Propane-, lithium

Gas-phase oxidation of propylene using oxygen in the presence of a molten nitrate salt such as sodium nitrate, potassium nitrate, or lithium nitrate and a co-catalyst such as sodium hydroxide results in propylene oxide selectivities greater than 50%. The principal by-products are acetaldehyde, carbon monoxide, carbon dioxide, and acrolein (206—207). This same catalyst system oxidizes propane to propylene oxide and a host of other by-products (208). 

In a pioneering investigation on the addition of the following chiral lithium enolate to propanal, only poor substrate-induced diastereoselectivity (57 43) was obtained54-35. 

The use of hydrazone or enamine derivatives of ketones or aldehydes offers the advantage of stcreocontrol via chelated azaenolates. Extremely useful synthetic methodology, with consistently high anti selectivity, has been developed using azaenolates based on (S)- or (R)-l-amino-2-(methoxymethyl)pyrrolidine (SAMP or RAMP)51 58 (Enders method, see Section 1.5.2.4.2.2.3.). An example which illustrates the efficiency of this type of Michael addition is the addition of the lithium azaenolate of (5 )-l-amino-2-(methoxymethyl)pyrrolidine (SAMP) hydrazone of propanal (R = II) to methyl (E )-2-butenoate to give the nub-isomer (an 1 adduct) in 80% yield with a diastereomeric ratio > 98 2,... 

The addition of the lithium azaenolate of the SAMP hydrazone of propanal to methyl (E)-2-butenoate to furnish the (S,S,S)-adduct in 58% yield with > 96% ee and de is illustrative for the efficiency of this asymmetric Michael addition10°. Only the anti-isomer (an / adduct) is found. This methodology was used in the synthesis of pheromones of the small forest and red wood ant200. 

The stereochemical outcome of the addition of lithium enolates of aldehydes and ketones to nitroalkenes is dependent upon the geometry of the nitroalkene and the enolate anion. The synjanti selectivity in the reaction of the lithium enolates of propanal, eyelopentanone and cyclohexanone with ( )- and (Z)-l-nitropropene has been reported1. 

Introduction Since we had already developed the novel asymmetric addition of lithium acetylide to ketimine 5, we did not spend any time on investigating any chiral resolution methods for Efavirenz . Our previous method was applied to 41. In the presence of the lithium alkoxide of cinchona alkaloids, the reaction proceeded to afford the desired alcohol 45, as expected, but the enantiomeric excess of 45 was only in the range 50-60%. After screening various readily accessible chiral amino alcohols, it was found that a derivative of ephedrine, (1J ,2S) l-phenyl-2-(l-pyrrolidinyl)propan-l-ol (46), provided the best enantiomeric excess of 45 (as high as 98%) with an excellent yield (vide infra). Prior to the development of asymmetric addition in detail, we had to prepare two additional reagents, the chiral modifier 46 and cyclopropylacetylene (37). 

In fact, crystalline graphites usually cannot be operated in PC electrolytes, unless effective film forming electrolyte additives are used (see above) as propane gas evolution [35], creation of solvated graphite intercalation compounds (sGICs) [36], and graphite exfoliation take place. Recently [37, 38], it was found that propylene evolution is observed at graphite, while absent at lithium active metallic anodes, e.g., Sn and SnSb. 

Bromopene Propane, 2-bromo- (8) 1-Propene, 2-bromo- (9) (557-93-7) tert-Butyllithium Lithium, tert-butyl- (8) Lithium, (1,1-dimethylethy )- (19) (594-19-4)... 

The bromomethoxy compound 115 undergoes lithiation by attack at hydrogen when treated with BuLi, rather than transmetallation of the bromine atom (Equation 10). Reaction with propanal then gives a mixture of 116 and 117, suggesting that both mono- and di-lithiation have occurred <1998T6485>. Lithium tetramethyl piperidide was less satisfactory than BuLi, and gave low yields after reaction with propanal. Neither the parent compound 64 nor the 8-methoxy derivative reacted with BuLi. 

The final step is to convert the carboxylic acid into a primary alcohol by heating it with lithium aluminium hydride (LiAlH ) dissolved in ether (ethoxyethane). This is a reduction reaction and delivers the target molecule, propan-l-ol. 

