionalized z fluoroalkene dipeptide isosteres
Chemical Communications, 2006Co-Authors: Tetsuo Narumi, Ayumu Niida, Kenji Tomita, Shinya Oishi, Akira Otaka, Hiroaki Ohno, Nobutaka FujiiAbstract:By a novel one-pot reaction sequence involving consecutive organocopper-mediated reduction, transmetalation and asymmetric alkylation, a highly diastereoselective synthesis of functionalized (Z)-fluoroalkene dipeptide isosteres was achieved in good to excellent yields.
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unequivocal synthesis of z alkene and e fluoroalkene dipeptide isosteres to probe structural requirements of the peptide transporter pept1
Organic Letters, 2006Co-Authors: Ayumu Niida, Kenji Tomita, Shinya Oishi, Akira Otaka, Makiko Mizumoto, Hiroaki Tanigaki, Tomohiro Terada, And Kenichi Inui, Nobutaka FujiiAbstract:Described is a novel synthetic route for dipeptide isosteres containing (Z)-alkene and (E)-fluoroalkene units as cis-amide bond equivalents via organocopper-mediated reduction of γ-acetoxy- or γ,γ-difluoro-α,β-unsaturated-δ-lactams. The synthesized isosteres were evaluated in terms of their affinities for the peptide transporter PEPT1. trans-Amide isosteres tended to possess higher affinities for PEPT1 as compared to the corresponding cis-amide bond equivalents.
Yoshito Tobe - One of the best experts on this subject based on the ideXlab platform.
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Functionalized surface-confined pores: guest binding directed by lateral noncovalent interactions at the solid-liquid interface.
ACS nano, 2014Co-Authors: Kazukuni Tahara, Keisuke Katayama, Matthew O. Blunt, Kohei Iritani, Steven De Feyter, Yoshito TobeAbstract:We present here the construction of self-assembled two-dimensional (2D) molecular networks that contain pores equipped with functional groups that promote guest-specific binding at the liquid/solid interface. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, DBA-F, having perfluoroalkyl groups at the end of the three alternating alkoxy chains connected by para-phenylene linkers was synthesized. For comparison DBA-H, having the same carbon backbone without fluorine substituents, was also prepared. STM observations revealed that these molecules formed porous 2D networks whose pores were decorated with either Fluoroalkane or simple alkane perimeters. Hexakis(phenylethynyl)benzene, HPEB, and its octadecafluoro derivative, HPEB-F surrounded by 18 fluorine atoms, were employed as planar guest molecules of suitable size. The Fluoroalkane-lined pores present in the network of DBA-F exhibited good binding ability toward both guest molecules via fluorophilicity and electrostatic interaction, respective...
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Functionalized Surface-Confined Pores: Guest Binding Directed by Lateral Noncovalent Interactions at the Solid–Liquid Interface
2014Co-Authors: Kazukuni Tahara, Keisuke Katayama, Matthew O. Blunt, Kohei Iritani, Steven De Feyter, Yoshito TobeAbstract:We present here the construction of self-assembled two-dimensional (2D) molecular networks that contain pores equipped with functional groups that promote guest-specific binding at the liquid/solid interface. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, DBA-F, having perfluoroalkyl groups at the end of the three alternating alkoxy chains connected by para-phenylene linkers was synthesized. For comparison DBA-H, having the same carbon backbone without fluorine substituents, was also prepared. STM observations revealed that these molecules formed porous 2D networks whose pores were decorated with either Fluoroalkane or simple alkane perimeters. Hexakis(phenylethynyl)benzene, HPEB, and its octadecafluoro derivative, HPEB-F surrounded by 18 fluorine atoms, were employed as planar guest molecules of suitable size. The Fluoroalkane-lined pores present in the network of DBA-F exhibited good binding ability toward both guest molecules via fluorophilicity and electrostatic interaction, respectively. In contrast the binding ability of the alkane-lined pore of the network of DBA-H for the fluorinated guest HPEB-F was poor as a result of weaker electrostatic interaction. Interestingly, with HPEB as a guest, this network underwent a periodical structural deformation through an induced-fit mechanism to form a superlattice structure consisting of free and occupied pores. These observations are discussed based on modeling experiments using molecular mechanics and quantum chemical methods to elucidate the roles of lateral noncovalent interactions and size matching between the pore and the guest molecules used for 2D guest binding
Xiaojian Jiang - One of the best experts on this subject based on the ideXlab platform.
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Enantioselective Suzuki cross-couplings of unactivated 1-fluoro-1-haloalkanes: synthesis of chiral β-, γ-, δ-, and ε-Fluoroalkanes.
Journal of the American Chemical Society, 2015Co-Authors: Xiaojian Jiang, Mark GandelmanAbstract:The incorporation of fluorine atom into a stereogenic center is a highly challenging transformation with current methodologies offering access mainly to chiral α- and β-Fluoroalkanes. In this article, the development of a novel general approach to construct β-, γ-, δ-, and e- Fluoroalkanes with good enantioselectivity is described. Different directing groups, such as benzyl, ketone, and sulfonyl, were shown to give good enantioselectivity under Suzuki cross-coupling conditions in the presence of a Ni catalyst and chiral diamine ligand. It includes the first examples of enantioselective synthesis of chiral fluorine-containing centers at as distant as δ or e positions from the functional groups.
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efficient synthesis of secondary alkyl fluorides via suzuki cross coupling reaction of 1 halo 1 Fluoroalkanes
ChemInform, 2015Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:The title reaction is found to be very efficient for a large variety of 1-halo-1-Fluoroalkanes (syntheses described), where in most cases the bromo substrate is used.
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Efficient Synthesis of Secondary Alkyl Fluorides via Suzuki Cross‐Coupling Reaction of 1‐Halo‐1‐Fluoroalkanes.
ChemInform, 2015Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:The title reaction is found to be very efficient for a large variety of 1-halo-1-Fluoroalkanes (syntheses described), where in most cases the bromo substrate is used.
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efficient synthesis of secondary alkyl fluorides via suzuki cross coupling reaction of 1 halo 1 Fluoroalkanes
Journal of the American Chemical Society, 2014Co-Authors: Xiaojian Jiang, Sekarpandi Sakthivel, Kseniya Kulbitski, Gennady Nisnevich, Mark GandelmanAbstract:Organofluorine compounds have found extensive applications in various areas of science. Consequently, the development of new efficient and selective methods for their synthesis is an important goal in organic chemistry. Here, we present the first Suzuki cross-coupling reaction which utilizes dihalo compounds for the preparation of secondary alkyl fluorides. Namely, an unprecedented use of simple 1-halo-1-Fluoroalkanes as electrophiles in Csp3-Csp3 and Csp3-Csp2 cross-couplings allows for the formal site-selective incorporation of F-group in the alkyl chain with no adjacent activating functional groups. Highly effective approach to the electrophilic substrates, 1-halo-1-Fluoroalkanes, via iododecarboxylation of the corresponding α-fluorocarboxylic acids is also presented. The conceptually new route to organofluorides was used for the facile preparation of biomedically valuable compounds. In addition, we demonstrated that an asymmetric version of the developed reaction for the stereoconvergent synthesis of ...