Lithium isopropoxide

Surprisingly, aromatic nitriles were found not to yield 1-arylcyclopropylamines under these conditions. However, this deficit is compensated for by a complementary method developed by de Meijere et al. using diethylzinc in the presence of methyltitanium triiso-propoxide and lithium isopropoxide (Scheme 11.40). While aliphatic nitriles 152 gave primary cyclopropylamines 155 in only 12—16% yield with this reagent mixture, aromatic nitriles 156 and 158 furnished 1-arylcyclopropylamines 157 and 159 in moderate (28—40% for substituted benzonitriles 156) to good (70% for 3-cyanopyridine 158) yields (Scheme 11.40) [138],... 

Lithium isopropoxide [2388-10-5] Lithium methoxide [845-34-9] Flammable solid, SR(2)3057A ... 

MeOC6H4, respectively. The titanium enolates were converted into silyl enol ethers 54 by treatment with chlorotrimethylsilane and lithium isopropoxide. Additionally, cyclic enones lb and Ic, and linear enones Id and le, are also good substrates for the asymmetric conjugate addition of phenyltitanium triisopropoxide, giving the corresponding arylation products with over 97% enantioselectivity. 

Oppenauer oxidation, using alkoxides other than aluminium, operates via a hydride transfer mechanism similar to the one depicted in the above Equation, although a complexation of the metal with the carbonyl group may not be present.22d Evidence for a radical mechanism was put forward in the case of the interaction between lithium isopropoxide and benzophenone.24... 

Cyanopyridines undergo titanium-mediated reductive cyclopropanation to give pyridylcyclopropylamines in good yield <20030L753>. Both 2- and 3-cyanopyridine react with the titanium species 81 formed from diethylzinc and methyltriisopropyloxytitanium in the presence of lithium isopropoxide to give the cyclopropylamine product in 80% and 82% yield, respectively (Equation 55). 

Reaction of YCI3 with lithium isopropoxide, LiOCHMea (LiOPr ), affords an alkoxide Y50(0Pr )i3, which does not have a simple structure but has a cluster of 5 yttriums arranged round a central oxygen. The Y NMR NMR spectrum is shown in Figure 7.5. 

Lithium chloropropargylide, 279-280 Lithium cyanocuprates, 329-330 Lithium diisopropylamide, 280-283, 309 Lithium hexamethyldisilazane, 82, 283 Lithium hexamethyidisilazide, 82, 283 Lithium iodide, 283 Lithium isopropoxide, 283 Lithium o-lithiobenzylate, 86-87 Lithium methoxy(trimethylsilyl)methylide, 284... 

Phosphonoacetate cycHzation. Intramolecular cyclization of keto phosphonates can be used for construction of macrocyclic a, -unsaturated lactones. Stork s laboratory found that use of lithium isopropoxide or lithium hexamethyidisilazide in THF containing 1% HMPT minimized formation of cyclic dilactones. Use of sodium or potassium counterions was much less satisfactory. An example is shown in equation (I). 

Assessment of the role of the cation in MPV reduction is difficult, Conversion of alcohol to alkoxide certainly enhances the reactivity towards hydride donation, and aluminum ions aid via chelation in arranging alkoxide and carbonyl compound properly for reaction. However, alkoxides bearing cations other than aluminum may also exhibit good hydride-donating tendencies. Lithium isopropoxide reduces steroidal ketones efficiently and magnesium alkoxides derived from chiral alcohols have been used extensively in chiral syntheses. Isobomyloxy magnesium bromide (52) has been used widely for this purpose (equation 27). ... 

In addition to adding structural integrity, correctly chosen powders added to the evacuated cavity in a vacuum container help to eliminate gas from the system or generate a product or products which can be adsorbed by another gas adsorbing material such as activated carbon. For example, carbon dioxide is readily removed in this manner with mixtures of carbon and lithium alkoxides such as lithium isopropoxide. The lithium isopropoxide reacts with carbon dioxide to form lithium carbonate and to liberate diisopropyl ether which is strongly adsorbed by activated carbon (21). Although carbon dioxide is also adsorbed by the activated carbon, it slowly desorbs, reenters the gas phase and is subsequently converted to diisopropyl ether where it is permanently removed from the gas phase. 

The chiral auxiliary mediated aza-Claisen rearrangement of /V-allylketcnc. V.O-acetals also allows the diastereoselective construction of quaternary carbon centers642. Butyllithium proved to be an unsuitable base for the neutralization step in this case because the increased steric hindrance at C-l causes C-2 nucleophilic addition to become competitive with C-l deprotonation. However, this problem can be overcome by the use of lithium tov-butoxide or lithium isopropoxide. This is shown for the achiral. V-allylketene A. O-aceta] precursor 8. 

Lithium Isopropoxide =175 mg (25 mmol) of clean lithium are dissolved in 20 mL of refluxing anhyd /-PrOH to give a 1.25 N soln of Li(O-i-Pr). This concentration is 25% greater than required for the subsequent reduction. (Gives a final working concentration of approximately 1.0 N.)... 