A cation arriving with a nncleophilic anion is another important factor. The nucleophile can attack the substrate in the form of a free ion or an ionic pair. As a rule, lithium salts are less reactive than sodium and potassium salts. Russell and Mndryk (1982) reported several examples of this. The sodium salt of ethyl acetylacetate reacts with 2-nitro-2-chloropropane in DMF yielding ethyl 2-(wo-propylidene) acetylacetate. Under the same conditions, the lithium salt does not react at all. Potassium diethyl phosphite interacts with l-methyl-l-nitro-l-(4-toluylsulfonyl)propane in THF and gives diethyl 1-methyl-l-nitro-l-phosphite. The lithinm salt of the same reactant does not react with the same substrate in the same solvent. 

Lithium aluminum hydride reduced )J-azidoethylbenzene to j8-aminoethyl-benzene in 89% yield [600], The azido group was also reduced with aluminum amalgam (yields 71-86%) [149], with titanium trichloride (yields 54-83%) [601], with vanadous chloride (yields 70-95%) [217] Procedure 40, p. 215), with hydrogen sulfide (yield 90%) [247], with sodium hydrosulfite (yield 90%) [259], with hydrogen bromide in acetic acid (yields 84-97%) [232], and with 1,3-propanedithiol (yields 84-100%) [602]. Unsaturated azides were reduced to unsaturated amines with aluminum amalgam [149] and with 1,3-propane-dithiol [602]. 

Similarly, lithium aluminum hydride gives different products. / -Naphthyl p-toluenesulfonate affords p-thiocresol and ) -naphthol, and phenyl meth-anesulfonate gives methyl mercaptan and phenol. On the other hand, propyl p-toluenesulfonate yields />-toluenesulfonic acid and propane, and cetyl meth-anesulfonate and cetyl p-toluenesulfonate give hexadecane in 92% and 96% yields, respectively [680]. 

The sulfur-lithium exchange catalyzed by an arene (DTBB, 3.5%) generates in THF at —78°C, the 1,3-dilithium synthons, namely the l,3-(phenyhnercapto)propane 477, which is then treated with a carbonyl compound R R CO at the same temperature. After final hydrolysis 1,5-diols 478 were obtained (Scheme 133) °. 

Deprotonation of 3-picoline is more difficult (the anion cannot achieve stability through resonance, as happens with the others) and a much stronger base, LDA [lithium diisopropylamide (lithium propan-2-ylamide)], is needed. Once achieved, however, the conjugate anion behaves as a nucleophile and undergoes typical carbanion reactions (indeed, it is more reactive than its counterparts, since reactivity is most often the opposite of stability ). 

The enantiomerically pure a-stannyl ether, (R)-l-benzyloxymethoxy-l-tributylstannyl-propane, can be obtained by resolution of the precursor compound. The tin - lithium exchange reaction, as well as the electrophilic substitution, occurred with retention of configuration to give (I )-2-(benzyloxymethoxy) butane only28. A later study examined more examples and also confirmed this result27. 

To a solution of 1.5 mmol of KDA, prepared from potassium lerl-butoxide, diisopropylamine and butyl-lithium, in 7 mL of diethyl ether is added dropwise, under an argon atmosphere, a solution of 0.293 g (1 mmol) of (/ )-2-methoxy-2-phenyl-l-[( )-3-phenyl-2-propenyloxy]propane in 2 mL of diethyl ether at — 100 °C (liquid nitrogen/methanol). After stirring for 5 h the resulting dark-red suspension is treated with a solution of 0.284 g (2 mmol) of iodomethane in 1 mL of diethyl ether. The mixture is stirred until the red color disappears (about 2 h). Then, the bath is removed and 5 mL of phosphate buffer (pH 7) are added, the mixture is extracted with ethyl acetate several times. The extracts are washed with aq NaCl, dried over MgS04, and concentrated. The residue is purified by TLC on silica gel to give (7 )-2-methoxy-2-phenyl-1-[(ii)-3-phenyl-l-butenyloxy]propane yield 0.232 g (75%). This is hydrolyzed to 3-phenylbutanal by treatment with aq perchloric acid (40 %)/diethyl ether. 

Die Umsetzung von Carbonsauren zu Nitro-alkanen gelingt fiber die Zwischenstufe eines a-Carbanions der Carbonsaurc. Dazu setzt man die Carbonsaure mit Lithium-diisopro-pylamid in Phosphorsaurc-tris-[dimethylamid]/THF um1. Das so erhaltene a-Carbanion wird bei —40° mit einem 3fachen UberschuB an 1-Nitrooxy-propan versetzt und durch Zugabe von Saure decarboxyliert1. 

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