- A versatile synthesis of chiral β-aminophosphines
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A method for the preparation of chiral β-aminophosphines having substituted P-aryl groups is described. Ring-opening of cyclic sulfamidates with metal diarylphosphinites yields β-aminophosphine oxides, which are then reduced to the corresponding phosphines. Effects of the diarylphosphinite countercation on the regioselectivity of the ring-opening reaction (P- versus O-alkylation) are discussed. This method enables the introduction of electron-deficient, electron-rich and sterically hindered diarylphosphino groups, as demonstrated by the synthesis of a series of novel, P-aryl-substituted β-aminophosphines derived from tert-leucinol, valinol and phenylglycinol. Access to these derivatives will create new opportunities for steric and electronic tuning of β-aminophosphine-derived chiral ligands and organocatalysts.
- Su, Hsin Y.,Song, Yixiong,Taylor, Mark S.
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- Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines
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The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine"makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP)5 have been formed in good conversion, with the crystal structures presented. The use of catalytic quantities of iron(III) acetylacetonate provides significant improvements in conversion in the context of diphosphine (Ar2P)2 and alkyl-substituted cyclotetra- or cyclopentaphosphine ((AlkylP)n, where n = 4 or 5) formation. Both iron-free and iron-mediated reactions show high levels of selectivity for one specific ring size. Finally, investigations into the reactivity of Fe(acac)3 suggest that the iron species is acting as a sink for the hydrochloric acid byproduct of the reaction.
- Barrett, Adam N.,Woof, Callum R.,Goult, Christopher A.,Gasperini, Danila,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 16826 - 16833
(2021/11/04)
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- Rhodium catalyzed C-C bond cleavage/coupling of 2-(azetidin-3-ylidene)acetates and analogs
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The C-C bond cleavage/coupling of 2-(azetidin-3-ylidene)acetates with aryl boronic acids catalyzed by a rhodium complex was studied with a "conjugate addition/β-C cleavage/protonation" strategy.
- Yang, Xuan,Kong, Wei-Yu,Gao, Jia-Ni,Cheng, Li,Li, Nan-Nan,Li, Meng,Li, Hui-Ting,Fan, Jun,Gao, Jin-Ming,Ouyang, Qin,Xie, Jian-Bo
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supporting information
p. 12707 - 12710
(2019/10/28)
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- Copper-catalyzed C–P cross-coupling of secondary phosphines with (hetero)aromatic bromide
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A novel and convenient approach to the synthesis of various tertiary phosphines via a copper-catalyzed cross-coupling of (hetero)aromatic bromide with secondary phosphines has been developed. The reaction employs cheap copper as the catalyst, 2,6-bis(N-methylaminomethyl)pyridine (L4) as a perfect ligand and KOtBu as a base; all reactions are carried out under argon atmosphere. A variety of sterically hindered and/or functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields. Moreover, ten new tertiary phosphines were first reported in this process.
- Li, Chun-Jing,Lü, Jing,Zhang, Zhi-Xun,Zhou, Kun,Li, Yan,Qi, Guang-Hui
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p. 4547 - 4562
(2018/04/20)
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- Metal-Free Reduction of Phosphine Oxides, Sulfoxides, and N-Oxides with Hydrosilanes using a Borinic Acid Precatalyst
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The general reduction of phosphine oxides, sulfoxides, and amine N-oxides was achieved by combining bis(2-chlorophenyl)borinic acid with phenylsilane. The reaction was shown to tolerate a wide range of substrates and could be performed under mild conditions, with only 2.5 mol % of the easily synthesized catalyst. Mechanistic investigations pointed to a key borohydride as the real catalyst and at bis(2-chlorophenyl)borinic acid as a precatalyst.
- Chardon, Aurélien,Maubert, Orianne,Rouden, Jacques,Blanchet, Jér?me
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p. 4460 - 4464
(2017/11/22)
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- Facile, Catalytic Dehydrocoupling of Phosphines Using β-Diketiminate Iron(II) Complexes
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Catalytic dehydrocoupling of primary and secondary phosphines has been achieved for the first time using an iron pre-catalyst. The reaction proceeds under mild reaction conditions and is successful with a range of diarylphosphines. A proton acceptor is not needed for the transformation to take place, but addition of 1-hexene does allow for turnover at 50°C. The catalytic system developed also facilitates the dehydrocoupling of phenylphosphane and dicyclohexylphosphane. A change in solvent switches off dehydrocoupling to allow hydrophosphination of alkenes.
- King, Andrew K.,Buchard, Antoine,Mahon, Mary F.,Webster, Ruth L.
