502926-59-2Relevant academic research and scientific papers
Didentate phosphine ligands with alkenyl and alkynyl linker units as building blocks for dendrimer fixation
Findeis, Ralf A.,Gade, Lutz H.
, p. 3952 - 3960 (2007/10/03)
Using diethyl-2-methylmalonate as a starting material, the two diphosphines HC≡CCH2C(CH3)(CH2PPh2) 2 (7) and H2C=CHCH2C(CH3)(CH2PPh 2)2 (13), containing alkynyl and alkenyl unit in the ligand backbone were prepared in multistep syntheses. These two ligands were employed in the synthesis of [{(CH3)3SiC≡CCH2C(CH3) (CH2PPh2)2}PdCl2] (8) and [{(CH3)3SiC≡CCH2C(CH3) (CH2PPh2)2}PtCl2] (9) as well as [{H2C=CHCH2C(CH3)(CH2PPh 2)2}PdI2] (14b), all of which were characterized by X-ray diffraction. Reaction of Si[(CH2)3SiMe2Cl]4 (= "G[0]-[Cl]4") with four molar equivalents of the in situ lithiated alkynyl diphosphine 7 cleanly yielded the four-fold functionalized derivative G[0]-[C≡CCH2C(CH3)(CH2PPh 2)2]4 (15) which was converted to the metallated derivative G[0]-[C≡CCH2C(CH3)(CH2PPh 2)2PdCl2]4 (16). Since the fixation of the alkenyl-functionalized diphosphine ligand 13 to the SiH-silane Si[(CH2)3SiMe2H]4 (= "G[0]-[H]4") by Pt-catalyzed hydrosilation proved to be unsuccessful due to the negative interference of the phosphine with Karstedt's catalyst, the chloro-substituted precursor of 13, H2C=CHCH2C(CH3)(CH2Cl) 2 (12) was used. Hydrosilation of G[0]-[H]4 with four molar equivalents of 12 readily gave the functionalized dendrimer G[0]-[CH2CH2CH2C(CH3)(CH 2Cl)2]4 (17) which was then reacted with eight equivalents of LiPPh2 to yield the phosphinated derivative G[0]-[CH2CH2CH2C(CH3)(CH 2PPh2)2]4 (18).
