Butyl 4-methoxyphenyl

Vinylsilane to copper transmetallation has entered the literature,93 93a,93b and a system suitable for catalytic asymmetric addition of vinylsilanes to aldehydes was developed (Scheme 24).94 A copper(l) fluoride or alkoxide is necessary to initiate transmetallation, and the work employs a copper(ll) fluoride salt as a pre-catalyst, presumably reduced in situ by excess phosphine ligand. The use of a bis-phosphine was found crucial for reactivity of the vinylcopper species, which ordinarily would not be regarded as good nucleophiles for addition to aldehydes. The highly tailored 5,5 -bis(di(3,5-di-tert-butyl-4-methoxyphenyl)phosphino-4,4 -bis(benzodioxolyl) (DTBM-SEGPHOS) (see Scheme 24) was found to provide the best results, and the use of alkoxysilanes is required. Functional group tolerance has not been adequately addressed, but the method does appear encouraging as a way to activate vinylsilanes for use as nucleophiles. 

Conducted in toluene. BHA = 2,6-di-ter -butyl-4-methoxyphenyl Naph = naphthyl Cy = cyclohexyl Ar = 2,6-diisopropylphenyl ent = enantio. Molar equivalents to the amounts of organolithium. 

Dimethyl-2-oxo-butyl 4-methoxyphenyl tellurium dichloride decomposed at 210730 torr to bis[4-methoxyphenyl ditellurium and l-chloro-3,3-dimethyl-2-oxobutane3. 

Dimethyl-2-oxo-l-butyl 4-Methoxyphenyl Tellurium Dichloride1 A suspension of 1.02 g (3.0 mmol) of 4-methoxyphenyl tellurium trichloride in 10 m/ benzene is mixed with 0.516 g (3.0 mmol) 3,3-dimethyl-2-trimethylsiloxybut-1 -ene. The mixture is refluxed for 10 h, then treated with 100 ml methanol/water (1 1), and extracted with chloroform. The organic phase is separated, dried with anhydrous magnesium sulfate, filtered, and the filtrate evaporated. The residue is chromatographed on silica gel with chloroform as the mobile phase. The product is recrystallized from chloroform/petroleum ether (30-60°) yield 80% m.p. 90-92°. 

Michael addition of the anion 477 to chalcones, trityl enones and 2,6-di-(fert-butyl)-4-methoxyphenyl cinnamate took place exclusively with high diastereoselectivity682 (Scheme... 

Aryl Esters 2,6-Di-re/t-butyl-4-methylphenyl esters (BHT esters) and 2,6-di-tert-butyl-4-methoxyphenyl esters (BHA esters) provide steric suppression of the carboxyl reactivity so they do not react with RMgX or RLi reagents.BHT and BHA esters... 

Refluxing of 2,6-bis(te/ t-butyl)-4-methoxyphenyl 1-nitrocyclopropanecarboxylate in tetrahy-drofuran containing methylmagnesium bromide resulted in reductive alkylation and formation of 2,6-bis-(/er/-butyl)-4-methoxyphenyl l-[hydroxy(methyl)amino]cyclopropanecarboxylate in 66% yield. 

The esters were prepared from the phenol and the acid chloride plus DM AP (or from the acid plus trifluoroacetic anhydride). In these esters the steric hulk of the ortho substituents protects the carhonyl from nucleophilic reagents, making them difficult hydrolyze. Although the diisopropyl derivative can be cleaved with hot aqueous NaOH, the di-f-butyl derivatives could only be cleaved with NaOMe in a mixture of toluene and HMPA. The related 2,6-di-f-butyl-4-methoxyphenyl ester can be cleaved oxidatively with ceric ammonium nitrate. These hindered esters have found utility in directing the aldol condensation. ... 

Bis(dipheny lphosphino)ferrocene [(4R)-(4,4 -bi-l,3-benzodioxole)-5,5 -diyl]bis[bis (3,5-di-tcrt-butyl-4-methoxyphenyl)phosphine] Enantiomeric excess... 

Tomioka has also extensively investigated conjugate 1,4-additions to a,p-un-saturated BHA (2,6-di-tert-butyl-4-methoxyphenyl) esters stilbene-derived di-... 

Oxidative regeneration of the carboxylic acid from its 2,6-di-r-butyl-4-methoxyphenyl ester is the basis for the use of this auxiliary in a stereoselective a-hydroxyalkylation of carboxylic acids. The smooth removal of p-anisyl (eq 7) and p-anisylmethyl groups from an amidic nitrogen atom by Ce oxidation makes these protective groups valuable in s)uithesis. 

R)-DTBM-SEGPHOS = (R)-(-)-5,5 -Bis[di(3,5-di-tert-butyl-4-methoxyphenyl)phosphino]-4,4 -bi-1,3-benzodioxole = 4-MeOC0H4, Ph, 4-BrC0H4, 4-MeCOC0H4, 2-Furyl, 2-Thienyl, c-Hexyl, /-Pr, 2-MeC0H4,... 

The methyl region of the 150 MHz NMR spectrum of a polypropylene sample produced with a catalyst bearing a very bulky substituent (Ar = 3,5-di-ferf-butyl-4-methoxyphenyl) is shown in Figure 8.11. The active catalyst was obtained by reacting precatalyst 2 with MAO, and the... 

Our initial attempts at metalating hydrazones of methyl and tert-huiy pyruvate and trapping them with electrophiles were unsuccessful and led primarily to self-acylated products (scheme 12). Only after we sterically blocked the ester reactivity as the 2,6-di-t rt-butyl-4-methoxyphenyl ester was the direct manipulation of the corresponding azaenolates possible. 

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