4963-91-1Relevant academic research and scientific papers
Cyclization of Bisphosphines to Phosphacycles via the Cleavage of Two Carbon-Phosphorus Bonds by Nickel Catalysis
Fujimoto, Hayato,Kusano, Momoka,Kodama, Takuya,Tobisu, Mamoru
supporting information, p. 4177 - 4181 (2019/06/17)
The nickel-catalyzed cyclization of bisphosphine derivatives to form various phosphacycles is reported. The reaction proceeds via the cleavage of two carbon-phosphorus bonds of the bisphosphine. Unlike the previously reported palladium catalysts, the use
Raney-Ni reduction of phosphine sulfides
Demchuk, Oleg M.,?wierczyńska, Wioletta,Dziuba, Kamil,Frynas, S?awomir,Flis, Anna,Pietrusiewicz, K. Micha?
, p. 64 - 68 (2016/12/24)
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).
Cyclic Phosphine Oxides and Phosphinamides from Di-Grignard Reagents and Phosphonic Dichlorides: Modular Access to Annulated Phospholanes
Gregson, Aaron M.,Wales, Steven M.,Bailey, Stephen J.,Willis, Anthony C.,Keller, Paul A.
, p. 9774 - 9780 (2015/10/12)
The reaction between 1,4-di-Grignard reagents and phosphonous(III) dichlorides is a classical method for the direct synthesis of phospholanes. Reported here is an extension of this approach to the preparation of value-added, annulated phospholane oxides, achieved through the combination of carbocyclic-fused di-Grignard reagents and readily available phosphonic(V) dichlorides. The procedure is amenable to (benz)annulation at both the 2,3- and 3,4-positions of the phospholane ring, and a variety of aliphatic, cyclic and aryl P-electrophiles are tolerated in reasonable to excellent yields.
Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System
Buonomo, Joseph A.,Aldrich, Courtney C.
supporting information, p. 13041 - 13044 (2015/11/02)
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.
Catalytic wittig reactions of semi- and nonstabilized ylides enabled by ylide tuning
Coyle, Emma E.,Doonan, Bryan J.,Holohan, Andrew J.,Walsh, Killian A.,Lavigne, Florie,Krenske, Elizabeth H.,O'Brien, Christopher J.
supporting information, p. 12907 - 12911 (2016/02/18)
The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodium tert-butyl carbonate, and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity up to >95:5, E/Z. Time for a tune up: Catalytic Wittig reactions with semi- and nonstabilized ylides were enabled by use of a masked base (NaOCO2tBu) and/or ylide tuning. The acidity of the ylide-forming proton was tuned by varying the electron density at the P center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement of E selectivity.
METHODS FOR PHOSPHINE OXIDE REDUCTION IN CATALYTIC WITTIG REACTIONS
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Page/Page column 32, (2014/09/29)
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.
Breaking the ring through a room temperature catalytic wittig reaction
O'Brien, Christopher J.,Lavigne, Florie,Coyle, Emma E.,Holohan, Andrew J.,Doonan, Bryan J.
supporting information, p. 5854 - 5858 (2013/06/27)
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
Part I: The development of the catalytic wittig reaction
O'Brien, Christopher J.,Nixon, Zachary S.,Holohan, Andrew J.,Kunkel, Stephen R.,Tellez, Jennifer L.,Doonan, Bryan J.,Coyle, Emma E.,Lavigne, Florie,Kang, Lauren J.,Przeworski, Katherine C.
supporting information, p. 15281 - 15289 (2013/11/06)
We have developed the first catalytic (in phosphane) Wittig reaction (CWR). The utilization of an organosilane was pivotal for success as it allowed for the chemoselective reduction of a phosphane oxide. Protocol optimization evaluated the phosphane oxide precatalyst structure, loading, organosilane, temperature, solvent, and base. These studies demonstrated that to maintain viable catalytic performance it was necessary to employ cyclic phosphane oxide precatalysts of type 1. Initial substrate studies utilized sodium carbonate as a base, and further experimentation identified N,N-diisopropylethylamine (DIPEA) as a soluble alternative. The use of DIPEA improved the ease of use, broadened the substrate scope, and decreased the precatalyst loading. The optimized protocols were compatible with alkyl, aryl, and heterocyclic (furyl, indolyl, pyridyl, pyrrolyl, and thienyl) aldehydes to produce both di- and trisubstituted olefins in moderate-to-high yields (60-96 %) by using a precatalyst loading of 4-10 mol %. Kinetic E/Z selectivity was generally 66:34; complete E selectivity for disubstituted α,β-unsaturated products was achieved through a phosphane-mediated isomerization event. The CWR was applied to the synthesis of 54, a known precursor to the anti-Alzheimer drug donepezil hydrochloride, on a multigram scale (12.2 g, 74 % yield). In addition, to our knowledge, the described CWR is the only transition-/heavy-metal-free catalytic olefination process, excluding proton-catalyzed elimination reactions. A point of difference: By utilizing an organosilane to chemoselectively reduce a phosphane oxide precatalyst to a phosphane (see scheme), the first catalytic (in phosphane) Wittig reaction has been developed. The methodology has been applied to the synthesis of 22 disubstituted and 24 trisubstituted olefins, including a multigram synthesis of a precursor to the anti-Alzheimer drug donepezil hydrochloride.
In situ phosphine oxide reduction: A catalytic appel reaction
Van Kalkeren, Henri A.,Leenders, Stefan H. A. M.,Hommersom, C. Rianne A.,Rutjes, Floris P. J. T.,Van Delft, Floris L.
supporting information; experimental part, p. 11290 - 11295 (2011/10/19)
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
Probing the importance of the hemilabile site of bis(phosphine) monoxide ligands in the copper-catalyzed addition of diethylzinc to N-phosphinoylimines: Discovery of new effective chiral ligands
Bonnaventure, Isabelle,Charette, Andre B.
, p. 6330 - 6340 (2008/12/22)
(Chemical Equation Presented) The hemilabile ligand Me-DuPHOS(O) 2 has proven to be a successful ligand for the copper-catalyzed addition of diethylzinc to N-phosphinoylimines. The corresponding α-chiral amines were obtained in high yields (80-98%) and enantiomeric ratios (19.0:1 to 99.0:1 er). Furthermore, this Cu?2 catalytic system has been shown to be effective in the addition of diethylzinc to nitroalkenes and in the reduction of β,β-disubstituted vinyl phenyl sulfones. This paper describes a general structure/selectivity study in which the three ligand subunits (chiral phospholane-linker-labile coordinating group (Z)) are systematically modified and tested in the copper-catalyzed addition of diethylzinc to the N-phosphinoylimine 1 derived from benzaldehyde. This study led to the discovery of a new class of effective chiral ligands that combine a chiral phospholane unit and an achiral phosphine oxide.
