Giving phenyllithium a right-handed double-helical twist. Syntheses and crystal structures of enantiopure alkyl-, aryl-, and amidolithium aggregates

Unexpected structural similarity between the chlorocopper(i) unit and the methyllithium and phenyllithium units. First complexes between (−)-sparteine and copper(i) chloride: synthesis and structural characterisation

“…Cu(3) is essentially Perhaps the most curious feature of this investigation becomes apparent when the complexes described in this article are compared with their methyllithium and phenyllithium counterparts. 7 With methyllithium and (À)-sparteine, a dimer completely analogous to 1 is obtained. 7 [Cu 2 Cl 2 spa 2 ] (1) and [Li 2 Me 2 spa 2 ] 7 crystallise with the same unit cell and space group and are almost isostructural, the main difference being that the Li 2 C 2 rhombus is more regular than its Cu 2 Cl 2 counterpart, in that the bridging Li-C bonds do not differ appreciably from one another.…”

“…Structural information on copper (À)-sparteine complexes appears at present to be limited to dichloro{(À)-sparteine}copper(II) 3 and {(À)-sparteine}copper(II) diacetate. 4 Owing to our ongoing interest in complexes between copper(I) and hard-donor ligands 5 and, moreover, in the use of various metal complexes containing chiral ligands for organic synthetic applications, 6,7 we embarked on an investigation of those complexes formed in a direct reaction between copper(I) chloride and (À)-sparteine.…”

NMR studies of chiral lithium amides with phosphine chelating groups reveal strong Li-P-interactions in ethereal solvents

“…Such ladder-type structures have also been observed previously for NN-chelating lithium amides. 16 The presence of two different types of aggregates is also supported by 13 C NMR spectra, which shows two sets of signals for the lithium amide, i.e. the cyclic trimer and the ladder-type tetramer of the lithium amide.…”

Indolizidine and quinolizidine alkaloids

“…111 The crystal structure of the 1 : 1 complex of (−)-sparteine with methyllithium also turned out to be a dimer similar to 306; but with phenyllithium, a tetranuclear ladder-like Li 4 Ph 4 core with bridging phenyl groups was capped by sparteine at each end, as shown in the schematic diagram 308. 112 The fascinating feature of 308 is that the chiral ligand confers a helical twist on the structure; more specifically, the structure approximates to a right-handed double helix, with a twist of about one ninth of a full rotation.…”