Organolithium compounds complex derivatives

J-Oxygen-functionalised sp3 organolithium compounds react with alkenyl-carbene complexes to generate the corresponding cyclic carbene complexes in a formal [3+3] process (see Sect. 2.8.1). In those cases where the organolithium derivative contains a double bond in an appropriate position, tricyclic ether derivatives are the only products isolated. These compounds derive from an intramolecular cyclopropanation of the corresponding cyclic carbene complex intermediate [89] (Scheme 83). 

The crystal structures of numerous organolithium compounds and complexes with 0—Li bonds are now available (2-5). Table IV lists a number of these species, as well as two derivatives of heavier alkali metals. As with the C—Li derivatives just discussed (Tables II and III), clustered (ROLi) tetramers and hexamers, as well as ring dimers, are prevalent. Note that (OLi)2,3 ring systems also are pseudoplanar (Fig. 21a). However, extensive stacking leading to polymers will only occur if the substituents on 0 are small and if polar ligands are absent. Otherwise, limited (double) stacks or unstacked rings form. 

The stability of the alkyl and aryl derivatives increases with the number of phosphines bound to nickel(II). The bis-phosphine derivatives can be prepared according to equations (144)-(146) and using organomagnesium halides or organolithium compounds.1224-1231 A tetrakis phosphine complex was obtained similarly (equation 147). 

Ketoenamines derived from chiral cyclic amines were found to react with Grignard reagents or organolithium compounds by a 1,2-addition. Subsequent hydrolysis gives R- (or (5)-a-hydroxycycloalkanones in high enantiomeric excess. The stereochemical selectivity is caused by different structures of the intermediate formed by complexation of the different organometallic compounds320 (equation 238). 

In experiments on metallation of silacyclopentenes by organolithium compounds, the ROP was observed [100]. Weber et al. [101-108] showed that polymerization can be performed by treating monomer with catalytic amounts of alkyllithium compounds complexed with polar compounds (HMPA, TMEDA) in THF at -78°C. In terms of phenomenology, symmetrically [101-103] and un-symmetrically [101, 103, 105] disubstituted derivatives of l-silacyclopent-3-ene with methyl, phenyl, and vinyl radicals, hydro derivatives of l-silacyclopent-3-ene [106, 107], 1,1,3-trimethyl- and l,l,3,4-tetramethyl-l-silacyclopent-3-enes... 

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