Lithium butoxide formation

Solutions of butyllithium in hexanes and sec-butyllithium in cyclohexane were purchased from the Aldrich Chemical Company, Inc. It Is recommended that only freshly opened bottles or extremely well protected solutions be used as the presence of lithium butoxide in partially decomposed bottles results in formation of the corresponding butyl ester as an undesired by-product. 

Formation of the lithium /-butoxide in this manner is very exothermic and causes the hexane to boil during addition. 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

A pentane solution of terf-butyllithium (purchased from either Alfa Inorganics, Inc. or Lithium Corporation of America, Inc.) was standardized by one of the previously described titration procedures (Note 1). If possible, it is desirable to use a freshly opened bottle of lert-butyllithium since previously used bottles of this reagent often contain lithium ferf-butoxide which will lead to formation of a contaminant in the final product (Note 10). 

The propargylic alcohol 102, prepared by condensation between 100 and the lithium acetylide 101, was efficiently reduced to the hydrocarbon 103, which on treatment with potassium tert-butoxide was isomerized to the benzannulated enyne-allene 104 (Scheme 20.22) [62], At room temperature, the formation of 104 was detected. In refluxing toluene, the Schmittel cyclization occurs readily to generate the biradical 105, which then undergoes intramolecular radical-radical coupling to give 106 and, after a prototropic rearrangement, the llJ-f-benzo[fo]fluorene 107. Several other HJ-f-benzo[fo]fluorenes were likewise synthesized from cyclic aromatic ketones. 

Further studies were directed to examine different SCBs and the effect of different counterions. Potassium counterions provide improved efficiency as compared to lithium or sodium counterions. The most efficient system in terms of formation of carbanions was achieved with diphenylsilacyclobutane in combination with potassium tert-butoxide and diphenylethylene <2004MI856>. Di-block copolymers from ethylene oxide and methyl methacrylate (or styrene) were synthesized by this method with 85% efficiency (Scheme 14) <2004MI856>. 

The crucial point of the procedure is the control of the stoichiometry of the reaction between the living A chains and the DPE derivative, otherwise a mixture of stars is produced. A major problem is the fact that the rate constants for the reaction of the first and second polymeric chain with the DPE derivative are different. This results in bimodal distributions because of the formation of both the monoanion and dianion. In order to overcome this problem polar compounds have to be added, but it is well known that they affect dramatically the microstructure of the polydienes that are formed in the last step. However the addition of lithium sec-butoxide to the living coupled DPE derivative, prior to the addition of the diene monomer, was found to produce monomodal well defined stars with high 1,4 content. Finally another weak point of the method is that, as in the case of the DVB route, the B arms cannot be isolated from the reaction mixture and characterized separately. It is therefore difficult to obtain unambiguous information about the formation of the desired products. 

Single alkene diastereomers are accessible through a Wittig-Homer reaction only if it is performed in two steps (Figure 11.10). A 1 1 mixture of the phosphorylated lithium alkoxides syn- and anti-D is still formed but if the mixture is protonated at this point, the resulting phosphorylated alcohol diastereomers C can usually be separated without difficulty. The suitable diastereomer will be deprotonated with potassium-ferf-butoxide in the second step and then be converted into the stereouniform trans- or cis-alkene E via stereospecific oxaphosphetane formation and fragmentation. 

The direction of ring-opening of 5,10-epoxy-9(ll)-enes by bases depends upon the reaction conditions.235 Thus the a-epoxide (288) loses a proton from C-12 with potassium t-butoxide to give the 5a-hydroxy-9,11-diene (289), but lithium dial-kylamides favour formation of the 10a-hydroxy-4,9(1 l)-diene (290). These and related results suggest that the lithium dialkylamides are poorly dissociated, and favour a 1,2- rather than a 1,4-epoxide-opening reaction.235... 

Reductive cleavage of cyclic ethers This complex is effective for reductive cleavage of cyclic ethers. The order of reactivity is epoxide > oxetane > tetrahydrofurane>tetrahydropyrane>oxepane. It is less effective for cleavage of acyclic ethers, except for methyl ethers. The reaction involves formation of a complex of the ethereal oxygen with aluminum r-butoxide followed by Sn2 displacement with lithium triethylborohydride. Steric and electronic Victors are involved, but yields are >90% in favorable cases. 

The intramolecular Claisen condensation of the dimeric model (22, R = Me) of PMMA was observed during NMR analysis, even at low temperature. This condensation results in the formation of a cyclic /3-keto ester (23), methyl 2-lithioisobutyrate and lithium f-butoxide (equation 26). 

Treatment of either cis- or franx-2,4-diphenylthietane-l oxide (stereochemical notation refers to arrangement of phenyl groups) with potassium t-butoxide in dimethylformamide gives mainly the cw-l,2-diphenylcyclopropane derivatives, 124 and 125, via the anion 123. ° Stereospecific cyclopropane formation occurs on treatment of 3- -hexylthietane 1-oxide with lithium cyclohexylisopropyl amide. ... 

Color reactions Boric acid (hydroxyquinones). Dimethylaminobenzaldehyde (pyrroles). Ferric chloride (enols, phenols). Haloform test. Phenylhydrazine (Porter-Silber reaction). Sulfoacetic acid (Liebermann-Burchard test). Tetranitromethane (unsaturation). Condensation catalysts /3-Alanine. Ammonium acetate (formate). Ammonium nitrate. Benzyltrimethylammonium chloride. Boric acid. Boron trilluoride. Calcium hydride. Cesium fluoride. Glycine. Ion-exchange resins. Lead oxide. Lithium amide. Mercuric cyanide. 3-Methyl-l-ethyl-2-phosphoiene-l-oxlde. 3-Methyl-1-phenyi-3-phoipholene-1-oxide. Oxalic acid. Perchloric acid. Piperidine. Potaiaium r-butoxIde. Potassium fluoride. Potassium... 

The reaction of diiodomethane with a variety of bases (sodium hexamethyldisilazanide, lithium diisopropylamide, potassium triphenylmethanide, potassium iert-butoxide, potassium hydroxide under phase-transfer conditions, methyllithium) and alkenes does not afford iodocyclo-propanes. The thermal decomposition of diiodomethyl(phenyl)mercury in an alkene also does not result in the formation of iodocyclopropanes." ... 

Most alkylidenecyclopropanes have been prepared by reacting cyclopropylidenetriphenyl-.i -phosphane with aldehydes and ketones. The phosphorus ylide is either prepared by treating cyclopropyltriphenylphosphonium bromide, a stable compound, with base, e.g. phenyl-lithium, potassium er/-butoxide, sodium hydride, or by generating both the phos-phonium salt and the ylide in situ from (3-bromopropyl)triphenylphosphonium bromide employing two equivalents of base. ° The latter method seems to give somewhat better yields, as indicated by the synthesis of l-diphenylmethylene-2-methylcyclopropane (1) from ben-zophenone. ° The yield has also been increased by adding a catalyst. Considerable improvements have in particular been observed by using tris[2-(2-methoxyethoxy)ethyl]amine, a phase-transfer catalyst, e.g. formation of The use of several phosphorus ylides and bases is summarized in Table 25. 

By contrast with the reaction of lithium rert-butoxide with triphenylbismuth diacetate, which gave ferf-butyl phenyl ether (r-BuOPh) in 66% yield, the same reaction with triphenylantimony diacetate appeared to stop at the stage of the formation of (/err-butoxy)acetoxytriphenylantimony. The ligand coupling did not proceed, and re/t-butanol was recovered after hydrolysis of the mixture. ... 

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