Beilstein J. Org. Chem.2012,8, 1814–1818, doi:10.3762/bjoc.8.207
cyclopropanation and Michael addition reactions. Although there was no increase in stereocontrol, upon computational evaluation using both M06LandB3LYPcalculations, it was revealed that a pseudo six-membered ring exists, through H-bonding of a cubyl hydrogen to the copper core. This decreases the steric bulk
above the copper center and limits the asymmetric control with this ligand.
Keywords: chiral ligand; cubane; M06LandB3LYPcalculations; Michael addition; Introduction
Since the initial synthesis of cubane in 1964 by Eaton and Cole [1][2], numerous studies have been undertaken on its derivatives
are well within the required H-bonding length of <3.2 Å [31]. In addition, the C…Cu lengths of 2.85 and 3.03 Å with M06L and B3LYP, respectively, were well within the required 4.0 Å limit [31]. This produces pseudo six-membered rings having a C–H…Cu bond angle of 125.1° or 122.9° with M06LandB3LYP
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Graphical Abstract
Figure 1:
Structure of (1R,2R)-N,N’-bis[(4-iodocuban-1-yl)methylene]-trans-1,2-diamino cyclohexane (1).