B-Allyl-9-BBN reacts vigorously with acid chlorides (Scheme 6.4) and acid anhydrides (Scheme 6.5), slowly with carboxylic acid esters (Scheme 6.6), and N,N-dimethylamide (Scheme 6.7). Acid chlorides, esters, and N,N-dimethylam-ides react with 2 equiv of the allylborane acid anhydrides utilize 4 equiv (Table 6.9) [1]. In case of acid chloride, sticky gel is formed due to the generation of hydrogen chloride resulting from the protonolysis of chloroborane. This difficulty is circumvented by the addition of 1 equiv of lithium isopropoxide before adding 2 equiv of ethanolamine. 

In the case of the use of aryltitanium reagents in the rhodium-catalyzed asymmetric 1,4-addition to cyclic and acyclic a, 3-unsaturated enones, only one report was found in literature. Hayashi and coworkers [63] reported a study concerning the use of aryltitanium reagents. The intermediate chiral titanium enolates formed were isolated as silyl enol ethers by way of titanate-type enolates generated by the addition of lithium isopropoxide to the titanium enolates. High enantioselectivities were achieved using (5)-BINAP (Scheme 5.19). 

Cyclodecanediol has been prepared by the hydrogenation of sebacoin in the presence of Raney nickel or platinum, by the reduction of sebacoin with aluminum isopropoxide or lithium aluminum hydride, and by the oxidation of cyclodecene with osmium tetroxide and pyridine. ... 

Reactions of lithium and titanium compounds 2, generated in situ by deprotonation of alkynylsilanes with tm-butyllithium, followed by addition of titanium(IV) isopropoxide and an aldehyde result either in a-hydroxyallenes without axial dissymmetry or in /J-hydroxyalkyn-es90 91. 

Oxidation reactions r-Butyl hydroperoxide-Dialkyl tar-trate-Titanium(IV) isopropoxide, 51 m-Chloroperbenzoic acid, 76 Reduction reactions Chlorodiisopinocampheylborane, 72 Diisobutylaluminum hydride-Tin(II) chloride- (S) -1 - [ l-Methyl-2-pyrrolidi-nyljmethylpiperidine, 116 Lithium borohydride, 92 Lithium tri-sec-butylborohydride, 21 B-3-Pinanyl-9-borabicyclo[3.3.1]-nonane, 249... 

Zirconium(IV) isopropoxide, 352 Reductive alkylation of aromatic rings Birch reduction, 32 (S)-Prolinol, 261 of carbonyl groups Trityl perchlorate, 339 of other substrates Lithium-Ammonia, 158 Reductive cleavage (see also Reduction of epoxides)... 

Reaction with a hindered epoxide.l The trans-epoxide (1) of tetramethyllimonene is inert to KOH (130°), LiAlH4 (THF, 90°), and even lithium triethylborohydride. It is opened by aluminum isopropoxide (110°) to give 70 30 mixture of 2 and 3. Reaction with LDA is more selective and gives 2 in 95% yield. In contrast, reaction with N-lithioethylenediamine (1, 567 570) gives 3 in 90% yield. The 70 30 mixture of 2 and 3 is converted by N-lithioethylenediamine to the more stable isomer 3. 

Z)-x,p- Unsaturated nitriles.2 The lithio derivative of 1 reacts with aldehydes to form a mixture of (Z)- and (E)-a,/J-unsaturated nitriles with some preference for the former isomer. The stereoselectivity in favor of the (Z)-isomer in reactions with aliphatic aldehydes is markedly improved by use of the boron derivative, obtained by treatment of the lithium reagent with boron isopropoxide. Addition of HMPT also favors the (Z)-isomer. 

PETERSON REACTION Alkyidimesitylboranes. Chloromethyldiphdnylsilane. Ethyl trimethylsilylacetate. Lithium l-(dimethyl-amino)naphthalenide. Methyldiphenylchlo-rosilane. Phenylsulfonyl(trimethylsilyl)-methane. Titanium(IV) isopropoxide, Tri-methylsilylmethylmagnesium chloride. 

Ignition on contact with furfuryl alcohol powdered metals (e.g., magnesium iron) wood. Violent reaction with aluminum isopropoxide -f- heavy metal salts charcoal coal dimethylphenylphosphine hydrogen selenide lithium tetrahydroaluminate metals (e.g., potassium, sodium, lithium) metal oxides (e.g., cobalt oxide, iron oxide, lead oxide, lead hydroxide, manganese oxide, mercur oxide, nickel oxide) metal salts (e.g., calcium permanganate) methanol + phosphoric acid 4-methyl-2,4,6-triazatricyclo [5.2.2.0 ] undeca-8-ene-3,5-dione + potassium hydroxide a-phenylselenoketones phosphorus phosphorus (V) oxide tin(II) chloride unsaturated organic compounds. 

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