Tetrakis ketones

Titanium tetrakis(diethylamide) selectively adds to aldehydes in the presence of ketones and to the least hindered ketone in compounds containing more than one ketone. The protection is in situ, which thus avoids the usual protection-deprotec-tion sequence. Selective aldol and Grignard additions are readily performed employing this protection methodology. ... 

A reagent more reactive than tris(dimethylamino)arsine employed by Weingarten and White 39) was tetrakis(dimethylamino)titanium (145). With this compound it was possible to prepare N,N-dimethyl(l-isopropyl-2-methylpropcnyl)amine (147) from diisopropyl ketone. Weingarten and White 39) have suggested a possible mechanism for this reaction (see p. 88). If benzaldehyde 39,111), formaldehyde 111), or acetaldehyde 39) is used, the corresponding gem diamine or aminal (143) is formed. 

Besitzen Aldehyd und Keton a-H-Atome, so werden diese zunachst durch Hydroxy-methyl-Gruppen ersetzt. Auf diese Weise erhalt man z. B. aus Acetaldehyd und vier Molen Formaldehyd Pentaerythrit (73% d.Th.)4 bzw. aus Cyclohexanon mit fiinf Molen Formaldehyd 2-Hydroxy-1,1,3,3-tetrakis-[hydroxymethyl]-cyclohexan (73-85% d.Th.). Da es sich hierbei zunachst um eine Aufbaureaktion handelt, wird diese Umsetzung in Bd. VI/la/2, S. 1314f. geschlossen abgehandelt (vgl. auch Lit.s). 

The formation of ethers such as 1806 by EtsSiH 84b can also be catalyzed by trityl perchlorate to convert, e.g., benzaldehyde in 84% yield into dibenzyl ether 1817 [48]. The combination of methyl phenethyl ketone 1813 with O-silylated 3-phenyl-n-pro-panol 1818, in the presence of trityl perchlorate, leads to the mixed ether 1819 in 68% yield [48] (Scheme 12.15). Instead of trityl perchlorate, the combination of trityl chloride with MesSiH 84a or EtsSiH 84b and sodium tetrakis[3,5-bis-(trifluoro-methyl)phenyl]borane as catalyst reduces carbonyl groups to ethers or olefins [49]. Employing TMSOTf 20 as catalyst gives very high yields of ethers. Thus benzaldehyde reacts with O-silylated allyl alcohol or O-silylated cyclohexanol to give the... 

The inherent chemistry above is not altered by substituting the phenyl rings of the ketone or pinacol with methyl groups. The ketone 4,4 -dimethylbenzophenone, as well as the pinacol 1,2,2-tetrakis-(4-methylphenyl)ethane-l,2-diol (TBP) react with U giving tetrakis-(4-methylphenyl)ethylene and l,l, ,2-tetrakis(4-methylphenyl)ethane. A lsl mixture of benzophenone and 4,4-dimethylbenzophenone gives the six expected coupling products. 

Table 1. Common materials used in quenched-fluorescence oxygen sensing (Ru(dpp)3(C104)2 tris(diphenylphenantroline) ruthenium(II) perchlorate PtOEPK platinum(II)-octaethyl-porphine-ketone PtPFPP platinum(II)-tetrakis(pentafluorophenyl)porphine PS.poly(styrene), PSu poly(sulfone) PSB poly(styrene-butadiene) block co-polymer PVC polyvinylchloride) APET amorphous poly(ethyleneterephthalate) PE poly(ethylene).

Thorpe reaction org chem The reaction by which, in presence of lithium amides, a,(rt-dinitriles undergo base-catalyzed condensation to cyclic iminonitriles, which can be hydrolyzed and decarboxylated to cyclic ketones. thorp re,ak-shan TMPC See tetrakis(hydroxymethyl)phosphonium chloride, thulia See thulium oxide. thu-le-a ... 

Other techniques, such as C.D. spectral change, have been used to demonstrate the presence of octa coordination for lanthanide ion in a system containing Eu(FOD)3 and alcohols or ketones (28). However, the anionic tetrakis complexes e.g. Eu(acac)i, Eu(benzac)i, Eu(DBM)i, Eu(BTFA)4, tend to dissociate into the tris-complex and L in alcoholic solution. The degree of dissociation depends on the complex as well as the polarity of the medium. In alcohol-DMF medium the dissociation is enhanced compared to the alcoholic solutions (29). The end product of these dissociation reaction may well be an octacoordinated species. Fluorescence emission from the coordinated europium ion was also helpful in estabhshing the nature of the species in solution 29). 

Lithium aluminum hydride dissolves in pyridine and forms lithium tetrakis-(A -dihydropyridyl)aluminate which itself is a reducing agent for purely aromatic ketones [440, 441]. 

With slight modification, the methods used to prepare fluorothioacyl fluorides can also be used for synthesis of fluorothioketones. Hexafluorothioacetone, the member of this class that has been studied most extensively, is readily obtained by high-temperature reaction of hexafluoropropylene and sulfur (53). The thio-ketone is a deep-blue liquid, bp 8° C, that dimerizes on standing to 2,2,4,4-tetrakis-(trifluoromethyl)-l,3-dithietane. 

