- Hydrophosphorylation of Alkynes Catalyzed by Palladium: Generality and Mechanism
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We carried out a comprehensive study on the generality, scope, limitations, and mechanism of the palladium-catalyzed hydrophosphorylation of alkynes with P(O)-H compounds (i.e., H-phosphonates, H-phosphinates, secondary phosphine oxides, and hypophosphinic acid). For H-phosphonates, Pd/dppp was the best catalyst. Both aromatic and aliphatic alkynes, with a variety of functional groups, were applicable to produce the Markovnikov adducts in high yields with high regioselectivity. Aromatic alkynes showed higher reactivity than aliphatic alkynes. Terminal alkynes reacted faster than internal alkynes. Sterically crowded H-phosphonates disfavored the addition. For H-phosphinates and secondary phosphine oxides, Pd/dppe/Ph2P(O)OH was the catalyst of choice, which led to highly regioselective formation of the Markovnikov adducts. By using Pd(PPh3)4 as the catalyst, hypophosphinic acid added to terminal alkynes to give the corresponding Markovnikov adducts. Phosphinic acids, phosphonic acid, and its monoester were not applicable to this palladium-catalyzed hydrophosphorylation. Mechanistic studies showed that, with a terminal alkyne, (RO)2P(O)H reacted, like a Br?nsted acid, to selectively generate the α-alkenylpalladium intermediate via hydropalladation. On the other hand, Ph(RO)P(O)H and Ph2P(O)H gave a mixture of α- and β-alkenylpalladium complexes. In the presence of Ph2P(O)OH, hydropalladation with this acid took place first to selectively generate the α-alkenylpalladium intermediate. A subsequent ligand exchange with a P(O)H compound gave the phosphorylpalladium intermediate which produced the Markovnikov adduct via reductive elimination. Related intermediates in the catalytic cycle were isolated and characterized.
- Chen, Tieqiao,Zhao, Chang-Qiu,Han, Li-Biao
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supporting information
p. 3139 - 3155
(2018/03/08)
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- A alkene base phosphine acid ester compound preparation method
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The invention discloses a preparation method for an alkenyl phosphate compound. By taking palladium acetate or tetra(triphenylphosphine) palladium as a catalyst, an alkali, a ligand, a diazo compound and a halide or an alkali, tosylhydrazone and a halide react under protection of an N2 atmosphere in an organic solvent to obtain the alkenyl phosphate compound RR'C=C(Ar)(P(O)(OMe)2), wherein Ar represents substituted or unsubstituted aryl comprising phenyl, naphthyl and heterocyclic rings; R and R' represent substituted or unsubstituted aryl, alkyl, alkenyl or hydrogen. According to the reaction referred to the invention, an E-configuration alkenyl phosphate compound can be smoothly obtained. The preparation method is convenient and simple to operate and has good tolerance and universality on functional groups. Moreover, the use level of the catalyst is relatively small, neither the reagent nor the solvent is specially treated, and the reaction cost is relatively low, so that the preparation method can be widely used for preparing the alkenyl phosphate compound.
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Paragraph 0221-0225
(2017/07/26)
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- Synthesis of Alkenylphosphonates through Palladium-Catalyzed Coupling of α-Diazo Phosphonates with Benzyl or Allyl Halides
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An efficient method for the synthesis of organophosphonates through palladium-catalyzed coupling of α-diazo phosphonates with benzyl or allyl halides has been developed. Trisubstituted alkenylphosphonates bearing versatile functional groups can be easily accessed in good yields and with excellent stereoselectivity through this method. Moreover, with similar strategy α-substituted vinylphosphonates can also be attained by the palladium-catalyzed coupling reaction of N-tosylhydrazones and aryl bromides. Migratory insertion of palladium carbene is proposed as the key step in this reaction.
- Zhou, Yujing,Ye, Fei,Wang, Xi,Xu, Shuai,Zhang, Yan,Wang, Jianbo
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p. 6109 - 6118
(2015/06/30)
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- Applications of α-phosphonovinyl tosylates in the synthesis of α-arylethenylphosphonates via suzuki-miyaura cross-coupling reactions
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It has been demonstrated for the first time that α-phosphonovinyl tosylates could efficiently couple with a range of arylboronic acids to access α-arylethenylphosphonates. The unprecedented procedure exhibits excellent functional group tolerance, giving the terminal vinylphosphonates in good to excellent isolated yields (60-99%) under mild reaction conditions.
- Fang, Yewen,Li, Jinjian,Wu, Rong,Fang, Jianghua,Zhang, Li,Yuan, Meijuan,Li, Ruifeng,Jin, Xiaoping
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supporting information
p. 798 - 801
(2015/04/14)
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