3-phenyl- terminal

Vinylphenyl-terminated PBE dendrons were prepared as polymerizable den-drons from 4-vinylbenzyl chloride [37]. The vinylphenyl-terminated PBE dendrons are useful to make the lanthanide-cored dendrimer complexes polymerizable. The Ist-generation Tb +-cored dendrimer complex bearing the vinyl-phenyl terminal on the dendron subunits (Fig. 5) was copolymerized with N-iso-propylacrylamide in the presence of methylene bis-acrylamide (as crosslinker) in DMSO to give a green-luminescence transparent gel. The DMSO gel was con-... 

Quantitation of phenyl content in Sylgards was performed by comparison of areas of UV absorbance at 215 nm with a calibration curve generated with PS463, a phenyl terminated PDMS. In performing the integration for phenyl content the absorbance due to the THF peroxide band was omitted but other bands, due to lower molecular weight impurities which contain phenyls, were included to permit comparisons with bulk analytical methods, such as NMR. 

Scheme 3. Synthesis of phenyl-terminated silicon-based dendrimers and functionalization of the branches with Cr(CO)j units.

These findings might tempt one to predict that 3-phenylpropyl analogue 51 would be about equipotent with 1. Surprisingly, 51 was about 8 times more potent than 1. Furthermore, there is also a length dependency with phenyl terminators, as shown in Figure 7. These results suggest that a hydrophobic pocket exists in a putative artemisinin receptor with well-defined dimensions. A Pi acceptor in this pocket... 

Moran et al. 41 attached the Cr(CO)3 moiety to tetrakis(phenylsilane) 32 (prepared by the hydrosilylation of tetraallylsilane with four equivalents of dimethylphenylsilane) by treatment with excess Cr(CO)6 in dibutyl ether—THF at 140 °C affording the air-stable, crystalline tetrakis(chromium carbonyl) dendrimer 33, which was also prepared by reaction of tetraallylsilane with [r76-C6H5Si(Me)2H]Cr(CO)3) (Scheme 8.9). 42a Reaction of the corresponding eight phenyl-terminated analogues afforded the partially metalated silane dendrimer 34 as the major product, even with an excess of Cr(CO)6. 

Phenyl terminated polybutadiene (M 1300 daltons, 45% vinyl) was reacted with trichlorosilane and chloroplatinic acid and then mixed with a slurry of 105 p particle size silica gel having a 250 A average pore diameter in dry toluene for 24 hours. The quantity of trichlorosilane used was 2 mol per mole of polybutadiene. Pyridine was added to remove HCl, and the slurry was gently shaken for 18 hours at ambient temperature. The surface of the silica was blocked by addition of 1,2-bis(trichlor-osilyl)ethane, and the mixture was treated with pyridine. After three hours of shaking the reaction was worked up by vacuum filtration in a sintered glass funnel and washed with toluene and methanol. The modified silica gel was dried in the filter funnel by continued application of vacuum to the filter funnel. 

The above mthenium(II)-catalyzed intramolecular alkyne cyclotrimerizations probably proceeded via a ruthenacycle intermediate similar to the aforementioned ruthenacyclopentatriene complex 18 reported by Dinjus (see Scheme 4.5) [24]. This was confirmed by the isolation of a bicyclic ruthenacyde intermediate and its reaction with acetylene (Scheme 4.11) [25]. The stoichiometric reaction of 17 with the internal diyne 31 possessing phenyl terminal groups in CDCI3 at ambient temperature afforded the expected mthenacycle complex 32 in 51% yield as single crystals. X-ray analysis of 32 disdosed that its Ru-Ca bond distances of 1.995(3) and... 

Pyrolysis results for a polybutadiene sample phenyl terminated (45% wt. vinyl) with Mn = 1,000 and about 10% frans-1,4 and 5% c/s-1,4 is shown in Figure 7.1.2. The pyrolysis was done in similar conditions with the other polybutadiene sample. The peak identification for the pyrogram is given in Table 7.1.3... 

The traces obtained from the GLC analysis of the reaction (Figure 25) clearly show the production of what have been identified, through the use of GC/EI-MS, as linear phenyl terminated poly(dimethylsiloxane) oligomers (Ph-(Si(CE)j)20) -Si(CD3)2Ph). The subsequent removal of the terminal phenyl groups upon further reaction with triflic acid was seen to result in a rearrangement to small cyclic oligomers of per-deuterated dimethylsiloxane. 

Figure 37 Condensations leading to phenyl-terminated linear oligomers.

In the chain-growth polymerization of 35a with Ni(dppp)Cl2, the chain initiator is a dimer of 35a formed in situ as mentioned above. Kiriy and coworkers conducted polymerization of 35a with an externally added initiator, PhNi (PPh3)2Br, to obtain phenyl-terminated poly(3-hexylthiophene), although the polymerization was less controlled than the polymerization of 35a with Ni(dppp)... 

Figure 13.15 Storage (O) and loss ( ) moduli of 10 wt% 1.24 MDa polybutadiene in 1 or 1.5 kDa phenyl-terminated polybutadiene as measured with a dynamic mechanical spectrometer, using time-temperature superposition with a 100 K temperature range, based on data of Tapadia and Wang(26). Solid lines are stretched exponentials and sums of two power-law decays.

This reaction illustrates one of the methods by which R. Kuhn synthesised long polyene chains terminated at each end by phenyl groups. 

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