用双(仲)膦HP(R)〜PH(R)(连接基〜=(CH 2)3,R = Mes = 2,4,6 )处理2当量的Au(THT)Cl(THT =四氢噻吩)-Me 3 C 6 H 2(1),R = Is = 2,4,6-(i -Pr)3 C 6 H 2(2),R = Ph(4);〜=(CH 2)2, R =是(3); HP(R)~PH(R)= 1,1' - (η 5 -C 5 H ^ 4 PHPh)2的Fe(5)),得到双核配合物(AUCL)2(μ-HP(R)~PH(R))(6 - 10)。脱卤化氢与氨水,得到膦配合物[(Au)的2(μ-P(R)〜P(R))] Ñ(11 - 15)。二茂铁基和苯基磷酰基衍生物15和14不溶;后者通过固态31 P NMR光谱表征。异磷酸酯基络合物12和13产生了宽广的,不确定的NMR光谱。然而,均三磷酸复配物11是作为单一产物形成的,其特征在于多核溶液NMR光谱法(固态31)P
用双(仲)膦HP(R)〜PH(R)(连接基〜=(CH 2)3,R = Mes = 2,4,6 )处理2当量的Au(THT)Cl(THT =四氢噻吩)-Me 3 C 6 H 2(1),R = Is = 2,4,6-(i -Pr)3 C 6 H 2(2),R = Ph(4);〜=(CH 2)2, R =是(3); HP(R)~PH(R)= 1,1' - (η 5 -C 5 H ^ 4 PHPh)2的Fe(5)),得到双核配合物(AUCL)2(μ-HP(R)~PH(R))(6 - 10)。脱卤化氢与氨水,得到膦配合物[(Au)的2(μ-P(R)〜P(R))] Ñ(11 - 15)。二茂铁基和苯基磷酰基衍生物15和14不溶;后者通过固态31 P NMR光谱表征。异磷酸酯基络合物12和13产生了宽广的,不确定的NMR光谱。然而,均三磷酸复配物11是作为单一产物形成的,其特征在于多核溶液NMR光谱法(固态31)P
Effects of Linker Length on the Rate and Selectivity of Platinum-Catalyzed Asymmetric Alkylation of the Bis(isitylphosphino)alkanes IsHP(CH<sub>2</sub>)<sub><i>n</i></sub>PHIs (Is = 2,4,6-(<i>i</i>-Pr)<sub>3</sub>C<sub>6</sub>H<sub>2</sub>, <i>n</i> = 1−5)
作者:Timothy W. Chapp、Adam J. Schoenfeld、David S. Glueck
DOI:10.1021/om100174c
日期:2010.6.14
Catalytic asymmetric alkylation of the bis(secondary phosphines) IsHP(CH2)(n)PHIs (1a-e, n = 1-5, Is = isityl = 2,4,6-(i-Pr)(3)C6H2) with benzyl bromide using the base NaOSiMe3 and the catalyst precursor Pt((R,R)-Me-DuPhos)(Ph)(Cl) gave the bis(tertiary phosphines) Is(PhCH2)P(CH2)(n)P(CH2Ph)Is (2a-e, n = 1-5) via the intermediates Is(PhCH2)P(CH2)(n)PHIs (4a-e, n = 1-5). The rates of these reactions depended strongly on n, in the order 1a < 1b < 1c approximate to 1d approximate to 1e. The bulkier bis(secondary phosphine) Mes*HP(CH2)(2)PHMe5* (5, Mes* = 2,4,6-(t-Bu)(3)C6H2) did not undergo catalytic alkylation under these conditions. The alkylation selectivity also depended on n. Alkylation of 1b was meso-selective, while alkylation of 1a,c-e was roe-selective, occurring with similar diastercoselectivity and enantioselectivity for the longer linkers (1c-e). The product ratios suggested that the catalyst controlled the selectivity for 1d,e, while substrate control operated for ethano-bridged 1b, with negative cooperativity. Substrate control also likely occurred for I a, for which competition from the background alkylation was significant. Analysis of the observed diastereo- and enantioselectivity for Pt-catalyzed alkylation of 1c and the mixed secondary/tertiary phosphine IsHP(CH2)(3)P(CH2Ph)Is (4c) yielded quantitative information on the selectivity of both P-C bond-forming steps, which was consistent with predominant catalyst control, altered slightly by the influence of the substrate.