- Synthesis of a new chiral source, (1R,2S)-1-phenylphospholane-2-carboxylic acid, via a key intermediate α-phenylphospholanyllithium borane complex: Configurational stability and X-ray crystal structure of an α- monophosphinoalkyllithium borane complex
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A synthetic route to enantiomerically pure (1R,2S)-1-phenylphos-pholane-2- carboxylic acid (1), which is a phosphorus analogue of proline, has been established. A key step is the deprotonation-carboxylation of the 1-phenylphospholane borane complex 3 by u
- Sun, Xiang-Min,Manabe, Kei,Lam, William W.-L.,Shiraishi, Nobuyuki,Kobayashi, Jun,Shiro, Motoo,Utsumi, Hiroaki,Kobayashi, Shu
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Read Online
- Design, synthesis and application of a new type of bifunctional Le-Phos in highly enantioselective γ-addition reactions of N-centered nucleophiles to allenoates
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A novel class of cyclic phosphine derived bifunctional catalysts (Le-Phos) is reported, which can be readily prepared from inexpensive and commercially available starting materials and exhibit good performances in enantioselective γ-addition reactions of N-centered nucleophiles and allenoates under mild conditions. The salient features of this reaction include high product yields, good enantioselectivity, mild reaction conditions, and broad substrate scope and gram-scale scalability.
- Qiu, Haile,Chen, Xiaofeng,Zhang, Junliang
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p. 10510 - 10515
(2019/12/02)
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- Raney-Ni reduction of phosphine sulfides
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A variety of tertiary phosphine sulfides have been reduced by Raney-Ni to give the corresponding phosphineswith high efficiency and undermild conditions. Alkyl, aryl, acyclic, cyclic, aswell as sterically crowded phosphine sulfides are reduced with equal facility. Optically active P-stereogenic phosphine sulfides are reduced stereospecifically with clean retention of configuration at P. Reductions of unsaturated phosphinesulfides is not fully chemoselective and takes place with concomitant partial reduction of the double bond. Clean reduction of the unsaturated phosphine sulfides to the corresponding fully saturated phosphines can be achieved in one step by running the reduction under H2atmosphere (balloon).
- Demchuk, Oleg M.,?wierczyńska, Wioletta,Dziuba, Kamil,Frynas, S?awomir,Flis, Anna,Pietrusiewicz, K. Micha?
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- Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System
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The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi's azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction. Make it catalytic: A catalytic Mitsunobu reaction using innocuous reagents to recycle the stoichiometric phosphine oxide and hydrazine by-products was developed. The reported method is catalytic in 1-phenylphospholane and uses phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi's azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction.
- Buonomo, Joseph A.,Aldrich, Courtney C.
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supporting information
p. 13041 - 13044
(2015/11/02)
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- METHODS FOR PHOSPHINE OXIDE REDUCTION IN CATALYTIC WITTIG REACTIONS
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A method for increasing the rate of phosphine oxide reduction, preferably during a Wittig reaction comprising use of an acid additive is provided. A room temperature catalytic Wittig reaction (CWR) the rate of reduction of the phosphine oxide is increased due to the addition of the acid additive is described. Furthermore, the extension of the CWR to semi-stabilized and non-stabilized ylides has been accomplished by utilization of a masked base and/or ylide-tuning.
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- Cyclic phosphonium ionic liquids
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Ionic liquids (ILs) incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonyl)amide ILs with aliphatic and aromatic pendant g
- Lall-Ramnarine, Sharon I.,Mukhlall, Joshua A.,Wishart, James F.,Engel, Robert R.,Romeo, Alicia R.,Gohdo, Masao,Ramati, Sharon,Berman, Marc,Suarez, Sophia N.
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supporting information
p. 271 - 275
(2014/02/14)
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- Breaking the ring through a room temperature catalytic wittig reaction
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One ring no longer rules them all: Employment of 2.5-10 mol % of 4-nitrobenzoic acid with phenylsilane led to the development of a room temperature catalytic Wittig reaction (see scheme). Moreover, these enhanced reduction conditions also facilitated the use of acyclic phosphine oxides as catalysts for the first time. A series of alkenes were produced in moderate to high yield and selectivity. Copyright
- O'Brien, Christopher J.,Lavigne, Florie,Coyle, Emma E.,Holohan, Andrew J.,Doonan, Bryan J.
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p. 5854 - 5858
(2013/06/27)
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- In situ phosphine oxide reduction: A catalytic appel reaction
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Several important reactions in organic chemistry thrive on stoichiometric formation of phosphine oxides from phosphines. To avoid the resulting burden of waste and purification, cyclic phosphine oxides were evaluated for new catalytic reactions based on in situ regeneration. First, the ease of silane-mediated reduction of a range of cyclic phosphine oxides was explored. In addition, the compatibility of silanes with electrophilic halogen donors was determined for application in a catalytic Appel reaction based on in situ reduction of dibenzophosphole oxide. Under optimized conditions, alcohols were effectively converted to bromides or chlorides, thereby showing the relevance of new catalyst development and paving the way for broader application of organophosphorus catalysis by in situ reduction protocols. Copyright
- Van Kalkeren, Henri A.,Leenders, Stefan H. A. M.,Hommersom, C. Rianne A.,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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supporting information; experimental part
p. 11290 - 11295
(2011/10/19)
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- Novel phosphine ligands
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The invention is concerned with new phosphine ligands of the formula I wherein R1 and R2 are independently of each other alkyl, aryl, cycloalkyl or heteroaryl, said alkyl, aryl, cycloalkyl or heteroaryl may be substituted by alkyl, alkoxy, halogen, hydroxy, amino, mono- or dialkylamino, aryl, —SO2—R7, —SO3?, —CO—NR8R8′, carboxy, alkoxycarbonyl, trialkylsilyl, diarylalkylsilyl, dialkylarylsilyl or triarylsilyl; R3 is alkyl, cycloalkyl, aryl or heteroaryl; R4′ and R4 signify independently of each other hydrogen, alkyl or optionally substituted aryl; or R4′ and R4 together with the C-atom they are attached to form a 3-8-membered carbocyclic ring; dotted line is absent or is present and forms a double bond; R5 and R6 are independently of each other hydrogen, alkyl or aryl; or linked together to form a 3-8-membered carbocyclic ring or an aromatic ring; R7 is alkyl, aryl or NR8R8′; and R8 and R8′ are independently of each other hydrogen, alkyl or aryl; metal complexes with such ligands as well as the use of such metal complexes as catalysts in asymmetric reactions.
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Page/Page column 19
(2010/11/27)
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