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All total 4 Articles be foundSynthesis of novel chiral quaternary phosphonium fluorides: Reagents for simple asymmetric nucleophilic fluorination reactions
Beaumont,Kiely,Rooney
, p. 47 - 50 (2007/10/03)
The novel chiral quaternary salt (RP)-benzylmenthylmethylphenylphosphonium fluoride was synthesised. The compound was used in the asymmetric nucleophilic fluorination of 2-bromopropiophenone to give 2-fluoropropiophenone in a 35% yield with [α]D20 = +1.94°.
Ready Approach to Organophosphines from ArCl via Selective Cleavage of C-P Bonds by Sodium
Ye, Jingjing,Zhang, Jian-Qiu,Saga, Yuta,Onozawa, Shunya,Kobayashi, Shu,Sato, Kazuhiko,Fukaya, Norihisa,Han, Li-Biao
, p. 2682 - 2694 (2020/07/30)
The preparation, application, and reaction mechanism of sodium phosphide R2PNa and other alkali metal phosphides R2PM (M = Li and K) have been studied. R2PNa could be prepared, accurately and selectively, via the reactions of SD (sodium finely dispersed in mineral oil) with phosphinites R2POR′ and chlorophosphines R2PCl. R2PNa could also be prepared from triarylphosphines and diarylphosphines via the selective cleavage of C-P bonds. Na was superior to Li and K for these reactions. R2PNa reacted with a variety of ArCl to efficiently produce R2PAr. ArCl is superior to ArBr and ArI since they only gave low yields of the products. In addition, Ph2PNa is superior to Ph2PLi and Ph2PK since Ph2PLi did not produce the coupling product with PhCl, while Ph2PK only gave a low yield of the product. An electron-withdrawing group on the benzene ring of ArCl greatly accelerated the reactions with R2PNa, while an alkyl group reduced the reactivity. Vinyl chloride and alkyl chlorides RCl also reacted efficiently. While t-BuCl did not produce the corresponding product, admantyl halides could give the corresponding phosphine in high yields. A wide range of phosphines were prepared by this method from the corresponding chlorides. Unsymmetric phosphines could also be conveniently generated in one pot starting from Ph3P. Chiral phosphines were also obtained in good yields from the reactions of menthyl chlorides with R2PNa. Possible mechanistic pathways were given for the reductive cleavage of R3P by sodium generating R2PNa and the substitution reactions of R2PNa with ArCl generating R2PAr.
CsOH-promoted P-alkylation: A convenient and highly efficient synthesis of tertiary phosphines
Honaker, Matthew T.,Sandefur, Benjamin J.,Hargett, James L.,McDaniel, Alicia L.,Salvatore, Ralph Nicholas
, p. 8373 - 7377 (2007/10/03)
A mild and efficient method for the synthesis of tertiary phosphines and ditertiary phosphines has been developed. In the presence of cesium hydroxide, molecular sieves and DMF at room temperature, various secondary phosphines and alkyl bromides were examined, and the results have demonstrated that this methodology offers a general synthetic procedure to produce tertiary phosphines in moderate to high yields. Optically active tertiary phosphine synthesis is also described.
CATALYTIC ASYMMETRIC HYDROSILYLATION OF OLEFINS. III. CHIRAL PHOSPHINE-PALLADIUM(II) COMPLEXES AS HYDROSILYLATION CATALYSTS
Yamamoto, Keiji,Kiso, Yoshihisa,Ito, Ryuichi,Tamao, Kohei,Kumada, Makoto
, p. 9 - 18 (2007/10/02)
A palladium(II) complex of menthyldiphenylphosphine (MDPP) or epimeric neomenthyldiphenylphosphine (NMDPP) was used as an effective catalyst for the asymmetric hydrosilylation of styrene and some cyclic conjugated dienes, such as cyclopentadiene; the reaction giving optically active 1-phenylethyl-silane and 2-cycloalkenylsilane derivatives, respectively.MDPP and NMDPP, as ligands which have configurations opposite to each other only at the chiral C(3) center adjacent to the diphenylphosphino group, gave enantiomeric (S)-(-)- and (R)-(+)-1-phenylethyltrichlorosilane, respectively, in the hydrosilylation of styrene with trichlorosilane.However, this is not the case for 2-cycloalkenylsilane formation.Intervention of a ?-allylic palladium is suggested to account for the observed enantioselectivity as well as regioselectivity in the palladium complex-catalyzed addition of trichlorosilane to these olefins.
