Anti-conformations, copper complexes

Figure 8.2 Gauche- and anti-conformations of a copper(salen) complex.

Enolates of iron-acyl complexes have been studied extensively, especially by Davies and Liebeskind and their respective coworkers. The chiral complex [T) -CpFe(PPh3)(CO)COCH2R] is usually used it can be prepared in racemic or optically active form. The enolate usually has the anti conformation with regard to CO and Copper (Z)-enolates give predominantly syn aldols, whereas diethylalumin-... 

Figure 7-65 shows the X-ray structure of the complex [7,16-bis(ferrocenylmethyl)-l,4,10,13-tetrathia-7,16-diaza-cyclooctadecane]copper(i), [CuL ] and that of the free ligand L [186]. The copper(i) centre assumes a distorted tetrahedral geometry. With respect to the macrocyclic conformation of the free ligand, which possesses two gauche and two anti C-S-C-C bonds and two anti N-C-C-S bonds, complexation with copper (i) maintains the two gauche and two anti C-S-C-C bonds, but the two N-C-C-S bonds become gauche. 

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