Aluminum tris 2,6-bis

Scheme 2.128 Reaction of l /le3SiCF3 with a variety of carbonyl compounds (ATPH = aluminum tri(2,6-bis(tert-butyl)phenoxide) [64b, 65, 73].

Nucleophilic addition of the trifluoromethyl group to aldehydes, ketones and other carbonyl compounds leads primarily to the corresponding trimethylsilyl ether this must subsequently be hydrolyzed to the alcohol. Because typical reaction conditions are very mild, the method is widely applicable, even for sensitive substrates. In contrast with most other methods, fluoride-induced perfluoroalkylation via silicon compounds also works for enolizable carbonyl compounds. With c(, -un-saturated substrates 1,2-addition directly to the carbonyl group is strongly preferred [64b]. If the oxygen is coordinated to a bulky Lewis acid, for example aluminum tri(2,6-bis(tert-butyl)phenoxide (ATPH), the 1,4-addition products are obtained selectively [73f] (Scheme 2.128). 

ATPH aluminum tri(2,6-bis(tert-butyl)- ECF electrochemical fluorination... 

For example, although the reaction of ATPH-cinnamaldehyde complex and BuLi gave alkylation products as a 1 1 mixture of 1,4-adduct and 1,2-adduct, the use of aluminum tris[2,6-bis(4-fluorophenyl)phenoxide] (p-F-ATPH) resulted in dramatic improvement of 1,4-selectivity (Scheme 6.84). These results were explained by the high affinity between fluorine atom and lithium atom, thus, the coordination of fluorine atoms on p-F-ATPH to BuLi dominated this highly y-selective butyl transfer reaction (Scheme 6.4). 

Several modifications have been made to organoaluminum-based catalysts. Methylaluminum bis(2,6-di-tert-butyl-4-alkylphenoxide) (MAD) shows high diastereofacial selectivity in carbonyl alkylation (Scheme 72).31 11 Aluminum tris(2,6-diphenylphenoxide) (ATPH) has been developed as a catalyst for conjugate addition reactions. Since a carbonyl group is stabilized by steric effect of ATPH, the 1,4-adduct is obtained selectively.312... 

Aluminum tris(2,6-diplienylphenoxide) (ATPH), an aluminum-based Lewis acid with bulky substituents, is valuable as an extremely selective activator of less hindered aldehyde carbonyls (Scheme 10.8) [36]. In competitive aldol reactions of two different aldehydes, more fhan one equivalent of ATPH achieves highly chemoselective functionalization of less hindered aldehydes. Unfortunately, catalytic use of ATPH reduces the chemical yield and chemoselectivity. In contrast, a catalytic quantity of aluminum bis(trifluoromethanesulfonyl)amide 13 can promote the chemoselective aldol reaction. 

Benzene reacted with excess 3 in the presence of aluminum chloride at room temperature for 4 h to give peralkylated product," hexakis[2-(methyldichloro-sily I )ethyljbenzcne (4a) and other alkylated products pentakisl2-(mcthyldichloro-silyl)ethyl]benzenc (4b), tetrakis 2-(methyldichlorosilyl)ethyljbenzene (4c), tris 2-(methyldichlorosilyl)ethyl]benzene(4cl), and bis 2-(methyldichlorosilyl)ethylJ-benzene (4e) (Eq. (6)). The product distributions were plotted against mole ratios of 3/benzene in Fig. I. 

