Tetramethylpiperidine and

On the other hand, the predominant formation of the diastereomeric aldols 3 b results from the titanium enolate 1 b of (S )-5,5-dimethyl-4-tert-butyldimethylsilyloxy-3-hexanone. For this purpose, the ketone is first deprotonated with A-(bromomagnesio)-2,2,6,6-tetramethylpiperidine and the magnesium enolate, presumably (E) configurated, formed is thereby treated with hexamethylphosphoric triamide and triisopropyloxytitanium chloride. After sonification, the aldehyde is added to give predominantly aldol adducts 3b the diastereomeric ratio of 3b/2b surpasses 95 5 and the chemical yields range from 85 to 88%53b. 

Substituted tetramethylpiperidines and their oxidation products appear to act as UV stabilizers for polypropylene by weakly scavenging PP, PPO2 and possibly other radicals involved in the photo-oxidation. Their weak scavenging ability is off-set by the... 

The Dervan group discovered that addition of ferf-butyl hypochlorite to a solution of l-amino-2,2,6,6-tetramethylpiperidine and triethylamine in ether at —78 °C produces triethylammonium chloride as an insoluble white precipitate and an intense purple solution. The purple coloration, which is stable for hours at —78 °C, fades in minutes at 0 °C and was assigned to the 1,1-diazene 64. " " " ... 

A remarkable series of inverse crown compounds featuring organic guest moieties encapsulated within host-like macrocyclic rings composed of sodium/potassium and magnesium ions together with anionic amide groups, such as TMP- (TMPH = 2,2,6,6-tetramethylpiperidine) and Pr NT (Pr NII = diisopropylamine), have been synthesized and characterized. Table 12.8.1 lists some examples of this class of inverse crown molecules. 

Commercially important polyesters, e.g. poly[l-(2-ethylenyl)-2,2,6,6-tetramethyl-4-piperidinylbutane dioate] (146) [190] were synthesized from l-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidines and suitable dicarboxylic acids. Another polymeric HALS was prepared by transesterification of oligoesters of tetramethyl-butane-l,2,3,4-tetracarboxylate with 22,6,6-tetramethyl-4-hydroxypiperidine and 1,10-decanediol [191]. Compound 147 is a similar polyester type HALS. An ester-amide chain is created during esterification of 2-(2,2,6,6-tetramethyl-4-piperidinylamino)ethanol and dimethyl adipate [192]. 

Westheimer has reported on the results of a more deta d study of the formation of monomeric metaphosphate anion from (1,2-dibromo-l-phenyl-propyl)phosphonic acid, and its reaction with acetophenone. The yields of phenylethenyl phosphate can be raised to 40—80 % by careful choice of the nature and concentration of base. The effect of the pJ Ta of the added base appears to be complex some hindered bases, e.g., 2,2,4,4-tetramethylpiperidine and diisopropylamine, raise yields (to the maximum observed), but others, e.g. diisopropyl-methylamine, have the opposite effect. ... 

Treatment of tetramethylpiperidine and Y-methylacridinium salt [MA]" in the presence of a catalytic amount of the ruthenium complex [Cp RuH(dppm)] under gives monodeuterated products MAD and piperidinium salt in quantitative yields, respectively (Eq. 5). The stoichiometric reactions of [Cp RuH(dppm)] with Y-methylacridium salt [MA] in CHjCN or THF afford [Cp Ru(S)(dppm)] (S = CHjCN or THF) and MAH in high yields, respectively. This shows that the hydride at the Ru center is readily transferred to the acridium salt. A catalytic cycle proposed by Hembre and co-worker is shown in Scheme 6, where tetramethylpiperidine behaves as a base and the acridinium salt as a hydride... 

Ciba Irgafos 168 tr (2,4-di-tert-butylphenyl)phosphate, Trisftribromoneopentyl) phosphate Ciba Flamstab NOR TM 116, a reaction product of N, JV -ethane- 1,2-diylbis (1,3-propanediamine). cyclohexane, peroxidized 4- butylamino-2,2,6, 6-tetramethylpiperidine and 2,4,6-trichloro-l,3,5-triazine Magnesium hydroxide, melamine, and novolac APP/petol-based intumescent systems catalyzed by divalent and transition metal compounds... 

Flamstab NOR TM 116, a reaction product of N, N-ethane-1,2-diylbis (1,3-propanediamine). cyclohexane, peroxidized 4-butylamino-2,2,6,6-tetramethylpiperidine and 2,4,6-trichloro-... 

A comprehensive study by Cheng investigated a wide variety of N-lithioamide precursors such as morpholine, diethylamine, dimethylamine, diisopropylamine, piperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, and piperazine in all cases the resulting lithium amides were reported to be insoluble in hexane. Polymerizations with these lithium amide initiators did not generally proceed to completion (67-95%) and no molecular weight or molecular weight distribution data were presented. 

Pfaltz and coworkers [34] also found that varying the base had effects on the yield of the cyclohexenylation while enantiomeric excesses remained consistently high. Results of the base screen (Table 11.1) employing l,8-bis(dimethylamino)naphthaIene, 2,2,6,6-tetramethylpiperidine and A//-diisopropylethylamine showed that N,N-diisopropylethylamine was most successful. 

For primary alcohols, fewer peroxygen systems are available. In situ halogen, with or without photolytic activation, may be used for some substrates the carboxylic acid formed condenses with the starting alcohol under the acid conditions employed, sometimes giving the ester as main product [106]. The Fenton system may also be used in a few cases [107]. Also useful are methods based on nitroxides as catalytic active species. These nitroxides, which are 1-electron oxidants, are produced from fully a-substituted secondary amines (notably 2,2,6,6-tetramethylpiperidine) and a variety of primary oxidants. Such oxidants include hypochlorite [108], peracids [109], Caro s acid and H2O2. Where H2O2 itself is used, a second catalyst, such as tungstate, is probably required to catalyse the oxidation of the amine [110] (see section 9.5.1.7). 

Show all products of the reaction between 2-phenylethyne and fbutyllithium between n-butyllithium (1-lithiobutane) and 2,2,6, 6-tetramethylpiperidine and 1-lithiopentane. 

Draw and name the product of a reaction between 2,2,6,6-tetramethylpiperidine and butyllithium and then between hex-amethyldisilazane [(MegSilgNH] and butyllithium. 

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