Reaction of tris(dimethylamino)arsine or tetrakis(dimethylamino)-titanium with aldehydes or ketones to give enamines [164, 165]. 

The scope of the Negishi-coupling is not limited to aryl and vinyl halides and sometimes acyl chlorides might also be converted to ketones by this protocol. The 2,3-dihalopyrrole derivative shown in 6.22. was converted into its 2-lithio derivative by selective lithium-halogen exchange at -78 °C. Addition of zinc chloride effected the formation of the appropriate pyrrolylzinc chloride, which was coupled with a functionalised butyroyl chloride in the presence of tetrakis(triphenylphosphino)palladium and furnished the expected 2-acylpyrrole in 61% yield.27... 

Although the cofacial diporphyrins represent a vibrant and innovative direction in dioxygen activation, simple porphyrins and their derivatives also remain an important research area. The dichlorophenyl-substituted porphyrin tdcpp [5,10,15,20-tetrakis(2,6-dichlorophenyl)-porphyrin] forms a complex with cobalt(II), [Co(tdcpp)], and catalyzes the oxidation of conjugated olefins to (after experimental workup) ketones in the presence of dioxygen and triethylsilane (80) a hydroperoxide intermediate has been isolated from these reactions (81). 

Ring expansion of cyclic ketonesA new method for expansion of cyclic ketones to the expanded a-dithioketals involves addition of (CH3S)sCLi followed by treatment of the adduct with tetrakis(acetonitrile)coppcr(l) perchlorate or tetra-fluorohnrutc.2... 

In tetrakis(trifluoromethyl)allene (9), potassium permanganate in acetonitrile hydroxylates only one C = C bond 93 the resulting enol tautomerizes to an a-hydroxy ketone 10. The reaction has been repeated and extended to other perfluoroalkylated allenes92 achieving yields of 51-60%. 

Lithium-Ammonia, 158 Potassium hydride, 257 Tetrakis(triphenylphosphine)palla-dium(O), 289 Tributyltin chloride, 315 8,e-Unsaturated aldehydes and ketones Allyltrimethylsilane, 11 Lead tetraacetate, 155 Unsaturated amides Bis(benzonitrile)dichloropalladium(II), 34... 

Complexes of Th4+ with cupferron (as well as oxime) were investigated by determining the distribution of tracer amount of 234Th between the organic (chloroform or isobutyl methyl ketone) and aqueous phases.118 The distribution curves show the presence of complexes other than the tetra ones, but formation constants for the neutral tetrakis products were calculated on the basis of the two-parameter equation method of Dryssen and Sillen. 

Stereoselective allylic alkylations have been carried out with the aid of palladium catalysts. The 17-(Z)-ethylidene groups of steroids (obtained from the ketones by Wittig olefination) form n-allyl palladium complexes in the presence of copper(n) salts (B.M. Trost, 1974, 1976). Their alkylation with dimethyl malonate anions in the presence of 1,2-ethane-diylbis[diphenylphosphine] (— diphos) gives a reaction exclusively at the side chain and only the (20S) products. If one starts with the endocyclic 16,17 double bond and replaces an (S)-20-acetoxy group by using tetrakis(triphenylphospbine)palladium,the substitution occurs with complete retention of configuration, resulting from two complete inversions (B.M. Trost, 1976). 

Recently, a variety of (3-silylated carboxonium ions have been prepared and characterized by NMR spectroscopy.541 Kira et al.631 used the Corey hydride transfer method, whereas Olah, Prakash, and co-workers applied triphenylmethyl tetrakis (pentafluorophenyl)borate to silylate esters,632 ketones, enones, and carbonates633 [Eq. (3.91)]. The ions thus produced are resonance hybrids of oxocarbenium (327b) and carboxonium (327a) ions with the latter as the major contributors. Calculated (DFT/IGLO) 29 Si NMR chemical shifts agree well with the experimental data. 

Conjugate reduction of a,/l-enals and -enones. Tri-n-butyltin hydride in the presence of tetrakis(triphenylphosphine)palladium effects conjugate reduction of a, /J-unsaturated aldehydes and ketones in the presence of a proton source (water, acetic acid). Yields are improved by addition of a radical scavenger.15 Double bonds bearing... 

Quadrol 0 150 HB Chlor 214 571 357 472 489 A/,A/,A/, A/ -Tetrakis (2-hydroxy-propyl) ethylenediamine for alcohols, aldehydes, ketones, amino acids, essential oils... 

Hexagonal macrocycle 50 is produced from a 120°-angle-tecton 33 and 120°-angle-linker 49 <19990L1921> (Scheme 8). Tecton 33 is prepared by double oxidative addition of 4,4 -diiodobenzenophenone 47 with tetrakis(triethylphosphine)platinum(ll) followed by treatment with AgOTf. Bis(4-pyridyl)ketone 49 combines spontaneously with 33 at room temperature to form metallocycle 50. 

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