Lithium complexes sulfides

The 1-t-butylphospholane sulfide intermediate to TangPhos was also used to prepare the P,N ligands 48 by reacting the lithium complex with C02 and then oxazoline formation with a range of chiral amino alcohols [69b, 74]. The Ir complexes of these ligands have been successfully used in the reduction of / -methylcinnamic esters (80-99% ee) and methylstilbene derivatives (75-95% ee), a particularly challenging class of unfunctionalized olefins [4 c]. 

FIGURE 3. Calculated Gibbs free-energy values of unsolvated and solvated mixed complexes between a chiral lithium amido sulfide and methyllithium... 

Although these mixed complexes with chiral lithium amido sulfides appear promising structures for asymmetric addition reactions in general, it should be noted that they are only stable at low temperatures (<50 °C). At higher temperatures they readily decompose, most likely due to deprotonation of the acidic a-protons next to the sulfur. 

The reaction of [tris(3-p-tolylpyrazolyl)hydroborate)]MgMe with H2S produces the monomeric hydrosulfido complex [tris(3-p-tolylpyrazolyl)hydroborate)]MgSH, which has been structurally authenticated the Mg—S bond length is 2.35 A.Other monodentate sulfur ligands include 2-(l-methylethyl)-l,3-dimethyl-l,3,2-diazaphosphorinane 2-sulfide, whose lithium complex has been modeled with molecular orbital calculations, l,3-dimethyl-2-benzylide- 2-thioxo-1,3,2-diazaphosphorinane-S,S), and A-diisopropoxythiophosporylthiobenzamine. ... 

Commercially available, air-stable Pd phosphinous acid complex is an active catalyst for the thioether formation by the reaction of 1-cyclopentenyl chloride (49) with thiophenol (50) and hexylmercaptan (52) to give the thioethers 51 and 53 [15]. 1-Cyclopentenyl phenyl thioether (55) was obtained by the reaction of 1-cyclopentenyl triflate (54) with lithium phenyl sulfide [16]. 

Diphenylimidazole with palladium acetate forms the cyclometallated complex 80 (X = OAc) (97AOC491). The acetate group is replaced by chloride or bromide when 80 (X = OAc) reacts with sodium chloride or lithium bromide, respectively, to give 80 (X = C1, Br). Bromide with diethyl sulfide forms the mononuclear complex 81. Similar reactions are known for 1 -acetyl-2-phenylimidazole (96JOM(522)97). 1,5-Bis(A -methylimidazol-2-yl)pen-tane with palladium(II) acetate gives the cyclometallated complex 82 (OOJOM (607)194). 

Minerals belonging to the category of insoluble oxide and silicate minerals are many in number. Insoluble oxide minerals include those superficially oxidized and those of oxide type. The former category comprises mainly superficially oxidized sulfide minerals, including metals such as aluminum, tin, manganese, and iron which are won from their oxidic sources. As far as silicate minerals are concerned, there can be a ready reference to several metals such as beryllium, lithium, titanium, zirconium, and niobium which are known for their occurrence as (or are associated with) complex silicates in relatively low-grade deposits. 

The beneficial effect of added phosphine on the chemo- and stereoselectivity of the Sn2 substitution of propargyl oxiranes is demonstrated in the reaction of substrate 27 with lithium dimethylcyanocuprate in diethyl ether (Scheme 2.9). In the absence of the phosphine ligand, reduction of the substrate prevailed and attempts to shift the product ratio in favor of 29 by addition of methyl iodide (which should alkylate the presumable intermediate 24 [8k]) had almost no effect. In contrast, the desired substitution product 29 was formed with good chemo- and anti-stereoselectivity when tri-n-butylphosphine was present in the reaction mixture [25, 31]. Interestingly, this effect is strongly solvent dependent, since a complex product mixture was formed when THF was used instead of diethyl ether. With sulfur-containing copper sources such as copper bromide-dimethyl sulfide complex or copper 2-thiophenecarboxylate, however, addition of the phosphine caused the opposite effect, i.e. exclusive formation of the reduced allene 28. Hence the course and outcome of the SN2 substitution show a rather complex dependence on the reaction partners and conditions, which needs to be further elucidated. 

Opening of a bottle where some particles of lithium aluminum hydride were squeezed between the neck and the stopper caused a fire [68]. Lithium aluminum hydride must not be crushed in a porcelain mortar with a pestle. Fire and even explosion may result from contact of lithium aluminum hydride with small amounts of water or moisture. Sodium bis(2-methoxy-ethoxy)aluminum hydride (Vitride, Red-Al ) delivered in benzene or toluene solutions also may ignite in contact with water. Borane (diborane) ignites in contact with air and is therefore kept in solutions in tetrahydrofuran or in complexes with amines and sulfides. Powdered lithium borohydride may ignite in moist air. Sodium borohydride and sodium cyanoborohydride, on the other hand, are considered safe. ... 

Reduction of 5,5-dimethyl-2-pyrrolidone with 3 mol of lithium aluminum hydride by refluxing for 8 hours in tetrahydrofuran gave 2,2-dimethylpyrrol-idine in 67-79% yields [1123]. Reduction of e-caprolactam was accomplished by heating with sodium bis(2-methoxyethoxy)aluminum hydride [544], by successive treatment with triethyloxonium fiuoroborate and sodium borohydride [1121], and by refluxing with borane-d ras. )a.y sulfide complex [1064]. 

Cyclohexene was purchased from Wako Pure Chemical Ltd. Japan, or Aldrich Chemical Company, Inc., and used after distillation from lithium aluminum hydride. Borane-dimethyl sulfide complex was obtained from Aldrich Chemical Company, Inc., and was used as received. Trifluoromethanesulfonic acid was purchased from Wako Pure Chemical Ltd. Japan or Aldrich Chemical Company, Inc., and used without purification. The checkers used a freshly opened ampule of trifluoromethanesulfonic acid for each run. 

Birch reduction, followed by acid treatment and addition of diazomethane leads to the A9(11)-enone 159 in 41% yield. Then, the double bond is hydrogenated and, by using PhSeCl and hydrogen hydroperoxide, the double bond A13 is formed. Treatment of the enone with lithium disopropylcuprate-dimethyl sulfide complex gives an intermediate enolate that is trapped again using PhSeCl. Enone 160 is obtained via oxidative elimination (62%). 

In contrast to lithium aluminum hydride, sodium borohydride does not reduce amides. Another possible reagent would be DIB AH. However, in the present case four equivalents of borane-dimethyl sulfide complex was used as a 2M solution in THE The amine was obtained in 94% yield after workup with ethanol. 

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