Reactions atroposelective

Atropisomerism, the phenomenon of chirality due to restricted rotation about a single bond, has been an intellectually intriguing and practically widely applicable area of stereochemistry from the first resolution of a chiral atrop-isomeric biaryl by Kenner in 1921 through the discovery of numerous naturally occurring atropisomeric molecules and the development of atropisomeric chiral ligands. A high point in the history of atropisomerism must be the central role played by the atropisomeric ligand BINAP in Professor Noyori s share of the Nobel Prize for Chemistry in 2001. 

Chirality from Dynamic Kinetic Resolution By Helene Pellissier Helene Pellissier 2011 

In addition, the last fifteen years have seen families of atropisomers based on structures other than biaryls come forward as potential new sources of such structures, and atropisomeric anilides, benzamides and naphthamides have been used as chiral ligands, catalysts, auxiliaries and various starting materials. Indeed, a number of non-biaryl atropisomers have been successfully investigated for DKR. 

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As with atropisomeric biaryls, axial chirality in atropisomeric amides maybe introduced by stereochemical control in the atroposelective reactions of planar chiral complexes [115]. Enantioselective lithiation was reported in this context by Uemura, who showed that the achiral complexes 195,198,201 and 204 are de-protonated enantioselectively by treatment with chiral lithium amide bases (Scheme 50) [116-118]. The stereogenic C-C and C-N axes in these compounds are orientated such that the larger NR2 and acyl groups, respectively, are directed away from the chromium. A range of chiral lithium amides was investigated, and by careful selection it was possible to obtain products 196,199,202 and 205... 

The book is divided into five chapters corresponding to the different types of reactions evolving through DKR such as non-enzymatic methods based on the use of chiral auxiliaries, non-enzymatic methods using ehiral catalysts (metals or organocatalysts), enzymatic methods, methods employing enzymes and transition metals in tandem, and atroposelective reactions. 

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