GABA HMG-CoA HMPA HT LDA LHMDS LTMP NADH NBH NBS NCS NIS NK NMP PMB PPA RaNi Red-Al RNA SEM SnAt TBAF TBDMS TBS Tf TFA TFP THF TIPS TMEDA TMG TMP TMS Tol-BINAP TTF y-aminobutyric acid hydroxymethylglutaryl coenzyme A hexamethylphosphoric triamide hydroxytryptamine (serotonin) lithium diisopropylamide lithium hexamethyldisilazane lithium 2,2,6,6-tetramethylpiperidine reduced nicotinamide adenine dinucleotide l,3-dibromo-5,5-dimethylhydantoin A-bromosuccinimide A-chlorosuccinimide A-iodosuccinimide neurokinin 1 -methyl-2-pyrrolidinone para-methoxybenzyl polyphosphoric acid Raney Nickel sodium bis(2-methoxyethoxy)aluminum hydride ribonucleic acid 2-(trimethylsilyl)ethoxymethyl nucleophilic substitution on an aromatic ring tetrabutylammonium fluoride tert-butyldimcthyisilyl fert-butyldimethylsilyl trifluoromethanesulfonyl (triflyl) trifluoroacetic acid tri-o-furylphosphine tetrahydrofuran triisopropylsilyl A, N,N ,N -tetramethy lethylenediamine tetramethyl guanidine tetramethylpiperidine trimethylsilyl 2,2 -bis(di-p-tolylphosphino)-l,r-binaphthyl tetrathiafulvalene... 

LPG LP gas. See Liquefied petroleum gas LQ-770. See Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate LSP 33. See Tallow dipropylene triamine LT 8049] LT 8052. See Epoxy resin, broniinated LTAC. See Laurtrimonium chloride LTBA. See Lithium aluminum tri-t-butoxyhydride... 

To avoid some competitive side reactions, Yamamoto recently reported that highly reactive intermediate can be stabilized by the coordination of bulky Lewis acid (Scheme 6.102). That is, bis(2,6-diphenylphenoxide) aluminum triflimide, as a sterically bulky Lewis acid, efficiently catalyzed [2 + 2]cycloaddition of phenyl acrylate with tris(trimethylsilyl)silyl enol ethers to give cycloadducts with high diastereoselectivity [121]. 

Multiplicative Prefixes. The multiplicative prefixes bis, tris, etc., are used with certain anions for indicating stoichiometric proportions when di, tri, etc., have been preempted to designate condensed anions for example, A1K(S04)2 I2H2O, aluminum potassium bis(sulfate) 12-water (recall that disulfate refers to the anion S20jfi. 

Butylmagnesium bromide-Methyl-aluminum bis(2,4,6-tri-r-butyl-phenoxide), 203 p-Chlorobis(cyclopentadienyl)-(dimethylaluminum)-fjL-methyleneti-tanium, 71... 

NMO NMP Nu PPA PCC PDC phen Phth PPE PPTS Red-Al SEM Sia2BH TAS TBAF TBDMS TBDMS-C1 TBHP TCE TCNE TES Tf TFA TFAA THF THP TIPBS-C1 TIPS-C1 TMEDA TMS TMS-C1 TMS-CN Tol TosMIC TPP Tr Ts TTFA TTN N-methylmorpholine N-oxide jV-methyl-2-pyrrolidone nucleophile polyphosphoric acid pyridinium chlorochromate pyridinium dichromate 1,10-phenanthroline phthaloyl polyphosphate ester pyridinium p-toluenesulfonate sodium bis(methoxyethoxy)aluminum dihydride (3-trimethylsilylethoxy methyl disiamylborane tris(diethylamino)sulfonium tetra-n-butylammonium fluoride f-butyldimethylsilyl f-butyldimethylsilyl chloride f-butyl hydroperoxide 2,2,2-trichloroethanol tetracyanoethylene triethylsilyl triflyl (trifluoromethanesulfonyl) trifluoroacetic acid trifluoroacetic anhydride tetrahydrofuran tetrahydropyranyl 2,4,6-triisopropylbenzenesulfonyl chloride 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane tetramethylethylenediamine [ 1,2-bis(dimethylamino)ethane] trimethylsilyl trimethylsilyl chloride trimethylsilyl cyanide tolyl tosylmethyl isocyanide meso-tetraphenylporphyrin trityl (triphenylmethyl) tosyl (p-toluenesulfonyl) thallium trifluoroacetate thallium(III) nitrate... 

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