Enantiofaces definition

C-nucIeophilicity, 13-14 oxidative cleavage, 285 Robinson anellation of, 73, 298 synthesis from ketones, 13, 88 by oxn. of ten. amines, 138-139 Enantiofaces definition, 359... 

An optically active Grignard reagent has the ability to differentiate between the two enantiofaces of a carbonyl compound such as 45 [64], In the example shown, the (S)-enantiomer of the product alcohol, 46, is obtained with a high degree of optical purity (= specific rotation of mixture- - specific rotation of one pure enantiomer X 100 for definitions of other terms used in this work, see [65]). 

The first aspect is the concept of the enantiofaces of the Michael acceptors. Fig. 2 shows how the re- and M-enantiofaces of the Michael acceptors can be defined. Here, the first priority is always given to the C= group irrespective of the other substituents. This definition is relatively insensitive to changes in the substituents compared to the conventional re/si-face definitions. Since the Michael acceptors possess two prochiral centers, the a-carbon and P-carbon, an enantio-face can be described as, for example, re(a),M(P),si(a)/si(P), or 2l(oc)/ (P). The enantiofaces si(a) or re(P) indicate the si-face with regard to the a-carbon atom and the re-face with regard to the P-carbon atom, respectively. 

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