Tri-tert.-butyl

Zur Spaltung von Tetrahydrofuran-Ringen kann auch Lithium-tri-tert.-butyl-oxy-hydrido-aluminat/Triathyl-boran verwendet werden. Die Reaktion wird in Tetrahydropyran durchgefiihrt, das vom Reagens nur langsam angegriffen wird. 

Zur Reduktion von l,3,5-Tri-tert.-butyl-l,4-benzochinol zum 4,6-Dioxo-l, 3,5-tri-tert.-butyl-cyclohexan s. Bd. VII/3b, S. 736. 

Cp pentamethylcyclopentadienyl Tmp 2,2,6,6-tetramethylpiperidine Dipp 2,6-di(iso-propyl)phenyl Trip 2,4,6-tri(iso-propyl)phenyl Mes 2,4,6-trimethylphenyl Mes 2,4,6-tri(tert-butyl)phenyl Ada adamantyl dmap 4-(dimethylamino)pyridine Tms trimethylsilyl (SiMe3)... 

Stable silanetriols such as Me3CSi(OH)3 or 2,4,6-tris(tert-butyl)phenylsilanetriol have also been prepared and reviewed [49]. 

The sole recent example in this category is the condensation (in hot aqueous ethanolic sodium hydrogen carbonate) of o-phenylenediamine (399) with tri-tert-butyl 2-hydroxy-3-oxo-l,2,6-piperidinetricarboxylate (400) to give tert-butyl 3-[3-(tcrt-butoxycarbonyl)-3-(tcrt-butoxycarbonylamino)propyl]-2-quinoxalinecarboxy-late (401) in 87% yield.276... 

The trityl radical (gold-coloured) is readily oxidized to peroxide (white) the comparable 2,4,6-tri-(tert-butyl)phenoxy radical (blue) in, e.g., cyclohexane was applied by Paris et al." to so-called free radical titration (either potentiometric or photometric) of oxygen or antioxidant (the latter by hydrogen abstraction). 

Irradiation causes ring closure by valence isomerization of 1,3-diphosphacyclobutane-2,4-diyl 42 (R = 2,4,6-tri(tert-butyl)phenyl) to 2,4-diphosphabicyclo[1.1.0]butane 43 which on thermolysis yielded the gauche-1,4-diphosphabutadiene 44 <99AG(E)3028>. The same group of workers have isolated the carbene 45 (R as above) as the lithium salt of a trimethylalane complex 46 <99AG(E)3031>. 

Tri- tert-butyl-1,3,5 -triphosphabenzene (128, Scheme 53) undergoes a ring contraction over a potassium mirror,159 with the elimination of potassium phosphine and formation of the aromatic 2,4,6-tri-tot-butyl-1,3-diphosphacyclopentadienide anion 129 with three bulky substituents (Scheme 53). The driving force of this reaction could be the higher aromaticity of the five-membered ring. 

The treatment of tri(tert-butyl) ester (511) with trifluoroacetic acid gave compound 1620 (85CC583). 

Tri-tert-butylphosphine Phosphine, tri-tert-butyl- (8) Phosphine, tris(1,1 -dimethylethyl)- (9) (13716-12-6)... 

Some examples of the sensitivities of the sensitized PMMA coatings are shown in Table 1, where 2,4,6-tri-tert-butyl phenol is most effective. 

Tri-tert-Butyl Phenol 4,41-Thio-bi s(6-tert-Butyl-3-methyl Phenol) 2,2 -Methylene-bi s(4-methyl -6-tert-Butyl Phenol) 2,2 -Methylene-bi s(4-ethyl -6-tert-Butyl Phenol) 330 150 131 133... 

The electron microscope images of the fine patterns obtained by PMMA itself and PMMA sensitized by 2,4,6-tri-tert-butyl phenol on the silicon wafer appear in Figs. 10 and 11, respectively. 

The comparison of the resistive property in the plasma etching process between PMMA itself and PMMA sensitized by 2,4,6-tri-tert-butyl phenol is shown in Fig. 12. Following the etching tim the thickness of the PMMA coating becomes thinner. The rate of the decreasing of the film thickness is proportional to the etching time in the former case, but it becomes very slow in the case of the sensitized PMMA. Therefore, the sensitized PMMA is a superior resist than PMMA itself in both properties of the sensitivity and the resistivity. This fact is true in the cases of other sensitizers. 

Some breakthrough was finally achieved by using Pd2(dba)3 as the Pd complex, tris(tert-butyl)phosphine as the ligand, and sodium ferf-butoxide as the base [90]. This combination of reagents proved to bring about the synthesis of unsubstituted phenazine (137) by reaction of two molecules of 2-bromoaniline (131). Remarkably, no reaction takes place under the conditions of the 133 117 transformation. Currently the scope and limitations of this new sequential inter-Zintramolecular AT-arylation for the synthesis of AT-heterocycles... 

Let us now direct our attention to the P=C bond in phosphaalkene ion-radicals. The literature contains data on two such anion-radicals in which a furan and a thiophene ring are bound to the carbon atom, and the 2,4,6-tri(tert-butyl)phenyl group is bound to the phosphorus atom. According to the ESR spectra of anion-radicals, an unpaired electron is delocalized on a n orbital built from the five-membered ring (furanyl or thienyl) and the P=C bond. The participation of the phosphaalkene moiety in this MO was estimated at about 60% and some moderate (but sufficient) transmission of the spin density occurs through the P=C bridge (Jouaiti et al. 1997). Scheme 1.6 depicts the structures under discussion. 

An interesting picture was revealed by Gouverd et al. (2006) as a result of comparison between the neutral chromium tricarbonyl complex of C,P-diaryl phosphaalkene [(CO)3Cr<—PhCH=PMes ] and its anion-radical [(CO)3Cr <— PhCH=PMes ] (Mes is 2,4,6-tris(tert-butyl)phenyl). According to the ESR and DFT data for the anion-radical, about 40% of the negative charge is localized on Cr(CO)3 moiety. This is understandable if one takes into account the known electron-acceptor... 

Nitrosobenzenes are commonly used as spin traps. They are stable and convenient to identify radicals (Zuman and Shah 1994). Most often, however, not nitrosobenzene itself but its 2,4,6-trimethyl and 2,4,6-tri(tert-butyl) derivatives are utilized for this purpose sometimes 2,3-dichloro- and 2,6-dichloronitrosobenzenes can be used. Nitrosobenzenes, ArN=0, have a wider application than other traps. This is explained by the fact that the structure of spin adducts strongly depends on the nature of the added radical. Some radicals can form Ar-N -OR adducts, others form ArN(0 )R adducts. 

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