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supporting information
p. 15960 - 15963
(2015/11/03)
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- Stereoelectronic factors in iron catalysis: Synthesis and characterization of aryl-substituted iron(II) carbonyl P-N-N-P complexes and their use in the asymmetric transfer hydrogenation of ketones
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A series of five (S,S)-trans-[Fe(CO)(Br)(PR2-CH 2CH=NCH(Ph)CH(Ph)N=CHCH2-PR2)][X] compounds (1a-c, X = BPh4; 1d,e, X = BF4) were synthesized and tested for the asymmetric transfer hydrogena
- Sues, Peter E.,Lough, Alan J.,Morris, Robert H.
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scheme or table
p. 4418 - 4431
(2011/10/10)
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- Catalytic asymmetric intramolecular hydroamination of alkynes in the presence of a catalyst system consisting of Pd(0)-methyl Norphos (or tolyl Renorphos)-benzoic acid
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(Chemical Equation Presented) Enantiomerically pure methyl Norphos (A), tolyl Norphos (B), CF3 Norphos (C), methyl Renorphos (D), and tolyl Renorphos (E) were synthesized and used as chiral bisphosphine ligands for the catalyst system, Pd2(dba)3·CHCl3/PhCOOH, in an intramolecular hydroamination of aminoalkynes 15. Among the Norphos series, methyl Norphos (A) was the best ligand for the hydroamination, and the corresponding five- and six-membered nitrogen heterocycles 16 were obtained in high yields with high enantioselectivities. Among the Renorphos series, tolyl Renorphos (E) gave the best result; both methyl Norphos (A) and tolyl Renorphos (E) afforded high yields and high enantioselectivities. NMR investigation using Me-Norphos revealed that this ligand was oxidized gradually in the presence of Pd2(dba)3·CHCl3 in C6D 6 even under the conditions using Ar atmosphere to give Me-Norphos oxide, which prevented the intramolecular hydroamination. On the other hand, Me-Norphos was rather stable in C6D6 in the absence of the palladium catalyst under Ar atmosphere and was not converted to its oxide even after 3 days. The gradual oxidation of ligands (A and E) in the presence of the Pd catalyst is perhaps a reason why 20 mol % of A or E was needed to obtain high yields and high ee's of 16.
- Narsireddy, Meda,Yamamoto, Yoshinori
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supporting information; experimental part
p. 9698 - 9709
(2009/04/07)
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- A METHOD FOR GENERATING SECONDARY PHOSPHINES
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This invention provides a method for generating secondary phosphines from secondary phosphine oxides in the presence of a reducing agent, such as diisobutylaluminum hydride (DIBAL-H), triisobutyldialuminoxane, triisobutylaluminum, tetraisobutyldialuminoxane, or another reducing agent comprising: (i) an R1R2AIH moiety, wherein R1 and R2 are each an alkyl species or oxygen, and wherein at least one of R1 or R2 comprises at least 2 carbon atoms, or (ii) an R1R2R3AI moiety, wherein R1, R2, and R3 are not hydrogen, and wherein at least one of R1, R2, and R3 is an alkyl species comprising a β-hydrogen, not including triethylaluminum. Preferred reducing agents for the present invention include: diisobutylaluminum hydride, triisobutyldialiuminoxane, triisobutylaluminum, tetraisobutyldialuminoxane, and combinations thereof.
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Page/Page column 12-13
(2008/06/13)
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- Reductive cleavage of the carbon-phosphorus bond with alkali metals. III Reactions of arylalkylphosphines
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The reductive cleavage of phenylalkylphosphines Ph2PR, PhPR2 (R = Bu, iPr) with Na/NH3 is unselective; both phenyl and alkyl groups can be cleavaged and Birch reduction may occur.Reaction of Ph2tBuP gives a high yield of diphenylphosphide.Polar groups (CO2Na, SO3Na) at the ω position of primary alkyl groups may lead to an increase in selectivity; Birch reduction is suppressed and a functionalised secondary phosphide is obtained.From diarylbenzyl- and diarylallylphosphines, the benzyl and allyl groups are selectively removed; Ar2PH and ArRPH are formed in high yield after hydrolytic work-up unless the aryl group bears F, CF3 or (CH3)2N substituents.From the reaction mixture of Ph2PCH2Ph we have isolated 1,2-diphenylethane. 2-Methoxyphenyl and 2,6-dimethoxyphenyl groups are selectively removed from Ar2BuP, ArPhBuP and Ar2P(CH2)3PAr2, forming ArBuPH, PhBuPH and ArP(H)(CH2)3(H)PAr, respectively.A double-cleavage reaction of Ar2RP may occur in low yield. 2,6-(dimethoxyphenyl-dibutylphosphine gives dibutylphosphine in moderate yield.When compounds with a 2,6-dimethoxyphenyl moiety are allowed to react with Li/THF, removal of a methyl group leads to novel phosphinophenols.It is concluded that cleavage of alkyl groups R selectively occurs when R radical is relatively stable (tBu, PhCH2> iPr > Bu).
- Doorn, Johannes A. van,Meijboom, Nico
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p. 170 - 177
(2007/10/02)
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