Lithium theoretical studies

Watts, R. O., Clementi, E. Fromm, J. (1974). Theoretical study of the lithium fluoride molecule in water. Journal of Chemical Physics, 61, 2550-5. 

The reactivity of lithium enolates has been explored in a theoretical study of the isomers of C2H30Li, such as the lithium enolate, the acyl lithium, and the a-lithio enol. Imides containing a chiral 2-oxazolidine have been employed for enantioselective protonation of prochiral enolates.A degree of kinetic control of the product E/Z-enolate ratio has been reported for the lithiation of 3,3-diphenylpropiomesitylene, using lithium amides/alkyls. " °... 

The rearrangements of 3-methylbut-l-ene oxides" and l,2-epoxybut-3-ene on lithium phosphate have been studied, and a detailed theoretical study of the rearrangement of allene oxide (342) to cyclopropanone (344), which shows that the transformation proceeds via an intermediate oxyallyl (343), has been presented. It has been shown that aldehydes, ketones, and cyclic ethers are all produced... 

Unfortunately, the only available theoretical study on lithium-acetylene species is that of Apeloig and coworkers on dilithioethylene, in which the most stable isomer of Li2C2H2 was found to have a C2v geometry with two lithium atoms bridging the C—C bond and the C2H2 group in a cis planar position. This seems to indicate structure 5 more probable than structure 4. Consequently, the structure, which meets best all conditions, is 5 (Scheme 3). ... 

MNDO calculations suggest a stacked-bowl arrangement of the two tetraan-ionic corannulene moieties in a convex-to-concave geometry with four lithiums inside the sandwich as the global energy minimum (Figure 11 Thus, in agreement with theoretical studies on the isolated tetraanions (see above), the corannulene tetraanion also prefers a bowl-shaped conformation when the countercations are included in the calculations. 

Theoretical studies also supported the reaction mechanism of A-lithium derivatives of NH2OR- and NHR OR-type reagents with organolithiums Erdik also provided experimental evidence for the reaction of A-lithium and iV,iV-dilithium derivatives of NH20Me la by trapping these intermediates with electrophiles. ... 

Tetrasubstituted alkenes (214) were obtained with high Z selectivity (>99 1) by reaction of ynolates (211) with a-oxy- and a-amino-ketones (212 X = OR, NR2) (g) at room temperature. According to experimental and theoretical studies, the high Z selectivity is induced by orbital interactions in the ring opening of the /3-lactone enolate intermediate (213), rather than by the initially presumed chelation of the lithium atom.260... 

Chen, J. Cunico, R. F. a-Aminoamides from a carbamoylsilane and aldehyde imines. Tetrahedron Lett. 2003, 44, 8025-8027. Viruela-Martin, P. Viruela-Martin, R. Tomas, F. Nudelman, N. S. Theoretical studies of chemical interactions. Ab initio calculations on lithium dialkylamides and their carbonylation reactions. J. Am. Chem. Soc. 1994, 3 36, 10110-10116. 

The one-pot condensation of an ester enolate with an imine is a very powerful synthetic procedure toward azetidin-2-ones (Equation 183). Various types of esters and imines can be utilized. Although in the vast majority the reactions have been mediated by lithium, various other metals mediate the reaction as well. Some examples include zinc, aluminium, tin, boron, indium, and titanium <1996MI119>. Theoretical studies on these reactions have been reviewed <1998JCC1826>. 

Holzwarth, N. A. W., S. Rabii, and A. Girifalco. 1978. Theoretical study of lithium graphite. I. Band structure, density of states, and Fermi-surface properties. Phys. Rev. B 18 5190-5205. 

These theoretical studies were given real credibility when Hoffmann showed, in 1995, that the Li-(C=C) interaction can be observed by heteronuclear coupling in the NMR spectrum of 5-hexenyl-1 -lithium 184.166... 

Ashby and Boone s proposed mechanism was not verified until 2001, when Luibrand et al. carried out a theoretical study on the lithium aluminum hydride reduction of formaldehyde6 (Scheme 4.III). Two types of complexes are possible between formaldehyde and LiAlFLt, depending on the geometry of LiAlFLt complex A is from tridentate r 3-LiAlFLt, and complex B is from bidentate ri2-LiAlH4.7 Calculations indicate that the intermediate product OLiAl would be formed via six-membered transition state A, derived from complex A, which is more stable than transition state B by 2.0 kcal/mol. 

Poster 10. Young-Ah Jeon, Yang-Soo Kim and Kwangsoo No (Korea Advanced Institute of Science and Technology, Korea Basic Science Institute) Theoretical Study of Lithium Intercalation in Titanium Sulfides and Titanium Oxides... 

In order to analyse the origin of regioselectivity in the lithiation of enamines in hydrocarbon solvents using alkyl lithium reagents, Stork and coworkers54 carried out a theoretical study at the 3-21G level of the lithiation of various vinylamines. 

Recent studies have suggested that coordination with a lithium cation may be responsible for the stereochemical outcome in Meyers-type enolate alkylations . In fact, the hypothesis that the diastereofacial selectivity observed in these reactions might result from specific interactions with a solvated lithium cation was already proposed in 1990 . Nevertheless, the potential influence exerted by solvation and lithium cation coordination was not supported by a series of experimental results reported by Romo and Meyers , who stated that it would appear that neither the aggregation state of the enolate nor the coordination sphere about lithium plays a major role in the observed selectivity. This contention is further supported by recent theoretical studies of Ando , who carried out a detailed analysis of the potential influence of solvated lithium cation on the stereoselective alkylation of enolates of y-butyrolactones. The results showed conclusively that complexation with lithium cation had a negligible effect on the relative stability of the transition states leading to exo and endo addition. The stereochemical outcome in the alkylation of y -butyrolactones is determined by the different torsional strain in the endo and exo TSs. 

Compared with metal enolates, there have been very few reports on the direct structural analysis and theoretical studies of ynolates. An X-ray crystal structure of a vanadium complex of lithium ynolate with a porphyrinogen ligand (56) is reported. This metal complex was incidentally formed from VCl3(THF)3 with tetralithium salt of the octaethyl-porphyrinogen ligand. In this complex, the lithium cation seems to interact with the 7T-electrons of the ynolate. The four atoms of the ynolate group in 56 are not collinear due to a partial sp character of the group in this complex. 

S -Analogues of lithium or sodium ynolates (thioalkynolates or alkynethiolates) are prepared from lithium or sodium acetylide and sulfur, and are trapped as alkynyl sulfides with bromoethane (equation 77). In a synthetic approach analogous to equation 72, 5-lithio-l,2,3-thiadiazoles (198) also afford lithium alkynethiolates (199) by elimination of nitrogen (equation 78) . Alkynyl sulfides (200) are treated with lithium in ammonia to afford lithium alkynylthiolates (199) (equation 79) °. Theoretical studies on the structure of alkali metal alkynylthiolates are reported. ... 

Selenium analogues of lithium ynolates are prepared by methods similar to those used to prepare sulfur analogues . Theoretical studies show that the negative charge is distributed over the whole molecule but is predominantly located on the selenium atom. The HOMO in the methyl-substituted case (201) has the largest coefficient on the Cp atom the largest HOMO coefficient of the phenyl-substituted one (202) is on the selenium atom. ... 

---