Lithium pyridines

Natriumboranat/Pyridin > Lithium-tetrakis-[l,2-dihydro-pyridyl-(l)]-aluminat > Natriumboranat/Alkohol > Lithium-tri.-tert.-butyloxy-hydrido-aluminat > Lithiumalanat > Lithium-trimethoxy-hydrido-aluminat > Aluminiumhydrid > Bis-[2-methyl-propyl]-aluminiumhydrid... 

Gold - Water-soluble gold porphyrin ions, [Au(TPPS4)]3 and [Au(TMPyP)]5+ (as the 3- and 4-pyridyl isomers), were obtained from the respective free-base porphyrins in a mixture of water/pyridine/lithium chloride containing KAuCl4 [142]. The products were purified by extraction with acetone and methanol and subsequent HPLC, however, the counterions were not determined. 

Figure 69 The structure of tetrakis((/i3-tert-butylethenolato-0,0,0)-pyridine-lithium).

A variety of bases can be used, including pyridine, lithium carbonate (Li2C03), or potassium rerf butoxide. This provides a two-step method for introducing a,(3-unsaturation in a ketone. This procedure is only practical in some cases, and yields are often low. 

Pyridine lithium chloride Ethylene derivs. from mesylates s. 28,906... 

Iodine Acetaldehyde, acetylene, aluminum, ammonia (aqueous or anhydrous), antimony, bromine pentafluoride, carbides, cesium oxide, chlorine, ethanol, fluorine, formamide, lithium, magnesium, phosphorus, pyridine, silver azide, sulfur trioxide... 

Metahation of 2-fluoropyridine with lithium diisopropylamide (LDA) gives 2-fluoro-3-hthiopyridine, thereby providing entry to 3-substituted pyridines (388). This technique has been used to make fluorine analogues of the antitumor eUipticines (389). 

Ethynodiol diacetate (53) is prepared by reduction of the 3-oxo group of norethindrone (28) with lithium tributoxyalurninum hydride, followed by acylation with acetic anhydride-pyridine (78,79). It has been reported that higher yields can be obtained in the reduction step by using triethylanainoalurninum hydride (80). 

Several derivatives of cellulose, including cellulose acetate, can be prepared in solution in dimethylacetamide—lithium chloride (65). Reportedly, this combination does not react with the hydroxy groups, thus leaving them free for esterification or etherification reactions. In another homogeneous-solution method, cellulose is treated with dinitrogen tetroxide in DMF to form the soluble cellulose nitrite ester this is then ester-interchanged with acetic anhydride (66). With pyridine as the catalyst, this method yields cellulose acetate with DS < 2.0. 

When the catalyst is triethylamine, the yield is nearly 100% cycHc oligomers but if pyridine is used, the polymer is nearly 100% linear. A basic catalyst in the second step, such as lithium stearate or an organic titanate [bis-(acetylacetonato)diisopropoxytitanium], produces a polycarbonate with a molecular weight of 250,000—300,000 when polymerized at 300°C for 30 min. A fiber glass composite has been prepared using this basic procedure (39). 

In contrast to pyridine chemistry, the range of nucleophilic alkylations that can be effected on neutral azoles is quite limited. Lithium reagents can add at the 5-position of 1,2,4-oxadiazoles (Scheme 16) (70CJC2006). Benzazoles are attacked by organometallic compounds at the C=N a-position unless it is blocked. 

MICHAELIS BECKER NYLEN Phosphonylation Nucleophilic attack oi lithium dialkylphosphonates on pyndkim sells to produce pyridine phosphates... 

An aiyl methane- or toluenesulfonate ester is stable to reduction with lithium aluminum hydride, to the acidic conditions used for nitration of an aromatic ring (HNO3/HOAC), and to the high temperatures (200-250°) of an Ullman reaction. Aiyl sulfonate esters, formed by reaction of a phenol with a sulfonyl chloride in pyridine or aqueous sodium hydroxide, are cleaved by warming in aqueous sodium hydroxide. ... 

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. ... 

Semicarbazones are used as protecting groups as a consequence of their stability to reducing agents such as potassium borohydride, sodium boro-hydride and lithium borohydride. Semicarbazones are cleaved by strong acids and by heating in acetic anhydride-pyridine. " ... 

The azidohydrins obtained by azide ion opening of epoxides, except for those possessing a tertiary hydroxy group, can be readily converted to azido mesylates on treatment with pyridine/methanesulfonyl chloride. Reduction and subsequent aziridine formation results upon reaction with hydrazine/ Raney nickel, lithium aluminum hydride, or sodium borohydride/cobalt(II)... 

The alkynylation of estrone methyl ether with the lithium, sodium and potassium derivatives of propargyl alcohol, 3-butyn-l-ol, and propargyl aldehyde diethyl acetal in pyridine and dioxane has been studied by Miller. Every combination of alkali metal and alkyne tried, but one, gives the 17a-alkylated products (65a), (65c) and (65d). The exception is alkynylation with the potassium derivative of propargyl aldehyde diethyl acetal in pyridine at room temperature, which produces a mixture of epimeric 17-(3, 3 -diethoxy-T-propynyl) derivatives. The rate of alkynylation of estrone methyl ether depends on the structure of the alkyne and proceeds in the order propar-gylaldehyde diethyl acetal > 3-butyn-l-ol > propargyl alcohol. The reactivity of the alkali metal salts is in the order potassium > sodium > lithium. 

Selective hydroxylation with osmium tetroxide (one equivalent in ether-pyridine at 0 ) converts (27) to a solid mixture of stereoisomeric diols (28a) which can be converted to the corresponding secondary monotoluene-sulfonate (28b) by treatment with /7-toluenesulfonyl chloride in methylene dichloride-pyridine and then by pinacol rearrangement in tetrahydrofuran-lithium perchlorate -calcium carbonate into the unconjugated cyclohepte-none (29) in 41-48 % over-all yield from (27). Mild acid-catalyzed hydrolysis of the ketal-ketone (29) removes the ketal more drastic conditions by heating at 100° in 2 hydrochloric acid for 24 hr gives the conjugated diketone (30). 

Vinylic fluorines offluoralkenes are replaced with chlorine or bromine when treated with lithium halide salts in methoxyethanol, dimethylformamide, and pyridine [77]. 

Cyclic enamines can also be obtained by the reduction of pyridine and isoquinoline with lithium aluminum hydride (163-165), and the latter reduction has also been accomplished with sodium in liquid ammonia (166). 

None of the 3-halogenopyridines yield 2-piperidinopyridine. This substance was obtained as the only product from the reaction of 2-fluoropyridine (24, X = F) with lithium piperidide under the same conditions in 97% yield. Finally, it was found that 4-chloropyridine (32, X = Cl) was converted in 95% total yield into a mixture of 0.4% of 3-piperidino- (29, Y = NC5H10) and 99.6% of 4-piperidino-pyridine (34, Y = NCsHio)- Thus, in contrast to the amination with potassium amide, 4-chloropyridine reacts with lithium piperidide almost exclusively via the addition product 33 (X = Cl, Y = NC5H10). 

Those reactions of halogenopyridines with potassium amide and lithium piperidide which proceed via 3,4-pyridyne form the 3- and 4-substituted pyridine derivatives in ratios of 1 2 and 1 1, respectively (see Section II, A, 1). It appears that the ring nitrogen atom has an orienting effect on these additions, but the quantitative divergence of the addition of ammonia and piperidine is not understood at present. 

---